Need a ThermoQuad?
- Thread starter Dr.Jass
- Start date
TheIronSausage
Two brain cells left.. rubbing together for warmth
If he comes to your show, and he's got any 9801s, or 9811s.. I'd be glad to give you guys my proxy. I'd consider up to $150-$200 for a unicorn, less for a core.
TheIronSausage
Two brain cells left.. rubbing together for warmth
I'm good for the dough if it's serviceable, but I'm not going to shell out buckets of money when all I'm really looking for is the electric choke. I've got five or six '72-'73 340 T-Quads, with appropriate jetting for a decent small block.. I just lack the provisions to make the choke work on either the LD4B (going on the early 318 in stock form bound for my Dart) or the mildly built 318 in my truck (with J heads and a cam that I might stick my LD340 on).
Out of curiosity, (I know I've probably broached this subject before).. I've got two LD4Bs..
Jass, this one's for you.. I've got a Superquad, and a Performer on the truck (W150) now. Do I want a LD4B on my big port, big valve "J" heads with the Summit 6900 RV cam (not my build, just the hardware I'm working with). Or, do I want the LD340 for overall flow? I'd think I want the torque provided by the smaller runners at a lower rev range because it's a 4x4 and a truck I haul stuff with. At the same time, somebody's spent some money building a ('72) 318 with flat top pistons and big valve J heads.. I can rev the tits off of it now with the Superquad and the performer, but that's not the point of this truck. Which manifold with my Superquad will bring home the bacon in truck form with an NP 435 and a 3.23 rear? I have other manifolds, like a Weiand dual plane, and a Holley street dominator laying around.. But my understanding is that none of them hold a (streetable) candle to the small port LD4B, the big port LD340, or the holy grail of small block manifolds, the RPM airgap. Yes, I'm aware of the square/spreadbore design, and I have the adapters.. It's T-Quad for me all the way in terms of initial cost layout, availabilty (my shelf), cruising economy, and five gallon bucket secondaries..
Of the two vintage manifolds, which will move the truck and a trailer at 1500 RPM with the above inherited setup? LD4B? Or LD340? I'm looking for more useable torque here (duh?) and I'm running headers with high flow cats, glass packs (about to be changed to turbos) and 32x11.5x15 BFG All Terrains. I love the tire, hate the size.. Stock 31x10.5x15 would be great.
Do I want flow to match the heads and valves? Or do I want small port velocity for torque despite the head setup? Or is the difference negligible in this application? If it's a difference of 5 ft/lbs off idle, I don't know that I care.. If it's 20 ft/lbs, my interest has been piqued.. Of course, either one is better than the Performer.
Out of curiosity, (I know I've probably broached this subject before).. I've got two LD4Bs..
Jass, this one's for you.. I've got a Superquad, and a Performer on the truck (W150) now. Do I want a LD4B on my big port, big valve "J" heads with the Summit 6900 RV cam (not my build, just the hardware I'm working with). Or, do I want the LD340 for overall flow? I'd think I want the torque provided by the smaller runners at a lower rev range because it's a 4x4 and a truck I haul stuff with. At the same time, somebody's spent some money building a ('72) 318 with flat top pistons and big valve J heads.. I can rev the tits off of it now with the Superquad and the performer, but that's not the point of this truck. Which manifold with my Superquad will bring home the bacon in truck form with an NP 435 and a 3.23 rear? I have other manifolds, like a Weiand dual plane, and a Holley street dominator laying around.. But my understanding is that none of them hold a (streetable) candle to the small port LD4B, the big port LD340, or the holy grail of small block manifolds, the RPM airgap. Yes, I'm aware of the square/spreadbore design, and I have the adapters.. It's T-Quad for me all the way in terms of initial cost layout, availabilty (my shelf), cruising economy, and five gallon bucket secondaries..
Of the two vintage manifolds, which will move the truck and a trailer at 1500 RPM with the above inherited setup? LD4B? Or LD340? I'm looking for more useable torque here (duh?) and I'm running headers with high flow cats, glass packs (about to be changed to turbos) and 32x11.5x15 BFG All Terrains. I love the tire, hate the size.. Stock 31x10.5x15 would be great.
Do I want flow to match the heads and valves? Or do I want small port velocity for torque despite the head setup? Or is the difference negligible in this application? If it's a difference of 5 ft/lbs off idle, I don't know that I care.. If it's 20 ft/lbs, my interest has been piqued.. Of course, either one is better than the Performer.
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Dr.Jass
Pastor of Muppets
He shows a 9811S with working idle screws and no frozen shafts for $50. Unfortunately, he's way out of our way for this weekend's road trip... and he won't ship.
Might want to click here and see what that's all about. Nothing listed online, really, except the chart shows they have electric-choke conversions available... ?
As far as truck manifolds go, you're much better off with the Performer than any other intake listed. It's designed for small-port heads in the first place and has good velocity at low RPM. That's why they sold a million of 'em... people feel the increased bottom-end torque and think the vehicle's got more power, even though above 2,500-3,000RPM it falls on its face in comparison to even a stocker. Marketing at its finest, that intake. That's why it's great for what you want. Leave the LD-series intakes for something fast. They're counterproductive in this application.
Truth be told, your problem lies in the cylinder heads and pistons. You have no compression. You've got a '72 engine, which had smaller chambers from the factory; as such with the 1.720" compression distance of the pistons you'll find that your flat-tops are more than .100" down the hole at TDC (.102" to be precise, with an exact 9.6" deck height which isn't likely). The key here is this: do the pistons have valve reliefs? If not, they're stock replacements. There's no squeeze with a 71-74cc chamber; my calculations have you at 7.6:1 with 71cc. :doh:
I can't believe I'm going to say this, but for the purposes of a truck I'd suggest finding an '85-up roller-cam 318 (any non-cop M-body, not sure about truck) and grabbing the cylinder heads. You're specifically looking for "302" castings. They've got a small, high-swirl chamber design along with small ports and unfortunately small valves. That being said, they'd boost your compression by at least a point while enhancing cylinder filling down low by virtue of the small ports. Companies such as Aerohead (and several magazines) used to push the 302s hard because they were easy to find and the compression increase really bumps up the seat-of-pants meter. Problem is, at absolute max porting with 2.02"/1.60" exhaust valves, they flow about as well as an as-cast 2.02" J-head.
If you leave them alone, the engine will grunt like a female Russkie weightlifter but fall on its face below 5,000RPM. You takes some, you has to give some. There's more than one way to skin this cat, but what I would consider a minimum would be at least doing a 3-angle valve job, and ask the machinist to do a throat cut (bowl cut, pocket cut) which is a final cut that opens up the "long side" of the valve pocket (bowl) area. Break out the die grinder and smooth in the machined area, as well as the whole bowl area especially including the valve-guide boss. Do not touch the short-side radius, on either the intake or exhaust, other than to just clean up/smooth the port-to-seat transition! Don't be afraid to grind out some of the long-side radius (port roof) to increase the pocket volume in that area, just don't go berserk--it does you no good to have more volume there than you do further up the port toward the intake or exhaust. That introduces port stall, which is something you've already got in spades with a Performer intake bolted to J heads. At the intake manifold surfaces, port-match the openings to the intake (or vise-versa, keep reading). Notice I did not say "gasket match". Never use a gasket as your template; it's a fool's errand. It causes the mixture to lose velocity at the matched area, then try to regain it inside the cylinder head. Make a nice template from the intake manifold itself, or the head itself in the unlikely event the head openings are larger than the intake's. Just taper it smoothly into the port 1/2" to 3/4". Don't try and reduce the pushrod hump in the port much; there's precious little space there before you're open to the pushrod hole. Leave the main length of the port alone; that's your velocity and will hurt low-RPM cylinder filling. On the exhaust side, since you're using headers anyhow, gasket-match the ports use that as a guide to port all the way to the valve--but again, don't touch the short-side radius (floor) of the port except to smooth it with sandpaper rolls.
Without getting too much into it, maintaining the short-side radius is critical. It's a fluid-dynamics thing, involving boundary layers and such. You want the final approach to/from the valve to be basically as straight as possible, meaning perpendicular to the valve face. That radius helps, a lot.
The above would get you crisp throttle response and good performance into the low-4,000RPM range. The next improvement would be to install 1.60" exhaust valves from a 360 LA during the valve job and gut the exhaust ports to match them. I see no reason to require brand-new valves; if you've got a decent set of used ones that could pass a machinist's inspection those would work since you're doing a valve job anyhow. If you can swing it, have them back-cut, too (this doesn't mean undercutting the stems; your machinist should know the difference). With long-tube, small-primary headers and the small intake ports, working the exhaust side first would really accentuate cylinder filling throughout the RPM spectrum, but particularly in the lower and midrange RPM.
Throwing the 1.88" intakes with the same bowl-port treatment would increase top end a bit, with a small cost in down-low grunt. With the mild cam you've got, I still think you'd be pretty happy overall. Again, don't hog the overall port size. Velocity = torque.
I think with any arrangement, even bone-stock 302 castings freshened, you'd be pretty happy with the results including a noticeable improvement in fuel economy. If you swapped the truck to 3.55 gears, it'd be much happier towing. You might also see an improvement in fuel economy, believe it or not, just because the engine is operating at a better point in its volumetric efficiency range. This seems to have a bigger effect with carburetors than it does with EFI, possibly due to the effects of better atomization and the increased effectiveness of port-wall film. Lugging the engine also encourages fuel puddling. I may be totally wrong about the "whys" but I had a carbureted 6.6L car that got 20+MPG on the highway and ran 12.90s in 100% street trim, with a cruise RPM of ~2,600 at 60MPH (5 over the federal speed limit back then).
All that being said, I despise 302 heads. They are the most overrated LA head in history, which as mentioned was a marketing thing because they were cheap and easy to find, and shops were selling them out of magazines as fast as they could find 'em. They really have no place on a typical performance build. The only heads that are actually worse for a normal performance build are the abysmal '64-'72 273/318 castings, which have no performance value whatsoever. There are no performance versions of those heads; even the D-Dart used the same shitty castings you'd find on a 2-barrel Belvedere sedan (which is why it was such a spectacular failure). They'll give you a compression bump, yes, but the ports are terrible, the chambers are terrible, they have a low detonation threshold, you name it. For anything other than platinum-restoration purposes, they're not worth even treating to a valve job.
Might want to click here and see what that's all about. Nothing listed online, really, except the chart shows they have electric-choke conversions available... ?
As far as truck manifolds go, you're much better off with the Performer than any other intake listed. It's designed for small-port heads in the first place and has good velocity at low RPM. That's why they sold a million of 'em... people feel the increased bottom-end torque and think the vehicle's got more power, even though above 2,500-3,000RPM it falls on its face in comparison to even a stocker. Marketing at its finest, that intake. That's why it's great for what you want. Leave the LD-series intakes for something fast. They're counterproductive in this application.
Truth be told, your problem lies in the cylinder heads and pistons. You have no compression. You've got a '72 engine, which had smaller chambers from the factory; as such with the 1.720" compression distance of the pistons you'll find that your flat-tops are more than .100" down the hole at TDC (.102" to be precise, with an exact 9.6" deck height which isn't likely). The key here is this: do the pistons have valve reliefs? If not, they're stock replacements. There's no squeeze with a 71-74cc chamber; my calculations have you at 7.6:1 with 71cc. :doh:
I can't believe I'm going to say this, but for the purposes of a truck I'd suggest finding an '85-up roller-cam 318 (any non-cop M-body, not sure about truck) and grabbing the cylinder heads. You're specifically looking for "302" castings. They've got a small, high-swirl chamber design along with small ports and unfortunately small valves. That being said, they'd boost your compression by at least a point while enhancing cylinder filling down low by virtue of the small ports. Companies such as Aerohead (and several magazines) used to push the 302s hard because they were easy to find and the compression increase really bumps up the seat-of-pants meter. Problem is, at absolute max porting with 2.02"/1.60" exhaust valves, they flow about as well as an as-cast 2.02" J-head.
If you leave them alone, the engine will grunt like a female Russkie weightlifter but fall on its face below 5,000RPM. You takes some, you has to give some. There's more than one way to skin this cat, but what I would consider a minimum would be at least doing a 3-angle valve job, and ask the machinist to do a throat cut (bowl cut, pocket cut) which is a final cut that opens up the "long side" of the valve pocket (bowl) area. Break out the die grinder and smooth in the machined area, as well as the whole bowl area especially including the valve-guide boss. Do not touch the short-side radius, on either the intake or exhaust, other than to just clean up/smooth the port-to-seat transition! Don't be afraid to grind out some of the long-side radius (port roof) to increase the pocket volume in that area, just don't go berserk--it does you no good to have more volume there than you do further up the port toward the intake or exhaust. That introduces port stall, which is something you've already got in spades with a Performer intake bolted to J heads. At the intake manifold surfaces, port-match the openings to the intake (or vise-versa, keep reading). Notice I did not say "gasket match". Never use a gasket as your template; it's a fool's errand. It causes the mixture to lose velocity at the matched area, then try to regain it inside the cylinder head. Make a nice template from the intake manifold itself, or the head itself in the unlikely event the head openings are larger than the intake's. Just taper it smoothly into the port 1/2" to 3/4". Don't try and reduce the pushrod hump in the port much; there's precious little space there before you're open to the pushrod hole. Leave the main length of the port alone; that's your velocity and will hurt low-RPM cylinder filling. On the exhaust side, since you're using headers anyhow, gasket-match the ports use that as a guide to port all the way to the valve--but again, don't touch the short-side radius (floor) of the port except to smooth it with sandpaper rolls.
Without getting too much into it, maintaining the short-side radius is critical. It's a fluid-dynamics thing, involving boundary layers and such. You want the final approach to/from the valve to be basically as straight as possible, meaning perpendicular to the valve face. That radius helps, a lot.
The above would get you crisp throttle response and good performance into the low-4,000RPM range. The next improvement would be to install 1.60" exhaust valves from a 360 LA during the valve job and gut the exhaust ports to match them. I see no reason to require brand-new valves; if you've got a decent set of used ones that could pass a machinist's inspection those would work since you're doing a valve job anyhow. If you can swing it, have them back-cut, too (this doesn't mean undercutting the stems; your machinist should know the difference). With long-tube, small-primary headers and the small intake ports, working the exhaust side first would really accentuate cylinder filling throughout the RPM spectrum, but particularly in the lower and midrange RPM.
Throwing the 1.88" intakes with the same bowl-port treatment would increase top end a bit, with a small cost in down-low grunt. With the mild cam you've got, I still think you'd be pretty happy overall. Again, don't hog the overall port size. Velocity = torque.
I think with any arrangement, even bone-stock 302 castings freshened, you'd be pretty happy with the results including a noticeable improvement in fuel economy. If you swapped the truck to 3.55 gears, it'd be much happier towing. You might also see an improvement in fuel economy, believe it or not, just because the engine is operating at a better point in its volumetric efficiency range. This seems to have a bigger effect with carburetors than it does with EFI, possibly due to the effects of better atomization and the increased effectiveness of port-wall film. Lugging the engine also encourages fuel puddling. I may be totally wrong about the "whys" but I had a carbureted 6.6L car that got 20+MPG on the highway and ran 12.90s in 100% street trim, with a cruise RPM of ~2,600 at 60MPH (5 over the federal speed limit back then).
All that being said, I despise 302 heads. They are the most overrated LA head in history, which as mentioned was a marketing thing because they were cheap and easy to find, and shops were selling them out of magazines as fast as they could find 'em. They really have no place on a typical performance build. The only heads that are actually worse for a normal performance build are the abysmal '64-'72 273/318 castings, which have no performance value whatsoever. There are no performance versions of those heads; even the D-Dart used the same shitty castings you'd find on a 2-barrel Belvedere sedan (which is why it was such a spectacular failure). They'll give you a compression bump, yes, but the ports are terrible, the chambers are terrible, they have a low detonation threshold, you name it. For anything other than platinum-restoration purposes, they're not worth even treating to a valve job.
TheIronSausage
Two brain cells left.. rubbing together for warmth
As always.. This is excellent info, and thanks for your time. It's late, so I'll try and keep this short. My motor and trans came out of a same year ('86) donor truck that had hit a tree hard enough to bend the frame rail (let's be honest, parking lot speed). I know that the motor is a '72 block that was "rebuilt, with tons of work and receipts" it reportedly had 9,000 miles since the rebuild.. The donor truck did have 3.55 gears, something I didn't swap over due to the extra pain in the ass of cutting U bolts and swapping axles. Also, my 3.23 is a sure grip, and the 3.55 was open and had pinion bearing whine. I haven't stuck a borescope in the motor, nor have I seen the receipts.. My heads are a 915 casting, but might be a factory overrun because they have no "J" stamped in the pad. I know my cam is the Summit 6900, because I put a dial indicator on a rocker arm, got the lift, did the math with a factory rocker ratio, and went to the Summit site after seeing ten stickers in the back window. What I don't know is if the heads were shaved to get a little back in compression. I assume that if I put a compression tester to it, I should see a number around 150 if they were above kerosene burning levels... What I do know, is that this motor pulls pretty hard up to what I assume is about 5,000 RPM.
So much for keeping this short. The truck in this state of tune seems to have way more power than the previous stock 318/727 BBD combo that came out of it.. It's a little more sluggish off the line due to the second gear starts and 3.23 rear (6-1 first gear) but really wakes up around 1500-2000 rpm, and is almost kinda quick considering it's a small block moving 5,000 lbs.. I'd be interested to pop a head off, and see what's been done under there. I've heard that you can shave J heads down to keep compression up on a 318.. I'd like to think it's been done here, but I'm not sure what numbers I'd see during a compression test either way.. Fuel mileage is down to about ten from the lofty 11-15 I got city and highway before, but I attribute that to the gearing, constant stop/start of small town driving, loss of torque converter, and the effect that the back barrels of the Tquad have on my pea brain's ability to control my right foot.. I'm in the gas way more than I used to be..
That being said, I agree with you that something is amiss here out of a dead stop.. It doesn't snap off the line like the old stock setup did (not that you'd get whiplash), and I wasn't sure how much of that was gearing, or a wrongish top end combo. Now that the four speed swap is done, if I had my druthers I'd get a 360 for the truck, and dump the 318 into one of my other cars..
So much for keeping this short. The truck in this state of tune seems to have way more power than the previous stock 318/727 BBD combo that came out of it.. It's a little more sluggish off the line due to the second gear starts and 3.23 rear (6-1 first gear) but really wakes up around 1500-2000 rpm, and is almost kinda quick considering it's a small block moving 5,000 lbs.. I'd be interested to pop a head off, and see what's been done under there. I've heard that you can shave J heads down to keep compression up on a 318.. I'd like to think it's been done here, but I'm not sure what numbers I'd see during a compression test either way.. Fuel mileage is down to about ten from the lofty 11-15 I got city and highway before, but I attribute that to the gearing, constant stop/start of small town driving, loss of torque converter, and the effect that the back barrels of the Tquad have on my pea brain's ability to control my right foot.. I'm in the gas way more than I used to be..
That being said, I agree with you that something is amiss here out of a dead stop.. It doesn't snap off the line like the old stock setup did (not that you'd get whiplash), and I wasn't sure how much of that was gearing, or a wrongish top end combo. Now that the four speed swap is done, if I had my druthers I'd get a 360 for the truck, and dump the 318 into one of my other cars..
Dr.Jass
Pastor of Muppets
The biggest difference, really, is the camshaft. I'd be astounded to find out the original camshaft has even .410" lift. Those 318 cams look like broomsticks. The heads obviously help, but they're only helping on the top end. You've essentially got a 340 top end with a restrictor plate (Performer intake) and sub-basement compression. Even with a sketchy .050" cut off the cylinder heads, you're still a scosche under 8.2:1 compression with stock pistons, which is less than stock for any 318 of which I'm aware. A swap to .028" Mr. Gasket head gaskets would net you two tenths of a point, still below stock. As far as the lack of top end I'm guessing it's a lack of total timing combined with the obvious cork of an intake manifold bolted to it. If they're in fact big-valve J-heads, meaning 2.02" intakes, you've also got a shrouding issue--the small bore is blocking intake flow. Yes, you can grind clearance in the block, but that results in even lower compression. Even with all that, something's hinky here. With no bottom end, you should at least have something up top. I'm thinking there's a tuning issue as well, based on your last post.
Any 360-headed (1.88" intake) 318 with a stock 4-barrel intake, TQ, K6900 cam, and headers should pull well past 5 grand with mid-8s for compression; it's nothing more than a mini 340 at that point. The '73 340 used shit heads and essentially an identical cam and will pull to at least six grand if not considerably higher, and the 318 has less reciprocating weight. You should be able to run a good bit of timing with your arrangement. Do you know what your total timing (not initial) is? Which distributor are you using? Please, please tell me you're using the vacuum advance. I think there's some smiles to be found in this department, but I've gotta know exactly what you've got now.
One cannot just pop the J heads off and keep milling them willy-nilly until reaching the desired compression. Ask 68R/T about what happens when too much is cut off a small-block head. .050" is much further than I would take them. They don't have a particularly beefy deck in the first place, and there's only 10 head bolts. They are very prone to warping after heavy deck cuts. The 318 can be a very torquey engine despite a fairly short stroke, but huge ports aren't the answer. Port velocity and compression are. That's why I suggested pocket-porting a set of heads I can't fathom using myself. For anything I'd personally build, they are, to use the French term, jeanc. But for gut-wrenching torque from a short-stroke LA, they'd be the hot ticket.
The 360 is a great idea, much better actually, but you'd need to have your flywheel balanced for it. Well worth that expense for the extra torque throughout the powerband. Even with the larger cubes and longer stroke, I'd suggest pocket porting only to keep as much velocity through the head at low RPM as possible. You're still somewhat limiting the party upstairs, but not horribly so starting with the good heads you've already got. They'd certainly be better than an as-cast head throughout the RPM range. Of course, with added cubes comes decreased fuel economy, but you should be getting better than what you do currently, even with your current combo (which raises the tuning issues again).
This is a hard situation to advise, really. I mean, you mentioned the 360 which seems an obvious choice for a truck that tows. If that's what you ultimately want, do some tuning on your current combo and without throwing money at it. It's all wasted cash that could be going toward the bigger engine. At the same time, maybe once you get the 318 tuned a little you'll see enough merit there to simply keep it, and improve upon it with some heads better suited to your needs. A 318 is a great little engine, no doubt.
I can't make that call for you, especially on a truck--I'm not a truck guy. But you've gotta determine a clear goal and shoot only for that. Playing with the timing and probably the carb on your current engine will probably help you decide what's next.
Keep in mind, though, that even with a 360, the current Performer/TQ setup is the champ for economy and grunt. Anything with larger ports--even a stock iron unit--is going to move both the torque and HP further up the tach scale. Yes, there will be more of both, but at hundreds more RPM. With your current gearing and tires, that's counterproductive. Speaking of economy, switching to the 4-speed should've improved economy were it done as a standalone mod. Torque converters are lossy devices, especially below their stall speeds. It's not like you pulled out a lockup 46RH.
Get back to me with some information on the current tune: Timing, distributor, carb, etc.
Any 360-headed (1.88" intake) 318 with a stock 4-barrel intake, TQ, K6900 cam, and headers should pull well past 5 grand with mid-8s for compression; it's nothing more than a mini 340 at that point. The '73 340 used shit heads and essentially an identical cam and will pull to at least six grand if not considerably higher, and the 318 has less reciprocating weight. You should be able to run a good bit of timing with your arrangement. Do you know what your total timing (not initial) is? Which distributor are you using? Please, please tell me you're using the vacuum advance. I think there's some smiles to be found in this department, but I've gotta know exactly what you've got now.
One cannot just pop the J heads off and keep milling them willy-nilly until reaching the desired compression. Ask 68R/T about what happens when too much is cut off a small-block head. .050" is much further than I would take them. They don't have a particularly beefy deck in the first place, and there's only 10 head bolts. They are very prone to warping after heavy deck cuts. The 318 can be a very torquey engine despite a fairly short stroke, but huge ports aren't the answer. Port velocity and compression are. That's why I suggested pocket-porting a set of heads I can't fathom using myself. For anything I'd personally build, they are, to use the French term, jeanc. But for gut-wrenching torque from a short-stroke LA, they'd be the hot ticket.
The 360 is a great idea, much better actually, but you'd need to have your flywheel balanced for it. Well worth that expense for the extra torque throughout the powerband. Even with the larger cubes and longer stroke, I'd suggest pocket porting only to keep as much velocity through the head at low RPM as possible. You're still somewhat limiting the party upstairs, but not horribly so starting with the good heads you've already got. They'd certainly be better than an as-cast head throughout the RPM range. Of course, with added cubes comes decreased fuel economy, but you should be getting better than what you do currently, even with your current combo (which raises the tuning issues again).
This is a hard situation to advise, really. I mean, you mentioned the 360 which seems an obvious choice for a truck that tows. If that's what you ultimately want, do some tuning on your current combo and without throwing money at it. It's all wasted cash that could be going toward the bigger engine. At the same time, maybe once you get the 318 tuned a little you'll see enough merit there to simply keep it, and improve upon it with some heads better suited to your needs. A 318 is a great little engine, no doubt.
I can't make that call for you, especially on a truck--I'm not a truck guy. But you've gotta determine a clear goal and shoot only for that. Playing with the timing and probably the carb on your current engine will probably help you decide what's next.
Keep in mind, though, that even with a 360, the current Performer/TQ setup is the champ for economy and grunt. Anything with larger ports--even a stock iron unit--is going to move both the torque and HP further up the tach scale. Yes, there will be more of both, but at hundreds more RPM. With your current gearing and tires, that's counterproductive. Speaking of economy, switching to the 4-speed should've improved economy were it done as a standalone mod. Torque converters are lossy devices, especially below their stall speeds. It's not like you pulled out a lockup 46RH.
Get back to me with some information on the current tune: Timing, distributor, carb, etc.
TheIronSausage
Two brain cells left.. rubbing together for warmth
Sweet! Thanks for your continued interest. I'll get you more information when I get the truck back to the house.. I use it primarily for work these days, not a daily driver like I used to.. It was my only vehicle for a couple of years. The reason I mentioned the torque converter wasn't fuel economy so much as its torque multiplication off the line.. I should've swapped in the 3.55 front and rears when switching to the four speed. There's a reason the factory put them under an identical truck minus the 727. Hindsight 20/20... I'm doing an ignition tuneup on the truck because it occurs to me that it's past due.. I've got a distributor machine in the basement with an electronic conversion. I'll fire it up, and let you know what this turd is running. My guess is that it's a very stock distributor that was born pre lean burn.. I can tell you for sure that I've got vacuum advance hooked up, and that it works.. I know what a race car is, and why no aspect of a good one is street worthy. What I don't know until I pull the dizzy is what unit it's got.. My guess is the near ubiquitous 11 degree unit.
Again, thanks for your time.. I'll never expect this thing to get bags of torque and 20 to the gallon, but I think it'd be great if it wasn't embarrassing in either direction. I'll get you more info on ignition and jetting as I figure it out..
Again, thanks for your time.. I'll never expect this thing to get bags of torque and 20 to the gallon, but I think it'd be great if it wasn't embarrassing in either direction. I'll get you more info on ignition and jetting as I figure it out..
TheIronSausage
Two brain cells left.. rubbing together for warmth
Update..
Ignition is a Mopar chrome box, (stock was cutting out around 4,500 rpm, I've had problems with orange boxes and MSD) unmodified distributor with an 11r advance. The advance works now, the one I pulled out two days ago was dead. That explains a lot right there. The carb is a Superquad, that has been "modified for use with a warm 318" by some highly revered member of forabodies I've never heard of.. It required minimal adjustment, and I'm extremely happy with it. I put a compression tester on it, (one cylinder, didn't remove the other plugs.. It was late, and I was hungry) I came up with 90 PSI. :doh: Not good. However, it does scream up to 6,000 for sure.. I need a new tach in it, mine starts failing around 4,000, and sticks at 4500. I can zing that motor up to places that make me nervous.. Anybody know what RPMs a chrome box falters at? There.. I've had the motor there.. Didn't feel any valve float, the ignition stumbles.. Happened twice, didn't like it.. The vacuum advance solved a lot of my problems.. Initial timing is 8 degrees, and it's all in around 38-40 from what I can tell. Hard to figure out what RPM it's all in at, but I'd have to guess in the low threes.
Dude, thanks for the call. I didn't recognize the number, and you would've been the fourth shitty recording I got today. Ha! I've never actually heard somebody tell me no when I asked if they were a robot..
Ignition is a Mopar chrome box, (stock was cutting out around 4,500 rpm, I've had problems with orange boxes and MSD) unmodified distributor with an 11r advance. The advance works now, the one I pulled out two days ago was dead. That explains a lot right there. The carb is a Superquad, that has been "modified for use with a warm 318" by some highly revered member of forabodies I've never heard of.. It required minimal adjustment, and I'm extremely happy with it. I put a compression tester on it, (one cylinder, didn't remove the other plugs.. It was late, and I was hungry) I came up with 90 PSI. :doh: Not good. However, it does scream up to 6,000 for sure.. I need a new tach in it, mine starts failing around 4,000, and sticks at 4500. I can zing that motor up to places that make me nervous.. Anybody know what RPMs a chrome box falters at? There.. I've had the motor there.. Didn't feel any valve float, the ignition stumbles.. Happened twice, didn't like it.. The vacuum advance solved a lot of my problems.. Initial timing is 8 degrees, and it's all in around 38-40 from what I can tell. Hard to figure out what RPM it's all in at, but I'd have to guess in the low threes.
Dude, thanks for the call. I didn't recognize the number, and you would've been the fourth shitty recording I got today. Ha! I've never actually heard somebody tell me no when I asked if they were a robot..
TheIronSausage
Two brain cells left.. rubbing together for warmth
HAHAHA! Who writes this shit? What a maroon!
Seriously, never trust that the idiot before you did his job, especially if you yourself are prone to idiocy
TheIronSausage
Two brain cells left.. rubbing together for warmth
The post above that remark explains what I found..
TheIronSausage
Two brain cells left.. rubbing together for warmth
It was functioning in my brain, because I tested it when I put the tquad on last year.. It wasn't functioning where it counts.. In the distributor. That, and the abysmal comp test are/were the main culprits. To be fair, I oughta do a real compression test with all the plugs out. After finding the dead vacuum, and going through boxes of parts looking for a good one, my "twenty minute tune up" turned into nine at night, and I still hadn't had dinner. I know that a compression test can't mathematically give you a compression ratio directly, but 90's pretty bad.
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TheIronSausage
Two brain cells left.. rubbing together for warmth
I'd like to break 100, anyway.
Dr.Jass
Pastor of Muppets
Yeah, I understood it. It was just funny (to me, anyhow) to post such a reaction.
38-40 seems like a ton of advance, but if you're not getting knock I can't say it's wrong. Still, you might find a little more power and a little less falter up top with a few less degrees. "The ragged edge of detonation" is not your optimal timing, contrary to popular belief. It's just a good measure of where you should be timing-wise around your torque peak, with low-RPM/high-load situations being your limiting factor overall. An optimal timing curve usually looks like a low-amplitude sine wave, where the center dip is at peak torque, with gentle, rolling peaks before and after. It really can't be accomplished with a typical flyweight system.
A chrome box should be good well past 6K. The major difference between the three MP ECUs is the dwell time; the fancier the box the longer the dwell. A gold box will either smoke the coil or desolder itself in pretty short order on the street because of the heat generated from such a long dwell period.
90PSI is abysmal. I think you'll find it's better with a proper test, but I wouldn't expect impressive numbers regardless. You might do well to pop your timing cover and check your cam timing, too. You might do well to advance it if your timing set has the keyways for it. Not a lot of time spent in a truck at 6K. A few extra degrees of cam advance would help the grunt at the expense of high-RPM rip.
68R/T
I got drunk and swallowed my teeth, now
Depending on how many miles are on the timing set, you may also be looking at a worn & stretched chain, causing retarded timing.
TheIronSausage
Two brain cells left.. rubbing together for warmth
I'm always the first to admit a mistake, but I try to be funny about them.. Especially if it's a doozy. This wasn't, but I like to keep in practice.
I was kinda surprised by that much timing myself, shouldn't 30-32 be about the ceiling? It's hard to hear above the obnoxious exhaust, but even next to a jersey wall, I don't hear any pinging.. It oughta happen most at light throttle just off cruise, right?
As for the 6k, this truck spends more time there than it should.. It's kind of addictive.. The motor goes from being a total slug where it should shine, to the upper rev range and it's like flipping on a light switch. The back barrels open up, the induction noise is excellent, the glass packs actually sound good instead of sounding like a wet fart, there's some change in inertia.. Not much, I won't say it's fast, but it does set you back in the seat. Almost rewarding.
Hey, if my compression ratio is shit, that'd explain the bags of timing it can take, right? It's not detonating, because it can't squeeze. What a lump.. I'm driving this thing like a race car, because I'm trying to get something out of it.. Also because I was sort of a hoodlum in my misspent youth, and I'm surprised I can still carry a license..
I was kinda surprised by that much timing myself, shouldn't 30-32 be about the ceiling? It's hard to hear above the obnoxious exhaust, but even next to a jersey wall, I don't hear any pinging.. It oughta happen most at light throttle just off cruise, right?
As for the 6k, this truck spends more time there than it should.. It's kind of addictive.. The motor goes from being a total slug where it should shine, to the upper rev range and it's like flipping on a light switch. The back barrels open up, the induction noise is excellent, the glass packs actually sound good instead of sounding like a wet fart, there's some change in inertia.. Not much, I won't say it's fast, but it does set you back in the seat. Almost rewarding.
Hey, if my compression ratio is shit, that'd explain the bags of timing it can take, right? It's not detonating, because it can't squeeze. What a lump.. I'm driving this thing like a race car, because I'm trying to get something out of it.. Also because I was sort of a hoodlum in my misspent youth, and I'm surprised I can still carry a license..