My 71 Duster work in progress

There's a photo and Hayden part number for the shortest fan clutch available (period) in the "Signet-ficant Other" thread, along with a couple of minor caveats regarding installation. I don't have time at the moment to dig for it, but it's what I needed for the Valiant with the 5-blade MP/cop fan. Another option would be two smaller-diameter electric fans, say 8", staggered diagonally across the core. I believe on the 22" radiator I could stagger a 12" and 8", covering most of the tubes. Neither fan motor would be anywhere near the water pump so clearance shouldn't be an issue.

You shouldn't have to remove both valve covers to get the intake off. Take off the easier one (driver's side) and lift the intake out on that side first. Fel-Pro intake gasket sets for TBI and Vortec Chevy V8s only come with one valve cover gasket for exactly that reason.

When I installed my icemaker, I ran a compression tee from the cold side of the kitchen faucet to a ball valve, then copper line to the back of the freezer. At that point, anything that failed would have to be integral to the icemaker (which had its own internal water valve). That fridge eventually failed, and I never bothered with another icemaker since I almost never use ice. The line's still there behind the fridge, awaiting an icemaker that'll never come, shut off at the ball valve. Hasn't leaked a drop in 8 years.
 
I don't know WTF happened with the ice maker but all at once it started working. Gina blamed it on running a lot of water in the sink. Maybe that cleared something that had plugged the saddle valve but that's unlikely. I don't GAS, just happy I'm not spending more $$ on the stupid thing.

Per the Signet thread the part number for the fan clutch is Hayden part #2947. It's going to rain tonight and tomorrow so I might find time to get the flex fan off so I can take a proper measurement.

I thought I'd be able to get the intake out with just one valve cover removed. I remember when I first put the old blue 340 duster together, the intake was leaking so I unbolted it to replace the gasket but couldn't get it off. Before long I had the cherry picker hooked to the intake and pulled the car well up on the suspension before deciding that wasn't helping. Eventually I noticed the valve covers were holding it on.
 
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So at best there's 2-3/4" and at worst 2-5/8" between the front of the pulley and the the radiator. Rock auto specification for the 2947 is "Sitting at only 2.7" tall". Boo. It'll have to be electric. On the + side, now that I've got the fan out of the way and measured, I might be able to offset one or two small ones.

I've also got a truck rad but I remember taking it out of another duster because it wasn't cooling the 340. Add that to the need to drill holes or make brackets, and I'm skeptical that I'll even try it.
 
After taking the measurements I slapped it back together with a 16" factory fan and no fan clutch in place of the flex fan.


It's still above the top of the tubes.

I started it up and let it run to 210* and climbing. That didn't make me feel real good. I forgot to take the cap off so I'm not sure if the thermostat opened or not.

It also sounds about like dog shite, but it's got no vacuum so I don't expect much else.


Can't believe I forgot to show the vac guage on that, but it's around 3 inches, idling in neutral at about 1k.

It's got a bad bog off idle that's only going to get worse once it's in gear and the torque converter is in play. Once it's got that it takes off OK. Still needs a fan belt too.
 
The icemaker was probably air-locked. You may not have heard it fart, but it did and now all's well. I'm sure you know the feeling.

I have one American dollar that I'd bet on your intake gaskets leaking on the valley side. The Valiant managed more than twice that vacuum reading at 850RPM with an idiotic (by comparison) solid roller and leaking intake gaskets. Hell, it had more than that with two corners broken off the throttle body... and I could hear the screaming leak during that. It would also explain the temperature, since lean mixtures burn very hot.

If you're going to run electrics, get measurements and install them diagonally across the core. For control, I'd suggest using a fan-control switch from a later application to activate relays (one per fan), rather than using a manual switch or hot-wiring to key-on 12V+. At speeds above ~35MPH, the natural airflow through the radiator is enough to cool the engine so the fans would eventually kick off and freewheel. There's no point in loading the alternator more than necessary. That'll help fuel economy a bit. Fusing can be a bit of a challenge, since each fan may only draw 5-10A running but can demand 20+ inrush amps at startup each (the ever-popular Ford Taurus dual electrics pull 50!). See what the running current is, multiply it by 1.5, and use slow-blow fuses from the hardware store. Or, just experiment with fast-blow fuses until you find one that doesn't blow on fan startup. Fuse each fan independently so if one fails the other still runs (which is why you want discrete relays too).

I have a cheap electric fan here that I bought for the Valiant but didn't use (it stays locked on 180° with the clutch fan). I'm not sure who made it but it's part #5481 and looks a lot like the the Proform 67010:

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Proform claims 1,000CFM. I dunno 'bout that, but if memory serves mine's reversible (as is the Proform) and according to the label it draws 80W (<7A). Most importantly, across the flats it's 10.75" and across the rounded part it's 11.375". Just for fun, and because I had digital film to spare, I took mine outside and set it on my Pure Chinesium 22" radiator out of the Valiant. It's against the shroud bracket on the left and the tank at the top. It looks like two would fit diagonally with some very-minor trimming at the proposed overlap area:

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That solution would not provide 100% tube coverage but it's very close and certainly better than your original setup or probably even my unshrouded clutch fan. Looking at various retailers of what appears to be the same unit, ratings run anywhere from 643 to 1,100CFM.

As a final cooling note, I started a thread (and have repeated ad nauseum) about using the right thermostat. Get a 180° factory-style thermostat, be it Atlas, Mopar, or Robertshaw. They have a balanced high-flow poppet and are far superior to anything available new these days. They're only available NOS but can be found relatively easily on eBay for under $20 shipped. NOTE: If it looks tarnished, it's used regardless of the stated condition. NOS ones are bright brass with a bright copper slug. There are photos in the thread of what you want. On my car, even with the lean mixture of a leaking intake (and carb, as mentioned) and higher compression, I could not get the gauge pointer over 180° no matter what.
 
I'm in the midst of replacing the intake gasket. It's a helluva mess, lots of corrosion at the heat riser due to being under a tarp(s) for 10 years or so with the scoop and hood cut so water could get in. It looks like it's leaked at the bottom of the head side of at least one pair of cylinders. It had a shit ton of red RTV on it, and I'm pretty sure gasoline melts that stuff too.

I just bought what I could get local, which is just the pan with the heat riser unblocked. I'm not trying to squeeze every little bit of performance out of it so I'm sure that'll be fine. I've got several FelPro gaskets (1/32) and a roll of 1/64 gasket paper. IIRC when I finally got the intake sealed up on my gTx I had cut 4 gaskets out of the 1/64 paper and used them on both sides. If I can get the bolts started that is the plan this time too. I'll use Indian Head shellac on both sides of the paper.

I thought I'd found the fix after I got the intake off - it's got one of those two port big and little vac plugs in it. The big one connected to the PVC but the small one that I couldn't even see is capped with a tiny wire nut. The wire nut screwed on and passed a suck test so it might not be leaking there but I'm plugging that thing before the intake goes back on anyway and moving the PVC to the carb vac outlet.

I looked at the cam in the valley, and there's no paint marks or anything on it. I figure it's just a stock smogger 400, straight out of a C-body.

If I could get two of those fans in it'd probably do the job. I was thinking I could get a 16" and offset it a little bit in the opposite direction of the engine offset and that would fit too. If that worked then I could probably stick a factory style shroud on it to cover it so it cools better. The attachment shows about where the center of the water pump is relative to the radiator.

output.jpg

I feel like I need to know the difference between the thickness at the back of the motor and the thickness where the motor starts, and of course they don't give you that.

This is a 3-row chineseum radiator too. Do you know if those AT cooler ports are real or are they just due to using the same tank whether it has a trans cooler or not? I get the feeling they're not connected to anything inside but I've never checked.
 
Never, ever use paper facings on the turkey pan gasket. Use the metal alone, and spray the sealing surfaces with Permatex High-Tack spray gasket adhesive, #80065 (yes, it's gasoline-proof). Nothing else works; I've been down this road more times than I care to count. Listen to me now and believe me later. All you're doing by facing the gasket is adding two more potential leak points per side while incorrectly spacing the intake from the heads. Chrysler never used gaskets facings (or even the Permatex for that matter) and sold millions of big blocks with no vacuum leaks.

b-body-bob said:
I feel like I need to know the difference between the thickness at the back of the motor and the thickness where the motor starts, and of course they don't give you that.
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I'm not sure exactly what you mean by that, but I can give you any dimensions off the one I have on-hand. I left it outside but the package measures 2-7/16" thick on the outside, and the cardboard's about 1/16" thick so it's no more than 2-5/16" from mounting surface to the back of the motor. Apparently I went full-skate cheap on this; Amazon currently sells a pair of 'em for like $35 (I kept trying to find where I got it; still haven't but I found those). Same decals, same everything. Might be worth that much just as proof of concept before stepping up to Derale, Flex-A-Lite, or Spal units. Hell, they might work for years.

Judging by your diagram, which I'm guessing is from the engine side of the radiator, I'd think you could use two of these opposite to how I had the one in my photo: One on the upper passenger's side, the other on the lower driver's side. If it's from the grille side of the radiator, my arrangement should clear.

No clue on the cooler since my car's a 4-speed, but since it's out of the car I'll blast some brake cleaner in there and see if it comes out the other fitting. They don't leak into the coolant; I know this because coolant doesn't leak out of them. 😁
 
Can confirm continuity betwixt the cooler fittings. Sprayed brake cleaner in the one and it dumped out of the other. Looking inside the holes, it appears to be some kind of waffle-plate arrangement with very small holes... not an arrangement I've seen previously. It looks restrictive but it took no time for the brake cleaner to get from one end to the other so I'm guessing it's pretty decent flow-wise.
 
I just proved to myself that one .030 gasket per side won't work.

Using gaskets was the only way I got the intake on my GTX to seal. I must have just used one.

Of course Permatex 80065 isn't available locally. Best they can do is via Napa, pick it up tomorrow.

I'm done tonight anyway.

I'll take a closer look at my rad - if it's got a trans cooler built in, that lets me get rid of the aux cooler, or run that and the rad cooler.
 
b-body-bob said:
Using gaskets was the only way I got the intake on my GTX to seal.
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Then I'd respectfully submit that the heads were milled without correcting the intake face. Or, in short form, milled by a Chevy shop/guy (none of them seem to understand the concept). It's also possible the block was decked many thousandths beyond design height. Either situation is why they make intake spacers and thicker gaskets (W2 gaskets are, or at least were at one point, available at up to .150" thick). Since your 400 appears to be stone stock inside, it's a safe bet that no such silliness has been performed. Skip the facings. I've literally never used them with any success. I've solved a ton of problems by removing them, though...

b-body-bob said:
I'll take a closer look at my rad - if it's got a trans cooler built in, that lets me get rid of the aux cooler, or run that and the rad cooler.
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If you use both, run through the radiator cooler first. It's a more-effective cooler (liquid/liquid) and makes the auxiliary cooler's job a bunch easier.

b-body-bob said:
FWIW I found that 80064 looks to be the same thing in a 6 oz size (80065 is 12 oz). O'reilly's has it in stock I'll pick up a can tomorrow.
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I was not aware of the smaller can. I've only ever bought the 12oz., which I will continue to do. It's excellent stuff and the only thing worth a damn on intake gaskets. Follow the directions on the can; it's not spray paint.
 
OK it's back together. Still little to no vacuum. The gauge works. Revving the engine saw it shoot up to 10 and that was about it.

I plugged the dumb vac port on the intake. I've got the PVC connected to the carb. I've got the distributor connected to the metered vacuum. I give up.

It seemed to start easier and the idle adjustment seemed more effective. It rumps a little bit more at idle. The thermostat opens. Oh and it's got 915 heads on it which surprised me. The heads look to have some miles on them but who can tell without a bench inspection anyway. It doesn't smoke so they're at least that good.

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And an oddity - see the 25705 cast into the intake? That's my zip code.
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I also took the dumb hi-rise valve cover bolts off the one side and replaced them with studs. That makes dealing with the cover gaskets a lot easier.
 
Anyway, the cam probably went in dot-to-dot so that could be a problem too. I figured it was a stock lo-po 400 cam but now that I noticed the 915 heads I'm not so sure. There was no paint visible on the shaft, so I'm pretty sure it's not a MP performance cam but it could be anything. There's an Erson sticker on one elephant ear that might be trying to tell me something.

I'm not going to worry about that anyway, since there's nothing I can do about it without opening another can of worms because of the elephant ears.

Advance definitely affects the vacuum, so maybe it needs more initial. If that's the case I'll have to rework the distributor to limit the max advance - but that needs to be done anyway. But at least I can crank in a few more degrees and see what happens to the vacuum and starting.

Also, remember the original distributor was all in as soon as it started. I've still got the old distributor and could try dropping that in to see if it helps with the vacuum. All I remember about that one is the timing jumped bad at idle and there was no where near enough timing @ 3k because it needed more initial since it was all in at start up. Now that I know that where I set it is where it will stay, I can just set the initial at 35 and see what happens.

Other than that, I dunno.
 
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I went through a lot of timing nonsense with the Valiant, and I'm trying to remember what I was told about how to set it. It was dramatically different than what I'd normally do, but I do remember being told to run the vacuum diaphragm off manifold vacuum, which seemed counterintuitive to me. Any time I've done that in the past, I had an erratic idle.

I want to say I was told to keep advancing the base timing until the engine stopped picking up RPM and/or vacuum, reconnect the advance hose, then adjust the idle RPM back down to the desired level... but I can't swear to it, and that may also be taking into account the relatively-rowdy camshaft in my 340. I know at one point my initial was extraordinarily high--like 60°BTDC--but I had no starting difficulties while hot. I don't expect that my cam makes much cylinder pressure during cranking either, though.

I'm going to have to go through my notes again and see what advice I'd gotten. I was making some headway but that's when the oiling/valvetrain issues arose, and the car's been apart since.
 
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