Can't get carb to seal

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rurcon
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Can't get carb to seal

Post by rurcon »

Hi all,

Having trouble getting my 2150 2bbl carb to seal on my stock 360. It (was) a new gasket/spacer set -- thin one, phenolic one, thick one, placed in that order from the intake up. It never really ran right, and we discovered that it had a huge vacuum leak somewhere between the carb and the intake. After removing the carb, we found the phenolic spacer had snapped in the same damned place as the last one (see attached pic).

So, something is clearly off-kilter here... has anyone seen this problem before?
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1979 Jeep J10 360 4-speed, 3" lift, 31x10.5's (Jolene)
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tgreese
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Re: Can't get carb to seal

Post by tgreese »

Have not seen this before ... but it seems clear that the assembly is obstructed somehow.

I would try to find a Ford-style solid phenolic spacer, and use two flat gaskets. Here's the Holley aftermarket spacer: http://www.holley.com/17-72.asp Make sure it covers all the passages on the Motorcraft base, so you avoid vacuum leaks.

I used to be able to find the Ford OEM spacer pretty easily in teh California junk yards, but your success will likely depend on where you are and how many old cars are in the yards. Look at old Ford vans in particular - many of them had carbureted V8s.

http://www.ebay.com/itm/like/261309614225?lpid=82 - this one should wourk, if it covers all the passages in the base of the Motorcraft carb.
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Stuka
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Re: Can't get carb to seal

Post by Stuka »

How does the gasket surface on the intake look? If you set the phenolic down on the intake, does it rock at all? Are there any gaps below it? Although, I guess you need a new spacer to really test this.
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tgreese
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Re: Can't get carb to seal

Post by tgreese »

The first thing I would do would be to test the manifold surface with a straight edge, like a 12" machinist's rule. Check that the manifold surface is flat across any and all directions of the gasket surface. Then chech the base of the carburetor. You are looking for an obstruction that lifts one corner of the carburetor or spacer.

I would then install the spacer and carburetor without the paper gaskets, and see if the carburetor sits down level on the spacer and manifold, with no gaps between the carb, spacer and manifold.

And don't be Charles Atlas when you tighten the mounting bolts. Just snug should be fine.
Tim Reese
Maine beekeeper's truck: '77 J10 LWB, 258/T15/D20/3.54 bone stock, low options (delete radio), PS/PDB, hubcaps.
Browless and proud: '82 J20 360/T18/NP208/3.73, Destination A/Ts, 7600 GVWR
Copper Polly: '75 CJ-6, 304/T15, PS, BFG KM2s, soft top
GTI without the badges: '95 VW Golf Sport 2000cc 2D
Dual Everything: '15 Chryco Jeep Cherokee KL Trailhawk, ECO Green
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rurcon
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Re: Can't get carb to seal

Post by rurcon »

Thanks for the suggestions. Having trouble getting the new phenolic spacer shipped in (was supposed to be here yesterday, now not coming for another week), need the truck running now to get it into a garage for some unrelated work. Are there any downsides to running it with just the thick gasket and no phenolic spacer? Seems like it would still be well-insulated...
1979 Jeep J10 360 4-speed, 3" lift, 31x10.5's (Jolene)
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rurcon
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Re: Can't get carb to seal

Post by rurcon »

Just took the carb off, the phenolic spacer isn't cracked at least. I have attached a pic of the gasket set. The top (thick) gasket had a lot of gasoline all over it, and I'm pretty sure it wasn't spilled when taking off the carb. The bottom (thin) gasket is a little gas soaked, as seen in pic.

The bottom of the carb looks fine, and the mating surface of the intake manifold seems okay (didn't have a machinist's rule, but checked it with a straight edge).

Any ideas on why this won't seal?
1979 Jeep J10 360 4-speed, 3" lift, 31x10.5's (Jolene)
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rurcon
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Re: Can't get carb to seal

Post by rurcon »

and the photo. You can also notice how the imprint on the thin gasket doesn't go all the way around, with a small gap towards the bottom.
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Jjkage84
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Re: Can't get carb to seal

Post by Jjkage84 »

I ended up having to get a new thicker gasket because mine didn't seal with the thick gasket that came with the rebuild kit
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Re: Can't get carb to seal

Post by Stuka »

That sure is a lot of fuel. Is the power valve blown by chance? If it ever backfired back through the carb, it most likely is. Which will result in it running VERY rich.

Also, what are you torquing the nuts that hold the carb in place too?
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Re: Can't get carb to seal

Post by rurcon »

Jjkage84, do you mean that you got a thicker version of the thick gasket? where to?

Stuka, I don't think the power valve is blown, though I haven't checked. It was clear there was a massive vacuum leak between the carb and the intake -- with the engine running, I could take my hand and seal off the carb's air intake completely, and the she would smooth out. As for torquing the nuts, we torqued them pretty snug -- possibly a little too tight?
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Stuka
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Re: Can't get carb to seal

Post by Stuka »

They only need to be 10-12ft lbs. Pretty much impossible to get even an inch pound torque wrench in there. But it gives you an idea as to how tight they should be. Too tight can result in breaking the spacer.

I am sure you had a vacuum leak, thats obvious. But that is quite a bit of fuel.
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rurcon
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Re: Can't get carb to seal

Post by rurcon »

point taken, I'll check the power valve tomorrow. I haven't done that before, but I was told before that you just need to take off the housing, and if there's fuel there, it's blown? Is it very hard to change?
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rurcon
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Re: Can't get carb to seal

Post by rurcon »

okay, I took the power valve housing off, and it was nearly filled to the brim...

The last guy that worked on her, over the winter, didn't screw in the spark plugs very tightly, so when a couple of them came loose, she was backfiring pretty bad for a bit until I found the problem -- could that have blown the power valve? The only other backfiring I've been having is when gearing down and engine breaking up to stop signs, but I'm wondering if that is more a symptom of a blown power valve, rather than a cause.
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Stuka
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Re: Can't get carb to seal

Post by Stuka »

Back firing out the exhaust won't hurt the carb. Back firing out the intake will, and it really only takes one big one.

If there was fuel on the cover side of it, then it's bad.


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Re: Can't get carb to seal

Post by Jjkage84 »

Yeah, a thicker thick gasket. I wanna say I got it from auto zone, fel pro. Let me look and see if I still have the info.
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Re: Can't get carb to seal

Post by Jjkage84 »

Image

This is the one I got and it worked like a charm
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rurcon
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Re: Can't get carb to seal

Post by rurcon »

Well, we replaced the power valve and used all new gaskets, and she wasn't any better.

At that point, we figured it must be the carburetor, and sure enough, we hooked up an old 2100 that came off my '67 cougar, and she ran fine.

The 2150 I have that doesn't work is supposedly set up the same as the original would have been. It is brand new, well in the sense that it is a new rebuild, that I got from Autoline. It was running better before, so I guess the power valve must have been blown somehow after putting it on the truck. Are any other parts that typically get damaged in a situation where the power valve is blown?
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Re: Can't get carb to seal

Post by letank »

just the power valve, replace seal, check for plane level of power valve cover.
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rurcon
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Re: Can't get carb to seal

Post by rurcon »

Hi all,

So it turns out the carb was really dirty (black carbon-like stuff). It only took a matter of weeks to get that way. Is it possible that it's coming in from the charcoal canister? Either through the fuel bowl vent line somehow, or possible through the fuel? I know that the fuel tank vents into the canister -- maybe the charcoal is getting into the tank somehow?

Also, I'm not sure the fuel bowl vent valve is being actuated properly, seems to be open all the time. Could that be a problem as well?
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Re: Can't get carb to seal

Post by carnuck »

Could there be something nasty in the tank? I saw similar when my ex-wife split from the guy she dumped me for. He brought the vehicle in to the shop where I recently started working and it had a brand new carb on it (second one) which was messed up again. Turned out she put a styrofoam coffee cup in the tank. After a new tank, lines, filter and another carb clean out, it ran okay but started burning oil. I felt bad for him, but that's what you get for trifling.
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