Replacing Manifold/Stove-Pipe Gaskets

[mrichard]

All,

I have finally acquired the right gaskets for my manifold-to-head and -to-intake. Quick question - I plan to use the factory service manual to do the job, but are there any tips/tricks with respect to the carburetor? Does it basically just unplug from the hoses and unbolt? Am I viewing that right?

I'm assuming that's it - then just unbolt the rest (after a good soaking in silikroil or similar). But if there is any wisdom out there I should know I would appreciate it.

Also - any suggestions on whether I should just go ahead and replace the manifold while I have it out? Any places that sell reputable replacements?

Car is very accessible as it has no A/C, PS, etc.

Mark
72 Dart, 225

 

[slantsixdan]

Don't know what gaskets you got, but it is very much worth your while to get the good gaskets for the manifolds-to-head and intake-to-exhaust junctions. For installation tips and techniques, see here and here and here.

Should you replace the exhaust manifold? Well...that depends. If yours is in good shape, not cracked or warped, and the heat riser works and doesn't leak, then that's a good argument for keeping it. But an argument for replacing it is that the '70-'72 exhaust manifolds use an open stove style choke setup, the gasket for which is not available. You can make your own, kinda sorta. The '73-up style exhaust manifold uses a cast choke pocket that requires no gasket, though you'll have to install a different choke thermostat (a number 1233 Electric choke kit would be my pick). If you do go shopping for a new manifold, take your time and shop carefully. All the aftermarket ones are Chinese at price from $110 to over $300. Quality is okeh, usable but not up to factory standards. You will have to spend time grinding away casting flash and slop to have easy access past the runners to install the hardware. New factory Chrysler-made manifolds go by fairly regularly on eBay and they tend to go for reasonable money; that would be the type to get if you are replacing it. Or you could take the opportunity to upgrade and prevent future manifold breakage by installing Dutra Duals. :-D

 

[RustyRatRod]

I have a very nice manifold with the cast in choke stove. No cracks, no broken bolts and the heat riser works great. I don't need it because I plan to use a header. If you are interested, shoot me a PM.

 

[mrichard]

Dan, thanks. Always great advice. I got the gaskets you had recommended in another thread - from Australia. So I think I'm good there. I sent a PM on the manifold. I think I'll do the upgrade on this thing and put a new one in there.

 

[mrichard]

Dan- if I upgrade to the 73 manifold as I'm thinking I'll do, and convert to Electronic Choke - would my kit be 1231?

In that post it says: "For all slant-6 applications with 1bbl carb from 1960 through 1972, the kit number is 1231."

I have a 1bbl carb for 72. Why did you recommend 1233? curious

 

[cudamark]

slantsixdan's articles are great on that manifold installation. In my experience the only studs to worry about are the end ones. I've never had a problem with snapping the inner ones. Naturally, if you have a bent one or bad threads, then, yeah, change it out. I've had the best luck with the Felpro sets and not using any sealer unless the surfaces have major corrosion and then I just use some Copper Coat by KW. With the suspended copper in the sealer, it helps conduct heat away.
One thing that wasn't mentioned much was resurfacing the manifold(s). Every one that I've seen that has been resurfaced has failed shortly afterward so I would recommend against it. If they're bad enough to need resurfacing, replace them with ones that haven't been and don't need it.
As for the new replacement manifolds on the market, the ones I've seen are terrible. I was going to stock them here at work but when I saw the actual part, I sent them all back. The port sizes were all different and on different planes. On one manifold, the #1 port was only 2/3 the size of the others! The angles were off too. After mounting the new manifold to an intake, the exhaust's head surface was at a different angle than the intake's head surface. If you bolted the manifolds to the head first, there was a 1/8" to 1/4" tapered gap between the manifolds! Hopefully, someone has come out with a better casting recently or you may be in for an ordeal. Once again, the proper hardware and torque specs are the key to a long lasting installation unless your burning our California oxygenated fuel and then it's just a matter of time before it cracks again!

 

[ESP47]

One thing that wasn't mentioned much was resurfacing the manifold(s). Every one that I've seen that has been resurfaced has failed shortly afterward so I would recommend against it. If they're bad enough to need resurfacing, replace them with ones that haven't been and don't need it.

This is the first I've heard of this Mark. Could you tell me why you think resurfacing them would lead them to failing? From my experiences and everything I've heard, not resurfacing almost guarantees you a vacuum leak, especially if they aren't pulled off the car together.

To the thread starter, I have the exact gaskets Dan pointed you to as well as the open choke pocket. I had the manifolds resurfaced and I used black rtv gasket goop on it and even though people have told me that was a bad idea, it's worked perfect for about 5 years now. I went to Kragen and bought a sheet of gasket composite material with the metal mesh on the inside. I cut out a choke pocket gasket and used a little grinder to grind the edges smooth. I put a little black rtv on each side, put the cup back in and it hasn't leaked in 5 years either.

 

[cudamark]

This is the first I've heard of this Mark. Could you tell me why you think resurfacing them would lead them to failing? From my experiences and everything I've heard, not resurfacing almost guarantees you a vacuum leak, especially if they aren't pulled off the car together.

To the thread starter, I have the exact gaskets Dan pointed you to as well as the open choke pocket. I had the manifolds resurfaced and I used black rtv gasket goop on it and even though people have told me that was a bad idea, it's worked perfect for about 5 years now. I went to Kragen and bought a sheet of gasket composite material with the metal mesh on the inside. I cut out a choke pocket gasket and used a little grinder to grind the edges smooth. I put a little black rtv on each side, put the cup back in and it hasn't leaked in 5 years either.

Good question....I wish I knew exactly. I've just gone by feedback from my customers and my own experience with those manifolds. Those that surfaced them had problems and those that didn't, didn't. If I was to guess, I would say that somehow the clamping stresses get changed when the manifold get surfaced and the new stesses don't get relieved properly. Maybe if you surfaced each manifold separately and the same amount, it might work ok. Otherwise, if you do them together, you can't follow the installation procedure and tightening sequence in the same way.