Fixing horrendous intake leaks on a '48 216. I've searched and read many threads on this topic.
So I scoped out a FelPro gasket at O'Reilly's (formerly Kragen), and it's an MS9193B. I suspect it's for a 235, because when I lay it over my old gaskets, the port diameters are about a 16th bigger. The gaskets will fit my engine, but I'm pretty certain it's not the exactly correct gasket. This would result in internal gaps around the perimiters of my port connections once mated.
My question is, when I orer this gasket http://www.classicparts.com/1947-53-Manifold-Gaskets-216-CI/productinfo/80-404/# , will it fit specifically and exactly around my ports just like the old one? Or is this just another 235 gasket?
I don't think it would hurt this ol' girl much in terms of performance, but if the right gasket's out there, I want it.
If the manifold assembly is not flat, it will not make a good seal. The original gaskets were thicker than modern gaskets, if you get a small leak, you could try two sets of gaskets. Otherwise, you will need to find a machine shop to plane/true the mating surface on the manifold assembly.
Thanks fellas. Yes, I have planarity issues to resolve first. Individually, the intakes appear fine and so do the exhausts...but, as an assembly, all the exhaust ports seem to have pulled back from the intakes (away from the head), so I'm hoping that once I break the heat-riser connection, there will be enough play in the stud holes to simply pull the exhaust back in to get them all planar. Otherwise, it's off to the Bridgeport.
I'm going to get that 8590 part number and hopefully it's a perfect match with my ports ;o)
I bought a full 216/235 engine gasket kit from Napa and all the gaskets that I've used from the kit lined up and worked very well. IIRC the kit was around $70 Good luck on getting the manifolds planar. Dave
I am surprised no one mentioned the one piece Remflex intake and exhaust gasket. It is made of solid graphite, good to 3000 degrees and is claimed to seal gaps as large as 1/8 inch. This will take care of many warped manifolds and eliminate the cost of machining the manifolds. A bit more costly than stock gaskets but well worth it unless you want a stock look for judging. My exhaust guy has only Remflex gaskets hanging in his shop and says it is the only way to go.
Gasket #2027 is one piece, making installation a breeze and is listed for 216, 235 and 261. Kent
Coilover mentioned he had used hi-temp RTV silicone on an inline engine successfully about 3 or 4 months ago when this topic came up. As I recall, some folks have had problems with those gaskets breaking, cracking, blowing out, etc. I have no skin in the game at all. I've never had a problem getting manifolds to work using regular gaskets.
~ Jon 1952 1/2 ton with 1959 235 | T5 with 3.07 rear end
The packaging warns "Do Not Bend", as they will crack. Also, the suggested torque on application is only 20 ft/lbs. Improper handling and/or installation may cause the problems described. I can only speak for my experience, which is one time. But my exhaust guy has been using nothing but Remflex for a couple of years, day in and day out, so that is why I mentioned him. I measured the thickness of mine and it is 3/16 thick, and I think the claim of sealing up to 1/8 inch is plausible. Kent
Last edited by Lightholder's Dad; 07/28/20207:01 PM.
Not on this forum, but elsewhere I've read of those problems for over 10 years now and they're always the same. Gasket cracks, gasket blows out, falls out, breaks apart, etc. Some have said they believe the gasket becomes internally damaged when you install it...but you may not know it for a while. From what I've read, too little torque and they fail, too much torque and they fail...some saying if suggested torque was 20, then use 10 or 15 but in no case use more than that. And in my opinion that's a low number for a manifold for which GM said use 30~35. Recently on a Subaru forum a poster said he followed the instructions and they worked great for a while and then 3 out of 3 failed and others chimed in saying they had the same issues. And then there are always people who think these are the best thing since the polio vaccine.
But as I said I've never used one so I'm on the sidelines watching. If I look back over the years there have always been products that claimed to be what everyone needed for this or that. Magnets on the fuel line to increase your gas mileage. A special screen that goes between your carburetor gasket and manifold to increase horsepower. Ball bearings you put inside your tires to keep them perpetually balanced. Things you pour in your gas tank to "rebuild and revitalize" your engine. All snake oil and sideshow stuff.
Coilover's comment took me a moment to find. It was:
If someone has had a problem with a RemFlex gasket on a 216/235/261 engine please let us know the results. (no need to tell us about other engines)
Also, let us know if you had the head and/or the manifold mating surfaces re-surfaced. Let us know who did the re-surfacing. Let us know if the re-surfacing on the manifolds was done with the manifolds bolted/torqued together.
Also, 1. let us know if you used alignment rings and/or adapter rings; and, 2. let us know if the rings were first "shaved" to fit the new less-deep depths of the "joint" holes ("shaving" should be done to decrease for the lost metal when the mating surfaced were resurfaced).
I do not know if alignment/mating rings are needed/used with the RemFlex gasket?
Coilover mentioned he had used hi-temp RTV silicone on an inline engine successfully about 3 or 4 months ago when this topic came up...
It's interesting you should mention this as about one month ago a friend was ready to do this on either a 350 Chev or a 360 Jeep, but I don't recall which. It would not have occurred to me to use silicone on the exhaust manifold otherwise, and I don't think I really like the idea. Although I suppose it might work.
If the secret of the Remflex manifold gasket is its ability to squish in some areas, yet still seal in others, they should start making Remflex gaskets for warped Model B carburetors.
1952 5-window - return to "as built" condition | 1950 3100 with a 235 and a T-5 transmission
If the secret of the Remflex manifold gasket is its ability to squish in some areas, yet still seal in others, they should start making Remflex gaskets for warped Model B carburetors.
Jon (CarbKing) and I discussed that same idea a couple of years ago and decided maybe (a long maybe) the pvc gasket material available today might be adaptable or some gas-resistant variant of the rtv sealing material. We later agreed it might not be worth the time and expense, though. But I do think either of these might work.
~ Jon 1952 1/2 ton with 1959 235 | T5 with 3.07 rear end
I am using a Remflex gasket on my 261 that was rebuilt last year. So far, I've put about 1,000 miles on my truck, and it is sealed tight. I do have issues with the manifold stud/collector pipe connection coming loose, and having to snug it up periodically. Hopefully the Remflex is a good long term gasket, I've replaced manifold gaskets in the past on my old 216 and it was not fun.
-Patrick 1953 Chevrolet 3100 261 / 4-speed / 4:11 / Commercial Red
Is the stud coming loose or the nut, one can double nut or safety wire a nut or stud after assembly to stop that. Brass nuts anywhere on an exhaust manifold do not get welded to the stud like steel nuts do.
Ed
'37 GMC T-18 w/ DD 4-53T, RTO-610, 6231 aux., '95 GMC running gear, full disc brakes, power steering, 22.5 wheels and tires. '47 GMC 1 ton w/ 302, NP-540, 4wd, full width Blazer front axle. '54 GMC 630 w/ 503 gasser, 5 speed, ex fire truck, shortened WB 4', install 8' bed. '55 GMC 370 w/270, 420 4 speed, grain, dump bed truck from ND. Works OK.