New exhaust manifold porblems.

[Allan]

I was a bit harsh about the quality and finish of these new manifolds compared with the originals in a previous posting a little while ago. Today I made a discovery which reinforces my less than favourable opinion of them. I have a customer who wants the second one my previous customer double ordered. I have a set of the new heavy, one piece copper gland rings which do a really good job.

I had trouble getting these to fit in the first manifold, and had to file a decent taper on the gland ring to get them to start in the manifold port, but i did manage to set them home with a little help from a vice and a block of wood to drive them in. Being straight, the manifold mated up to the block nicely, which makes them fit for purpose.

There was no way these gland rings were going to fit in this second manifold. I checked the rings in a good straight original manifold I keep in reserve, and they fitted well.They would not start in the new manifold ports, so I measured them. Given some variance on the original, the ports in it were within .005" of 1.25". The new manifold ports were some .020" undersize. With careful mounting in the lathe, and by taking miniscule cuts to avoid tearing them out of the chuck, I was able to machine one side of the gland ring down enough to make them fit.

Tomorrow I get to fit my handiwork. While the use of split gland rings and the round copper gasket may not have given the same trouble, it would be nice if the new manifolds were closer to original specifications.

Allan from down under.

[Adam]

I’ve installed 6 new reproduction exhaust manifolds this season and haven’t had any issues.

[Steve Jelf]

Adam, are you using one-piece gaskets, or the original style? I can see how the originals would fit better if the holes are a little undersized. I use the original type because they work and they cost about 1/3 the price of the one-piece type. But as the holes are machined, I would think the maker could make them the right size just as easily as .020" under.

[John Codman]

I installed a reproduction manifold from Lang's several years ago. It fit perfectly, everything lined up, and it's run fine since the day that I installed it.

[Adam]

I have one on the bench here and made precision measurements with a telescope gauge and micrometer. The holes are 1.247” to 1.250”. If the target size is 1.250”, then these holes are .003” undersize. I wonder if that is outside of spec on the Ford print? Anyone have the print?

I only use the original style copper / steel ring and gland set and have had no issues.

[Philip]

i found the flimsy split rings that came with the ring and gland to be not strong enough to prevent warping so i made solid ones. philip

[DanTreace]

Just measured a new manifold on hand and the port i.d.’s run about 1.242-47. Don’t know the Ford spec.

The std.repo Ford steel glands are split to adjust, some need filing to open gap if gland doesn’t seat. Or you can spread some. The copper compression gasket rings fit over and get compressed to seal.

As for the one-piece gaskets, have tried, but for me don’t seal. The copper or brass formed part seems work hardened and can’t be compressed at all, and stood too proud off the block. Don’t know if parts meet Ford spec for I.d., but at this port only one side of the new one-piece fits into a port.

Prefer the repo glands and copper sandwich gaskets with a new repo manifold.

[henryford2]

Not a machinist by any means, but I've been around my share of it in my career. Depending upon the specific industry, but in general a 3 decimal place dimension would be toleranced to plus or minus 0.005, a two decimal tolerance plus or minus 0.01. I wouldn't be surprised that the original dimensioned drawing for the exhaust manifold was dimension in fractions rather than decimals. In my honest opinion this is far from a precision part requiring a 3 decimal place tolerance for a "hole".

[Allan]

Today's fitting went well. with the one piece copper rings in place in the manifold, a slight bevel on the other side of the rings to make alignment with the block easier and a smear of exhaust sealant each side, the whole lot just fitted nicely. I was very happy with the result in the end, despite the tribulations.

Allan from down under.

[Mark Nunn]

Allan, what did you use for an exhaust sealant? I have a Ford FE V8 that does not use exhaust gaskets. It has embossed sheet metal shields where a gasket would normally go that compress, deform and seal when the manifolds are attached. My cylinder head rebuilder recommended using anti-seize on the mating surfaces because it won't burn off. That is what I used when I rebuilt the engine 11 years ago and still have had no leaks.

[Allan]

Mark, It is a product called Maniseal. It comes in a tube and has a consistency somewhat stiffer than toothpaste. Hence it also holds stuff on place while juggling things to fit. It is valuable in filling any voids in faces and ports. It has a silica content which hardens as it cures. I carry a tube in my toolbox as a matter of course.

Allan from down under.

[jsaylor]

I recently ran into a problem with a repo exhaust manifold where the port recesses were not machined deep enough. I had difficulty getting it to tighten up against the block. I fought this thing for several hours before I measured the depth. They were only .115 deep where an original was .190+. I had purchased it from one of the vendors some time ago waiting for a slow time to put it on. This one is a heavier casting than the new ones I have seen recently, and almost needs longer studs. I didn't save the receipt, so I don't know who i got it from. So to use it, I will have to either trim the rings or have some one bore it deeper. Ended up buying another repo one from Langs and it fit perfectly.

[Scott_Conger]

Joseph, your memory has served you well. In industry, the tolerances you have stated are standard. The drawing itself will typically have a "Tolerance Block" where tolerances for the part are actually spelled out. In some product lines such as gyros and superfinishing of gas bearings, tolerances will be far closer, but in automotive, this would be very unusual outside of perhaps turbos, and I only know of one such turbo on a "T" and that fellow for certain did not manufacture it.

For everyone else:

John Saylor's experience is a great example of how to never take anything at face value when dealing with reproduction parts. Some manufacturers have designed very good parts, with industry standard specs, and then follow that up with quality checks and reputable machine houses...others not so much. We're often dealing with cottage industry parts and they are often not made to the level you hope to think. Checking fits is a really good practice to get into. Coincidentally, on manifolds I always check the gland to fit into the block at least nearly 1/2 way, and also into the manifold at least nearly 1/2 way. Once the gasket is in place, you won't go wrong. I have never found a bad manifold like John did, but have found plenty of blocks which have been machined so much on that face that it was nip and tuck to get the glands with gasket, to fit (and I nearly always have to nip a 1/32-1/16" off the gland ring to get a little "spring" to it and ensure it will even go into the gasket, much less machined holes (they're not exactly a precision thing).