I am considering not using exhaust manifold gaskets on my 66 like it came originally. I trued up the sealing surfaces on the manifolds to insure they are flat. Is there any reason I should still install gaskets? I understand the gaskets will offer a buffer for any irregularities on the sealing surface but I don't like torquing manifold bolts down on a cast part that was not designed for use of gaskets. I'm probably being concerned about nothing but wanted to see what the consensus was.
If you have trued up the manifold surfaces, I would not use the gaskets. Had a 403 Olds engine in a Regal that kept blowing out the exhaust manifold gaskets even after truing the manifolds. Finally a wise man asked me, "why are you replacing the gaskets when the engine was assembled without them". Tried it and had no more problems without them. Believe it or not, I use a wide belt sander to make sure the manifold surfaces are as even as I can get them, and it works fine.
With manifolds, I say no gaskets. You will have the added benefit of heat dissipation through the manifolds as well. Erik
If you manifolds are machined flat, do not use gaskets. Using a thin coating of high-temp RTV can't hurt. This will be more durable than gaskets, as the gaskets can compress and that will end up loosening the bolts, which will blow out the gaskets.
It seems the statement is always "when using manifolds". I suppose it changes when using headers - correct? See the attached pic of headers. I wonder why the surfaces on headers seem to be so rough? I saw one set of custom sbc headers at a car show recently that were smooth. Maybe even enough to skip the gaskets.
Because some idiot welded beads on the flanges and forgot to machine them smooth? Don't forget that the HEAD surface needs to be smooth and flat just as much as the manifold surface. The only difference is that the manifold is more likely to warp. I have the exhaust gasket surface of the heads machined while the heads are getting the valve job.
I am a sorta alternative type sometimes and mochine my manifolds/heads smooth/flat by dragging them around on the concrete driveway-fits my budget and works fine:TU:
Dan, "Alternative Type?" We need to talk! LOL!! I don't use gaskets unless the factory put them in. Flat surfaces are the key, no matter how you achieve it! I usually draw file the flanges cause I'm kinda cheap and not into paying for something I can do myself. Tim
i am right here..... I am with Dan on this,,,, my 64 riv has a exhaust leak right now because some one put manifold gaskets on it and they burned out.... I never use them,,, they are just trouble waiting to happen....
Yea thats what I did too. No need to send to a shop. Just takes a little time and if done right is just as good. I used a 6" long 320 grit stone to finish the surface after filing. Thanks for the replies everyone :beer
Buick recommended not using gaskets on the exhaust manifolds because the gaskets do not allow as much heat transfer from the heads.
I just corrected mine,,,, took both manifolds off and ditched the burned out gaskets.....filed the head surfaces back true flat with a big flat file with some 80 grit sand paper wrapped around it.... then I sandblasted them and painted them with ti-temp gray paint.... and coated the bolts with anti-seize....:laugh:
Does anyone have the service bulletin or other factory lit(or know the source) in which Buick recommends against the manifold gaskets? Tom Mooney
Question; has anybody ever seen a new buick with exhaust manifold gaskets????? I havent, I have bought several new Buicks in my time and none had the gaskets...
As I recall, the Buick 'head' sets with the gaskets for valve jobs didn't have any ex manifold gasket, but aftermarket sets did-
Reason not to use gaskets if your manifolds are true: you will warp a set of perfectly good manifolds. Non-compressible copper would be fine, but the sandwiched lawnmower headgasket type gaskets will compress much more under the bolts and take the manifold with it. I've seen it over and over. Someone put them on just because they came in the full gasket set. I fix by removing the manifolds, truing them, and putting them back on without gaskets. Bolts stay tight, and manifolds stay straight because there is nothing slowly compressing between manifold and cyl head. I have had good luck using those gaskets with headers though.
A really good set of headers will have really thick flange bars and I would most likely use copper gaskets with those....but would not rule out no gaskets if the rough edges of the pipe welds were machined off and the flange bars were thick.....think about it, the heads will limit how much the header will bend....
