Pontiac 400 Exhaust maifold gasket

[jasonL78]

I'm not a Pontiac guy from a 1970 400... are these the oval port gaskets? They don't look like D shaped to me? I guess there was 2 style heads? I was told not to use the metal which these are what are my options? This is the passenger side the driver side is broke in two. That drivers manifold is stuffed in there that side is going to be fun to get out.

http://i35.photobucket.com/albums/d189/jasonchale/gasket_zpsqzz6seu6.jpg (http://s35.photobucket.com/user/jasonchale/media/gasket_zpsqzz6seu6.jpg.html)

[StealthBird]

Jason, that's the standard d-port Pontiac configuration.

The d-port verbiage comes from the fact that center two exhaust ports are one large oval, but have a dividing wall, so it looks like a couple back-to-back D's (bottom).

The round port heads have 4 large exhaust ports, all separated. Those are RAII, RAIV, and SD-455 (top).

[68 Vert]

Don't forget the '71-'72 455 HO round port engines.

[jasonL78]

Awesome that is just what I was looking for. The owner drove the car into my garage and shut it off. When I got it on the lift I new it was going to need an exhaust. Well I installed a new exhaust started it up and exhaust manifold leaks both sides. I was able to drop the passenger side down to get this one out. The driver side is going to be tricky. The Z-bar is in the way of the back bolt on drivers side. The drivers side is stuffed in there. So if I had taken the manifold all the way out I would have seen that D port. Thanks for the pictures greatly appreciated.

[StealthBird]

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: 68 Vert</div><div class="ubbcode-body">Don't forget the '71-'72 455 HO round port engines. </div></div>

Yes, and I forgot the 1971-1972 455 H.O.'s.

[jasonL78]

Guys what gaskets are you using on these 400 TA manifolds. I changed them out with stock looking fel-pro and the driver side is still leaking. I removed the manifold today cleaned up the face of manifold. Using a straight edge it looks like the manifold is warped. The center port is lower than they the two outside ports. So I tried to get them square to each other. But after I installed the manifold it still is leaking on the center port. So do they make a thicker gasket for these pontiac manifolds?

[Steve_Hoog]

Jason

If it were me and I had a little money, I'd step it up a little. Screw the gasket and get some bad boy manifolds.

http://www.ramairrestoration.com/

I think there is going to be something to fit almost any Pontiac combination.

http://www.originalho.com/1963LeMans/1963LeMansEngineExhaustManifoldLeft.jpg

[jasonL78]

Thanks for the info. Not my car I'm doing it for someone. I installed a new exhaust on it. Started it up and manifolds are leaking. It sounds awful. If it was mine I'd have headers on it. I've already spent way to much time on this one manifold. Just looking for a thicker gasket to install. I think I'm going to try a set of Mr gasket ultra seal gaskets.

[njsteve]

If you REALLY want some leaks, get a set of headers! Pontiac engines, headers and exhaust leaks go together like a ménage a trois. <<GRAEMLIN_URL>>/naughty.gif

[jasonL78]

Really Steve? No fix out there? LOL

[Steve_Hoog]

njsteve

Have you reached the point of Long Branch is the only way to roll?

[njsteve]

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: jasonL78</div><div class="ubbcode-body">Really Steve? No fix out there? LOL </div></div>

The manifolds tend to warp due to the lack of clamping pressure from the small number of mounting bolts. You have to get them machined flat or get another manifold.

[jasonL78]

Well I talked with the owner. I told him what I found he wants to have them fixed. So I'm going to try and find a machine shop to cut them down. He also said what option do we have to buy new? Any replacements out there? Steve you mentioned the ram air manifolds. I already have the exhaust bought and fit to these manifolds. Are the ram air manifolds a direct replacement to factory manifolds. I don't know the part numbers of the stock manifolds until I get them back out of car. I'm going to have both sides done.

Jason