I have an exhaust gasket leak on the driver side manifold on my 73 cc. Sent the car in to replace the gasket and was told the manifold itself is warped due to the leak having been there for a while. Is this BS? Without removing the manifold and only seeing the space where the gasket is gone from the underside, can you determine the thing is warped? I would think it needs to come off to make that determination.

 

I would say BS. Replace it yourself or take it somewhere else. No way to tell without putting a straight edge on the manifold. And even then, I would just try a good gasket and see if it lasts. If it don't, then it will at least be easier to remove the second time.

 

The factory didn't use gaskets between the manifolds and the heads.

Its extremely easy to check manifold flatness with a straightedge.

 

If the manifold is on the workbench

that said, what is the limit? ANY manifold will have SOME degree of variation from flat. I would think a reasonable limit would be about 0.020" [twenty thousandths] over the long way.

 

That was my question to them. How do you know its warped if you knuckleheads didn't even remove it? My hunch is they didn't bother getting to it and are making excuses. Why bother scheduling a service if they can't get to it all day long.

 

I think they are all warped after use to a extent. I have had leaks on both my 70 VC and 71 Cutlass. I put in gaskets where there were none before and used brand new grade 5 high quality bolts. Tightened them from inside out in increments of torque. No more leaks. doesn't look original though, but sounds good.....

 

When working in a shop as apprentice, one time an Olds V8 came in with a manifold leaking. That is where I found out that they didn't come new with a manifold gasket and when they leaked, a gasket fixed them.

 

So would it be accurate to say due to the thickness it would be pretty hard to warp? I could see gaps developing due to aged rust but not actually warping. And if it does warp over time, does that mean the mating surface of the block warps as well? If so, really both need to be planed but I assume nobody does this.

 

Also, can any 455 manifold be used to replace? I was thinking if I have to pull one side, the other isn't far behind. And if I'm pulling them off and have some on the shelf from a Toro, why not restore them cosmetically before reinstalling. This type of logic is why I have a half dozen projects to do.

 

Toro manifolds are completely different.

 

Firstly, I would determine exactly where the leak is coming from. It could be the exhaust pipe flange as there is no gasket there either. The down pipe may be off center and leaking. If it is the manifold to block seal then you could try a gasket if the warp is not too bad. You could also have the surface machined to correct the warp to some extent. I also used my graphite plate electrolysis tank to remove all rust and carbon. It came out like new (did driver's side only). Good luck with it because we all know how we hate the sound of a manifold leak.

 

Will any B or C 455 manifold work on this car?

 

71 and newer ones.

 

I've used these 2 with success in similar situations, Victor Reinz Exhaust Gaskets MS15141 or Felpro MS90021. Both are under $10 at your local parts store or off the net.