The Stovebolt Site Forums The Shop Area Engine Shop 235 exhaust manifold

Is it a common problem to have a exhaust manifold leak out the bottom at the head ? It seams tight as can be but has room for feeler gauge up from the bottom on 3 and 6 . this is on a rebuilt motor first start so new gaskets . Do 235 exmanifolds warp ?

I would take it to a machine shop and have them surface grind it flat.
Jay D.

Jay D.

Are you using alignment rings with the manifold?

Is it possible the manifold is "hanging out on" alignment rings with a manifold that has been surfaced a few times (this has happened to me).

You might have to carefully (for your hand/fingers) grind down the rings?

Any chance you separated the intake from the exhaust when you were rebuilding the motor to replace the gasket?

Yes they can warp. I've read that they can even crack when re-installing.
First check both manifolds with a straightedge. If warped, best to have a surface grind.

I had mine off to work on a stuck heat riser.
Make sure everything is clean on the mating surfaces.
It's a balancing act getting the intake, alignment rings and exhaust loosely bolted in.
I do finger tight. Tighten from the center out.
Sometimes I have to lightly shake the manifolds to get it all centered up.
If an alignment ring is not in place properly, you can crack the manifold.
Then maybe a half turn on each bolt with the wrench and repeat till it just becomes snug.
Final tightening is torqued to 15 to 20 ft/lbs (check the shop manual for the spec).
The problem is that the access area is limited to most socket type torque wrenches.
I practice hand tightening on an accessible bolt and check with a torque wrench till I get the feel.
Mine leaked with new gaskets.
I let the exhaust cool a bit, put on some gloves, then loosened the exhaust bolts a little and then re-torque.

I think it is common practice to loosen the bolts and nuts attaching the two manifolds together before installing the manifold assembly. As the assembly gets drawn to the head, the connection between the two manifolds is gradually tightened at the same time. With my 216, sometimes the gasket set is more suitable for a 235 and it is possible to have the exhaust gasket offset such that a leak occurs.

I am in the school of don’t separate the manifolds unless you have to. And if you have to, you should put a straight edge across The manifold faces and see if they are level with one another horizontally. If not, you want to take the assembly to a machine shop and have The manifold faces dressed level. Then throw away the stock intake and exhaust gaskets, and use a Rimflex one piece gasket.

Second the Remflex gasket.

good thing to check
Jay D.

just spent the last hour trying to get the ring to slide inside the intake with no luck, I was wondering about seperating the 2 manifolds because with the ext on the outer studs the intake wont come any where near lining up with the rings

thats the way to do it, I know the danger of splitting manifolds but I had to loosen the two manifolds noticed the gasket was gone any way so i replace it, with the 2 loose the intake slides right onto the guide ring that I placed in the head, need a few extra hand or maybe more to get every thing lines up and held in place while tightening the hold down bolts, this was a bad design

Remember to leave the bolts/nuts holding the 2 pieces together loose until the manifolds are tightened to the block. Then tightened them.🛠