The Stovebolt Site Forums The Shop Area Engine Shop exhaust manifold 235 (new thread)

Resurrecting the main topic here - "tired of exhaust leaks ..." and in my case intake leaks on my '55 Early Series. Having mounted the muffler and not getting any lower decibel noise level - I pulled the intake and exhaust manifolds off. Spray & rev reveal all three intakes leaking and maybe the "collar" (?) carburetor sits atop.

Pictures show plenty of sources for intake and exhaust manifold leaks (gasket "wear" - maybe 30 driven miles and a few hours of carb adjustment on the rebuilt motor). "To machine or not to machine?" - that is the question. Leaks across the manifolds. While the manifold metal facing seems smooth - there is some concave / curvature noted by blue tape in picture. Not sure there is a lot of base to machine on the exhaust ports.

I noted the REMFLEX suggestion earlier (PN2027 looks to be a one-piece replacement on the 235).

Opinions on machining?

If you do decide to have your manifolds machined, I would suggest strongly that you assemble the intake and exhaust manifolds back together, leaving the nuts an bolts loose.
Then install the assembly to the head without the gaskets.
Then tighten the bolts which hold the manifold assembly to the head.
Once the bolts going into the head are tight, tighten up the bolts and nuts which you left loose earlier.
Remove the manifold assembly from the head and take it to the machine shop and have the assembly machined as a unit.

52 Carl has the right solution when it comes to getting the manifolds mated up and secure so both manifolds get machined at the same time.

The one big potential exhaust leak that this won't fix is the really uneven surface on the heat exchange box where it mates up to the exhaust manifold (picture 1 - mostly upper left corner area).

That surface is just too uneven to allow a gasket to prevent exhaust leaking, especially at the top left corner in the picture. It either needs to be cleaned up to allow good gasket seating (don't forget to check the corresponding surface on the exhaust manifold) or filled/leveled to create a better sealing surface. Changes in this surface area shouldn't be enough to cause misalignment of the manifold to head ports, if not too drastic.

Otherwise, you may want to see about finding another intake manifold (and exhaust manifold depending on what condition problems you may find there).

Am sure others will chime in here on possible solutions/options.

Dan

Edit by Moderator: moved to start new thread.

Thank you. Will follow the sage re-assembly advice. Going to have them peered at by by more experienced mechanic locally before deciding.

Also check the rings that fit in the head and intake to make sure they are in all of the way ,if the manifolds were shaved down then you may have to file the rings a touch .

HouckCO Someone ask what the advantage of Fenton split manifold was...this may be one of those advantages !! The intake always cooled by incoming fuel/air mixture doesn't suffer as bad as the hot exhaust,especially on trucks that are loaded and really working hard. In the olden days you had a head suracer that was just a stone on an iron surface plate. Now it's liable to be a Blanchard super surfacer expensive to use,lot of trouble to set up on something hard to get a grip on.

Thank you for all the input. Visiting machinists today. I always get value from the experience out here in these forums.

The bottom of that intake is kinda sketchy but a skim cut and doubling up gaskets might be ok. They are a bit challenging to hold while machining but if all else fails just cut it in half

Back before everybody got fixated on getting everything machined, draw filing the gasket surfaces and checking with a straight edge and a feeler gauge worked well. I've got a couple of 14" long files that get used frequently for such operations, as well as preparing connecting rod caps for reconditioning.
Jerry

Final update on my intake and exhaust manifold leaks.

Thank you all for the great tips! Took the manifolds in (after re-bolting them up to square with the head) and found that the "heat exchange box" on the exhaust manifold where it pairs to the intake manifold was in need of machining. 40/1000ths worth!!! Using REMFLEX for the ports and "stock" heat exchange box gasket - reassembled and it purrs like is should. A few trips around the neighborhood and all seems well seated and thankfully QUIET! Onward to the Spring and Summer shows and "drive your old truck" events in the Colorado Springs, CO area!

Shout out of many thanks for the very helpful comments to:
Curt
Kevinski
finite7
Gdads51
52 Carl

Now - on to the '31 and seeming carburetor issue.

Thanks for coming back and providing a closing report with the problem and solution.

Next time your out on a drive, post a note and some pictures in the Stovebolt Driving Report in the GTT!

Very glad she purring right along!

Dan

CurtB That is interesting work,in the olden days they would hack-saw a slice out of the manifold 2 cuts then braze on 2 covers, then install the other dump. Seems like the Fenton would be a lot easier and better. guess you could even make a cross over. Then need to heat the intake somehow.