The Stovebolt Site Forums The Shop Area Engine Shop Manifolds

Almost got the engine together just waiting for timing gear and retainer for the cam. Dug out the manifolds and they are pretty rusty plan on sandblasting and powder coating them. How smooth should the manifolds be where they mount to the motor or am better off taking one off another motor and cleaning it up? I have 3 complete motors 2-216 and 1-235. The truck originally was a 216 but I am putting in a 1953 235 is it better to use a manifold off of the 235 or 216?

Running a 216 manifold on a 235 will require a set of stepped-down alignment rings since the 235 has larger intake ports. Some of the parts vendors who advertise here have the adapter rings you'll need. Running without the rings almost guarantees a vacuum leak due to gasket misalignment. Running a 216 carb on a 235 will result in a rich mixture at part thottle and midrange, and reduced HP at wide open throttle due to the smaller venturi diameter of the 216 carb. A 235 carb has a wider bolt spacing, so swapping a 235 carb onto a 216 manifold requires some machine work to relocate the studs. It's simpler to run the manifold the engine was intended to have.
Jerry

"Running a 216 carb on a 235 will result in a rich mixture at part throttle and midrange"

Jerry, really gotta give you credit on that one. Hardly anyone realizes that a carb jetted for a smaller engine will run rich on a larger engine due to the increased signal from the higher flow. Even the hot rod magazines miss that one. I'm impressed!

Jerry do you know what angle the exhaust manifold at the bottom is I have a new old exhaust for the truck so I assuming I need an angle piece to bring the exhaust back to vertical. I will stick with the 235 manifold. Do I need new rings or will the ones off the manifold work. I would think that motor should be better than the one I have as far as corrosion is concerned it has been sitting in my garage intact for the 20 some years.

I have many customers running 216 manifolds and carbs on 235's, they seem to have better throttle response and low end torque.
In theory they may run richer but I have checked plugs and it does not show this.

Dave, do you use a 4-gas infra-red exhaust analyzer to evaluate those 216/235 hybrids? Back when I had a full engine dyno setup in operation it would have been pretty simple to pull some of the records of our dyno runs to prove my point, but the school system in its infinite wisdom chose to convert my shop into special ed classrooms, auctioned off the equipment I used for 30-something years, and trashed all my research files.

I get the last laugh when I meet former students who run their own auto shops and racing teams, however!
Jerry

Dave, the difference between a 216 and 235 may be small enough to not see much change in the air/fuel ratio, particularly with a spark plug check, but it does happen. If you go from a 350 to a 454 with the same carb, you will change a bunch of jet sizes. I had experience in working with carbs developing fish hooks (fuel curves) and emissions settings, and worked along side some of the best Holley reps. Also worked with Bendix/Autolite in spark plugs and O2 sensors. Have put in a lot of dyno time while doing engine and component development.

I've learned over a lot of years of dealing with exhaust systems that the simplest, and usually least expensive approach is to let a shop with a pipe bender make up a transition piece. The end result is a pipe that looks like original equipment and a good pipe guy can make the job look easy.
Jerry

Re. exhaust pipe, you'll need to make a new header pipe that will allign with 235 angled exhaust, vs. 216 that went straight down.

Not all the 216 manifolds exhausted straight down

Here is my 216 manifold on a 54 235
...pic...

That set up has worked extremely well for me
Carter YF carb
Almost always average 16MPG over the last 4 years.

Stepped alignment rings

Manifolds started angling back in 1949.

you will probably figure this out on your own, and if the fella doing the powder coating has any ethics. He will tell you that what you are really after is ceramic coating. At least that is what the powder coater I went to told me. He said that powder coating will burn off. That may or may not be true, as I saw no reason to spend like $200 just to test out the theory. I ended up getting eastwoods do it yourself ceramic coating, I got a harbor freight touch up gun for applying the coating. They are still shiny after 3 years.

My 235 with a 235 manifold and carb was running filthy rich due to the carb base gasket being wrong and covering the vacuum source for the power piston. Was getting only 10 to 12 mpg babying the thing. Pulled the plugs, and they were as white as could be,no indication of running rich at all. Maybe it's the Blue Flame combustion chamber design.

Brokenhead I've seen powder coating advertised that is supposed to be good up to 1200 degree's. I plan on powder coating it myself.

Comments I found led me to the POR-20 Heat Resistant Paint. I think it comes in black and aluminum (silver). I used the aluminum. A pint easily does two manifolds (probably four). It brushes on easily and looks good. You cure it in the oven. Rated 1400F. After about 10 miles it still looks good.

The truck is in the paint shop, so that's all the miles it has so far.