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Background info for those that do not remember or not know:

My son has a 1946 2 ton truck with a 235 that he uses for his catering business. He has a wood burning pizza oven on it. His original engine dropped a valve and needed a rebuild.

At the same time I got a generous gift of a 1954 235. We decided to have 1954 one rebuilt and put into his truck.

Then engine just got back from the rebuilder and the repair shop is in the process of putting the engine back in the truck. This is when I got the call that the exhaust manifold was over .030" warped and the metal looked to thin to send out to have it machined.

This has started my search to find an exhaust manifold.
I found a 58 235 engine that appears clean, low mileage, well kept. I have been told that 58 manifold will fit.

Told my son about this engine and his concern is what are the odds that this manifold maybe bad. So what are the chances I would be wasting my money on that old engine.

My son has been tow baring his truck to his catering events for a while and wants to get his truck under it's own again soon as possible.

So I mentioned that they make Fenton cast iron dual headers.

I told him the advantages are that they will fit and work right out of the box so he would get his truck back on the road faster.

I said the headers should not impact performance or MPG much because the intake and exhaust are still stock. Am I right on this assumption?

Will there be a drivability issues using the Fenton headers?

Any other potential problems you guy's can clue me in own that I have missed?
Thanks Jeffrey.

Should work. MPG will remain close to what it was previously. May require a little fine tuning on the carb but not much. It's a cool truck and it needs to arrive on the job site under its own power. Go for it.

You can find a manifold. In your situation, I'd lean toward the stock setup so you don't have to engineer some sort of heat source for the intake. And then of course a whole new exhaust system.

I actually have a manifold with a stuck heat valve. You'd be welcome to it but shipping might be prohibitive.

you would think they would fit right out of the box, but you will have to mess with the little clips or whatever you call them that hold the manifolds on. I actually had to use a hacksaw and cut a couple of them to fit. It wasn't horrible but it took a good long time, and if I remember right the linkage got hung up and I had to bend up a new one. (I could be wrong on that though) It isn't all as easy as you are hoping. Not to mention the entire exhaust system that has to be built. (at least the one pipe, some setups are made to use the original, and you only need to add the extra.)

Most Fentons are off shore copies. Some are not done as well as others, but no way to tell which you will get.
You will need to replace the the locating pins (first and last bolt) with studs (if GMC has them) and you will have to play games to get hold down washers to come out even (grinding or adding spacer blocks, etc.)
Fenton design was to allow the owner to bolt up the original pipe to one header and just make 1 new exhaust pipe.

....or take a shot on getting the one you have trued up anyway.
Can you use TWO gaskets??
Just trying to think out of the box. .030 is not much on a manifold unless its been re-surfaced before. Just me thinking out loud....

Thanks for all of the replies. I'm starting to think that taking a gamble on that 1958 235 engine. It looks clean and low mileage. Hate to strip off a manifold on a complete engine from the fan back to the flex plate. Jeffrey

Will a exhaust manifold from a 1957 261 fit?
Jeffrey

Work on which year/size head/block (sorry, but a few engines/years have been mentioned above).

Stick with the stock setup if possible. Duals make nice eye candy and add a little performance at the top end of the RPM range, but the carburetor really needs that manifold heat to run right, especially during warm-up. Be aware that the position and angle of the outlet changed a time or two, so some tweaking of the exhaust pipe might be necessary, and/or a modification of throttle linkage, depending on which exhaust manifold you end up with.
Jerry

Sorry for the confusion tcederlman. The truck is a 46, but we got a 1954 235 for free and had the 1954 engine sent to the machine shop to be rebuilt.

The repair shop found the 54 exhaust manifold to be warped too much, over.030" and the metal too thin to resurface.

But my search is over, I hope. Yesterday my son found a clean low mileage 235 that came out of a 1958 Chevy Biscayne for sale on Long Island for $350.

I went and saw the engine today and bought it for $230. The engine sits in my garage now. Tomorrow I will take off the exhaust manifold.

Jerry you are right about better to keep things stock.

Jeffrey


Edit Sunday morning because I left out the year for the engine I just bought for the donor exhaust manifold.

Jerry is right though about the difference in exhaust manifold exit angle differences. The original one exited straight down while your new one (insert bearing engines) will be on an angle.

Good to hear that you are making progress.

Paul

I sprayed some liquid wrench on the manifold about 7 pm Saturday evening then again about 9:30 am Sunday morning.

Around 1 I got to working on the 58 engine. Took off the carb to keep it safe. Then I took off the intake and exhaust in one piece. I was surprised how easy the bolts came out of the head.

While doing this a 72 YO neighbor that is a retired mechanic and drag raced, and my good friend 74 YO retired mechanic came over. So the discussion came up what was I going to do with this 58 235.

I said being that it is a side mount engine I doubt I would use it. Even if it dropped in the way the 1954 engine does into the 46 truck I'd rather find a 1954 261 to get that 149 HP.

Then I mentioned that I needed to look to see if the head has the casting number 848 to see if the 1958 engine had the higher compression head.

While putting stuff away the neighbor pointed to a casting number and said: is this the number you were looking for, as he pointed to the 848 on the side of the head.

Hope my luck does not run out. If not for the people on Stovebolt I would not have learned about the 848 head's. Again thanks to all. Jeffrey

In my recent rebuild we found some heavy corrosion between the Siamese exhausts.that and the intake seemed to be slightly shorter (used another layer of gaskets). It was machined quite heavily, probably in neighborhood of 50 thou. Now with new gasket too it works terrific.

32vid
You may want to start looking for another spare,the weight(pizza ovens) and miles on that style truck seem to eat motors.

The company in Ct doing what you are with similar trucks keeps a spare motor in shop.

The "848" head was used on at least 75% of high-pressure 235 engines (all heads from 1956 onwards).

My son and I are planning on
doing that. Though after going through all the little things that popped up I may just get his 46 rebuilt and converted to bearing inserts.

Back to an 11" clutch.

I got a NOS 1946 GMC oil pressure gauge. However the gauge numbers are printed on the glass so even though my son has 35 PSI at idle his gauge reads 15. I can buy a repro GMC instrument panel glass with the correct oil pressure numbers.

The problem is when swapping out the Chevrolet IP glass with a GMC glass the speedometer will not be correct. Win one lose one.

Though I think my son's 54 235 rebuilt engine should last along time. He is driving it and not an employee. He rather go up a hill slower then shift up and work the engine harder.

Also most of his work is on east end forks. The north fork runs are 10 miles or less one way. Montauk can be 30 by ferry of 60 road one way. He does some work in western Suffolk and Nassau maybe 60 - 70 miles one way. Compared to Connecticut and upstate New York the hills are not as long.

We went with the 54 for 17 HP more. Though my son has only driven it to two jobs since the rebuild was done he is not sure if he is feeling the extra HP from the 54 engine. Jeffrey

That extra HP will only be apparent if he's willing to downshift and keep the engine revved up near its upper limit. Lugging up the hills in too high a gear will do more damage to the bearings than letting it wind up and produce the power it needs to get the job done. Depending on whether the engine was originally used with a standard trans or a Powerglide, it was HP rated at either 3700 or 4000 RPM. I'll bet he's not winding it anywhere near that tight. Don't ever let it get below 2000 RPM- - - -that's where the torque peak is.
Jerry

My son had his truck at my house the past few days for he had to take it for a state inspection. This morning I had to follow him out to the north fork where he keeps his truck because he needed a ride back home to get his car.

Today on I495 LIE, he hit hill that climbed 77' for .75 miles long. I think a 1.8 grade. With the original engine he would start the climb at 40-45 mph and he would slow down to 30 mph at the top.

Today he hit it at 46 mph and was doing 41 mph at the top and he had a lot of gas pedal travel left. He was able to keep the truck between 41 to 46 on the interstate ride to the north fork. Still breaking the engine in.

I never did a compression test on the 1946 engine for it appeared to run well. When I pulled the head aside from finding the 6 cyl dropped a valve another cylinder had a slightly a slightly burnt exhaust valve.

So never driving a new 1946 2 ton 235 93 hp or one running well or a freshly rebuilt 46 235 I can not say exactly how much better the rebuilt 1954 235 112 hp with 19 more hp is. Though my son is happy. Jeffrey

Is his oven a brick oven ?

Inside appears to be a special concrete floor and dome.
The sides, back, bottom and top has a sheet metal covering.

The front had brick opening around the opening and the rest of the front had a gray particle board that looks like the stuff used to sheath bathroom walls before the tile is put on.

So my son tiled the front. Link to see pictures of the truck.
The first one is the truck after we got it back on the road before the pizza truck work was done. Jeffrey

http://www.pizzarita.org/gallery/

looks awesome, now I'm hungry