The Stovebolt Site Forums The Shop Area Driveline 235ci for 216ci Swap

Hello. I am sure this is posted somewhere else but am new to this forum and old Chevys as well. I recently purchased a 1951 3100 with what appears to be the original 216 engine. It has a factory 4 speed on the floor. I have the opportunity to buy a rebuilt (and hopped up - cam, dual carbs, split exhaust manifold, electronic ignition) 1955 235 that has been redone to use unleaded gas. My question is, how easy is the swap and will it bolt right up to my stock 4 speed transmission? I want to keep it looking mostly original (with some period correct upgrades for performance and driveability) but don't want to change out everything. I will be keeping the original 216 put away to keep with the truck if I ever sell it.
Thanks for any advice/help you can provide.
Frank

The biggest problem will be the position of the water pump. In mid year 1955 the pump was moved about 3 inches lower on the 235 block and a different shaft and pulley arrangement was used. To use the later engine in the 1951 truck you'll need to install a water pump with a shortened shaft, or use a relocation plate a member here sells to install the 216/early 235 water pump. Just about everything else is a bolt-in swap. Be sure to use the flywheel and starter from your 216 engine to avoid a mismatch between the 12 volt 55 starter and the 6 volt flywheel. The tooth pattern from 6V to 12V is different but the 6V starter works well on 12 volts if the truck has been converted to the high voltage system.

Buy a large bottle of Advil or some other good headache remedy- - - - -you'll need it when dealing with the dual carbs!
Jerry

Frank,

What kind if dual carbs do you have? Most are too big, as HrL warns.

The Carter-Weber 740 Ford carburetors (I think for a 1600 cc engine, single carb) sold by Tom Langdon are a pretty good match to a 235.

Most people use larger dual-carbs and they are not smooth (to say the least) at all/any RPMs.

I am not sure what kind or size the dual carbs are. My next question is should I just stick with my original 216 and rebuild it? Can I add any performance parts and build it to run on unleaded gas? I have just heard it is expensive to do and if I am going to spend the money that I should just upgrade to a 235. Thanks again for all of the help/advice.

The 235 will be a noticeable upgrade, particularly one that's been beaned up a little. The extra cubic inches and the insert-bearing connecting rods are worth the effort to make the swap, but stuff like multiple carburetion and dual exhausts on the 235 cylinder head that's basically a glorified tractor part that was designed in the early 1930's is a lot of wasted time and effort. The thing can't breathe well enough to take advantage of the extra cam, carburetion, and exhaust capability. It's like taking a world-class Olympic sprinter and making him run with his mouth duct taped shut and a couple of soda straws glued up his nose.

The dual carbs and exhaust will impress the rubes at the weekend show and shine car show who don't know a camshaft from a chamber pot, though!
Jerry

So I just checked my engine and it looks like I already have a 235ci (block # 3835692 and head # 3835909 - looks like a 1952 engine from what research I have done). I can't find the serial number. The area behind the distributor looks smooth like it was ground off. I guess I will keep this engine and rebuild it. Let me know what you think.
Thanks.

Is there any reason why it would have the valve cover with the two bolts on top rather than the four on the sides?

Well, it could be a 1953 and earlier engine;

or, it could be 54-63 engine that has adapter bolts to allow the use of the two bolt valve cover. Are there four screw holes in the head around the perimeter of the valve cover?

What is your engine serial number pressed into the bllock to the rear of the distributor?

Based on the block and head codes and what I found in other forums, it looks like a 1952. There is no serial number. From my research, sometimes the mechanic installing a replacement block would not stamp the serial numbers on the block. The valve cover covers the head so I can't see top. I have a picture of my engine but don't know how to attach it to a post.

A 1952 235 will be a low oil pressure "splash oiler" engine, the one with Babbit bearings built into the connecting rods. It's an upsized version of the 216 that was originally used in medium-duty trucks and military vehicles from 1941 to 1953 or so. It's an interesting engine, but old geezers like me who remember how to work on them are getting few and far between. Virtually nothing on the early 235 interchanges with the later model engines with the insert bearings. Speed equipment- - - - -forget about it! Even the camshaft and crankshaft is different than the later engine, and the pistons are made of cast iron, not aluminum.

If you're building a numbers-correct restored show truck, stay with the early engine. For practical purposes and ease of repair, go for the 54-up later design 235.
Jerry

Thanks for all of the great information and advice. I guess I have some thinking to do. It will never be a high-dollar, trailer queen restored truck but I do want it to look original. This is the engine I am thinking about buying. I think it will mate right up to my factory 4 speed and I can get everything minus the 5 speed for $1500. The listing is on Craigslist.

https://lakeland.craigslist.org/pts/6165066566.html

Thanks again,
Frank

For that kind of money, you definitely need to hear it run before you get out the checkbook! If I'm seeing the picture correctly, that's a 54 or 1st. series 55 engine with the high water pump. That's a good thing for your application- - - - -IF the casting number is correct. It could also be a 216 from 1953.
Jerry

The other option I have nearby is a 1954 235ci that is complete (and supposedly running when removed) but not rebuilt for $550 (asking price). I would then want to go through it/rebuild before installing it in my truck.

https://daytona.craigslist.org/pts/6185241453.html

I'd choose the second one, but once again, listen to it run before you fork over the green!
\Jerry

Sounds good. Thanks again for all of the help and advice.
Frank

Let us know what you did, and how it worked out.

Ed

These straight 6 engine swaps are relatively easy. I swapped out a 235 for the original 216 in my 1946 1/2 ton. Take your time and do it right. Also, not to be nitpicky but I am not sure a factory 4 speed on the floor came in a 1951 3100 but I could be wrong.

A regular production option for 3100s in 1953 was the SM420 4-speed (shifter through the floor).

http://chevy.oldcarmanualproject.com/chevyresto/53153.htm

I stand corrected. Thank you Tim!

I use 2 Rochester b carbs on my 54-235 and have no problems. At one time I had a heat riser carb and just plugged the heat holes. Used it for years, now have matching carbs.

they sell a waterpump adapter to move the water pump up to the center of the radiator, I had to put one on my 235 when I put it in my 46 1/2 ton, it is just a panel that you have to take the back of the waterpump off and bolt the adapter to it

Take the 2nd one and rebuild it ,,,I have a 56 235 in my 46 1/2 ton, and I rebuilt it before i put it in, mine was a 216 before I swapped it.....but be careful what u buy to rebuild it... mine cost almost 6000 to rebuild....because i bought all the hi performance stuff, and it still runs like a 6 cylinder.... But it still has alot more power than the 216 and runs smoother

Which is the 2nd one?

The 1954 high-pressure 235? That engine would not need the water pump relocation plate. It would be the easiest stovebolt-upgrade replacement engine (except for a 54/55st 261).