The Stovebolt Site Forums The Shop Area Engine Shop Engine Swap 261 to 235

Guys I'm new to the stovebolt forum. In fact this is my wifes truck we are talking about. It came with a seized 261 and I've picked up a running 235. Is there much difference that I'm going to run into, making the swap?? The truck is a 5 window 54 with the 261 and the 235 engine came from a 46 dump truck. Any help would be appreciated. Fred

Depends.....if the 235 is a 55 or newer you're headed in the right direction. If it's an older low-pressure babbet engine I'm afraid you're taking a giant step backwards.

You need to ID the specific year of the 235....hopefully it will be at least a 54 (insert bearings) or maybe even a 55-62 mill.

A 54 engine would switch in without any issues and the radiator would have clearance from the fan. In a 55-62 install you'd need to use an adaptor plate to adapt an "early" style waterpump to the block and give yourself proper fan clearance.

Before I did anything I'd check out the 261 block and see why it was stuck. By far, the 261 full pressure engine is the preferred upgrade to add a little "zing" to the pickups.....I'd ID both the 261 and 235 for their years of origin, figure out why the 261 is "stuck" and if not feasibly repairable, go back to a full pressure 235. Hope this helps.

Dave

235 is a 1946 2nd design. The 261 had the intake open due to the previous owner removing the hood and carb. 5yrs. of maine winters and summer rains. The pistons are soaking but after a week show no signs of freeing up. The 235 is a running ready to hook up motor. The wife doesn't care about flying down the road, if she did, I have a 94 LT1 with a 4L60 backing it up. I'm just asking if I can bolt up this 235, as it appears to be really close to the same set up. Fred

I agree the 261 is a better engine I have ran 235's in my 46 and had to move the radiator forward to clear the water pump shaft. I put a 261 back in and was able to move the radiator back to the original spot. the original moter in the 46 was a 216, then you get all the other problems, the splasher ( not oil pump) the bearings. The 261 is a heaftier moter and you get a few more horses (about 8) with full flow oil. If it turns out that you can get a short block for the 261 and have the heads re-done, I'ld go that route.

The 46 engine could be a splash 235, Chev started putting them in the big trucks starting in 1941.

One of my engines was really stuck bad we had to drive out the pistons. But it cleaned up fine, no cracks and it's been on the road for several years.

My 54 came with a stuck 235. Finally, after 2 years of MMO an penetrating oil it has finally freed up.

I too would prefer to get the 261 running again if at all possible. But, just because an engine is out of a '46 dump that doesn't mean the engine is original to the '46. Post the stamped numbers on the pad just behind the "dizzy" and any block and head casting numbers and someone on here can probably ID it. Who knows, you might have a great replacement engine there.

Guys I believe I didn't state my question clearly. I'm not doubting that the 261 isn't a better engine. My question is will the running, turn key, 235cid engine that i've aqquired, mount up to the exsisting mounts on my wifes truck?? I plan on keeping the 261 for a time when we could afford to get it overhauled.

She’s a drop in. It is the 1955 and later blocks have minor water pump, front mount, or linkage issues. Once you have a backup engine ready drive it like you stole it and you may be surprised how durable that old splash oiler really is.

My problem in answering your question is, what engine do you really have out of a 46? It could be any number of engines.
Could you link to some pictures or give casting numbers, or the number by the distributor?

If it is truly a 46 235 it will bolt right in.

I guess one of the possibilties is that the rad position has been changed to accomodate the 261 and an older engine might end up with quite a gap between the fan and the rad. Some photos would be really helpful.

THANK YOU!!!

I don't believe the question has been answered yet...
We need more info about the 235 engine, is it early or late?
Pictures of the "new" engine and how the 261 sits in there already would be helpful.

Sure, they both fit, but there may be some different details to making each fit "just right". Without knowing what you have exactly we can't advise on those details.

Grigg

I ran 235's in my 46 for allot of years until I could get a short block for my 261. Prretty much a "turn key" the water pump shaft thing and the fasteners for the bell housing dust covers were a little hard to reach, everything else was just a drop in.

Are you nuts? 261 to 235 is like gold to silver!

I'll take the 261, though, if you don't want it...