The Stovebolt Site Forums The Shop Area Engine Shop wanting to add a 261

browsing through the gallery I noticed several of you have put 261 in your older trucks. My question is I have a 1950 3600 chevrolet and a freebee 261 from a 1.5 ton and want to replace my blown up 216, how easy is it and what do I look out for? Thanks

bowie texas 50,

Welcome to the site.

There is a wealth of information in past postings regarding conversion to a 261 engine. Try a Search in the Engine forum (search on "261" or "261 conversion").

Here is a recent helpful discussion.

After reading a few old postings, you will be better able to ask specific questions. There are a lot of people here that are willing and able to provide assistance with 261 conversions.

Some of the major issues are:

1. front motor mount
2. water pump shaft length and pulley diameter and pulley location
3. clutch housing
4. flywheel, clutch assembly, and starter (6v versus 12v)

I did a conversion 35 years ago with little mechanical experience (but a lot of advice from gear heads).

Do you know the year of the 261 engine? There are casting codes on the starter side of the block and there is an engine serial number pressed into the ledge right behind where the distributor enters the block. Post those codes/numbers and people will help out with identification.

Good luck,
Tim

If you are capable of pulling the engine you have and drilling a few holes, you will be able to upgrade to the 261. It is a worthy swap. What year is the 261?

Its a rather easy conversion. You need to use the 216 motor mounts, the 261 will not work, the bell housing from the 216 has to be used, not the 261.
The water pump needs a shorter shaft, you can modify the one you got, I bought new from Patricks and it was built for this conversion. Hopefully you have the full flow oil filter, that was standard on the later 261, but you can modify that by drilling some holes if its an earlier model. As the previous posts mention, there is a lot of information out there on this conversion. I had a perfectly good 216 and made the conversion, now I will be able to run it on the highway.

Wow! I just posted this question last night and already have loads of help on the way. This is an awesome site!!! I will get the code info shortly, oh, and the truck it is in is a 54 with a dump bed. Big ol truck. I would just build that but the 50 model 3600 seems more of a driver to me. I have the bell housing from the old 216 and also for a 235. I spent $500.00 on having the 235 machined and the head redone but it will cost an equal amount for the new engine kit. The 261 is free and will run good with little expense so I guess I will put the 235 on ice for later. This is my first project which I have already completely tore down which was overwhelming at first, but now have the guts to dig into. I am looking forward to hearing the wealth of knowledge from everyone out there and hope I can help someone else. I will get some photos posted soon. Thanks again everyone! Trevor

The '54 261 should fit in without mods to the water pump.

Yes, the '54 should be the easiest to swap in.
You don't get the full flow oil filter, though. But you will like it.

This may be a really dumb question, but can I use a radiator from a 235? I already spent the money having the 235 radiator re-cored and the 261 radiator is shot. Where can I fing literature on the 261? doesn't seem like much is out there or maybe I'm looking in the wrong place.

bowie texas 50,

The 235 radiator will work fine.

A 1954 Shop Manual has information on the 1954 261 engine.

You will not find a GM Shop Manual with information on how to install the 261 in a small truck. This site is your best bet for that information.

Go ahead and ask the questions. You might want to do a search first (like "261 radiator", in this case) but you will get answers even if you just ask questions.

As everyone above has said, this might be new and strange but it is not technically difficult AND you will indeed like the extra power from the 261.

Tim

Thanks Tim! I can't say enough how helpful this site is. Hope to return the favor

alot of the stuff from the 235 will work on the 261....