The Stovebolt Site Forums The Shop Area Engine Shop From 235 to 261? An easy swap? Should I?

Fellas, here is what I'm pondering:

I found a good, fully functional 261 from a 57 Pontiac, 20 minutes from my shop. Complete from bellhousing to air cleaner for 400$CDN (325$US).

The 235 in my 53 is NOT the original motor, it's a non-pressurized oiling system, babbitt engine. It 'sounds' tired...

I'd like to eventually add an Offy twin carb intake and Fenton (or split) exhaust, maybe a mild cam? Just for the heck of it, for looks and sound...

I'll also be switching to a T5 trans and Blazer rear end.

I guess what I'm asking is: am I mistaking or does it sound like an easy, worthwhile swap???

I need some validation, fellas!

I'd jump on it if I were you. These old engines seem to be getting hard to find these days.

The 261 should drop right in. There should be some info in the tech tips, in an archive search, or in the technical section at www.oldchevytrucks.org .

Must be a Canadian model. I,ve never heard of a 6 cyl. 57 pont.

Before you hand over the cash, get the casting numbers off the block and check it out on the inliners site.

Whizzer,

GO FOR IT....sounds like a good deal if it is a 261 for sure. Since you are doing the T-5 and rear, why not go big and do it all at once. You can spruce up all the stuff you are going to install. When it is all ready to go, put it in and be back on the road sooner.

Wrench, yes, it is a Canadian model.

46, that is the plan! Offy, Fentons, T-5, etc...

I'm going to take my time, even if it takes me a year.
I want to make it right, with the right stuff...

I just cant help myself, I cant leave it alone. I love the go-fast goodies and like the idea of a 'sleeper': stock exterior with faded paint, scratches and dings and eye popping engine bay, nice and shiny with a healthy motor rumbling... :p

The 261 full pressure oiling will indeed fit the motor mounts etc. Your water pump will need to be adapted with the short shaft to clear the radiator, however this will make the original fan interfere with the lower supports. You can get an adapter to use an different water pump which requires an extra hole be drilled in the block or you can put a pusher fan in front of the radiator and eliminate the fan.
If you are going to add dual fenton exhaust, you will have to bring the oil filter lines out past the hot manifold with metal lines and adapt them to a remote filter. If you have the filter from the 261 with the large cannister for the PF 141 filter the housing may be cast aluminum and able to be polished. It will conveniently fit above the steering column on the firewall.
One of the past posting also suggest that you change over the clutch to the larger size (10.5 inch ?) to accomodate the extra torque of the 261.

Whizzerick,

At that price, I say go for it. I paid $275.00 for a '54 261 that was in dire need of a rebuild. Nonetheless, after the rebuild I am very happy with the results.

Since '57 261 you are considering came from a car and most likely has a fiber cam shaft gear, you may want consider replacing the timing gears with a new gear set containing an aluminum cam gear. The aluminum gear will make more noise; however, it much more durable that its fiber counterpart.

Good Luck. I am glad to hear of your find.

Great info fellas!

- Will I be able to use the clutch from my 235 (wich I believe should be 10,5) ?

I replaced my 235 with a '61 261 and really like it. I used an 848 head from a 235 so holes were drilled in it to match the extra water holes of the 261 block. I stayed 6 volt so had to drill new holes in my old generator bracket to match the mounting holes on the block. All in all, a pretty easy swap.

I just got my conversion running. (46 chevy 3/4 ton)
261
t5 tranny (from firebird with a chevy tail. No problems with the clutch, slipped right in without grinding the input shaft, had the higher spline count)

4.10 rear end

changed intake manifold to one from jim carter that fits a holly carb,

hei ignition
fenton headers to fit the intake better.
fired up with less than 2 cranks.
a bit loud going to the muffler shop but boyu was it fun.

Would do it again in a heart beat.

Ted, what is that 4.10 rear end out off?
What are you getting, MPG and MPH-wise with that setup?

A 261 is a pretty easy drop-in for a 235. You may or may not find the throttle pivot in the same location, though. The external dimensions of the block, crankshaft, bellhousing, flywheel, starter, manifolds, water pump, distributor, fuel pump, and covers are all the same.

I'm glad the only cure for this disease is more of it!