Curious about Canadian 261's

vanherk1 · Member

RE: Curious about Canadian 261's

long stroke · Canadian Poncho Superstar!

rrausch wrote:
What ever you do DO NOT USE A 235 HEAD ON A 261 BLOCK! Do not, do not, do not do it brother. If you do you will be crying, kicking and doing a lot of swearing. The 261 had steam holes that surrounded the bores and also had steam holes that matched up on the cylinder head. The 235 did not have these holes in either the block or head. The 235 head will bolt up but, and here is the BIG BUT! Your motor will over heat real bad my brother. 261 motors ran hot normally, hotter than the 235 because the 261 not only had a bigger bore it also had a higher compression. This is the reason and only reason for the steam holes. Let me repeat myself DO NOT PUT A 235 HEAD ON A 261 BLOCK OR YOU WILL BE CRYING LIKE A LITTLE GIRL. That sweet motor will over heat real bad and then blow. You can drill the 235 head by using the 261 head gasket as a template. The only thing is you have to drill on a angle and unless you know what you are doing you will ruin the 235 head. Best thing is to just use the correct 261 head. I sure hope you are taking me seriously because if not you have my condolences on that sweet 261 of yours. I love these motors and have one in my 1957 Pontiac. Check out my 261 and my 57 Pontiac in Members Rides under "My 57 Ride". Good luck with your sweet ride. Cheers. George.

That's an interesting swap on the '70 Cutlass.

I'm running a 235 head on my 261. It is the 848 head, and came off of a '59 or '60 235--I forget which right now. I do have the original 850 head for the 261, but from what I've read the 235 head will make a little more compression.

Thanks for the Inliners link. I have visited their site at times and found their info very useful. I'll check it out again.

CdnGMfan · Canadian Poncho Superstar!

vanherk1 wrote:

What crank are you using? As far as I know, you can't interchange the the 2. You'd wind up with a stroke that would bring the pistons wayyy above deck height. Or just a misprint?

I'm using a 6-counterweight 1964-66 292 truck crank, 4.125" stroke. You are right, that crank is designed to work in a tall deck 292 block. Using it in a 230 / 250 block means using a lot of custom parts and lots of machining for clearance. My block had to have the bottoms of the cylinder bores notched, plus I had to use custom made long rods & pistons with the pins way up high (almost into the ring lands) to minimize the rod angularity and make it work in the low deck block. The guy who built it has been building stroker motors for decades, and the race motors he builds stay together. With the big swing of the crank we even had to use caps screw rod bolts for clearance, plus there were oil pump clearance issues. I also have to run an electric fuel pump because the fuel pump mounting on the 292 is in a different place than the low deck blocks. All in all it is not a terribly practical sort of way to get the cubes. One would be better by starting with a 292 block but then hood clearance becomes an issue (unless you run side draft Webers or rig up a creative turbo arrangement).

long stroke · Canadian Poncho Superstar!

CdnGMfan wrote:
Sure it is all more bucks but it is all worth it. Beating by your own drum and not some body else's is far more full filling. Why go cookie cutter and belly button when you can make your own path. Cam your motor is not only beautiful, i have no doubt it will bury many a common V-8. An added bonus is at car shows and cruise nights you will stand out and be noticed instead of just blandly blending in. I commend you brother, sweet, sweet motor. Cheers. George.
That 1970 Cutlass S was Hillar's car? That being the case I must have met Hillar back in 1992 when I saw that car at Markington Square (Markham / Eglinton). There used to be a weekly cruise / show thing going on there back in the early 90s, much like the Route 66 deal now. I was impressed by the presence of an Oldsmobile Action Line 6 under the hood painted gold like the Oldsmobiles were. Lots of Clifford stuff on it. When I priced out Clifford headers for my 6 cyl Chevelle they asked $600. I said "No thanks!". Today I have got a hot rodded Chevy inline 6 being readied to go under the hood of my 67 Chevelle. It is a 292 built out of a low deck 250 block for hood clearance with the twin downdraft carbs I will be running. It was an expensive way to go with all the machining, custom rods & pistons... I am ordering a custom ATI damper for it shortly (more buck$).

As for the old 261 sixes, I thought the 261 Pontiac also had hydraulic lifters rather than solid / mechanical lifters like on the 235 & 261 truck sixes. I do remember a friend's brother's 57 Laurentian had a 261 that ran so quietly you didn't hear it running at all (it didn't have the Powerglide whine since it was a 3-speed manual).

-- Edited by CdnGMfan on Thursday 16th of December 2010 03:19:35 PM

vanherk1 · Member

Crazy. Actually, I believe the 6 weight was 63 only in the US, and used into 64 in Canada. I have the same crank in mine. Forged, I believe. I'm guessing you already have a copy of Leo Santucci's book?

vanherk1 · Member

Where did you get the Wayne side cover? A repro I would assume?

rrausch · Member

long stroke wrote:
What ever you do DO NOT USE A 235 HEAD ON A 261 BLOCK! Do not, do not, do not do it brother. ......The 261 had steam holes that surrounded the bores..........DO NOT PUT A 235 HEAD ON A 261 BLOCK OR YOU WILL BE CRYING LIKE A LITTLE GIRL. ........ Good luck with your sweet ride. Cheers. George.

Thanks George. Ahhhh... we aren't all fools down here in the US! :) I cunningly DID drill steam holes in the 848 head, and yes I had to angle the bit a bit. I used the 261 head gasket as a template. But thanks for your warning.

rrausch · Member

Yes, the Wayne side cover is a repro. I first went with a Clifford side cover but it was an absolute POS. It was too thin, was wavy and had not been machined at all. In contrast the Wayne side cover was more than twice as thick, twice as heavy, and machined and polished. They were about the same price. I had a lot of trouble with stuff I've bought from Clifford and I won't buy from them again.

vanherk1 · Member

I've heard similar things. Also the same with the Offy valve cover and Clifford valve cover. With the prices they charge...