Technical we need a dedicated 261 thread.

I'll go check, I have one of each.
i will see what the difference is between the Canadian & U.S. models.

 

Awesome old thread.

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It's together and running on the test stand with some changes to the Gilmer belt cam drives, tensioner, and water pump.

Next is dyno testing, and ultimately installation in the as yet unfinished '30's dirt track race car.

 

I have been looking for a set of pop up pistons for my 261. I checked with Ross who got the old Jahns specs and they gave me a pretty hefty number. I just talked to Tom Lowe and he quoted me a set of Ross pop ups with performance rings and .927 wrist pins for $880. This is for one custom set. I haven't ordered yet, but if anyone else would be interested, maybe we could get a volume deal. The real cost is in the setup. PM me or contact Tom at 12 Bolt and see what he says.

Warren

 

I am starting a file on responses and see where it takes us. I will contact you in a couple of weeks

Warren

 

I believe these pistons were originally designed by, and made for, the late Tom Finn,and feature in Ross Piston's advert in "the 12 port news".

I don't know their final compression ratio, but it'd be considerably over 8.8:1

 

That would depend on the head. 848 is about a point higher than a 913 or 850 casting. I'm opting for a lower compression head as I suspect they flow a little better due to their open chamber. Use the pop up to get compression. Also notice the recess for the intake valve which must be compensated for. Squish has to be figured, I think there is an optimum value for the clearance.

 

Head CCs
3836848 79.1 cc's
3835913 86.2 cc's
3836850 86.2 cc's
3703570 95.5 cc's"

 

From page 1 of this thread, it's all here somewhere. Squish or quench.

 

PM sent

 

I'm also all over this also Warren. I see you got your 261 all buttoned up and on the strip.

 

On one shift, I hit about 5700 RPM and bent a push rod., So I have Smith Bros. building me a new set. We were also lugging coming out of the hole, so I had Frank Lupo at Dynamic Converters build me a 8" high stall unit. The triple 97s work very well once the revs are up and the McGurk cam seems right at home. I have currently decided against the popups and am going to mill the head. Curt never did any head work for me so I am going to clean up the head this winter and install a set of Powerglide valves. The car is quite unbuttoned right now but it will return to its' former glory. How's the truck running? I will be out in Edmonton next summer with my hot rod on the way to Deuce Days in Victoria so we should get together.

Warren

 

The larger power glide valves will be a nice touch with the milling. You using the smaller chamber 848 head? I just ready to start my new 261 build up as im having a issue with the 235. I have the larger valves also ready for the new head work. Not sure if im going to mill it as that will also required the valves to be recessed but maybe someone might twist my arm just enough so I might just end up doing it. Spent early spring doing a few mods to the 235. Got a 2 barrel EFI setup. I used a Clifford Intake and modified it to properly fit the 235/261 heads as the way they sell them is kinda poor. Made my own adapter to work properly between the 2 barrel and the intake manifold. Bough myself a CNC machine for the garage and made up the adapter after I was happy with the 3d printed setup.

 

Hi all, glad to be part of the 261 club. I just picked one up with a 1955 Hydra-Matic attached to it. Unfortunately I can’t find a start for it so the engine will be attached to a SM420 with a new rear end.


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What is the maximum R.P.M. a 261 can turn without doing damage?

 

I run mine to 5500+, but you loose all power after 5000-. I have heard of 6000, but it probably only got there once. How are you doing Robert?

Warren

 

Good thank-you, I wanted to know for this summer.
The race car should be ready, we run everything from a medium banked 1/4 dirt to a 1/2 mile 36 deg bank dirt.
I needed to know for gearing.

 

What about a stock 261? What Rpm range should we keep it in for around town and city? 2000-2400? I have an SM420 I just rebuilt and I’m thinking about the rear end (3.43 or 3.08).


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Neat thread. I picked up this 1959 261 from a Viking 60 for my 51 burb. Going to up the compressor and put in a delta cam. Then run the dual Rochester and Fenton headers setup from my 235.

 

Here's my 55 that the 261 will go into. I'm running the stock SM420, with the stock 4.57 gears, and I will be putting a Brownie Junior overdrive in it, which is 0.82:1. I have a set of 4.10's for it but I decided that with the 34" tires that by the time I get into OD that I'd be under geared. Anyone disagree with that? My plan is to do some mild work on the 261. I'll put a cam in it, and run a nice upgraded intake and exhaust. This thing isn't built for speed anyway, so that's not my concern. It's very hilly where I live so I'd like to be able to pull the grades around here and hop on the freeway and feel safe in the right lane on a weekend morning.

 

it's Josh, right? Good to see you're still around....

 

That's me, Tony! Thanks. I'm glad to see you still around too. As I was reading through this thread again I found my self wondering how you're doing health wise.

 

I'm still alive despite the fucking disease...Thanks for asking...

 

Well, I'm glad. The not being alive thing has been going around lately. At least one guy that was posting early on in this thread, from what I have been able to find today, has passed. Road Runner. I look forward to getting your input on which direction I go. I need to run up to Ken Brown's place and pick up my 261 from him. It was one that Andy Siechen had left in the stash out here when he left for Minnesota. So if Andy thinks it's a good one, I think it probably is.

 

Are you certain Road Runner has passed? I am so bummed out. Had a few pm interactions with him, he seemed to be a private or busy person or both. Damn.

 

Well, I followed the links from his signature and they are not working. From there I went to his main site, and it's not active. When I did the search on the site, it came up as being associated with him as a fairly well known guitar and amplifier builder and he was active in forums relating to that. I saw posts that confirmed he had passed and there was an outpouring as apparently he was quite a talented guy. So, not 100%, but it sure seems like it.

 

Yes, gone but not forgotten, rip Chris Siegmund. A number of moving tributes on The Gear Page.

 

Found two 261's both without crankshafts. Can A 235 crank be used with the heavy 261 rods and larger pistons?? Newc

 

That 55 1st. design.......with NapCo 4wd.......with my favorite color.......takes my breath away ......love it.