The Stovebolt Site Forums The Shop Area Engine Shop 235/261 technical question

Aloha!

Bare with me please, OK I am/was looking for a 261 so i called a local guy that builds engines asking if he had one, he then went on and explained that the 235 is a better engine and I'll try to describe here as best I can what he said so you more knowledgable than I engine guy's can confirm or contest what he say's. "any new piston's you buy are .020 below the deck "in the hole" of the block at TDC, all of them, i don't care where you get them, chevy's specs call for .005 to 0 below the deck, I put the pistons .005 ABOVE the block by shaving the head and the block, this increases the compression ratio and gets you more horsepower but you are not running with a thinner cylinder wall as in a 261" Also mentioned not being happy with the stroke on the 261 and you can basically get to 261 by overboring the 235 but thinks it's silly. thats it in a nutshell, but absolutely thinks a 261 is a waste of money, he does have several 261 blocks available so he wasn't trying to sell me machine work on my 235, just strongly recommended the 235 instead.

What do you guy's think? And I mean engine guy's please, all due respect but I'd like to hear from guy's that build or that has documented the differance, not just installed a 261 and are comparing the differance from before to after, unless it's been dyno'd, nothing personal, this guy was pretty intense and very adament about the subject and I wish I could relay more accurately what he said but i think i got it close enough above.

OK many mahalo's

A HUI HAU

Balderdash!
O wait, I didn't dyno, would you like me to delete?

I agree on the "balderdash" statement. I don't see how the guy can state that "any new pistons you buy are .020 below the deck."

That's just not true. I don't know the specs for each and every piston on the market, but I know they aren't all offset to put 'em further in the hole.

You could have the block zero-decked but if it were me, I'd sure wanna see how far the pistons were inside before I started any milling.

I can't tell ya the difference between a 235 and a 261...but I sure like my ol' long stroke 292.

Either this guy is totaly ignorant or he's been smoking too much Maui Wowie...

1) A 261 has equal or greater wall thickness than a 235 - after all, this was Chevrolet's heavy truck engine.

2) The 261 has stronger rods and full-flow remote oil filtration (on later versions) which is something no 235 ever had.

3) The 235 and 261 have the same stroke.

4) He's right about one thing...to overbore a 235 to 261 is not only "silly", it's just not feasible, that's .187" and the block would fall apart if you didn't strike water first.

There's no substitute for cubic inches. Machining costs are the same, so why not go for another 28 cubic inches of torque?

To add to what sixpack said-

As far as different stroke, the strokes are the same. If the 261 rod is different length, he could have referred to rod/stroke ratio or perhaps even bore/stroke ratio.

Most oversize pistons do come with a slightly lower deck height built in. This serves two purposes: One- it keeps the compression ratio the same as stock and to prevent the piston from sticking out above deck on a block that's been shaved on an earlier build. I was told this by a pontiac engine builder. TRW forged flattops can end up .020 to .050" down in the hole depending on oversize used and tolerance stack-up. This will cause detonation problems on high compression ratio V8s due to the small unswept volume above piston.

chip

It's been my experience building a few 261's that the guy is right on one thing,stock style flat top pistons do fall from .020-.035 below the deck.But, so did the standard size old GM pistons I removed from those engines. You know, it's a low compression truck engine.That's why I milled the blocks to get the pistons within 10 thousands of the block deck at TDC.In fact, some stock style oversize pistons for 235's are .020 below the deck also.On the rest of it, he's a BSer like the guys above said.Sounds like he has no 261'a but a few 235's to get rid of.

Aloha brudda's! Already in this short amount of time since I posted you have confirmed what I thought, I didn't mention before but the guy is kinda scary, no, very scary, He's smokin Maui wowie dipped in hash oil laced with ????!!!!!!!

Sixpack; you reminded me, thats what he said the only gain was, torque.

Tony; I already have a 235 so he wasn't really trying to sell me anything, even though I did mention above I was looking for one, sorry, my mistake

The guy really seems to be a full nutter, but because he does build engines and has a lot of stovebolts i thought he had to know something about 'em. I learned long ago to avoid him at antique bike shows because he usually was some half-baked F'd up idea about something!

Thanks everybody, you too tonyM, I really don't think this needs to go further.

except where in thee H___ am I gonna find a 261, aint no way i'm gonna buy from this chump. They are really hard to find here in SoCal, please help!!

--------------------------------------------------
He lawai`a no ke kai papa`u, he pôkole ke aho;
he lawai`a no ke kai hohonu he loa ke aho.

literally; A fisherman of the shallow sea
uses only a short line;
a fisherman of the deep sea has a long line.

which means; A person
whose knowledge is shallow
does not have much,
but he, whose knowledge is deep, does.

Schoolbus or heavy truck.

Oh no!! he did tell me how to tell if my 235 had hydraulic or solid lifters, he said to look below and to the right of the cam cover on the back of the engine and if there was a small allen head set screw there it was hydraulic! Is this true? mine has one!!

ALOHA!

If he says a 261 is worth very little, offer him $20 and see if he'll take it.

Boy Ralphy, that is a lotta words to say nothing. So your basic point is 261's aren't that much greater than a 235. Is that really what the guy was saying? I believe the guy was saying 261's were less dependable and 235's better.

All things being equal the motors are almost identical with the 261 having more cubes and more hp. It has an different casting for the block and reinforced internal components. For many larger trucks the 261 was the largest motor you could get.

Tony M,
Your right, I used too many words. I will follow your lead and use less words and more postings to say nothing. :p

I like what you had to say Ralphy, thanks

Wally/Montana; EXCELLENT IDEA!!!!!!!!! although the wanker did say he was "hoarding them for some unknown reason". I'm gonna try that!! I'll keep ya posted if I score 'em,

Anyone got an answer about the hyd./ solid lifter allen head set screw I mentioned above?

And finally, I'm only looking to upgrade my '51 Carryall suburban to tow my '51 22 foot camper trailer to LOCAL (1 to 2 hour drive)campsites and vintage camper rallies and at the most up to a 5 hour drive (maybe!), not building a highway flyer or hotrod or cross country hauler, so Ralphy sounds like the 235 will handle that or do youse guy's think I NEED a 261? I have been looking for quite a while with no luck, and I got a few connections too, or so i thought huh?

CHEERS and ALOO----HA

well'p,I replaced a 216 with a upgraded 1962 261. Have had 235's. For a 22 foot trailer, I'd sure take the 261 if you find one. I had NO trouble getting new parts for my 261 rebuild. I did use an EXCELLENT machinist.And boy does it run.

Don't worry Ralphy, there was a lotta good stuff there. It is just that anything over 100 words becomes tedious to read. So when you read between the lines your basic premise was that the guy wasn't all wet and 235's are better engines in some way.

Well, the guy is all wet. The 235 is not a better engine in any way, power or longevity. Both are great engines. The 261 will have more grunt.

With the proper transmission you could easily tow a trailer up to maybe 2500lbs. Maybe a little heavier for short hauls. Trailerbrakes are always a must except for on the smallest trailers regardless of engine size.

Mornin!

Trailer weight unknown yet, but fully loaded maybe 2500lbs, electric brakes, single axle. see it at;

http://community.webshots.com/user/kimo90803

NOW, although he's all wet and smokin strange stuff has anyone really THOUGHT OUT what he's getting at by putting the piston .005 out of the hole and increasing comp ratio. Just for a minute put your preferences for the 261 aside and think about it or even better, has anyone else done it?

geez if I thought he could type I would recommend him getting on this board but ain't no way he has a computer and you'd never want to meet this guy in person, you'd end up killing him, trust me.

Alooha, summer is on the way!!

nice stuff you got,kimo. you got me thinkin. I checked with my machinist 'n he said he always checks for this kind of stuff(piston fit). On old motors he half expects a problem. My 261 was fine. I got the pistons from Patrick's.Runs GREAT! Goin for a ride now.

You cant always tell if a motor has hyd lifters by the drilled passage. Some engines from '55-62 had the drilled passage and still were fitted with solid lifters.

And I've never heard of sticking pistons above the deck, except on all-out race engines. You're bound to smack a piston into something doing that on an old engine like a 235/261.

chip

The 261 has siamesed cylinder walls but the 235 doesn't. That may be its only disadvantage since the flow of coolant to the head isn't as good.

I love my 261, I used it to pull a bed full of rocks (about 1500 lbs) up the Sunset hill at 55 mph yesterday and it didn't even seem like there was a load in the bed. My old 216 couldn't make it up that hill without slowing down, but the 261 was still pulling a strong vacuum. The temperature never went over 190 (with 180 thermostat). Nothing else about the truck is changed, same gear ratio and exhaust pipes.

4onthefloor, while I'm in awe of your knowledge about these old trucks, my experience is similar to your above post. LOVE THIS 261 !!!

I don't know as much as I sound like I do. I just tend to remember everything I read and then post it. It all comes from being a motorhead, I guess.

you know lots,4onthefloor. this site is amazing. I'm a beginner 'n you guys are awesome. Just took hound a ride in my 40' with 261.Stock otherwise. You DO NOT have to shift this brute out of 4th ANYWHERE. Love it soooooo.