Stroked 265 SBC characteristics, opinions?

Hi,

I recently picked up a 55 265 small block and I'm planning a cheap as possible sleeper build whilst keeping it dressed in period 50's clothes and this is what I've come up with so far.

As far as I see it, I could use the following parts combination on a 9.025 standard deck block and build a 339ci stroker motor.
stock 400 chevy 5.565" rods, flattop 60 over 3.796" bore 305 pistons with a 1.560" compression height and a cheap cast 383 / 3.750" stroker crank with the main journals turned down from 2.45" to 2.30"
As far as I work it out I'd end up with the pistion -0.025 down the bore and it all fitting together, this is obviously ***uming sufficient clearancing can be acheive which I think can based on the old fuelers taking out 265 / 283's out to 352.
The only other parts i have nailed done so far a set of 58 vette heads that a mate has. No firm plan on what I'd do to these yet but probably something like hardened seats, gasket matching and a port job. Exhaust would either be 2.5" rams or tri y headers. Intake wise I'd look at a factory cast 4 barrel with hopefully a factory 50's carb if I can get sufficient CFM by going that route, maybe a wcfb carb from a '59 348, opinions? I haven't planned far enough ahead yet to add for cam specs as don't know what it will go in yet, but it will be a stick car with 4.11's.

I'm quite confident it can be built but the reason of the post is to get opinions on what sort of characteristics this type of motor would have as far as HP, torque and rpm potential with it's long stroke and smallish bores and early style heads, intake and carb? Has anyone an idea or a desktop dyno to see what sort of curves it would put out with say a GM 327/350HP hydraulic cam 221/221 duration, .447/.447 lift on a 114 lobe?


So what do you think? And please don't say fit a 350 cause I want to have the 55 pre filter look.

Thanks in advance for your views

Gotzy

 

Coupla things: Crank won't fit--not just journal mods, but counterweights too big for a pre-63 or so block. You'd have to cttemdown and balance with heavy metal, I think?? 400 rods not optimum, and piston way down bore will make engine prone to spark knock and less responsive--you NEED tight quench, IMHO, so custom pistons.
Almost all 265 engines were bored out to 3 7/8 with 283 pistons as soon as rodders got them...

 

Not only will the counterweights be hitting the pan rails, so will any rod that you try with a 383 crank. In a typical 350 block the rod bolts hit the pan rails which is why the block is relieved on the rails and also at the bottom of the bore wall.

Save youself alot of trouble and $$$ and just do up the 265, squeeze the compression a little, find a good set of 283 fuelly heads or aftermarket equilivant. Push in a nice Dontuv spec cam, a low profile twin four intake or triples and some ram horn manifolds, have fun with it.

I had a stock twin four 265 in my 56 vett, it put out 210 ponies. Was plenty to have fun with.


Not to mention that the short stroke 265's and 283's are a hell of a lot of fun drive with a four speed.

 

The block change, done as the 327 was introduced, was to the roof of the crankcase area...it went from flat to curved to clear the longer stroke crank's counterweights.
265's went to 3 7/8, 283's to 4.00...283 and 301/302 displacement.
3.5 inch cranks were available in 283 days, and made a 301 into a 352.
An early Chevy NEEDS a Duntov solid lifter cam...the particular lope and slight clatter are a necessary part of a hopped early SBC!

 

I know I've done at least 1 similar deal for a customer. Man, I wish my memory was half as good as some of you guys. Pretty sure I had to cut the rod journals to small journal size so the rods would clear - still required notching the bottom of the cyls. and the pan rails I think. Don't remember having to cut the counterweights (although I've done so many through the years it's hard to be sure). Also this deal may have been for a 327 SJ block but should be about the same as a 265/283. I've got a 383 stroker crank here but sold my last 265 block or I'd see if it looked like it'd fit.

 

Well, I think and type slow - Bruce's info about the 327 block change makes me think these were done for the 327 blocks.

 

the 235 six had a similar bore/stroke ratio

 

Thanks people,

Whilst i expected to have to clearance the pan rail and the bottom of the cylinder bores i wasn't aware they rounded the internals of the block. Bruce, do you know if any additional webbing or strengthening was added at this time or if the factory simply clearanced their own castings?

Also Bruce, what to you mean when you say the psiton will be too far down the bore that it will create spark knock? I'm simply not familiar with the term. Acorrding to the calculator http://www.kb-silvolite.com/calc.php?action=deck a 3.750" stroke, 5.565" rod, 1.560" piston and a 9.025 deck puts it only -0.025 down the bore, why would it be a problem? I read that as being able to get a nice high (10+) compession with the early heads, is it a stroke or piston dwell characteristis or something?

Cheers for the info so far!!

Steve

 

gotzy,
talk to some of the tri five chevy restorers from memory they use 350 crank turned down to small journal size. some even offset grind the 350 crank to three and five eighths for more capacity. still have to do some block grinding for clearence.
Al.

 

spark knock is also known as pinging or detonation, it's why you don't want to run too much compression in any gasoline engine.

Quench is the narrow space between the flat part of the piston and the flat part of the head, it causes a lot of turbulence as the piston gets to TDC. This reduces the tendency to knock, so you can generally run more compression with a high quench engine. Reducing quench by not letting the piston go all the way to the top usually limits how much compression you can run. for exmaple if you had zero deck height you might able to run 10:1 with some particular octane gasoline, but with -.050" deck height you might only be able to run 9.2:1 (I made up the numbers here)

 

You can deck the block .020 to get to .005 deck clearance (.044 nominal) head clearance(with hypereutectics that can prolly be closed to .000,deck block .025 for .039 nominal) without head gasket clamping issues and cut a small d-dish in the piston (if one with the dish is not already commonly available) to bring the comp. ratio back in line with the standard of 10.0---10.5:1 comp. ratio.
Typically a 0 deck and a d-dish allows an increase from 10.0:1 to 10.5:1 in most wedge engines without detonation or preignition issues on high octane pump gas (hypereutectics have a tighter piston clearance which allows tighter deck clearance at piston rockover).
If you want to run the "cheap ****" (LOL) keep it at 10.0:1 max.
I cannot speak to the "crank counterweight /rod to block clearance issue" or non issues on a 265 block with a 3 3/4 stroke.
However a slightly over square engine,if it'll all fit together would be a screamer if not for the poor rod length to stroke ratio,roughly 1.48:1, with (1.7:1 or so as a best all around ratio).
Even though there is substantial room for disagreement about a short ratio working better with a stick and a long ratio working better with an automatic,1,48:1 I believe is still considered to be a poor ratio in almost all circles.
It's an interesting question.Good luck and happy building.

 

55' 265 CID engine blocks did not have a cast-in-block- oil filter mount. That did'nt come out till 56'. The 55' oil filter was an option and I don't believe was full pressure (not that any of them are with the byp*** relief valve). Not the best block to use to begin with; would be best left to a restorer, but I know you're in Great Brittain, and that's probably not a real concern as it's an American V-8. If you really have to use that block then do what everyone here says to do. Build it with the stock crank and rods, punch it to 283 and find some 283 F.I. pistons,Power Pack or #416 305 heads worked over,dual fours, a dual point, rams horns, and a decent cam=1960's Anytown, U.S.A. Would be cheaper and more nostalgic than what you're proposing. This is the engine from the burned out Nomad right? Did it have a transmission hung on it?BUTCH.

 

Yeah 265's ****.

 

Just read on Chevytalk that you can't even use a "late" 283 crank in an "early"283/265 block as the counterweights won't clear. I would guess early to mean front mount style only blocks; no side mounts. So what you propose is really not going to be possible.BUTCH.

 

Most of the old timers bought stroker cranks. There were a lot of guys selling them back before the 327's and 350's.

 

One of the neatest things about a hot 265 is its ability to rev quickley and high. The heads you talked about and a Duntov with a hot spark and a proper sized carb is all it needs. To get a big inch engine, start with one and save your money.

 

Can someone find and post the olde HRM article (circa 1961) on putting a 327 crank in an early engine?? That detailed the upper crankcase issue--early blocks flat roof there, later rounded...I don't remember all the details on that'
Pistons need to be as close as possible in the flat quench area for turbulence and good combustion...any space needed to drop compression needs to be under the open part of chamber.

 

Yeah thanks again for the input people!

Cheers Squirrel, thought it might be referring to detonation but not too worried as over here as we have better gas than you guys and would plan to try an hit close to 11 to 1 as I can.

That's also my understanding of the quench area hence my confusion and as Yo Baby says, it can be tightened up if necessary by decking the block. I also have a couple of piston choices.

Yo Baby, yeah the poor rod/stock ratio is one of the reasons for this post in the first place, trying and find out how it would effect it characteristics. From what I've learnt so far, short rods are good for reducing detonation as they reduce the pistons TDC dwell period which will be good for an iron head with high compression. So would the long stroke increase the torque of the motor whilst obviously hurting rpm? Is it also true short rods benefit from early opening of the exhaust valve and for that matter, increased exhaust valve size?

And Butch, not quite with you. My original post describe what I'm trying to achieve, a sleeper 265 dressed in 50 clothes, racing stroker cranks where been used as early as 58 (58 Lister, 5500cc stroked 283) so it's nostalgia all the way, maybe high end for the day, but period correct. I've already taken the correction from Bruce on the solid lifters so I don't see too many loose ends? Yeah it did come out a burnt Nomad and had a glide on it.

Ole Don, also planning a simple 283'd street motor as well, this one is for a little bit of racing use to **** in the "it's only a 265, should give it to the restorer" crowd, no offence Butch ;-)

Thanks once again Bruce, I'll try and track that article down. Fully with you now on your other points, cheers for the quench comments as well could have easily got incorrect or less than ideal slugs there!

Any one got a bare 265 and post 62 blocks and a camera sitting around?

Cheers

Gotzy

 

I've got a 1958 Hot Rod handbook that lists a 4 inch bore X 3.5 inch stroker kit for a 265. That gives you 352 cu.in. I don't know about boring a 265 to 4 inches. Probably enough corrosion on the wet side of the 50 year old cyls. to cause a problem. I'm still thinking I built a 400 crank for a block with no side mounts - the idea was to make everybody think it was a screaming 265. Wish I'd kept better records.

 

About the rod length. I've built a number of 383 inch smallblocks and I realize there's a lot of factors involved but it always seemed like the ones with the 400 (short) rods and 350 (cheaper) pistons didn't run as well as the 350 rod and expensive piston setup.

 

There are 2 or 3 excellent early books on souping the Chevy and several good HRM articles in the early years.
There were plenty of stroker cranks offered, but I think sources evaporated early on as it was always cheaper to move up to new hardware each time Chevy invented a new size...early cranks also typically added a couple of counterweights to better balance the shaft. I'm curious about max bore on a 265...283 was always considered safe, but my impression was that 4" was deep into Russian Roulette territory.
I don't think any rodder in those days ever bought an 030 piston...any Chevy needing work was bored right to 283 or 302. the crank needed made a 352 a fairly expensive motor for the big dogs, and provided one more nail in the coffin of the 348, which never really managed to ***ert itself over the 283 even...

 

When you get past all the above, you might find some of the rods hit the cam also. You're gonna really have to want this combo to deal with all the drama. Just to have a motor with no oil filter?

 

Yeah 2many as you and other have said, they can take at least a 3.500" stroke. If I could get a 4" bore then it'd be much cheaper cause as it stands i'm stuck with 305 bore sizes for the required piston height. Looks like only time will tell if a 3.750" crank will fit!

Popular opinion seems to be with you Bruce on the max bore size. If i can stumble across some cheap 265's over here I might get them sonic tested for thickness to see if a 4" bore is acheiveable, do you know how much metal should remain after boring for it to be regarded safe?

Do you recall the ***les of the early books you mentioned?

Thanks

Steve

 

Reference sonic testing, I once read 5/64th or 140 thou remaining for safe, sound right?

 

I'll check my library tonight...there are also some basic early Chevy articles in HRM, and any speed catalogs up into the early sixties might be useful.
On the rods, Dave Vizard, the (British) SBC expert, goes so far as to dismiss 383 conversions with short rods as a waste of time!
You should have a look at catalogs from Corvette restoration places...they have the Corvette valve covers, air cleaners, and wiring-routing stuff that is fundamental to the general look of early rodded SBC's.

 

I think you're really on a mission to spend too much money on a hand grenade! I'm not sure what safe is (you're shooting for a QUARTER INCH overbore), but putting a bunch of money in a motor, then splitting a cylinder wall is a real heartbreak.

 

on a similar note i read a 62 article on puling 462 cubes out of a 283 forget which mag it was tho

They had to knotch the sleeves so they didn't hit each other

 

I think I saw that, in one of the small minor mags--I remember a pic showing the ragged edges of the original cylinders after boring completely through them, and the solid row of shoulder to shoulder sleeves...I'm guessing the thing just about disintegrated during its first run. The bock was basically the structural equivalent of two shoe boxes after removing the cylinders...

 

Might have been Hotrod Parts Illustrated. I think they had a series of articles on welding in siamiesed sleeves to make big inch blocks. Also welding 2 diced up hemi heads together to make a hemi 6 cylinder Ford. Just a normal 1 cylinder sleeve job can cause a lot of block distortion - cutting them all out and welding 8 in would be interesting at least.

 

Yeah I know what our saying but I'd only do it to block that sonic testing says you can. The whole point of my investigations is to do a big cube 55 motor as cheap as possible using cast components with machining and only the balancer giving the game up. And that's only if I can get some £50 blocks to check. Don't forget my original plan was 305 pistons which are well short of stock 283 bore so no risks taken there. Rotating ***embly before machining for that is under $1k and I have no plan to throw money away taking big risks!