Inliners International Forums General Discussion Hi Performance Can You Stroke a 250?

I know it is possible to put a 292 crank in a 250, but I have heard that those engines don't hang together very well. I've also heard lots of negative feedback on running a 4 inch bore in a 250. Now here's what I am wondering. Can you offset grind the crank and stroke a 250 1/8"? If so, what rods would you have to use. And what would the crank work cost? If it is feasible this would give you 267 CID if bored .060, and I think the longer stroke would make the motor even stronger at low and mid range revs.

It's pretty easy to get .75 hp per inch out of a 250. On that basis, theoretically, the additional 17 inches would mean an additional 12.75 horses. Ya never now when 12 horses might be enough to shut down some mouthy kid in a rice burner, or some clown from the 350 bolt on billet store!

Boo

Have you thought about building a 292 instead of the 250? Machining cost the same, parts are very close in cost.

Of course I've considered a 292, and I'm still considering one, but with a 292 your looking at 4.125" of stroke, and long stroke engines don't wind up quick enough.
Boo

I believe that this wouldn't be a very significant factor. Not comparing hp/$$. For the money it would take to totally rework the crank and go to a custom rotating assembly I'm pretty sure you could add something extensive on the 292 to more than compensate. Just my opinion. Greg

hello...good question....let me add this... the 292 does not "wind up" as fast as you stated, but the torque that is created as the 292 "winds up" FAR out ways the torque and HP the 250 creates at same RPM.....I have read here on this Forum of the concept of using the 250 for better gas mileage also, well interesting concept...what works best? a fast reving 250 or a higher output, slower reving 292? the 250 will work harder to create same power and burn more gas than 292....the 292 will produce more usuable power at lower rpm...so whats best- more upper rpm power or more lower rpm power and THEN MORE as the 292 is capable of?...after having 3 250's and 3 292's since 1976, the 292 has proven to me, stroke over reving anyday=but where do u want to spend your gas $$$$? at low rpm's or high rpm's? 292 can do both, 250 cannot.....this doesn t mean the 250 is not a good engine, it just means what do you want? have you tried both engines in different forms?Does this make sense? does it really matter?
Lee

i know the 292 is the best to use. but maybe some of us have a lot of 250's laying around and just can not seam to find a 292. so we want to maks do with what we have.

But buying an engine that is already stroked (292)is much cheaper than stroking an engine you just happen to have around. If one can't afford a 292 one certainly can't afford to make a 250 outperform a 292 for less money.

A stock 250 has more hp per cubic inch than a stock 292. A 292 is a truck motor!

Boo

A stock 250 would also have more hp/ci than a stroked 250 without any other mods, so what's that prove? The added torque is what is needed for accelleration, not high end horsepower. The 250 and the 292 are basically the same design, the 250 was used in trucks also.

Yeah, you'd better not laugh at truck motors, the chevy 454 is a truck motor and it makes a little bit of power.

You guys crack me up! I ask a question and you all put in your 2 Cents worth, but not not one of you knows the answer. I don't know why everyone on the web is a self proclaimed axpert at everything, even when they don't know **** from shinola!
Boo

Actually, you asked a question and it was answered; you didn't like the answer. Offset grinding for 1/8 stroke would net you at least a .125 undersize rod journal unless you weld up the journals and regrind, very expensive and not worth the expense except to keep within certain limits for class racing. Call Crankshaft Company of Anaheim, CA for exact pricing, they did good work for me years ago.

sorry boo, yes you can do it if you have the money? is it worth it ? that is up to you. just went off because like you said every ones answer is get a 292.

No Baldy, the question was not answered! You and others did not know the answer so you shot off about your opinions. The question was, and still is, what rods do you use? If I wanted a 292 TRUCK motor, I would have bought one a long time ago. Around here they go for about $150 bucks! Less than the price of a camshaft!

It seems a simple matter of polite ettiquette that one someone asks a question you give the answer rather than popping off about your personal opinions. But, alas, on these forums everyone wants to play the expert and pontificate about matters beyond their understanding. It's my opinion that people who cannot answer difficult questions ought to remain quiet.

Boo

On the crankshaft company it should have read National Crankshaft Company.

As far as knowing anything from shinola, maybe your signature message should read "If you can't spell, you're too young."

Probably no one has stroked a 250 an eighth of an inch, so an exact answer may not be available.

Check to see if moving the stock rods .062 closer to the bores at the CPA causes interference, if not, you would be able to use them with custom pistons. Make sure all head work and decking have been done before specifing the pistons.

i did some checking in the shop today. it looks like you would have the clearance in the bottom. for pistons you could use 307 dished and cut the tops to get the deck clearance which would make them flat tops. you would only have to take about .060 off. i built some stroker 4 cyl. for racing using mercruser cranks. dont know if they have a 6 crank but it would be worth a look. the rods are bigger in them so you would have some to offset grind.

Hey Boo
Relax, everyone has an opinion.
If you don't like it, don't take it.
Terry

Boo, in your initial post, you mention a 250 block/292 crank combo not holding together too well. Why not? Is it just the long stroke, or what?
You could use small-block chevy rods which are plenty strong, the piston would only need a 1.39" compression height, which is definately reasonable, and would give a pretty light rotating assembley, especially compared to a stock 292 piston and rod!
I'm considering doing that. I've seen a few 292's around, but would rather keep the lighter 230/250 short-deck block and not have to debate storing/tossing the original 230 block from my '65 Nova.

Boo

If is stroke what you are looking for, down here, in Brasil, there´s a friend of mine that makes stroked crankshafts for the 250 Chevy. It is forged and it has a different type mouting hub in the snout(front end). It isn´t the woodruff key system but a chamfer snout. The crank also comes with the pulley(damper) with, but is a little expensive.
I can talk to him with you want to!

Seis Canecos 74

Hate to dig up old bones !!!! BUT, I just happen to have a good 250 block and a set of Howard 283 rods and a 292 crank. This sounds like it would work. Has anyone done this yet??? If not I think I will give it a shot...Want cost much, I already have the bearings. I just need some 307 pistons and a set of rings. The machine work will be free. SCRAP

Scrap
The 292 counter weights will need to be trimmed down to work in the 292. After the Holidays Get in touch with TOM Langdon. He used?? to sell crank and Piston combos for doing the 292 crank in the 250s for around 1000.bucks

Re: "theoretically, the additional 17 inches would mean an additional 12.75 horses"
No. 1/8" offset yields 1/8" more stroke, not 1/4". Final stroke: 3.656". Displacement: 259"
Additional displacement always results is less power per unit of displacement, and adding stroke is the least effective method.
Rough rule: (new stroke^.5) ÷ (old stroke^.5) = power increase.
In this case:
3.531^.5 = 1.879
3.656^.5 = 1.912
Power added: 1.8%

how about 280???? it has a 4" stroke. don't know what all they came in?? i think boats?? anyone???

See my ad in the "Classifieds " for a completely rebuilt 292 for sale CHEAP. $595

If you offset grind the 250 crank from 2.100 to 2.0 "you will not get .100 increase in stroke due to the inability of the grinder to keep the journal round. You will end up with an increase of .080 in stroke.
The 2" pin will now accept any rod with a 2.125 housing, 283 , 327 come to mind but they are not centered, although that may not matter. Regardless, the rod length can be compensated by decking the piston or using a piston with a greater compression distance,

The crank for the 250 Chevy, rod journal is 2.0 to start with....
Just some knowledge :-)