273 Stroker for ***** and giggles

Which stroke do I use for an un-feasible build?

  • 3.58

    Votes: 7 28.0%

  • 3.79

    Votes: 4 16.0%

  • 4

    Votes: 14 56.0%
  • Total voters
    25
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harrisonm said:
... 4. I would think that heads and flow would be a problem. I was under the impression (I've never built a 273) that larger valves (even 2.02) will not work in a 273. So wouldn't you be limiting the amount of flow your heads are capable of up front?
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A 273 will take as much flow as you can give it. I've run 1.88 "J" heads without a problem, no bore notches.

Seems like there was a Cadillac motor with 273 size pistons? Get ready to do the math with stroke, rod length, and piston pin to top calculations before you pick a stroke.
 
If your serious, buy a 4” crank with 2.00” rod journals, a set of 6.200 rods. You’ll need to have your head choice worked out and know the chamber volume. Then call diamond to discuss custom piston options. Why go to all the effort and $$$ to build it and then try to run some junk factory replacement pistons?
 
Also be very cautious about rod clearance around the BOTTOM of the cylinder, the smaller the bore, the more grinding is likely going to be needed
 
Since we're talking about an "unfeasible build" anyway, just have the 273 block sleeved out to 340 spec and all the custom piston and valve size worries go away... 426 here we come!
 
gagembassett said:
So I have just acquired a 273 for pennies from a junkyard. You hardly hear about them anymore so I figured for ***** and giggles Im going to make a stroker of it. Why? Because, why not? It doesn't have to make sense, it doesn't have to be perfect. Does a 318 or 36 have parts more readily available and make power easier, yep. But TWO SEVENTY THREE STROKER lol. So here's the debate, I can grab one of the extra 3.58 inch stroke 360 cranks I have sitting in the shop and have it turned, or I can try to snag one of the 3.79 stroke cranks made idealy for 340s, or we can get into some real dumb **** and do the 4 inch. Now we have one stroke that will keep it oversquare or two strokes that will make it undersquare. What's your vote? Pistons I'll have custom made, block will possibly be notched for 1.88/1.60 valves or might just work over a set of stock 318 heads with the 1.78/1.5
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That's what I've said about the Chevys 307. Custom made pistons or even if you use a Chevy piston / rod it's still going to be expensive.
 
Dan the man said:
That's what I've said about the Chevys 307. Custom made pistons or even if you use a Chevy piston / rod it's still going to be expensive.
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Oh I never said that due to me buying it for pennies meant it was going to be cheap. I meant it as I have a cheap playground to have fun on now
 
This seems like a bad idea. Take the smallest Cubic inch block and try to make it bigger?

No, this is a really bad idea.
 
Do-able, For the 4.00 inch crank, recipe: 9.600 deck, Rod, GM LS 4.8 LS7 or truck rod at 6.298 c/c, pin size .9452. Piston, Jeep/Dodge 4.7l comp dist 1.240, pin size .9455. Big end of rod needs to be narrowed to Dodge size, .940 to .925 inch. 4.00 inch stroke crank needs turned down to 2.100 journal from 2.125 size. And, off set grind this same amount, it if you want, to lessen the .062 inch final piston below deck that will be observed.
 
gagembassett said:
So I have just acquired a 273 for pennies from a junkyard. You hardly hear about them anymore so I figured for ***** and giggles Im going to make a stroker of it. Why? Because, why not? It doesn't have to make sense, it doesn't have to be perfect. Does a 318 or 36 have parts more readily available and make power easier, yep. But TWO SEVENTY THREE STROKER lol. So here's the debate, I can grab one of the extra 3.58 inch stroke 360 cranks I have sitting in the shop and have it turned, or I can try to snag one of the 3.79 stroke cranks made idealy for 340s, or we can get into some real dumb **** and do the 4 inch. Now we have one stroke that will keep it oversquare or two strokes that will make it undersquare. What's your vote? Pistons I'll have custom made, block will possibly be notched for 1.88/1.60 valves or might just work over a set of stock 318 heads with the 1.78/1.5
Click to expand...
I've read through the replies and as I thought it wouldn't be practical at all. Cost would be outta sight and I imagine that ring life would be short as the wrist pins are in the oil ring lands, that's the same problem with fords 347 stroker that's why they went with a 5.315" vs the 5.4" rods. It would be different for sure. And as they say different strokes for different folks. If you go with more than the 360 crank you are going to be limited to rpm's because of the longer stroke and the smaller bore size of the 273 will limit the breathing capacity of the engine.
 
Max1196 said:
Do-able, For the 4.00 inch crank, recipe: 9.600 deck, Rod, GM LS 4.8 LS7 or truck rod at 6.298 c/c, pin size .9452. Piston, Jeep/Dodge 4.7l comp dist 1.240, pin size .9455. Big end of rod needs to be narrowed to Dodge size, .940 to .925 inch. 4.00 inch stroke crank needs turned down to 2.100 journal from 2.125 size. And, off set grind this same amount, it if you want, to lessen the .062 inch final piston below deck that will be observed.
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This sounds very expensive as I've said. I think that you would be better off buying a 360 and building a 408.
 
Why would the pistons for this build be any shorter than for any other LA build? Aren't the deck heights all the same?

And I get that this it isn't the only issue related to pistons, just don't see why the compression height seems to be a big part of the discussion.

I like the idea. I'd put a 3.58 crank in it just to keep it under square, make sure it has good compression and run it. I bet it would make good power and be better on gas than most other LA's. Maybe build it for some RPM to make up for being down on displacement but add EFI so it runs clean at low RPM. I could see it being a sweet little motor.
 
trapster said:
I love it when people take an engine made for revs and turn it into one that isn't.
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You need heads that A. Flow enough and B. Have the correct size intake port.
In this case bore notching will be required and a set of either 1.94/1.60 j style ported 'least work, lighter valve, and least shrouding' or magnum style head, also worked some.
Other AM heads can take a 1.94 valve, but they're on the big side for this cid imo
I vote 3.58...but 4" motors in general will rev just fine outside of some novices mediocre home 'porked and demolished' heads.
Get someone who knows what they're doing and a cam ground for them... and the thing will wing ding like anything else....or use a 104 lsa lol
 
trapster said:
I love it when people take an engine made for revs and turn it into one that isn't.
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yet when I saw someone talk about their 8,500 rpm 273 people were jumping down his throat with the same "Build the 360 blah blah blah" not everyone wants the same ol' HOORAH build. Uniqueness turns heads, commonality doesn't.
 
While I agree a 273 stroker wouldn’t be the best bang for the buck. The OP didn’t ask for opinions about his build choice, at least that’s the way I read it. It’s his money, how he spends it is no business of mine.

As far as pistons and ring location goes, it obvious that there some internet experts regurgitating something they read posted by another internet expert. My stroker has a 4.125” crank with a 6.200” rod and the rings aren’t in the pin.

To the OP, if you have the resources build whatever you want, use decent parts so it has a fair chance to shine and keep us posted on your progress. :thumbsup:
 
I still like the idea of a really high rpm 273 with boost with the Crower crank. It would require custom pistons, main caps made for the 2-1/4 inch bearing diameter and spacers for the upper shells, but 3.65X3.145 makes 263 cubic inches. Add boost because it's not going to make any compression. And all this stuff would be appallingly expensive, including the 6.3 inch Oliver rods. Compression height would come out to around 1.73 with the bonus of lighter chevy pins, and rod ratio is 2:1. which works really well for boost. You should be be able to stiffen the block with at least a third fill of hard block.
But Wow! If nothing else, it would definitely win the unfeasible race.
Crankshaft 340 Dodge 3.145 stroke - Clearance
Oliver Racing C6300SMLT8 Oliver Standard Light Series Connecting Rods | Summit Racing
 
Garrett Ellison said:
I still like the idea of a really high rpm 273 with boost with the Crower crank. It would require custom pistons, main caps made for the 2-1/4 inch bearing diameter and spacers for the upper shells, but 3.65X3.145 makes 263 cubic inches. Add boost because it's not going to make any compression. And all this stuff would be appallingly expensive, including the 6.3 inch Oliver rods. Compression height would come out to around 1.73 with the bonus of lighter chevy pins, and rod ratio is 2:1. which works really well for boost. You should be be able to stiffen the block with at least a third fill of hard block.
But Wow! If nothing else, it would definitely win the unfeasible race.
Crankshaft 340 Dodge 3.145 stroke - Clearance
Oliver Racing C6300SMLT8 Oliver Standard Light Series Connecting Rods | Summit Racing
Click to expand...
Are you ok? :realcrazy::realcrazy: :lol::lol::lol:
 
I absolutely cannot fathom this idea of uniqueness.
No matter how you slice/dice a 273, it still has wee small bores, almost as small as the mighty 225; and stroked? it might as well be a stationary engine. With so many better options, I sure wouldn't go this route even if I was ElonMusk.
I won't guarantee that nobody will care at any car show, but I think only another guy like you will give it a second look. One thing that you are sure to get an earful of is this;
"you shoulda built a 340";
you'll get so sick of hearing it, that you'll just quit going to shows altogether, or,
you will put a 340 pie-plate on the aircleaner housing, and go hide in the beer-garden.
Building engines is like religion; Everybody is free to believe whatever, and everybody has an opinion on the truth . But the truth they seek is their own truth, not absolute truth. So, the trip thru life is tripy. Do whatever you want and whatever happens, happens. Just don't be crying when it doesn't turn out how you expected it to.....
BTW;
don't forget about the time factor. How long will it take to;
> get custom pistons made,
> to set the compression ratio,
> to get a custom cam ground,
> to get custom pushrods,
> find decent headgaskets.
> all the mock-ups, tear-downs, and re-cleaning.
> schedule the various machining operations
> etcetera
> what if the project drags on for months or years, not weeks . And then, when she is finally installed, you still have to put a trans behind it, and tune it.

Do I have a better idea?
IDK, but I think so; leave the 273+whatever/cleaned up, and super/turbo charge it, BOTH! now that would be truly unique, and everybody will drool all over it, all the time.
Jus saying; supercharging is the great equalizer, and not very many do it cuz it's pricey. But you seem not to be overly concerned about money..... ,it should be a great fit for you;
1) unique
2) pricey
3) attention-getting
4) performance-oriented
5) car-show killer
 
i bought several sets of carrillo rods on epay that the roundy round guys were replacing for less than 300 bucks per set , 6.2's n 6.3 length with . 81 pin and 1.88 crank pin and all were beam drilled for oil pressure to the wrist pins . had carrillo check them out and there plenty to budget race good or street hotrod with . and a lot of those 4 strokers use that honda bearing of 1.88 dia . and their turning more rpm every time out than you or i would be .
 
AJ/FormS said:
I absolutely cannot fathom this idea of uniqueness.
No matter how you slice/dice a 273, it still has wee small bores, almost as small as the mighty 225; and stroked? it might as well be a stationary engine. With so many better options, I sure wouldn't go this route even if I was ElonMusk.
I won't guarantee that nobody will care at any car show, but I think only another guy like you will give it a second look. One thing that you are sure to get an earful of is this;
"you shoulda built a 340";
you'll get so sick of hearing it, that you'll just quit going to shows altogether, or,
you will put a 340 pie-plate on the aircleaner housing, and go hide in the beer-garden.
Building engines is like religion; Everybody is free to believe whatever, and everybody has an opinion on the truth . But the truth they seek is their own truth, not absolute truth. So, the trip thru life is tripy. Do whatever you want and whatever happens, happens. Just don't be crying when it doesn't turn out how you expected it to.....
BTW;
don't forget about the time factor. How long will it take to;
> get custom pistons made,
> to set the compression ratio,
> to get a custom cam ground,
> to get custom pushrods,
> find decent headgaskets.
> all the mock-ups, tear-downs, and re-cleaning.
> schedule the various machining operations
> etcetera
> what if the project drags on for months or years, not weeks . And then, when she is finally installed, you still have to put a trans behind it, and tune it.

Do I have a better idea?
IDK, but I think so; leave the 273+whatever/cleaned up, and super/turbo charge it, BOTH! now that would be truly unique, and everybody will drool all over it, all the time.
Jus saying; supercharging is the great equalizer, and not very many do it cuz it's pricey. But you seem not to be overly concerned about money..... ,it should be a great fit for you;
1) unique
2) pricey
3) attention-getting
4) performance-oriented
5) car-show killer
Click to expand...

Do you know of anyone that has boost friendly pistons for a 273 on the shelf? Everything on your list has to be done on any build.
 
toolmanmike said:
Are you ok? :realcrazy::realcrazy: :lol::lol::lol:
Click to expand...
:rofl::rofl::rofl: NO! NOT AT ALL! Exactly the response I was hoping for, and I'm not disappointed! But I did once see a 273 in a barracuda drag car that sounded like a Honda CB750 twin cam with an open 4 into one header. Blap Blap Blap Blap Blap at idle and WHHAAAAPPP!!! when they winged the throttle. Pretty sure that was a destroker build.
 
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