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572 or 541? I'm inclined to stick w/AndyF's approval, but...

biomedtechguy

biomedtechguy

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Andy said he liked the 4.25 stroke. I can see quite a difference in piston speed between the two, but then again, I'm not likely to be wringing it's neck like a high compression, radically cammed 440 would.
I figured I'd put the question out on the forum. I'm getting to the point of paying for my rotating assembly. Molnar forged stroker crank, same price for a 451 (4.50 bore x 4.25 stroke) or a 4.5" stroke (572)
No clearancing required for either w/my Bill Mitchell block.
The builder recommends single line external oil pump pickup either way, although the 4.25 wouldn't require it. 7.100 rods/2.200 journal. Diamond pistons as Ross is way past the delivery date they've promised.
My main goal? 700 ft lbs torque across as wide an RPM spread as reasonable. Let the horsepower fall where it will, although 6XX is expected. 3x2 Holley carbs on the ModMan intake.
Thanks...
:popcorn2::popcorn2: :thankyou:
 
Either one will pull your sack juice out your back door. Right now you need to find available parts for either build. Otherwise it will be possibly years before you will see it run.
 
pnora said:
Either one will pull your sack juice out your back door. Right now you need to find available parts for either build. Otherwise it will be possibly years before you will see it run.
Click to expand...
Those brands have been being delivered in a "reasonable" time frame, although Molnar doesn't have rods right now.
I am getting a "jump" on it to the best of my ability.
Thanks.
 
572 for the win. Free power how can you go wrong?
 
It took me nearly 3 months to get Ross pistons last summer. From what I hear Diamonds time line was even worse. And they are local to me. I could have ordered Wiesco and got them way quicker. Of all the 572 and 540's I race with. The 572's are quicker. No replacement for displacement. Andy has built way more motors than me. But a lot of them are dyno mules. Mine gets beat on at the track. If you read most high end engine guys. Pick a stroke and a piston. Find a rod to connect the two. The rod stroke stuff isn't all that its cracked up to be. The longer rod does allow for a lighter piston. There are limits on how short a piston. But by that time, you are talking putting the pin in the oil ring with spacers. Look at BB Chevy deck height. Its nearly 1" shorter the an RB. Shorter even than a low deck BB Mopar. The 502" BB Chevy runs 4.5" crank from the factory.
Doug
 
Thanks again for the replies.
So far, "bigger is better" is 100%
@andyf Would you let us know your thoughts?
 
Want torque????

images.png
 
With your aftermarket block I don't think there is a drawback for the 4.5".
We had no problem fitting a 1/2" oil pickup with a 4 1/2" crank with a 2.2" rod in a b engine. We have scat h beams. I would think they would work well 2.
 
I've already emailed the builder.
572 it is. Paying for it this week. Life is short, I'm 60 years old this month and it looks funny for my fingers to type that.
Like I've posted before, if I don't actually DO this, it won't ever happen.
 
[QUOTE="dvw, post: 912125681, member: 2923" The 502" BB Chevy runs 4.5" crank from the factory.
Doug[/QUOTE]

502 is 4 inch stroke.
 
jamie said:
[QUOTE="dvw, post: 912125681, member: 2923" The 502" BB Chevy runs 4.5" crank from the factory.
Doug
Click to expand...

502” is 4 inch stroke.[/QUOTE]
Yup brain dead, 4.5” bore. Still plenty of 4.25” cranks in BB Chevy standard deck that’s .925” shorter than the RB’s 10.725”. How many 632” Chevys are there at 10.200” deck with 4.75” stroke?
Doug
 
Personally I think you've gone the best route@572. I don't know the cam specs your going to run or comp but you may know the spec on our 589 wedge. But here it is again>
Just 10:1 4.565x4.500, single puny old 950HP carb, small .625" after lash 260/[email protected] s/roller, 440-2 intake, -13 heads that prob only flow around 350cfm@our lift if that, 2.1/8" TTI's.
Dyno'd@ 695hp@5500-5900, [email protected] line external of course.
 
Last edited:
440rb said:
Personally I think you've gone the best route@572. I don't know the cam specs your going to run or comp but you may know the spec on our 589 wedge. But here it is again>
Just 10:1 4.565x4.500, single puny old 950HP carb, small .625" after lash 260/[email protected] s/roller, 440-2 intake, -13 heads that prob only flow around 350cfm@our lift if that, 2.1/8" TTI's.
Dyno'd@ 695hp@5500-5900, [email protected] line external of course.
Click to expand...
Great reply, thanks. My builder has a lot of experience building MOPAR stroker motors, so I'm leaving it up to him. I'm also going with a hydraulic roller cam and lifters. Again, not turning high RPMs, and they're "easy".
 
I agree, 572 is better. Better average hp and torque down low. No matter which heads you put on it, cubes rule.
 
same price, go with more cubes
 
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