I used 440sources 438 kit before with good results, but now noticed That Mancinis 432 kit has a 4.15” crank vs the 440 sources 3.75” crank. We are pushing a 1969 RR with a 4 speed and 3.55 gears, who’s kit is going to make the most power for this heavy car?? Either way, we plan on using the stealth heads, headers, good ignition system, a voodoo .475-.495 lift Cam matched in rpm to a dual plane intake manifold good for about 1400-5800 rpm range. Thank you moparts!!!!

4.15 stroke may make for some really short pistons. might have oil control issues and want to rock in the bores some. 4.15 should provide more torque than the 3.75, if you like the 3.75 stroke kit before use it again. not a really high revver of a high power engine stopping at 5800 rpm. so the shorter stroke with less problems would get my vote.

does the 4.15 crank use shorter rods?

No, both kits use a 6.76 rod

then I think you will have a short piston with the 4.15 crank.

what about muscle motors stroker kit for the 383?
i think it uses a 3.9 stroked crank with a shorter rod and yields 450 cid.

Those 4.15 cranks use Mopar rod journals which need the block to be clearanced while the 2.2" BBC journals on the 4.25 crank usually just drop in.

As has been posted the 4.15 crank needs the short 1.112 CH piston with the long rod.

4.25" gives you 489-496 cubes using the 6.535 rod and the 1.320" CH piston.

No replacement for displacement and it's the same price.

Kevin

Thanks Kevin

I have a 69 383 block here that i'm looking to do something with so i'll keep my eyes post here.

I would go with the 440 Source 4.250 kit. Mo cubic, mo better. It uses the 2.2 pins that you want and you don't have to deck the block.

What about the rod ratio with that kit?

I would go with the 3.9 stroke and 6.535 long rods. A really good combo.

David Reher said don't worry about rod ratio.

440 Source with light weight crank....493 cubes

My own:
440 crank offsetground to 3,9"
BBC rods + .250"
Flat top 454 pistons in any size. ? .060 -> 455 c.i.
You need to make valve reliefs in the pistons.
The crank prep is about the same as a 451/470 B stroker combo.

No superlight high $$$ parts here, just pieces to make cheap CI, as is the intention of using a 383 block.

The big en d width comes with a lot of side plat with the chevy rods....Is it ok to race an engine with so much side play ?

Bob Glidden, Smokey Y, The Grump, GM/Ford/Chrysler engineering all seem to think rod ratio is a fairly important factor.....and more than just a connection for the piston to the crank.

Of course it is To many keyboard racers focus on the wrong things on race motors
I've raced NHRA Stock, S/ST,S/G , I've built my own blue printed motors and helped several other former NHRA World champions on there Mopar cars engine builds, rod side clearances can be close or loose and the motor will still perform the same on the dyno or at the track
I've seen ONE stock Mopar V8 motor that had near the minimum Mopar FSM recommended rod side clearances, it was a early production 1966 street Hemi motor that had less than .016 on all the rods, I've also seen as much as .042 side clearances on 318 motors
My first pump gas 400 block stroker build with BB Chevy rods had from .052 to .039 side clearances, it ran fine, didn't use oil and revved like a SB did I shifted it between 7000 and 7800 RPM with no issues ever

4.25 stroke with a 6.535 rod is still a slightly better rod ratio than a stock 454 BBC.

Kevin

Cab....
I just took my 440 crank to the shop and the side play would be a total of .065 to .070...is this getting way too much ??
Thanks