I have heard that you can use a 4.125 stroke crank with 2.000 rod journal sizes and SB Chevy forged steel I beam or H beam rods without having interference with the cam or block on both the 340 and 360 stock LA blocks, is this true or baloney sauce
I'm thinking of doing this in a 360 block and want to hear from other Mopar SB LA engine racers on here before I end up finding out the hard way that you shouldn't or can't do that with a stock production OEM passenger car block
Thanks in advance for your help on this

True Story, BPE sells a 4.125 crank.

Cab,

This is a BPE 4.25" stroke in a stock .060" '71 360 block....uses 6.200" rods with 2.00" (327 chevy) sized journals.

Yep, it works. I will post up some pics tonight if I have time.

Rod

Thanks for that

Here's pretty much all you would ever want to know right here in the tech Archives:

https://board.moparts.org/ubbthreads/ubbt...html#Post912622

I did one of Rods kits last summer 4.125 chevy rod 360 40 over work out great very nice stuff and his prices or more the fair thanks rod

Stock 360 Block 4.250" crank with a 4.03" bore.

Rod

Stock 360 block with 4.250" clearance to pan rail.

Rod

I used one of Rods 4.125" cranks with 2.00" journals and 6.200" rods in my R1 block. The only issue was the crank key way is off 2.5°, no big deal just have to remember when timing it.

I'm curious about longevity with that much stroke in a stock block? At what performance level? High compression ect.

What is the clearance on the oil pump

With a 3.91 crank and alum 6.4 rods I had pickup tube problems. Had to eventually shim the oil pump to provide adequate clearance. Worked out well.

What was the rod journal size?

With my above mentioned crank and rod I had about .125" with the Milodon pick up.

Stock 360 block, with a 4.250" crank and the rods I supply with my kits. Milodon pick up also used here as well.

Rod

Justin I have MGP rods with 2" journals. Also on my pickup arm even after grinding and hammering it I still had to shim the oil pump. I believe the oil pump is sometime the problem.. After recently looking at several pumps their sizes are not standard even with the same part numbers. I'm sure it is because of different batches or different suppliers. I'm using steel rods in my next build so may not have the same problem.

Justin I have MGP rods with 2" journals. Also on my pickup arm even after grinding and hammering it I still had to shim the oil pump. I believe the oil pump is sometime the problem.. After recently looking at several pumps their sizes are not standard even with the same part numbers. I'm sure it is because of different batches or different suppliers. I'm using steel rods in my next build so may not have the same problem.