Hey guys , I'm in the middle of building a 540 ...Mega block RB...I know some guys are gonna complain about my crank...But it's a 4.500 fuel crank....Not cracked...And I have diamond custom blower pistons....And wanna run 7.100 Manley pro I Beams rods...The crank is Mopar journal...So my question is how tight is it gonna b...And I think it will hit the cam.....What's the fix

Did you sonic test that block first before boring it? If not do that now, a lot of the Mopar Mega blocks won't bore safely to 4.500 or larger, usually 4.410 or smaller is the normal bore size on them
As far as the steel rods on a 4.500 stroke crank with the Mopar rod journal size clearing the cam you should good, always check everything on any non stock motors
If it does not clear the fix is using the BB Chevy rod journal sizes and rods with the same stroke

I have run stock rods, 4.5 stroke, stock rb block, .500 lobe lift roller, had enough room. Hopefully the rods you have will also.

I thought aluminum rods cleared and it wasn't until you went 4.750 stroke that the cam got in the way

We didn't Sonic test the block....I think the bore 4.380...I was told the rods will hit the cam...And alot of block clearance ing.....And may have to get a custom cam ground....

I'm getting ready to put a old KB top fuel crank with Mopar rod journal sizes on it into a new World cast iron hemi block with Manley steel SS Hemi rods, I'm sure I will have to grind on the block to make clearances on the oil pump boss and maybe the bottom of the cylinder skirts below the cam
I've done one other old top fuel 4.5 crank with steel rods in another, probably, a early Mega hemi block, and the cam was not even close

Cool...Good to know...Thanks guys

When I went to assemble my 572 years ago (4.5 bore, 4.5 stroke) with mopar journal size my crower billet rods hit the cam (bolt and nut style rod). I rebalanced with a set of K1 rods and all was well. I have since has my crank cut down to Chevy size

15+ years ago,Lou Vignogna put together my Mega block with a 4.5 stroke and 4.310 bore.

I've always heard that 4.75" stroke w/ 2.2 journal steel rods will clear a std. cam height block, but aluminum will need a raised cam location.
Not sure where the end of the line is with the big mopar rod journals though.

Thats some grinding...What rod journal is on that crank...

You are going to buy 7.100 long rods with a Mopar rod journal on them? You are heading down a road where you have a big heavy rotating assembly with odd ball parts just because you started with the wrong crankshaft.

Yes...But that's what I have ...im looking to make 1200 to 1500 HP ....I can't just use an eagle crank like everyone else

Have you mocked it up yet. I run the chevy pin size 4.5 crank in two shortblocks. I clearance the stock late 70s block in the spots Hemi-it's posted and at the bottom of a few bores. I run a pro mod type aluminum rod by GRP in both. I also run big lift.

No I haven't got the rods yet....They are back ordered...Then I'll mock it up...I was told to custom grind a cam with a smaller base circle to clear the rod....Does that sound right

How much lift? I have .800 on my cast iron Indy heads on my stock block 540

Small cam....685 lift roller

That's the cam I have now in my old motor....May go with a different cam in the this mega block motor...Well see but nothing too wild I drive this on the street alot...

Just make sure you check it but I think you will be ok. Sometimes a redegree of the cam will gain you room.

So what's the plan to make 1200hp? Nitrous?

I have the car running now with my stock block 528...Its got an F2 Procharger on it ....Blow thru dominator....It will make the power I need...I just don't wanna break the block....So that's why it's getting the new short block