I'm just in the assembly of my Keith black 572 B1 engine after converting it from steel to Alu GRP rods. No other change, my rods are hitting cam close to TDC. (I'm sure not to have done mistake on the timing gears phasing) Do you know this kind of trouble on a 572 ?

yeah thats the problems with aluminum rods !u need a raised cam block or a set of oliver steel rods my 606 is soooo close with steel olivers 4.750 stroke no raised cam block! or a smaller cam is it a 4.500 stroke? did u degree cam in ??

If its just hitting you might go have the cam ground
to a smaller base circle
EDIT
assuming you have the cam in at the right location

Yes it's a 4.5 stroke with a Bryant crank and Venolia pistons. The rods are hitting just behind the rod bolt hole (at the outside of the hole).
The cam is degreed, it is a old Crane with .710" lift (in fact .800 because I have 1.7 rockers)
It was ok with my old set of Manley I beam rods, but they are too weak for my +1000 hp now.

i believe it's common practice to relieve the rods where they would hit the cam. obviously this needs to be done properly.

4.615 " Bryant crank , Oliver / RBRE rods , and KB block . Clears on my 557"
Chryco

We did a 572 about 5yrs ago, 4.5" stroke and the rods hit. We sent them back to Bill Miller [BME]and they put what they called a "indy notch" in the rods, which amounted to removing .200 above the rod bolt. This is a b1 headed engine still together running fine.

Clearancing an aluminum rod is a pretty common practice in a BB Mopar.

I'm assuming you have a std Mopar rod journal? A 2.200 would clear. You are only going to have interference on the 1st and 3rd journal. The way the cam/crank is phased, rods 1,2 5,6 are the only only that come close (assuming a std firing order camshaft). You will have to clearance the rods. A big journal rod has PLENTY of material. The area you will need to address is where the bolt hole exits the top half of the rod. .050-.060 is enough clearance.

I've had to clearence a number of motors over the years, as said I shoot for .060" clear. Since it's hard to reach in and get any sort of accurate measuremnt inthe cam tunnel with the crank and rods swinging around, one 'Trick' I always use is to wrap a meduium grade Ty-Wrap cable tie around the cam lobe, when it clears without touching you have .060 thou.

Thanks a lot, you're giving a lot of help ! Doing all those mods here in Paris is much more difficult than in your nice country (so much people driving hybrid Toyota here)

make sure this is done properly as in whatever you use to do the relieving should not cut across the beam. you always want to work/cut parallel not at right angles with the length of the rod.

With 2.2" journal rods and a 4.5" stroke I have room to spare even for a longer stroke. I doubt you'll have to take much off the rod. Be careful not to nick the rod beams, that would create a stress riser which could possibly cause a rod failure.

The cam has to be degreed before you start grinding rods--Most BME rods are already shaved--at least the ones from Indy are--have the cam in 5-6 degrees off and it won't work--the easiest guage is a piece of wire --you can bend it and get in there to measure easy--get wire diameter you need 060 or whatever.

Same thing happened 2 me, took a little off 2 rods at bolt hole and that was it.

I used GRP 5500 7.10in SERIES rods on my 588cdi
(4.50 bore\4.625 stroke)

Jowetu_6

After some shaving on a Bridgeport Mill, around 0.100" deep, it clear the camshaft now with 0.060" clearance. Thanks a lot to everybody here