speaking of SBC blocks

[Charliesauto]

I build a lot of 421's and I have used the Ultra H beam rods with a standard SB cam journal and using a 421 lobe I still have to use a reduce base circle of 1 inch. That being said there is no way you can use a 3.875 stroke crank and use a BB journal cam.

1.868" journal with around.425"-.430" lobe lift should be 1.000" base circle without out any further reduction. More LL than around .430" will be less than 1.00"base circle .

Based on the info you provided, his combo actually adds up. .100" smaller rod journal and .080" larger cam bearing journal.

2.000 rod only gives you .050 more clearance then the 2.100 its not the full .100 its half of that been there done that.

.080" larger journal size only gives you .040" less lobe to rod clearance so the two together nets you .010" more clearance.

[randy331]

These? https://www.cnc-motorsports.com/callies ... 50185.html

Summit has I beams https://www.summitracing.com/parts/cpi-u16101/

It's the H beam rod like cnc-motorsports has in that link. Summit has the wrong pic for that part number.

They do fit with a 3.875 stroke and a BBC cam journal.

Of course a raised cam tunnel would be better.

Randy