"Those dart blocks have mega-thick walls compared to OEM, thinner bores move around more than thick ones."


-We also filled it and run no water through it at all. We do run water through the heads. Bore stability is critical to ring seal. With the aluminum Fontana block even when filled Vacuum would go from 16 hg at idle to positive through the traps. With the Dart it has at least 6 hg in the lights.

bobR, do you have the 302 or cleveland Mains?
Just curious.

-Not sure what it has now. We've tried a few.

On a 9.5" deck windsor the big end of the rods do get up in the cam at anything over about 4" with steel rods, I have a 4.17" stroke 427 and also had to relieve the big ends and run a reduced base circle cam. the proximity is something.

-It is REALLY close. We use aluminum rods and we have to cut quite a bit. Hasn't seem to hurt the strength. YET.