Originally Posted by spf72
There was no 69 Corvette LT-1 and the 70 standard 350 had the same 186 heads as the LT-1 The LT-1 has the larger valves, screw in studs and guide plates. If the OP car has stock heads they can easily be made the same as an LT-1.
My heads are rebuilt and have not been used since the rebuild. I am away and will check what I have into them when I get home. Because I will include the price of the heads combined with machine work it will probably be twice what it would cost to have yours redone and they won't be any better.
Actually the valves were the same size between L46 and LT1. Not sure of base motor. LT1 Heads did have screw in studs, different springs and guide plates. Based on testing the 2-1/2" exhaust and the high rise aluminum intake on the LT-1 accounted for most of the power increase. Yes it revs higher but torque characteristics seem to be very close to L46.
What is interesting is than unless he has a numbers matching block and wants the correct heads, he is WAAAY better of buying some brand new aluminum heads. They will flow WAAY better out of the box and save weight.
Just my two cents as I have an all original L46 that I would like to make more power.