hey guys thanks for the help you have given me already. i am swapping a bigger cam into may '86 LB9. what is the the most duration i can run with a stock chip. i know too much duration will cause reversion back into the intake. but what is the suggested limit? i am lookin at cams with about 216/218 degrees of duration. how long in duration can i go if i use high bleed lifters? are high bleed lifters really worth it? the cam i'm lookin at is a crane with single pattern 216/216-.454/.454. or is a dual pattern cam better. such as teh 212/218--.488/.495. i am gonna try to burn my own chip but the guy i know that has the stuff to do it is hard to get ahold of, and i don't know how to do it yet. thanks again

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86 IROC
43,000 miles
305/700R4/3.23 gears
maroon, gold stickers, black interior, T-Tops.

current mods.
shift kit
headers
cat back exhaust

mods planned for this winter
cam
3.73 gears
subframe connecters

 

Dual pattern duration cams are better because they are designed to counteract the difference in Valve sizes (exhaust valve is smaller, thus gets more duration). Also the 305 will always have less power than an equally modified 350, the general rule of thumb for a 350 is no mroe than 220 degrees of duration (for tpi/computer controlled cars) so for a 305 bump it down a few degrees, personally I wouldn't run over 212 on a 305 of mine. Hope it helps. (dont forget lobe seperation its VERY important)

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