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Old 10-04-2006, 08:06 PM
TerroRx7 TerroRx7 is offline
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Built a High Comp chevy by mistake ... need help

hi all

my buddy built a high compression by mistake

the engine is 1996 LT1 << we got it really cheap
LT1 aluminum heads
4.02 bore
Speed Pro H345NP20 pistons ( Flat-top 5cc )
http://store.summitracing.com/partde...5&autoview=sku
GMPP LT1 carb intake
EDL-1407 750cfm performer carb
comp cams Xtreme 4x4 cam 12-239-3 ( Yes it is Hydraulic flat tappet )
http://www.compcams.com/Technical/Se...umber=12-239-3


before building the engine he sent the heads to be resurfaced
but he didn't know how much they shaved so lets assume it is 50cc-54cc ( since stock LT1s have 58cc chambers)
those pistons were used because he usualy use them on normal SBCs ( not LT1 like this one )
this yeilds a static compression between 11.4 - 10.8 and a dynamic compression higher than 9.5 which definitly won't work with local pump gas (95 octan)


he doesn't want to change the pistons
but he will remove the heads and will slightly enlarge the chambers by porting
also he wants to change the cam to get a lower dynamic compression

the engine is on a 1986 Chevy k10
sm465+np205
stock 10-bolts (rear+front) 3.08 gears
32 tyres
and is used mainly in sand and dunes



what is your advice?
and what cam do you recommend ?

your help is appreciated
thanks
and sorry for my crappy English
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