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Old 11-23-2012, 03:06 PM
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02 l31 5.7

ok got a question about this engine i bought for my 51 1/2 ton truck . i dont know crap about engine building so i need advice on tis engin 2002 L31 vortec . the guy i bought it from rebuilt it converted to carb which will be 800cfm rochester quad and put this cam it with no mods. will i have problems running this cam such as vac. lift, springs, mpg. if so can someone recomend a cam for me. like i said im not an egine builder. this will be a daily driver. all advice welcome. just want something with good streetability with a little gitty up.

valve lift int. .480 exh. .480
cam lift .320 exh. .320
duration [sae] 287 287 valve lash hyd.
centrline 107 111 spread 109

timing events@ .050 cam lift
opens btc 8 bbc46
closes abc 42 atc4
duration int 230 exh 230
rocker ratio 1.5

Thanks
John

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Old 11-23-2012, 06:50 PM
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Quote:
Originally Posted by johnstruck View Post
ok got a question about this engine i bought for my 51 1/2 ton truck . i dont know crap about engine building so i need advice on tis engin 2002 L31 vortec . the guy i bought it from rebuilt it converted to carb which will be 800cfm rochester quad and put this cam it with no mods. will i have problems running this cam such as vac. lift, springs, mpg. if so can someone recomend a cam for me. like i said im not an egine builder. this will be a daily driver. all advice welcome. just want something with good streetability with a little gitty up.

valve lift int. .480 exh. .480
cam lift .320 exh. .320
duration [sae] 287 287 valve lash hyd.
centrline 107 111 spread 109

timing events@ .050 cam lift
opens btc 8 bbc46
closes abc 42 atc4
duration int 230 exh 230
rocker ratio 1.5

Thanks
John
Before running it check the retainer to seal clearances. Chances are pretty good that if the stock seals were used in the rebuild and no mods made to the retainers or valve guide bosses that there could be a clearance prob w/0.480" lift.

The clearance has to be checked w/a solid lifter or a hydraulic lifter has to be made solid (stacked full of small washers or filled w/heavy grease).

If the valve springs are stock, they need to be changed for a set having more seat and open pressure. If this is the case you can get a set of springs and retainers that takes care of the clearance issues and will have enough pressure for the cam, too.

That cam wouldn't be my first choice for your DD truck, maybe someone can point you towards something else better suited to your needs (I don't recommend cams).

More info:

Vortec heads
Points to check
Geometry
Valve spring installed height
Adjust lifters
Cam break in
First start up
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