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L31 vortec 350 ?

10K views 12 replies 7 participants last post by  babygene41042 
#1 ·
Does anyone know what kind of cam came in a 98 model 350 vortec engine out of a truck? The cam is a roller, need to know the lift.

Thanks in advance.
T.
 
#4 ·
Using your dial caliper, measure across the nose and heel of any intake lobe. Now measure across the lobe side to side and deduct from the larger nose/heel measurement. Now multiply the answer by the rocker arm ratio and you have the theoretical valve lift. Now do any exhaust lobe the same way.
 
#6 ·
Others on this board like F-BIRD'88 may be better equipped to answer this question.

I'll give you my opinion though. I'd rather do some bowl blending and shaping than I would changing to larger valves. I'd be more interested in the shape of the mixture kernel as it passes the intake valve and would be afraid that shrouding the kernel with the larger valve would negate any benefits that the larger valve may provide.
 
#8 ·
The larger valves will fit, but without some deshrouding they won't do much good. Usually vortecs respond to pocket porting pretty well, but increasing valve size (depending on the porting) doesn't really do too much until the "mild" porting stage where the whole port is treated to mild work.

Lift should be in the .455-.465 range at the valve. Divide by 1.5 to get the lobe lift. I know that's not specific, but its a ballpark anyway.
 
#11 ·
From what we have seen the 906 and the 062 non Mexican heads work the best with 2.000 valves and no gain with a 2.020 valves and on the Vortec heads going to 2.020 and 1.600 valves is not the hot set up as on the Vortec heads its very thin between the two valves and we have seen them crack accross the deck of the head when guys have tried this.

We are restricted to 1.94 and 1.500 valves in these engines and with Ford flat tappet cams, 11:01, HP600 Carb we have seen 515 horse and 485 torque with just a good valve job, bowl hawg work and deshrouding on the intake side and no hand porting.

On the 383's we have built with this head we have seen 455 horse and the 355's we have seen 432 horse.

We have seen that the Vortec heads react to duration more then lift.

Now the RHS heads with no hand prting but some good seat geometry and bowl hawg work flow 253.
 
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