Advancing/Retarding cam effect P to V clearances?
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TECH Veteran
Joined: Mar 2003
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Advancing/Retarding cam effect P to V clearances? I was wondering about this. Let's say hypothetically you are running:
408 stroker
LS1 heads w/ 2.02-1.6 valves
10:1 compression
through an A4 trans.
Ideally, I'd like to WOT shift just shy of 6000rpms (5500-5800). So if you ran a cam like a 232/240 in that motor, I'd assume you'd have WOT shift points of 6400+, not what I am looking for.
If the cam was advanced around 4* wouldn't that bring the powerband down some?
Would advancing the cam have any determination of piston to valve issues?
Thanks!
408 stroker
LS1 heads w/ 2.02-1.6 valves
10:1 compression
through an A4 trans.
Ideally, I'd like to WOT shift just shy of 6000rpms (5500-5800). So if you ran a cam like a 232/240 in that motor, I'd assume you'd have WOT shift points of 6400+, not what I am looking for.
If the cam was advanced around 4* wouldn't that bring the powerband down some?
Would advancing the cam have any determination of piston to valve issues?
Thanks!
Re: Advancing/Retarding cam effect P to V clearances? Yes, advancing the cam will have an effect on P/V clearence. You change the cam timing, which will make the valve open at a diffrent point in the stroke. If you are close on P/V clearence, 4* will likley cause contact. Only thing you can really do is advance the cam, then check the clearence. Just depends on you valve reliefs as to how much you can advance.
TECH Senior Member
Joined: Nov 2001
Posts: 10,341
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Re: Advancing/Retarding cam effect P to V clearances? Dont forget the larger motor will swallow up some cam. I think you should be ok with what you have listed without advance if you go on 112LSA. Maybe 2 degrees tops.
Thread Starter
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Re: Advancing/Retarding cam effect P to V clearances? I remember you can have advange ground into a cam correct? Well would having advance in the cam result in lower lifts?
Also, the tighter LSA's of like a 110 or 112 have sharper power drop offs and power peaks at lower levels?
So the advancing doesn't really effect the power band too much, well I though it would have been more significant that that.
Thanks!
Also, the tighter LSA's of like a 110 or 112 have sharper power drop offs and power peaks at lower levels?
So the advancing doesn't really effect the power band too much, well I though it would have been more significant that that.
Thanks!
I can shift faster than you.
iTrader: (21)
Joined: Nov 2001
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From: Baton Rouge, LA
Re: Advancing/Retarding cam effect P to V clearances? Retarding the cam opens the exhaust valve earlier and the intake valve later. This give you more clearance on the intake side, and and roughly the same amount less on the exhaust side. In the case where your intake valve clearance was too tight and your exhaust side had plenty of room, you could retard the camshaft a few degrees (2*-4*) and gain some clearance.
Advancing a cam will bring the intake closer and the exhaust slightly further from the piston during the overlap period.
Jason
Advancing a cam will bring the intake closer and the exhaust slightly further from the piston during the overlap period.
Jason
