Performance Boats Forum banner

1 - 6 of 6 Posts

·
Registered
Joined
·
3,867 Posts
Discussion Starter #1
Okay lets say you are playing with cam degree numbers. You set cam at spec and feel like going 4 degrees one way or the other. Which will give you more valve clearance and which way for less? Just curious. M
 

·
Gone
Joined
·
1,824 Posts
Advancing tightens the intake clearance. Retarding tightens exhaust clearance.
Rule of thumb large roller cam BBC about .007 per degree (280 ish duration at .050).
 

·
Registered
Joined
·
3,867 Posts
Discussion Starter #3
Advancing tightens the intake clearance. Retarding tightens exhaust clearance.
Rule of thumb large roller cam BBC about .007 per degree (280 ish duration at .050).
Okay I see what you are saying but what if it would be a 240 @ .050 and you are hazing the exhaust valve and back of 4 degrees. what would that do! M
 

·
Registered
Joined
·
416 Posts
What about on a blown engine? I have heard that advancing the cam 5 degrees will allow the engine to make more boost?

Any truth to that?

Thanks
 

·
Gone
Joined
·
1,824 Posts
Wrong way.
Advance the cam and it will give the exhaust more clearance.....but tighten the intake clearance. Advancing will tighten the intake P/V clearance "X" amount.....and will loosen the exhaust clearance "x" amount.

I think you better check P/V clearance if you are "hazing". Also check valve springs.
 

·
Registered
Joined
·
3,867 Posts
Discussion Starter #6
Wrong way.
Advance the cam and it will give the exhaust more clearance.....but tighten the intake clearance. Advancing will tighten the intake P/V clearance "X" amount.....and will loosen the exhaust clearance "x" amount.

I think you better check P/V clearance if you are "hazing". Also check valve springs.
Thank you for easing my mind! for a while I was spinning around in my head which way to go and I think everybody has over thought a problem. Just for your'e info when I degreed the cam in it took 4 degrees to match the numbers on the retard side. Now I am going to a zero setting which will open up the exhaust clearance to be safe and probably I will loose the lazy response (throttle) I have now. Thanks again! M
 
1 - 6 of 6 Posts
Top