1.8 Rockers on BBC ?
#11
Registered
Join Date: Nov 2000
Location: Continental,United States
Posts: 372
Likes: 0
Received 0 Likes
on
0 Posts
I have ran the 1.8 rocker ratio on an otherwise stock motor, in an older jetboat I had, no problem in my motor. I saw a slight power increase to the tune of 100-150 RPM which approximately equated to 20 hp.
#12
Guest
Posts: n/a
Re: Re: 1.8 Rockers on BBC ?
Originally posted by ragtop409
Well for starters 0.483 divided by 1.7 (stock rockers) = 0.284 (lobe lift) times the 1.8 (roller rockers) now = 0.512. Correct?
I also agree with the fact that it gives you more duration but I think that is very minimal.
I had my engine builder go through my 502 (rectangle port) heads before I put them back on and he said they did not clearenced to run the 1.8's
Rag's
Well for starters 0.483 divided by 1.7 (stock rockers) = 0.284 (lobe lift) times the 1.8 (roller rockers) now = 0.512. Correct?
I also agree with the fact that it gives you more duration but I think that is very minimal.
I had my engine builder go through my 502 (rectangle port) heads before I put them back on and he said they did not clearenced to run the 1.8's
Rag's
I'm unclear on your motor. Your builder said your motor did not have adequate clearance to run 1.8s ??
#14
Guest
Posts: n/a
There would not be a problem with a .512" (or .520") cam, but what we are talking about here is increasing the effective lift of a .483" cam to .512" by changing the rocker arms from a 1.7 ratio to 1.8. This can cause a number of problems with clearance.
1. The 1.8 ratio is achieved by moving the contact point for the pushrod slightly closer to the valve, which means the pushrod may come into contact with the hole in the cylinder head that the pushrod passes through.
2. The pushrods may also be too tight against the guide plates.
3. The rocker arms will not clear stock valve covers.
That said, Rag is the first person I've heard say that he actually had clearance issues. Everyone else I've heard from says it is important to check, but they've never actually had clearance problems (except with the valve covers).
1. The 1.8 ratio is achieved by moving the contact point for the pushrod slightly closer to the valve, which means the pushrod may come into contact with the hole in the cylinder head that the pushrod passes through.
2. The pushrods may also be too tight against the guide plates.
3. The rocker arms will not clear stock valve covers.
That said, Rag is the first person I've heard say that he actually had clearance issues. Everyone else I've heard from says it is important to check, but they've never actually had clearance problems (except with the valve covers).
#15
Re: Re: Re: 1.8 Rockers on BBC ?
Originally posted by Ric232
My bad, .511" or .512" is correct, not .520".
I'm unclear on your motor. Your builder said your motor did not have adequate clearance to run 1.8s ??
My bad, .511" or .512" is correct, not .520".
I'm unclear on your motor. Your builder said your motor did not have adequate clearance to run 1.8s ??
Sorry Rag's
Thread
Thread Starter
Forum
Replies
Last Post
littledcsrodshop
Do It Yourself, Boating on a Budget
0
04-04-2008 02:10 AM