[BILL BOWMAN1]

How much of an increase or decrease in power can be realized by changing cam timing a few degrees? I was running 9.90's-10.00 at 494 inches and 290 cfm, now I am at 535 and 370 wideports and the best so far is 10.39. When I built this engine I used the old cam but didn't mark where it was positioned (my mistake!). I installed it straight up in this new engine. Could this make such a dramatic effect? .726 lift 276Int. 280ex @.050, 108 lobe sep.
I know this isn't the ideal cam for this engine, but I thought it would at least have repeated.
Thanks for any ideas.

[steve25]

I would think that now your main problem may be not enough jet since you picked up so much more airflow, I mean if your manifold is able to keep up with the new heads!
How was your 60ft, that should be better at least if your hookin?

[Ron H]

Did you degree it when installed straight up? Does the cam have any advance ground in it? If not and the timing chain is correct you are in at 108*. But ya don't know unless you degreed it.
Did you change anything on the exhaust? Are you blowing the tires out? What size carb?
Read the plugs, how's the tuneup?
What is the converter doing? Flashing higher than previous? What RPM at the trap vs MPH?

[BILL BOWMAN1]

Pro Systems 1050 Dominator, fresh rebuild, 90/90 jets are the same. adding more jet is on the list of things to try next time. Thanks.

[BILL BOWMAN1]

Originally Posted by Ron H

Did you degree it when installed straight up? Does the cam have any advance ground in it? If not and the timing chain is correct you are in at 108*. But ya don't know unless you degreed it.
Did you change anything on the exhaust? Are you blowing the tires out? What size carb?
Read the plugs, how's the tuneup?
What is the converter doing? Flashing higher than previous? What RPM at the trap vs MPH?

Yes I degreed it, hooks great, slowed though 1.40 previous now 1.45. Did not check trap RPM's, but 1-2 shift happened much faster and was at 7,000 before I could catch it. 1050 Pro systems 36* timing, slowed down when we took timing out of it. I know there is still alot of tuning that can be done, this was only the 5th pass. ran 134-5mph before, now only 131 best.

[grnmnstr]

You are definitely making more power. I would assume the converter will now flash higher.

Since the 60' dropped, I would start there. Probably have to launch at a higher RPM now.

[BILL BOWMAN1]

Originally Posted by grnmnstr

You are definitely making more power. I would assume the converter will now flash higher.

Since the 60' dropped, I would start there. Probably have to launch at a higher RPM now.

Waiting for my adjustable rpm module to arrive, then I can use the t.brake and see what rpm it likes.

[screamingchief]

I would agree that is the wrong cam for the new combo.

The tight LSA with the added cubes and head flow is likely just letting some HP go right out the pipes during overlap.

Get a similar SR cam on a wider LSA,I bet you pick up what's missing and a bunch more.

Tight LSA cams over roughly 270° @ .050" add a ton of overlap,with the weaker heads and fewer cubes that was needed to help fill the cylinders and "trap" a dense intake charge,but now you have the head flow and a stronger "draw" to fill the cylinders,and more "arm" to squeeze the charge,all that extra overlap is'nt really needed nor wanted,thus that is why I said it's possible a healthy dose of HP is going right out the pipes due to overscavenging or such.



Also,what is the before/after compression ratio picture like,if you changed that,it too would have had some impact on the situation as well.