norcalz28

iTrader: (13)

So I was wondering who's running this cam and what you guys have found to be a good base timing for this cam. Pretty simple. Thanks

Will

Burnout91

6* BTDC...the rest of the timing curve is in the tune (chip); my car was running 31* total, with no knock counts, so I set the base to 10*, which I believe would result in 35* total, still with no knock retard indicated on my scan tool. Depends on the combo....

Bill

norcalz28

iTrader: (13)

Does this cam have any advance built into it? I figured 6'BTDC would be alright, but I remember someone telling me comp cams had 4' built into them. Thanks for the help.

Will

norcalz28

iTrader: (13)

Still looking for a little info guys. After a couple coolant flushes, playing with the electric fans, the car still runs hot, the temps continue to climb at idle. I am going to try some different fan setups and see what happens, but I am also going to try advancing the base timing beyond 6' a little to see if it has any effect on the heat building up. I suspect it may be a bit retarded for this combo. Your input is appreciated.

Will

1989GTATransAm

iTrader: (3)

When I ran that cam I used the 6 degree base timing and 32 total advanced with Dart heads. That cam has 4 degrees built into it and if I remember correctly was to be installed on a 109 degree intake centerline.

With my new motor and AFR heads it did not like anything over 32 degrees and lost power. Made the same power at 30 degrees total advanced and we left it there. Your AFR heads may do the same. They burn very efficiently.

norcalz28

iTrader: (13)

What do I need to set it to 32' total advanced? I installed my cam with the timing marks, I did not degree it. I set base timing to 6' BTDC and it would bog at WOT as if the timing was retarded. I set it to about 9-10' BTDC and it runs much much better now, little to no hesitation at WOT. I had also heard about the 4' built into it. How would that affect me if I installed it straight up? would it be 4' advanced or 4 degress retarded? It would seem that by bumping my timing up to 10' base, maybe I hit the sweet spot. Keep the thoughts coming guys, I'd like to start driving this thing

Will

1989GTATransAm

iTrader: (3)

If you did indeed install it straight up you are 4 degrees advanced. The problem is with out actually degreeing the cam you don't actually know where you are at. Hopefully you are where you think you are.

What you really need is a custom tune. That way the timing curve can be set for what is best for your motor along with the air fuel ratio. Kevin91Z does that for us here in SoCal.

darkhorse91

yes comp does advance all of their standard cams 4* the xfi268 is set with a 109*intake centerline and a 113*LCA. if the cam was "straight up" it would have a 113* centerline. retarding and advancing the came mainly just effects where the power band comes in. Advancing the cam (smaller number) moves the power band down in RPM while retarding it helps the upper RPM area. That is how VVT engines can make the same power as a standard style engine with a smaller cam. it advances in the lower RPM and retards in the upper. (God I want a VVT LSX)

oh almost forgot to mention timing is usually decided by the combustion chambers and a better chamber will rock less advance because it is more efficient

3rd gen Will

iTrader: (8)

Hope you get it running right! I am contemplating running a very similar combo. I have a set of AFR 180's and want to run the 268XFI cam and a ported TPI.

norcalz28

iTrader: (13)

It runs pretty decent, pulls hard, just bogs sometimes and really needs to have the tune dialed in. Also think the ESC module is bad so I'll replace that and see how it feels.

3rd gen Will

iTrader: (8)

Awesome! It seems like a stout combo! Hope you get all the kinks worked out!