Camshaft help/advice

Post by **occasional demons** » Mon May 14, 2007 11:14 pm

I recently installed a 4884325AB Magnum cam in my 2001 SE with the scheduled timing belt change. It now acts like ign. timing is slow. (throttle response not as crisp as it was) Double checked timing belt all the marks line up perfectly. Don't get any CEL Have driven it 140 miles I would think the computer would have made whatever adjustments for the increased valve lift/duration. Is it possible I'll have to install an adjustable cam gear to advance the cam to bring power band to a more usable range? It seems to make power when I'm absolutely running the wee out of it but it's a bit unpractical to drive around like that. It just doesn't have the part throttle pull it had with the stock cam.

03blackrt · Post by **03blackrt** » Tue May 15, 2007 11:59 pm

That's what you get for putting in a bigger cam. You can help bring the powerband back down with an adjustable cam gear.

kc2005ptgt · Post by **kc2005ptgt** » Wed May 16, 2007 1:06 am

This can also be a result of having a stock ECU - timing maps are different, and though this is an upgrade, you still have a smaller intake and exhaust than the Mag head, which is possibly causing what you think would be a loss... I would beg to think that the power is up higher now than before with some loss in bottom end trq.

Also, did you replace your springs with magnum ones?

Craz1000 · Post by **Craz1000** » Wed May 16, 2007 12:03 pm

yea i would bet also its the ecu set to the regular timing, the head on the mags are way different also plus the intake and exaust manifolds are less restrictive. i wouldnt mess with the valve timing till i was sure thats whats doing it for sure, or at least was a big part of whats wrong

ive heard and seen arround this board that if you change to the mag cam you dont have to change the springs

Post by **occasional demons** » Wed May 16, 2007 8:59 pm

Thanks for the responses! Seems to be improving, but still doesn't have the same pull at the lower rpms. Stock ECU definitly not as agressive in timing/fuel as magnum as I pretty much knew that going in. I did replace the springs with mag ones (mainly because I figured with the mileage it was cheap insurance.) Also with the mag springs there's therorecticly less mass moving since the coils are bunched at the bottom. I guess the loss at bottom was more than I bargained for. Maybe I should have went with the 325AA as it has less duration. I'm sure a 2.25 exhaust would help but I don't know how much, as it pulls hard @ 5000 to shutdown. Pretty impressed that 1 7/8" outlet on the muffler flows that well. Haven't seen a drastic drop in fuel economy ( only when I'm testing the rev limiter) Maybe when I get this stuff paid for I'll look for a mag. head, try to find a used intake and well headers/exhaust are easy to get. Or just leave it like it is till the bottom end gives up and swap in a 2.4...