Engine perfrmance seems 'flat'

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78jeepstang
Posts: 1
Joined: May 26th, 2011, 2:18 pm
Vehicle Year: 1992
Vehicle Make: Jeep
Vehicle Model: Cherokee

Engine perfrmance seems 'flat'

Post by 78jeepstang »

I race a Cherokee in the TREC series at the Badlands - engines have to be more or less stock (no strokers / turbos / etc.). After grenading my #5 piston last year & destroying the block, I built a new engine over the winter. As long as I was in there (and because the cam was looking pretty funky), I put in a Crower Baja beast cam - a buddy of mine has one in both of his 258 / 4.0 head combos and they run like a raped ape. Once I got the distributor alignment figured out the engine runs great, but performance seems a little 'flat'. With cam swaps on these engines, is there any work that has to be done post-swap? The engine runs & free-revs fine, but it just seems like power is lacking. Checking fuel pressure tonight, but does anybody else have any other ideas? It actually feels less powerful than it did stock at low-moderate throttle, but the high end is definitely an improvement.

I should note - its a '92, with no other engine mods. AW4 auto
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gonridnu
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Posts: 332
Joined: December 22nd, 2008, 9:36 am
Stroker Displacement: 4.6L
Vehicle Year: 1989
Vehicle Make: Jeep
Vehicle Model: XJ 2 door

Re: Engine perfrmance seems 'flat'

Post by gonridnu »

Did you change pushrods? Most aftermarket cams require a different length pushrod as they are not ground on the same base circle as the stock cam.

Also did you check valve spring clearance to coil bind?

Did you degree the cam? I recently built an engine where the cam from a reputable grinder was the farthest off from the pin I have ever seen and had it been run that way it would have had zero power......
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SilverXJ
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Joined: February 14th, 2008, 7:14 am
Stroker Displacement: 4.6L
Vehicle Year: 2000
Vehicle Make: Jeep
Vehicle Model: Cherokee
Location: Radford, Va

Re: Engine perfrmance seems 'flat'

Post by SilverXJ »

x2 on what gonridnu said.

Also, what tires and gearing are you running and what does your buddy run?
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