I just replaced a cam in my 454...old cam wiped a lobe in less than 1000 miles (bad break in and oil selection). I installed a Lunati Voodoo 60204. I have a holley 850, full headers, duel plane high rise, 4 speed in a 68 Camaro.

In order to get the motor running well, timing is well advanced (off my gage, est 20 deg advanced). It idles well, very responsive off idle. My problem is that it just dies on top end. It quickly turns up to 4500 rpms, the just bogs.

The last cam (specs and brand unknown, only had 1007 stamped, no brand) allowed the engine to turn over 6000 (or more) with no problem. It was a mild cam with no rough idle. I made no other changes except for the cam swap.

So, my question...is my timing too advanced limiting top end rpms? I can take some timing out and lose some idle quality and responsivness...just looking for someone with more knowledge than me! Thanks in advance for any help!

 

The timing curve will have to be changed so that the total advance remains close to what was used for the old cam, but allow more initial timing. Too much spark advance can seriously damage the engine and cause severe loss of power. The type of heads affect the total advance needed, more than the cam. However; in the case of a big cam, more initial advance is needed to get enough vacuum at low RPM, and when the RPMs are up an the engine comes on cam (torque peak) the combustion pressure will be higher than on a small cam, and dangerous detonation can result unless the spark timing is reduced at that point. Depending on the distributor you are using, re-curving the timing could be a simple thing or a PIA. If you just use the car for drag racing, you could disable the spark advance mechanism and lock the distributor for the appropriate total advance, and make sure to keep the revs up in order to keep the engine from stalling.