Problems after cam change

[streetstang67]

I installed a Comp XE256H cam yesterday and roughly set the timing and somewhat adjusted the valves.

Problem 1: Oil leak somewhere causing #8 cyl. header to burn oil
Problem 2: Engine misses under accleration
Problem 3: Car is not any faster.
Problem 4: While idling, car will randomly cut off, without any fore-warning.

Overall, I would think these problems are results of bad valve adjustment, bad timing, or bad carb. adjustment. What do you think, and how can I fix this?
Thanks

 

[rbohm]

1: sounds like a valve cover leak to me.

2: vacuum leak likely, bad plugs or plug wires also.

3: gotta tune the new combo, timing, jetting, etc.

4: how smoothly does the engine idle? if not at all then likely a carb and timing adjustment are in order. as for valve adjustment, loosen each rocker in turn untill you hear the valve clatter, then tighten the rocker up untill it just goes away, then go 1/8 turn more.

 

[Dark Knight]

correct firing order? cam isnt ground with the late model firing order, is it?

check the back of the intake manifold too, for leaks..

prob 4 sounds like a loose wire somewhere.. check the coil connections etc..

 

[dennis112]

Problem 3: Car is not any faster.

The XE256H doesn't sound like much more than a stock replacement cam so I doubt if there would be much of a perceivable difference in performance. You should probably work on your "tune" a little more--Perhaps try advancing the cam.

 

[10secgoal]

Yeah. I has to be a major gain to feel anything in the butt dyno/ I made one mod, didn't really feel a difference. But picked up 2 tenths and 2.5 mph in the 1/4. So the butt dyno is about as accurate as a g-tech.

 

[69Rcode_Mach1]

DO NOT ADVANCE THE CAM. Compcams builds in an advance into their cams so they need to be installed straight up.

 

[streetstang67]

Isn't the cam and timing two different issues? How would I advance the cam?

 

[D.Hearne]

Problem 2 sounds like a full tune up is in order, if the valves are adjusted correctly. Problem 4 could also be a short in the ignition. If you've got an aftermarket tach, the green wire, even though it's a ground, will short against metal and kill the engine, look for bare wiring where it goes thru the firewall if that's the case.

 

[streetstang67]

Problem 2 sounds like a full tune up is in order, if the valves are adjusted correctly. Problem 4 could also be a short in the ignition. If you've got an aftermarket tach, the green wire, even though it's a ground, will short against metal and kill the engine, look for bare wiring where it goes thru the firewall if that's the case.

The tach is broke...good thinking.

 

[69Rcode_Mach1]

Isn't the cam and timing two different issues? How would I advance the cam?

This refers to the camshaft itself you can install it so that your cams timing marks are aligned differently from your crankshaft this is how you can advance or retard your cam. This is NOT necessary with a comp cams product however.

 

[D.Hearne]

The tach is broke...good thinking.

Not good thinking, rather this was gained from actual experience, way back when I ran an aftermarket tach for the first time, and did the wiring half assed. No grommet thru the firewall. and after a period of time, it came back to haunt me when that green tach wire shorted. :damnit: