kenny

I have a 79 Trans Am with the Olds 403, I just replaced the cam and now the engine starts well but the car dies once you put it in gear. The new cam is a 230 advertised duration with a .480 lift. My manifold vac is 16" hg. the new cam is mild and only slightly larger than the old. With good manifold vac, im not sure what happened. Can anyone help?

fourtwenty

My car did the same thing and it turned out to be weak spark from the coil worth a shot cheers Orrick

kenny

It could be, i just installed a new Pertronix distributer, but i did notice the cap was hot and smelled like it was burning, that electrical burn smell. I have another coil.

kenny

I installed another coil, thats not it.....any suggestions?

fourtwenty

next i would check the timing and make sure you are not 180 degrees out pull the first plug and the coil wire (so it won't start) then turn the engine over in small amounts until you hear the compression cycle ( a swoosh sound from #1) then check the rotor and see if it is close to #1 spot on the distributor. You can get closer by turning by hand until the #1 piston is all the way to the top. The engine will run 180 out.

TripDeuces

Do you have a full 12 volts going to the Pertronix while running? Being a 79 it should but I thought I'd ask.
My other thought is a vacuum leak which could be from anywhere.
Is the cam installed correctly? If it's off by a tooth or more the timing could be severely retarded.

kenny

well I checked the rotor, it is installed correctly, I degreed the cam so I know its right as well. Something strange is when I check the timing with the timing light, the line on the balancer is bouncing around. Why would that happen?

TripDeuces

I'll assume it's not a loose timing chain so maybe the advance mechanism is sticking. Vacuum or mechanical. Also some timing lights don't function well with HEI type distributors. Have another timing light to use? I'd start checking every vacuum line, port, seal etc. If you don't another timing light you can always static time it to get you in the ball park

kenny

Well I have 14.2 volts to the distributer while the engine is running, I dont suspect a vac leak because I can put my hand over the carb and it idles up then dies.

kenny

I have also replaced the module in the distributer, just for the hell of it. No luck. I drove the car and it has no power anywhere, idle ,part throttle, or WOT. Just a dog.

fourtwenty

Have you tried moving the distributor while it is running to get the best idle by ear. Maybe the balancer has spun a little. as for timing jumping around try moving the pickup closer to the plug or to the distributor. maybe try posting in another forum like builds to freshen the pot of mechanics on this site looking at this thread. keep us informed kiddo

kenny

Well I believe I found the trouble, the cam selection is too big. I went with a 42-223-4 Comp Cam with 223/230 duration and I should have stayed with the 42-208-4 with much less duration. Lesson learned. Dammit!

TripDeuces

That is not that big a cam. You probably just need more initial timing and a higher idle.

kenny

All I know is the car ran fine with the old cam, which was a 42-208-4. I just thought it could use a little waking up. I contacted Comp and they recommended the 42-223-4. I called on 3 separate occasions and got the same answer 3 times, use the 42-223-4. I installed this thing and degreed it in to 106. started the car and it idled ok, put the car in drive, it died. I drove the car and it was flat throughout the powerband. Alot worse than the 42-208-4. I called comp cams and they said "wow that cam seems large". Not Good. I am now going to replace the cam with the original 42-208-4 and call it a day. I was looking for low end torque and thats not what i found. I am using a 9.063 :1 compression, that is measured. Stock heads which are 84cc, stock intake and the Q jet. I am also using cast exaust manifolds. This I believe is as good as it will get with the package I have.

TripDeuces

Kenny I had a cam this size in a 70 Toronado that went like a bat out of Hell. From everything you say it sounds severely retarded in timing. What's your initial timing? Total timing? Telling us you have the cam degreed in at 106 means nothing without a reference point. Is the distributor off a tooth? Your compression is a tad low which is all the more reason to add more timing to this engine. Maybe a lobe got wiped out on run in? You're putting blame on a cam that's perfectly fine. But that's my opinion and it's obvious yours is different. Sounds like your mind is made up.

kenny

Well, thank you for all of your help, I changed the cam to a 42-208-4 which is in the 212 advertised duration ballpark and the darn thing runs fine. The converter is a little tight, butother than that all is well. Thanks again!