CamShaft Q

[Narnian]

If I have somehow prematurely worn out my camshaft, what would the symptoms be?

[ibnfe]

lack of power, bad idle quality, if it gets bad, then you'll start getting backfires through the carb when you let off the load. why do you expect premature wear?

[Lindel]

You'll also have a hard miss. If you have bad oil consumption, or leaks (rear main seal, for one) it's easy to loose track of the oil in the pan, and starve the engine.
Camshaft will suffer quickly, and you can wear a lobe down in no time. Pull the valve covers off, and watch the rocker arms. If one doesn't move, and the rockers are tight, the pushrods are in the right place, then the camshaft is probably gone.

[Narnian]

I replaced the balancer last fall. The original broke off and spun away. One of the posts here I read said you could damage the cam when you install the pulley if you spin it too much. I put the Holley fuel injection on rght after the pulley went on, and I've had several problems. A) less power than I had with the carb. B) worse mileage than I had with the carb. C) occasional backfiring (through the throttlebody) under load at low RPM - but not generally when letting off the load.

Ralph and I found a leak in the intake manifold and fixed it. That helped but I still get occasional backfire, and I definately don't have the power I should. It stumbles very badly under load at low RPM.

Do you think I should pull the valve cover and try that little test or am I hunting down the wrong alley?

[Lindel]

It would be relatively cheap insurance, since if everything shows good, you might be out the cost of a pair of valve cover gaskets. If, on the other hand, you do need to replace the cam, you're that much farther along. You might have only jumped a tooth on the timing chain, since that was one of the stressed parts when the balancer let go.

[Narnian]

It actually feels like I jumped a tooth. I had a Jimmy that had been put on one tooth off. I drove it for a year and a half like that. I don't know how to check for that either.

[Veepster]

Narnian..............when you hear hoofbeats think horses not zebras...........your symptoms sound like your fuel injection adjustments are off..........

[Narnian]

I'm going to have to remember that - that's a great phrase!

My fuel adjustments might be off still, but I've fiddled with the silly thing endlessly to no avail. Ralph suggested finding someone "certified" to work on Holley TBI.

I'm starting to think it might just be my timing is off. It runs pretty darn good once it gets to higher rpm.

[Veepster]

is there such a thing as a certified Holley EFI guy??..........I struggled a BUNCH with my EFI in the "transition high load" area also....I finally got it perfect but it was definitely time consuming!....big tires, heavy vehicle makes that part of the fuel curve very difficult to tune....the tough part is getting that transition stage rich enough with being too rich in the top end.....it is a balancing act!.Good luck Bro!.........and if you ever want to talk about all this off-line let me know...I have spent WAY too many hours tuning/building aftermarket EFI systems and I may be able to shed some light on the subject for you.........too much to discuss in e-mail, phone would be best.....Good Luck!.......and that is one of my favorite sayings also! ;)

[David Simon]

When my camshaft went bad it made noises similar to an exhaust leak. Lots of tapping from the space between the lifters and the cam lobes. The first two were rounded off.
It was hard to see the small difference in the rocker movement but I think you can use some type of gauge to test them. Hopefully it's an adjustment on your EFI, which I know nothing about.
David

[Jeff West]

I just got done replacing my timing chain, cam, and all the seals that come with it. Also replaced the intake gasket. My cam was worn a little and my Jeep backfired like you would not believe. I have straight pipes with glass packs and it sounded like gunshots going off all over the place. I probably didn't need to replace the cam, but since I tore the whole front of the motor apart to get to the timing chain, I figured, what the hell, replace it anyways. Anyways, my problem was related to the timing chain. It had jumped a couple teeth and was way out of time. I would recommend checking your timing chain and making sure your dots line up at TDC. Why your in there, check the cam. They make a took which can check the lobes, and generally you can eyeball it and see if there is a lot of wear. Hope this helps!

[Lindel]

If you have the intake pulled, it's easy to pull a lifter, and look at the bottom of it. If the cam is worn, the bottom of the lifter will be concave (it'll be curved up into the lifter, like a coke can), and that's a sure sign it's in need of replacement. Otherwise, watch the rockers as the engine runs, and look to see if the move roughly the same amount and the valves acuate. No movement, bad cam, or push rod not in the lifter socket.