Help! Cam trouble!
 

Everyone:

Anyone that can help please let me know, I really am in dire straights on this one. Here is the situation:

I have my Cobra at the shop getting the cam and intake replaced and, the advance re-set (there was none), and the heads worked on a bit. They have just spent 20 hours pulling the whole thing apart, and then replacing the cam and intake and putting back together. Yesterday they did a 20 minute or so break in period on the new cam and saw no problems. This morning though, when they pulled the oil pan to check the cam, problems.

There is scarring along the top of one of the front cam lobes and the lifter it is hitting also has some nicks in it, and looks like it is going concave from the slightly convex shape they normally have. When I called the cam shop, they said the cam was not making it thru break in (that the lifter was not rotating) and should be pulled out and sent back to them so they can try to figure out what happened. I am having another guy in town look at it as well to try to measure the taper on the cam and the radius on the lifter.

So then the mechanic and I looked at the old cam and lfiter. It looked like the lifter from the same area of the engine was not rotating either. So here are my questions:

1) Do you all agree the cam is shot and needs to be taken out?

2) What do you think happened? If it was that the lifter wasnt rotating, how do I make sure it is before ruining another cam?

3) How do I make certain this doesnt happen again?

John

#1 yes, cam and lifters are wasted
#2 lifter didn't rotate, check lifter bore make sure new lifter can rotate, perhaps the lobes didn't have enough taper to force the lifter to rotate
#3 use quality components, check everything twice, get lucky

How can you make sure when you have the new cam in it that you dont waste the cam and lifters before you find out a lifter isnt rotating? Is there a way to do that?

An engine shop I workrd in for a period of time would put a fresh longblock on their stand, and rotate the crank with an electric motor. The lifters all had a tiny white stripe on their tops and you would spin the motor for fifteen seconds or so to make sure all the lifters spin before ever putting the intake on. Not really a do it at home solution. A very reputable engine builder I know has his cams ground with an extra 2 degrees of taper on the lobes to avoid this, and has them parkerized twice. I think both of those engine builders probubly lost a customer's motor and decided to not let that happen again, at least not for that reason.

I don't know, I just hone the lifter bores lightly, make sure my fingers can rotate the lifters with no sticking, and get lucky.

what is parkerization?

THanks for your ideas, very helpful - I am talking to my engine guy right now and passing along suggestions.

John

the heat treat to make it hard

Thanks Mr. Fixit.

I just got off the phone with the engine guy and he said he rotated the lifters in the bore with his fingers, that he ran his finger around the inside of each and they were smooth, also that the lifters cam out easy from the old ones and the new ones went in easy. Used the red colored engine building lube and really lubed the lifters and the cam prior to putting the thing back together.....to me it sounds like either the taper on the cam or the radius on the lifter was wrong, what do you think?

Also, they are still in pretty good shape although not usable now so I am sending them to a really reputable shop here that can measure the taper and the radius. If it comes back that they arent sufficient (thus that the grind was poor), should the cam shop replace the parts free of charge? I dont know how things work in this industry....

Thanks again for everything!

J

If you have a big cam with heavy inner and outer springs, did you break it in with only the outer springs??
Good luck with your next go around, Steve

Nope not using a real heavy cam. It is a hydraulic 230/238 with 530/535 lift and 108 degree lobe sep - single springs - 324 lbs.

I have heard when you are breaking in a new heavy cam, to use lighter springs or just one rather than two though...

J

Have seen instances where lifter bores had scratches or roughness. Couple of passes with some emory on a cartrige roll or brake cylinder hone cleaned it up. Then put some oil on the lifter to be sure it turns freely.

I like your idea of gaving a cam ground with a little more curve on it to insure the lifters rotate if block has a failure history because of this.

If using stiff springs, break the engine in with just the outer springs installed.

Something else I just tried on this engine was to have the springs polymer coated with an oil retentive coating to make them operate cooler, and last longer.

you could do away with the flattapet cam & put in a hydralic roller this will elemenate all of your problems after you fix the bore