My friend is running a mild 454 in his 70 chevelle. The motor really isn't built, maybe a mild cam. Aftermarket intake, holly 750, headers etc.

We heard what sounded like a nasty lifter tap (he put in octane boost and started hearing it after that if that matters). At idle the car sounds okay, under some load you can hear it tapping. Seems to go insink with the motor clack, clack, clack. So we tore it down to take a look at the lifters (we adjusted the valves with little luck). We had a hard time getting about 8 of them out ... extremly hard time getting 2 out. The edges of those lifters were rough and had an edge to them but the bottom of all the lifters were flat and smooth. We didn't noticed that any were shelled out.

With everything "looking" okay, could the fact that some of the lifters were "mushroomed" and hard to pull out indicate a bad lifter which could account for the lifter tap we couldn't get rid of?

We will be putting in some new lifters this weekend and making sure they are adjusted properly but im just wondering if what we found could be a cause of his pain?

Thanks,

Dave

Imho, it sounds like a cam is slowly going away if the lifters are mushrooming??

Maybe some of the guys know more about this???

pdq67

Yup ... usually mushroomed lifters mean cam going away. put two of the lifters together, flat side to flat side ... you should be able to "rock" them. Lifters are not perfectly flat on the bottom, they are curved. If they ARE flat, they are probably no good and the cam is starting to wipe. If this is the case, new lifters are going to be a waste of miney. The curve is very slight so you have to look hard. Check a couple of the cam manufacturers sites, they all have goo online pics and descriptions.