BB Chevy eating keepers
 

What would be the most likely cause of our engine chewing up keepers? It's a around 480 cu and we run a Comp Cams flat tappet cam. Sept of last year we caught one before it dropped a valve and replaced them all. Now one year later it happened again and it's on four different valves. I feel like we have used up all our luck and better get on top of this. Most seem to think bad springs are causing float or bad batch of keepers. Opinions? Thanks in advance.

Re: BB Chevy eating keepers
 

The two things that I would look at is make sure that the rockers have sufficient clearance by the retainers. Also make sure that your valve train geometry is correct and not causing excessive side load on the valve as it is opening
Chuck

Re: BB Chevy eating keepers
 

X2 on the rocker clearance.
If the rocker is contacting the retainer and leaving wear marks on the bottom of the rocker ,that could be your problem.
Really weak springs could be letting the valve bounce as well , that'll cause a whole bunch of valvetrain wear and breakage.

Re: BB Chevy eating keepers
 

Thanks for the reply's. The rockers HAVE been hitting the retainers very slightly and I didn't even make that connection. The springs have a ton of runs on them as well. I thought we had changed them out at least once since this problem surfaced but we haven't. Think I'll pull the heads and really go over everything.

Re: BB Chevy eating keepers
 

If the rockers hit the retainers, they're tilting the retainers and trying to un-key the valve every time the engine spins over 4 times. You're lucky that you haven't done even more damage. That is most certainly the problem.

Most modern rockers for a big block will clear a 1.650" spring and retainer with relative ease, provided the valvetrain geometry is correct.

Re: BB Chevy eating keepers
 

I'm wondering about the geometry. We do run lash caps and I can see witness marks on the underneath side so they must be the right depth. If I remember correctly the lash caps were supposed to help a geometry problem that we had. Will T&D or Jesell shaft rockers eliminate that problem?

Re: BB Chevy eating keepers
 

Well, shaft rockers are the way to go, if you can afford them, and Comp has a good deal on theirs.

If you're running lash caps and you're still hitting the retainers with the rockers, odds are your pushrod is too short.

Re: BB Chevy eating keepers
 

You definitely need to check the pushrod length also. This is something a lot of people never check. It isn't hard to do though. Set up one rocker and watch the tip as it rolls across the valve stem. It should stay in the middle of the valve stem the majority of its travel. Since it swings in an arc it will move back and forth, but should not come off the edge of the stem. As the previous post suggested, you may need a slightly longer pushrod. You definitely need springs though if you have that many runs on them.....another often overlooked item that is worth a bunch of power.

Good Luck!

Re: BB Chevy eating keepers
 

TD,
How do run so consistant with that issue ?
I don't know about the rest of you but I change out the springs every 100 runs or so. Sounds to me that the PR length is on the short side, easily confirmed with a good set of length checkers, I have a set in my trailer if you need to borrow them. I also know where you can buy new pushrods- Smith Brothers !
Just don't set on it fire again ! If I'm not there.

Re: BB Chevy eating keepers
 

Chuck, I'm not thinking this is the Tommy D that you are thinking it is. Unless you know two of them that have set their car on fire. lol
Chuck

Re: BB Chevy eating keepers
 

Only know one that had a car fire!
Anyhow the rest of the advise is good. My mistake !

Re: BB Chevy eating keepers
 

That is good advise Chuck, you know a lot of Tommy D's including this one. Tom Dillman here.

Re: BB Chevy eating keepers
 

Thanks Ron, hey why don't you just walk down the street and take a look at Gregs heads after you get done eating turkey this week?http://classracer.com/classforum/ima...ons/icon10.gif