BB Chevy eating keepers

tommy d · 11-20-2011, 11:31 PM

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.

C and W Racing · 11-21-2011, 08:59 AM

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

Tom Goldman · 11-21-2011, 09:18 AM

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.

tommy d · 11-21-2011, 06:44 PM

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.

Alan Roehrich · 11-21-2011, 07:42 PM

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.

tommy d · 11-21-2011, 09:04 PM

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?

Alan Roehrich · 11-22-2011, 01:30 AM

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.

Ron Finney · 11-22-2011, 09:52 AM

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!

Chuck Westcott · 11-22-2011, 11:26 AM

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.

C and W Racing · 11-22-2011, 03:07 PM

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

11-20-2011, 11:31 PM	#1
tommy d Senior Member Join Date: Oct 2010 Location: Indiana Posts: 791 Likes: 1,376 Liked 310 Times in 116 Posts	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. Last edited by tommy d; 12-30-2011 at 11:34 PM. Reason: close thread

11-21-2011, 08:59 AM	#2
C and W Racing Senior Member Join Date: Jul 2007 Posts: 554 Likes: 5 Liked 10 Times in 1 Post	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

11-21-2011, 09:18 AM	#3
Tom Goldman VIP Member Join Date: Jan 2003 Location: Allentown,PA Posts: 2,436 Likes: 776 Liked 700 Times in 204 Posts	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. __________________ Tom Goldman 1500 SG , 1506 STK

11-21-2011, 06:44 PM	#4
tommy d Senior Member Join Date: Oct 2010 Location: Indiana Posts: 791 Likes: 1,376 Liked 310 Times in 116 Posts	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.

11-21-2011, 07:42 PM	#5
Alan Roehrich VIP Member Join Date: May 2006 Location: Murfreesboro TN Posts: 4,915 Likes: 996 Liked 1,043 Times in 274 Posts	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. __________________ Alan Roehrich 212A G/S

11-21-2011, 09:04 PM	#6
tommy d Senior Member Join Date: Oct 2010 Location: Indiana Posts: 791 Likes: 1,376 Liked 310 Times in 116 Posts	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?

11-22-2011, 01:30 AM	#7
Alan Roehrich VIP Member Join Date: May 2006 Location: Murfreesboro TN Posts: 4,915 Likes: 996 Liked 1,043 Times in 274 Posts	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. __________________ Alan Roehrich 212A G/S

11-22-2011, 09:52 AM	#8
Ron Finney Member Join Date: Jul 2008 Location: Greenwood, IN Posts: 168 Likes: 0 Liked 0 Times in 0 Posts	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! __________________ Ron Finney 396V S/C

11-22-2011, 11:26 AM	#9
Chuck Westcott Member Join Date: Dec 2003 Location: Brownsburg,Indiana Posts: 326 Likes: 0 Liked 0 Times in 0 Posts	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. __________________ Chuck Westcott- S/C -S/G 225

11-22-2011, 03:07 PM	#10
C and W Racing Senior Member Join Date: Jul 2007 Posts: 554 Likes: 5 Liked 10 Times in 1 Post	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