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Loosing lash on one valve........ Ever had it?
#843277
10/31/10 11:51 PM
10/31/10 11:51 PM
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Joined: Apr 2007
Posts: 1,165
Central Ohio, USA
Bigbeep
OP
super stock
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OP
super stock
Joined: Apr 2007
Posts: 1,165
Central Ohio, USA
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Run the valves the other day before running the car on Wednesday at HC. #4 exhaust valve was tight. I checked all others and reset #4. Made 4 passes and the car fell off .015 in the 1/8 mile on the last pass. Pulled valve covers off and checked lash again. #4 exhaust valve had NO lash left. All .026" were gone. Only thing I can think off is I have a valve getting ready to break (stretching or tullipping the head) or I have a seat beating itself around in the head. I figure if it was lifter or the cam the lash should get larger not smaller.
Quick run down on combo. 440 block, stock lifter bores, comp roller cam, comp roller lifters, Smith Brothers pushrods, Harland Sharp 1.6 rockers, K-motion springs 245 on the seat- 690 over the nose. Indy 440-1 heads with indy valves.
When I found all the lash was gone I set it again and rolled the motor over(not fired)a couple of times and it was gone again. I just put it away and will inspect this week. I already had planned on pulling it for the winter and doing some work anyway, so now there is a reason. I am just glad I caught it before major damage was done. Anyone else ever have this happen.
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Re: Loosing lash on one valve........ Ever had it?
[Re: Bigbeep]
#843280
11/01/10 12:49 AM
11/01/10 12:49 AM
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Joined: Feb 2003
Posts: 3,456
Out West
408strokerdart
master
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master
Joined: Feb 2003
Posts: 3,456
Out West
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Quote:
Run the valves the other day before running the car on Wednesday at HC. #4 exhaust valve was tight. I checked all others and reset #4. Made 4 passes and the car fell off .015 in the 1/8 mile on the last pass. Pulled valve covers off and checked lash again. #4 exhaust valve had NO lash left. All .026" were gone. Only thing I can think off is I have a valve getting ready to break (stretching or tullipping the head) or I have a seat beating itself around in the head. I figure if it was lifter or the cam the lash should get larger not smaller.
Quick run down on combo. 440 block, stock lifter bores, comp roller cam, comp roller lifters, Smith Brothers pushrods, Harland Sharp 1.6 rockers, K-motion springs 245 on the seat- 690 over the nose. Indy 440-1 heads with indy valves.
When I found all the lash was gone I set it again and rolled the motor over(not fired)a couple of times and it was gone again. I just put it away and will inspect this week. I already had planned on pulling it for the winter and doing some work anyway, so now there is a reason. I am just glad I caught it before major damage was done. Anyone else ever have this happen.
I think you are on the right track with your first guess. I bet that valve isn't long for this world. Once they start to stretch the metal will yield easily and continue to loose lash until it seperates. I would say you saved yourself some coin by not running it. Interested in what you find though.
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Re: Loosing lash on one valve........ Ever had it?
[Re: 408strokerdart]
#843281
11/01/10 01:01 AM
11/01/10 01:01 AM
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Joined: Oct 2007
Posts: 4,206
New York
polyspheric
master
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master
Joined: Oct 2007
Posts: 4,206
New York
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X2 - the valve head is tuliping, seat receding, etc.
All other changes (rocker tip, pushrod ball, cam lobe) will increase lash.
Boffin Emeritus
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Re: Loosing lash on one valve........ Ever had it?
[Re: Bigbeep]
#843285
11/01/10 08:59 PM
11/01/10 08:59 PM
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Joined: Jun 2003
Posts: 9,225
Charleston
sixpackgut
Drag Week Mod Champion
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Drag Week Mod Champion
Joined: Jun 2003
Posts: 9,225
Charleston
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i would think the installed height growing would be noticable. i cant wait to hear the results
Gen 3 power 6.22@110, 9.85@135
Follow @g3hemiswap on instagram
performance only racing, CRT, ultimate converter, superior design concepts, ThumperCarbs
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Re: Loosing lash on one valve........ Ever had it?
[Re: camastomcat]
#843291
11/06/10 04:57 AM
11/06/10 04:57 AM
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Joined: Apr 2007
Posts: 1,165
Central Ohio, USA
Bigbeep
OP
super stock
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OP
super stock
Joined: Apr 2007
Posts: 1,165
Central Ohio, USA
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Well, tore the top end off the engine the other night. It is a lot better than I was expecting. It comes down to a "stupid human trick". A while back I pulled the rockers and checked a suspect spring problem on another cylinder. While reassembling the valve train I accidently tightened down the rockers with the pushrod out of the lifter cup on #4 exhaust valve lifter. After finding it and replacing a bent pushrod, I reassembled it correctly. Unbeknownst to me, I damaged the top of the lifter. It swelled the lifter at the top edge. My losing of lash was caused by the lifter just barely sticking in the bore. Weird thing is, I had checked the valves 2 times since than and never seen any issues with lash. When I pulled the head and found nothing wrong with the valve or seat, I went to the lifters. It was stuck, but not too tight that I couldn't pull it out with 2 fingers. I could also push it in to the base of the cam by hand. So, all in all not too bad. Chalk this one in to the lessons learned column. Thankfully the roller and camshaft have no damage. Beep 
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Re: Loosing lash on one valve........ Ever had it?
[Re: Bigbeep]
#843295
11/06/10 08:45 PM
11/06/10 08:45 PM
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Joined: Feb 2005
Posts: 20,179
PA.
pittsburghracer
"Little"John
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"Little"John
Joined: Feb 2005
Posts: 20,179
PA.
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Good job on the catch.  That could have turned ugly real fast. I think one of the hardest jobs for a racer to do is to load up their car because they fill something isn't right.
1970 Duster
Edelbrock headed 408
5.984@112.52
422 Indy headed small block
5.982@112.56 mph
9.42@138.27
Livin and lovin life one day at a time
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Not tighter 
