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02-24-2003, 12:36 AM
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Senior Club Cobra Member
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Join Date: Nov 1999
Location: Folsom,
CA
Cobra Make, Engine: ERA 623, 427 S/C Cobra. Ford FE 428 Cobra Jet, Ford Nascar TL 4speed - with a touch of raw; "less is more" theme
Posts: 3,884
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Not Ranked
Valve lash cap breaks right in half?
Hey big-block motorheads...,
any idea why a valve lash cap might break right in half, and all other caps look perfect? My builder is out of the country on business this week or I'd bug him first.
Engine: 428CJ
Valve Lash Caps: by Crower
Crower Cam: Solid Lifter / .640 lift
Rocker Assembly: Shelby / Stainless with end-stands
Two 6,400 rpm shifts; and 20 minutes later one failed. Broke right in half. Another guy in our Shelby Club said he has heard of this happening to others before.
Any thoughts? Bad materials? Who knows?
Thanks.
__________________
Duane
Western States Cobra Group 1998-2016.
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02-24-2003, 01:34 AM
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CC Member
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Join Date: Aug 2000
Location: Chicago,
IL
Cobra Make, Engine: ERA 454 S.O.
Posts: 1,684
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Not Ranked
The heat treat could be too hard. How is the lash on the rest of the valves? Another possibility is that that valve lost the lash for whatever reason then the cap broke in half. My guess would be the first.
__________________
Jeff
“If you can make black marks on a straight from the time you turn out of a corner until the braking point of the next turn, then you have enough horsepower.”
Mark Donahue
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02-24-2003, 04:04 AM
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CC Member
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Join Date: May 2001
Location: California,
Ca
Cobra Make, Engine: NAF 289 Slabside Early Comp Car with 289 Webers and all the goodies. Cancelling the efforts of several Priuses
Posts: 6,592
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Not Ranked
Metal Fatigue, improper heat treat or fit. Pick your poison.......
Rick
PS: Just an afterthought. The valve stems should have a very small chamfer on the end. If this is lacking the sharp corner could cut into the fillet machined in the recess of the lash cap creating a stress riser inside the cap itself.
__________________
Rick
As you slide down the Banister of Life, may the splinters never be pointing the wrong way 
Last edited by Rick Parker; 02-24-2003 at 11:17 AM..
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02-24-2003, 09:40 AM
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Senior Club Cobra Member
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Join Date: Mar 2001
Location: Seattle, WA,
Posts: 1,389
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Too much cam for the set?
__________________
Foolish consistancy is the hobgoblin of tiny minds
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02-24-2003, 10:41 AM
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CC Member
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Join Date: May 2000
Location: Leicester,
UK
Cobra Make, Engine: Crendon, windsor 408 stroker, tremec. Also GSX008
Posts: 1,406
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Not Ranked
Mismatch between the taper lock angles of keepers/ caps?
Can you even get different lock angle keepers for FEs?
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Wilf
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02-24-2003, 02:10 PM
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CC Member
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Join Date: Jan 2003
Location: Atlanta,
GA
Cobra Make, Engine: CAV GT40 with 331 KC
Posts: 2,187
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Not Ranked
Duane -
What cylinder heads are you using and what has been done to them - I am noting the amount of lift your cam has....
pb
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02-25-2003, 10:55 AM
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Senior Club Cobra Member
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Join Date: Nov 1999
Location: Folsom,
CA
Cobra Make, Engine: ERA 623, 427 S/C Cobra. Ford FE 428 Cobra Jet, Ford Nascar TL 4speed - with a touch of raw; "less is more" theme
Posts: 3,884
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Not Ranked
Re:
Hi Pat,
Edelbrock heads, solid lifter, added a 2nd inner valve spring... because they only handle .600 lift stock. .015 valve lash with aluminum heads. I'm in Wisconsin this week, and hopefully looking at it closer when I return. Closer inspection of the cam/lifters, etc...
Thanks.
__________________
Duane
Western States Cobra Group 1998-2016.
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02-25-2003, 09:12 PM
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CC Member
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Join Date: Jan 2002
Location: Northern California,
CA
Cobra Make, Engine: -Sold- Contemporary 427S/C # CCX-3152 1966 427 Med Rise Side Oiler, 8v 3.54:1 Salisbury IRS, Koni's.. (Now I'm riding Harleys)
Posts: 2,567
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Not Ranked
Same reason the pin on my pin Trigo pin drive wheel shattered the first time I applied an open handed slap to the allen wrench.. Crappy quality control.. What the hey.. It's under warranty..
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michael
A man that is young in years, may be old in hours, if he have lost no time. But that happeneth rarely. Generally, youth is like the first cogitations, not so wise as the second. For there is a youth in thoughts, as well as in ages... Sir Francis Bacon (1561-1626)
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02-26-2003, 08:22 PM
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CC Member
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Join Date: Sep 2002
Location: Auburn Wa,
Posts: 15
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I have seen some lash caps (name brand) that were poorly made and actually had a little left over tit sticking up on the flat surface that the valve mates up to (inside). Anyway that coupled with a heat treat would create enough of a stress riser to break it IMO.
Dale
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03-21-2003, 02:24 PM
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CC Member
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Join Date: Aug 2001
Location: SUISUN CITY CA,
Posts: 36
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lol broken aps?
i took my car to toe preformance for the same reason only weeks after my purchase. Tony the owner said the guy who did the wrench work overtightened it..oh yea I bought my car from you! l  maybe you should torque em......
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brizz
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03-21-2003, 02:45 PM
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CC Member
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Join Date: Jul 2001
Location: Senoia,
Ga.
Cobra Make, Engine: 427SO with big twin autolite inlines on custom intake, jag rear, top loader, wembeldon white, guardsmen blue stripes
Posts: 3,155
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Not Ranked
Dcooney, are you sure about the .15 valve lash?, If correct I would set at .17
to compensate for heat expansion. You might be down to .13 after it warms up.
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Perry
Remember!, there's a huge difference between a 'parts' changer, and a mechanic.
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03-21-2003, 04:02 PM
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Senior Club Cobra Member
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Join Date: Nov 1999
Location: Folsom,
CA
Cobra Make, Engine: ERA 623, 427 S/C Cobra. Ford FE 428 Cobra Jet, Ford Nascar TL 4speed - with a touch of raw; "less is more" theme
Posts: 3,884
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Not Ranked
Hi Perry,
.15 would be extreme without a zero in front of it. We are talking thousandths, not tenths here - right?
Up to .006 tighter (Initial set cold) on aluminum heads, per the cam MFG. I don't have iron heads... Yea, .017 hot would work..., My current cam calls for .022-I/.024-E hot and -.006 cold. Running it a little looser would seem safer to me too, but Crower says they'd like to see it even go tighter when set hot.
__________________
Duane
Western States Cobra Group 1998-2016.
Last edited by decooney; 03-22-2003 at 02:17 AM..
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03-23-2003, 05:00 PM
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CC Member
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Join Date: Jul 1999
Location: Prescott Valley,
AZ
Cobra Make, Engine: Previous ERA owner on break
Posts: 600
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Not Ranked
FWIW, 0.015" should be OK. I've got the Edelbrock heads and Crane cam, also. Recommended lash for the cam is 0.022. Both Crane and the builder said subtract 0.008 for the aluminum heads, so I set them at 0.014 and it seems to be running OK. My experience anyway. Seems like you might have just gotten a bad rocker arm. Any further analysis?
__________________
Some folks drink from the fountain of knowledge; others just gargle.
Yesterday's flower children are today's blooming idiots.
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03-23-2003, 07:08 PM
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Senior Club Cobra Member
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Join Date: Nov 1999
Location: Folsom,
CA
Cobra Make, Engine: ERA 623, 427 S/C Cobra. Ford FE 428 Cobra Jet, Ford Nascar TL 4speed - with a touch of raw; "less is more" theme
Posts: 3,884
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Not Ranked
Hey Chopper,
as per your question, and to make a long story short some additional analysis was done on my cam profile, overall lift, valvesprings, dampners and retainers, and total valve lash itself. A few suspect areas such as the particular valve springs I used, in combination with my solid lifter cam, profile, and revisiting usability prompted me to swap out my cam last weekend. Also ordered a set of matched Crower springs, dampners, lifters. Nothing conclusive yet, but working to eliminate variables that have been noted as questionalble ones. So far so good. Thanks.
__________________
Duane
Western States Cobra Group 1998-2016.
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03-23-2003, 11:02 PM
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CC Member
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Join Date: May 2001
Location: The Heart of the Citrus District,
NJ
Cobra Make, Engine: Sold 3047 & 3002 in 2012
Posts: 2,763
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Not Ranked
didn't read the whole thread but
If you are loosing a cam lobe or you somehow adjust it too loose, the slapping could cause the problem, Take you time and just look, It will come to you. It always does,
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