Life Span of Valves

Go down

Life Span of Valves

Post  JACKAZZFLATZ on September 12th 2016, 3:27 pm

SO, coupla weeks ago, had some problems at the track.  Gave away another race due to breakage.
According to the tell tale on the tach, it never saw 6300 rpm.  
I've been running these A-heads for about 8 yrs, is there an "end of life" expectancy for valves ?  OR just this one  ?
avatar
JACKAZZFLATZ

Posts : 245
Join date : 2009-11-24
Location : N/W MICHIGAN

View user profile

Back to top Go down

Re: Life Span of Valves

Post  dfree383 on September 12th 2016, 4:36 pm

No they don't last forever......
avatar
dfree383
BBF CONTRIBUTOR
BBF CONTRIBUTOR

Posts : 13968
Join date : 2009-07-09
Location : Home Wif Da Wife.....

View user profile

Back to top Go down

Re: Life Span of Valves

Post  IDT-572 on September 12th 2016, 4:39 pm

Sounds like about 8 years................ Rolling Eyes Sorry couldn't help myself, it's I've been around the Coug to long. Twisted Evil Razz
avatar
IDT-572
BBF CONTRIBUTOR
BBF CONTRIBUTOR

Posts : 4581
Join date : 2008-12-02
Age : 57
Location : Shelbyville Tn.

View user profile

Back to top Go down

Re: Life Span of Valves

Post  DaveMcLain on September 12th 2016, 7:27 pm

An intake valve broke so I would be really looking at the valvetrain especially the springs.  What do the keepers on the other valves look like?  Are they all polished up from "fretting"? Sometimes too a valve can be very slightly bent then each time it closes the spring forces it against the seat and it flexes it back and forth. Over time the fatigue breaks the stem.


DaveMcLain

Posts : 347
Join date : 2009-09-15

View user profile

Back to top Go down

Re: Life Span of Valves

Post  jones on September 12th 2016, 8:11 pm

This is one thing I would like to understand. The possible causes of valve failure other than piston to valve contact. Could a weak or broken valve spring caused it?

jones

Posts : 2212
Join date : 2008-12-02
Location : Philadelphia, MS.

View user profile

Back to top Go down

Re: Life Span of Valves

Post  cool40 on September 12th 2016, 8:38 pm

jones wrote:This is one thing I would like to understand. The possible causes of valve failure other than piston to valve contact. Could a weak or broken valve spring caused it?
absolutely ! A weak spring allows the valve to bounce on the seat which is far worse than high spring psi. Not saying this is the case here .........
avatar
cool40
BBF CONTRIBUTOR
BBF CONTRIBUTOR

Posts : 7135
Join date : 2009-08-31
Age : 47
Location : on the 1/8 mile dyno

View user profile

Back to top Go down

Re: Life Span of Valves

Post  rmcomprandy on September 12th 2016, 10:00 pm

jones wrote:This is one thing I would like to understand. The possible causes of valve failure other than piston to valve contact. Could a weak or broken valve spring caused it?

I am guessing you must think there is no such thing as metal fatigue...?

The more stress it is required to absorb, especially in tensile cycles ... the shorter the lifespan will be.

rmcomprandy

Posts : 4982
Join date : 2008-12-02
Location : Roseville, Michigan

View user profile http://www.rmcompetition.com

Back to top Go down

Re: Life Span of Valves

Post  jones on September 13th 2016, 12:35 am

rmcomprandy wrote:
jones wrote:This is one thing I would like to understand. The possible causes of valve failure other than piston to valve contact. Could a weak or broken valve spring caused it?

I am guessing you must think there is no such thing as metal fatigue...?

The more stress it is required to absorb, especially in tensile cycles ... the shorter the lifespan will be.




jones

Posts : 2212
Join date : 2008-12-02
Location : Philadelphia, MS.

View user profile

Back to top Go down

Re: Life Span of Valves

Post  gt350hr on September 13th 2016, 10:45 am

Far too many guys rely on "buzz words" . There is quality stainless material and then there is stainless material. Some guys only hear "stainless" and feel good about it. Just like the word forged. Some builders cycle them out by hours , others by laps or miles , and others by "seasons". Most stainless valves are made in Brazil or China , but some are still made here. Manley and Ferrea offer some excellent valves.

gt350hr

Posts : 423
Join date : 2014-08-20
Location : Anaheim , CA

View user profile

Back to top Go down

Re: Life Span of Valves

Post  JACKAZZFLATZ on September 13th 2016, 4:13 pm

Thankx for the comments and suggestions. The valves were the ones originally supplied with the heads. Ya, they've been thru a valve job, or two.
I really shouldn't bitch, and i'm not, it's just racing.
The springs were new at the beginning of the season, i'd havta check the log book to see how many runs actually.
When the covers were pulled, all the stems were in place, no broken springs. Just .250+" of lash on #7 Intake.
Like Blake says, this one was only good for 8 years. Must be kinda like rear gears, mine are only good for 2 years. Another hard lesson !
avatar
JACKAZZFLATZ

Posts : 245
Join date : 2009-11-24
Location : N/W MICHIGAN

View user profile

Back to top Go down

Back to top


 
Permissions in this forum:
You cannot reply to topics in this forum