Thread:

Valvespring life

Does valvespring life increase if you backoff your rockers when a motor will not see use for some time?

I've gotten into the habit of backing off the rockers but because they are shaft rockers I have to unbolt the shaft which is kind of a PITA. When I go to re-lash I have this whole production, cycling through to bolt down all the shafts, then set lash...(now Im silently wondering if I can just back of the adjuster nut and pull the adjuster all the way out? anyone know?)

Crane shaft rockers are what I am running.

I think if you know the engine is going to sit for extended periods, like more than a year, it doesn't hurt to back off on the springs. Just during the few months of off-season, I don't think it will make a lot of difference. It's a lot easier to just bump the engine a 1/4 turn every few weeks if you're concerned. I know if a boat's in storage or a differnet location that may not be convenient.

Originally Posted by steelcomp

Just during the few months of off-season...

Scott, you mean to tell me that there's an off season!?

FWIW, Engle did a test. They put a new spring in a vise, (old bench out back), and tightened it to coil bind. They left it there for a year in Santa Monica's damp salt air. Nothing changed........To back them off is a sure way to seal the cylinders for the winter, and not knowing which springs you run, certainly can't hurt. I also like the idea of turning the motor 90* every month or so if the valves are left adjusted. Another note, it is a good idea to check the adjustment before the first outing anyway, so backing them off and re setting doesn't really add any work for the new season...........Ray

Originally Posted by River Rat 005

Also if you oil the exhaust valve seats then back them off, it will keep them from rusting as when you shut it down they are dry.

Tim

If you watch the east coast racers button their stuff up after a race you'll see them "fog" the engine. Marvel mystery oil, or some other light oil down the intake until it fogs up the pits with smoke and stalls the engine. Their way of lubing stuff up inside for the trip home............Ray

Originally Posted by hotbo

im a firm believer in backing your valve train off.no matter the test or not i think imo with my weak ass mind,lol!!!that it has to help with spring longevity and it also seals the cylinders like stated,travis

Originally Posted by ol guy

Fwiw, I am a firm believer in backing of the rockers if the motor will sit longer than a month. just think about the valve rotation in relation to where the springs are. If you are out for the last romp and shut the motor down for the winter or whatever then you have some at close,some at half open and some at max lift!!! I understand that alot of guys will say that a good set of springs wont lose tension wherever they are but I believe in keeping all things equal. I would rather spend a few minutes running the valves rather than loosing RPM due to an un-equal spring pressure. Remember that the key to a balanced motor is ALL cyclinders being equal. IMLAO Mark

We are as well. I take them off after each race. Probably not necessary but in my mind I'm helping by not having everything under pressure. Jesel (or any shaft rocker) should maintain lash for the most part. I'll reinstall them, warm it up and set lash hot. Very rarely do I have to make adjustments!!

Originally Posted by MACHINEHEAD1

Just tore dwn the 477 pontiac after sitting 13 years. Springs dropped about 20lbs. from 190seat/620open. We put it up wet with about 20-25 passes on it in 1996. If that helps.

Question is, could the springs have already been down 20lbs when you put it away?

Originally Posted by steelcomp

I think if you know the engine is going to sit for extended periods, like more than a year, it doesn't hurt to back off on the springs. Just during the few months of off-season, I don't think it will make a lot of difference. .

Originally Posted by Moneypit

FWIW, Engle did a test. They put a new spring in a vise, (old bench out back), and tightened it to coil bind. They left it there for a year in Santa Monica's damp salt air. Nothing changed........To back them off is a sure way to seal the cylinders for the winter, and not knowing which springs you run, certainly can't hurt. Ray

Aside from it sealing the engine during storage, it doesn't do jack! Any one really believe the worse thing that happens to a valve spring in it's span is being held at full lift for extended periods? How long is to long? 1 minute, 1 hour, 1 day? Think thats tougher than cycling 45 times a second and running on the edge of turning cherry red? Absorbing, storing and releasing all that energy 4000 times a minute? It's the cycling that sacks and kills them. How long does it take for a L19 rod bolt to take set in a stored short block at it's stretched length? How long before stored short block with standard tension rings has low tension rings? This the best book I have ever read regarding metal stresses, failures, yields etc. This book should be required reading in every high school metal shop in the country!