I always have done this in the past.. Was told it was bad for the valvesprings if you did not. For me it is for 4 months. Know some guy's that don't do it! 800 lbs. seems pretty stout to leave on a spring for very long but what about the guy's that race occasionally all year long. Is it enough to just crank it over a little to change the load?
Thanks Mike

Motion wears a spring out, not a constant state...If that were the case springs that have set around on engines for years that have not been run would be junk.

I would think you could make the case for backing the rockers off to close the valves to prevent moisture and anything from entering an engine. I once seen a race engine that was left set over the winter, with large lift cam, that mice carried a cylinder full of seeds...

I wouldn't be worried about the springs, but I would be worried about condensation forming in the cylinders. Of course, if you live in the desert or somewhere that gets cold and stays cold, I wouldn't worry about that either.

Joe

Fyi seen the same thing with mice at a buddies shop, mice ran up the header and filled the engine with corn through an open exhaust valve. Found it when he pulled the header to install in his truck.

Spray moisture-displacing fogger "stuff" in the plug holes and rotate the crank to expose the valve seats while you're doing it. While it's the off season, rotate the crank 90* every month to ensure the same seats & valves aren't exposed the entire time. Plug or tape shut any exposed holes (carb, exhaust) to keep the elements from getting in.

I have first-hand experience w/ what happens when you DON'T do this; it required pulling the heads to get the valves & seats touched up that had rusted during the down time... totally self-inflicted.

Moisture/rust on the valve seat is the biggest threat. Back them off, stuff NERF footballs into the header collector, and be safe for next year.

Heated garage , I start mine up every so often, warm it up .. I like the smell of fresh 112 in the garage

For many years, all I do is fog the chambers and occasionally turn the motor over maybe 90 degrees with a long-handle ratchet.
My "seasonal" stuff sits in a heated (50* minimum) garage, on jack stands under suspension, cardboard underneath, no critters.
Never had a problem come the Spring-time light-off.

Stock shaft rockers are a pain with big springs. Jesel setup is super easy to R&R.
On a serious race engine I'd pull the rockers, especially if the car sits in an unheated shop or trailer. If the car is in a heated shop over the winter then rotating the crank once a month should be fine.

It's a pain but I back them off,easier on the rockers.I have PAC 1224's and mine sits until June.

I start mine up every so often

Most of the cylinder and ring wear occurs when starting it dead cold, Ricardo discovered this 100 years ago.
It's not warmed up - the water is. To warm up the oil (removing acid, water vapor, etc.) it must be run under load.

On the heads up car that sits for long periods of time we do not back anything off...We pull the carb and drain it clean it and WD40 it. We fog the engine after we have drained the fuel with a fogging agent while spinning it over. We then put plugs in the collectors and let it sit. These are springs that at 500 on the seat!! Wer worry way more about moisture especially since it spends extended periods back east in a trailer all summer. I do have a couple cars that sit more than get used and we will sping them over poeriodically but worry way more about moisture than anything else.

Like some that do or like some that don't...it's basically a personal choice. Moisture is the biggest concern. Years ago there were some collector plugs that were sold through Dan Dvorak, made of stainless and filled with desiccant that would draw the moisture out of the engine on the exhaust side. Memory (?). hmm... he stated to drain/remove the carb and silicone the areas that needed sealing in an attempt to keep all moisture to a bare minimum, he may have even mentioned backing off the valvetrain as well. From what I recall, the pair of plugs were about $125/set, at which point, I bought a set and they work quite well too! Nonetheless, good engine off-season storage/maintenance has been pretty-well covered in the above posts...eliminate the moisture and you're good, don't eliminate it and you'll have short-life in your expensive race toy!

I don't back them off on any of my cars or motors, even with high pressure roller cam springs, 250+ on the seats and 750+ open pressures.
I do make sure they get plenty of oil while running to help cool the valve springs