A question about valve springs.

[Mart]

I have read all the excellent threads on the subject but I have a question if you expert engine builders will indulge me.

I'm putting together a motor with a Schneider 270F cam (I think that is what it is called). The springs are much stronger than any I have used before. I am setting them up for about 60lbs spring pressure. I realise some use heavier pressure, but I will not be revving it to death.

This is not about cam choice, it is about break in.

Has anyone ever set up the motor initially with softer springs to allow a easier time during cam break-in?

I was thinking I could put it together with stock springs, and the only recently removed head gaskets, fire it, run it, get about 1/2 an hour run time in and then pull the heads, switch out the valvegear (fitting the new springs) and then button 'er up with the new gaskets and be able to just jump in and go, without worrying about the break in regime.

Am I daft to think this is a good idea? Is 60lbs still a modest figure anyway and I should just button it up right the first time and go for it?

I have a novel method for taking up the excess length of the Chevy valves, no shims required. I'll post that in another thread.

Mart.

[Fordestes]

Mart,
I was thinking about the same thing ,I opted to set spring pressure at 55 or 60 lbs. as per Ron and Pete,I am going to use special keepers or shims as needed, then after break in add the amount of shim or .030 or .060
keepers as calculated and recorded per valve at the time of rebuild .
maybe it will save a new cam from being trashed during break in.
keep us posted on the results.
Fordestes

[scooder]

Just a note. I've seen keepers out their that have extra meat on them to replace shiming when using chevy valves. This is not a good idea in a performance build, the shims should be at the valve head end of the spring, not the keeper end. Putting this extra weight, be it shims or a thicker keeper on the end, means more weight that the springs have got to control. This is also why the close wound coils go at the head end.
Mart, plop the stronger springs in it and just go with that. It'll be fine. I understand your thinking, but pay it no more mind.
Martin.

[flatjack9]

60 lbs is not a killer. Run with them. If you're concerned, use a good break-in oil. It is a major pain to go in a change the valve train for no good reason.

[GOSFAST]

I would break in the cam and let it go, a 60# pressure will pick up 2.5# with a .030" shim and 5# with a .060".

You will be about 63# or 65#, this amount of pressure will not cause a failure one way or the other!!

(Add) Jack pretty much called it above here.

Thanks, Gary in N.Y.

P.S. "Stay the course", with moly on the lobes/lifters and some 30 weight Brad-Penn break-in oil. We haven't lost a single lobe as far back as I can recall, at least not on the break-in.

[tubman]

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I hate to mention this on this forum, but it might help to backup your theory. For a long time now SBC's have had 1.3 ration rockers used for cam break in. They are a special part made for just this. I know OHV's and flatheads are different, but metal to metal contact is the same. I hate to bring the "enemy" in here, but I think your idea may have merit.

[Ol' Ron]

We used 60/65 Lbs on the stock car cam (400jr). Fired it up with Isky cam lub fast idle for 15 min and went racing. cam lasted the whole season. Lifters were alittle sad, but turning ofer 5K every sat night will do that. I'd just run it in for a few minutes and then drive the s**t out of it.

[scooder]

Originally Posted by tubman

I hate to mention this on this forum, but it might help to backup your theory. For a long time now SBC's have had 1.3 ration rockers used for cam break in. They are a special part made for just this. I know OHV's and flatheads are different, but metal to metal contact is the same. I hate to bring the "enemy" in here, but I think your idea may have merit.

That's only cus it's a mamby pamby monkey motion motor. And if they sell them, you gota have them. They brand X boys are so easily led, bless the little sheep.

In all seriousness, their used when they have brutal springs (triple springs) and all that jazz. And they have all that over head jiggery stuff that don't concern our engines. We're talking 60lb on the seat here, different world.
Stick um in and run it.
Martin.

[Mart]

Thanks for all the input, guys. I do think I will leave getting the motor running until the car is ready to roll. Then I can fire it and drive it straight away. Holding the revs up should be achievable with a fast idle and using low gears. All the bottom end is as previous, so I should get oil pressure straight away. (The car has a gauge).

Thanks also for the insight into the Bow Tie world. 1.3:1 rockers and triple springs. All that stuff is a completely unknown world to me.

Mart.

[Blownflatheaddeuce]

Mart imo its not reqd given the spring pressures we are playing with in our FHs.

Ive run numerous cams inc custom grinds and have had no issues with proper prep, break in technique and good oil in the engine.

Im about to fit a Winfield SU1A to the roadster and follow the same process again.

[Fordestes]

scooder,
The keepers I am referring to have the lock ring moved toward the spring, I can't see any extra metal. however I am going to get the mic. out and the magnifier lamp and take a closer look, it never hurts to be sure,the way I understand what you are saying is that being thicker will adversly affect the locking surface of the keepers and retainer.you have an interesting point.
fordestes,