Box Stock

Valve Float

Flash06 said:
You need more spring pressure with that much lift, also make sure when you are done running the engine, after you purge it you need to turn the motor to tdc to relieve some pressure from the springs before storing if for the next race. I run the dual green stripe with the 315/260 with 1.2's and have no problems with valve float or anything anywhere close to wear and tear from too much spring pressure. I have actually run 60lb duals in a motor and never had an issue with too much spring pressure, it's just good insurance IMO.
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Was just getting ready to use this combo and was debating if my 37lb springs would work well enough. Looks like I'll be using the duals.
 
kurly154 said:
Pulling it apart tomorrow. What's the best way to check installed height?
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Jason you are going to have to cut spring pockets in the head. I always do that to keep from coil binding the springs and also gives the spring a seat to sit on so it does not rock. Your tool man at your shop should have the little machinist rule like I use to measure spring height, they are very small rulers that measure to the 1/64s and have the conversion on the back of the rule. You measure from the bottom of the pocket to the bottom of the retainer on the installed spring. I cut my pockets with a hole saw with the drill bit removed in a cordless drill very slowly and checking often. I am not in the shop but I think it is a 5/8 hole saw you better measure and make sure. I know this sounds crude, but I have done 4 engines like this it works great if you are slow and careful.
 
I run the 356 cam and use 37 single springs.8000-9000 all day
I had the dual 55 in when I first built it then pulled the inner
out.but since then been using the 37 works fine.but I
also stayed 1:1 with my champion rockers.
 
old school mike said:
Jason you are going to have to cut spring pockets in the head. I always do that to keep from coil binding the springs and also gives the spring a seat to sit on so it does not rock. Your tool man at your shop should have the little machinist rule like I use to measure spring height, they are very small rulers that measure to the 1/64s and have the conversion on the back of the rule. You measure from the bottom of the pocket to the bottom of the retainer on the installed spring. I cut my pockets with a hole saw with the drill bit removed in a cordless drill very slowly and checking often. I am not in the shop but I think it is a 5/8 hole saw you better measure and make sure. I know this sounds crude, but I have done 4 engines like this it works great if you are slow and careful.
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I took the head to Roberts Kart shop today. He checked my installed height and its at .955. He did not have any dual springs in stock so I'm going to have to order some and then recheck it. But with my installed height being close to what Tim Isky recommends the inner spring seems to coil bind it feels like. With the inner spring it the motor was harder to turn over and felt kinda binding. Turning it over by hand. With just the outer spring it felt more free and not binding. Thanks for the tip Mike.
 
Turn it over and watch the spring, if it coil binds you will see the spring stop closing and the pushrod will start to bow
 
another thought that maybe you might want to check....if your hitting coil bind and valve float, maybe you need to check all your angles and measurements of the entire valve train. a high lift cam can cause all kinds of issues that you have to address one at a time. if your hitting coil bind and the pushrod looks like it wants to bend, then you need to look at shortening the pushrod. i used stock length puhrods in our motors at the start of the year. didn't think twice about them. then we noticed coil bind and the pushrods were flexing more than we liked, but it was race night and we needed to get to the track. i lost the intake rocker stud....my son lost the exhaust rocker stud and it bent the crap out of the pushrod. when we got home, we looked at everything and it was then that the light bulb came on.....we did everything we could EXCEPT take into account the higher lift that would put excessive strain on the pushrods and springs! so i ordered tow sets of short pushrods.....now we don't have any coil bind issues and everything is back in alignment....

jsut my thinking.....check this ...coil bind and pushrod length can lead to valve float because it's all out of kilter and your not getting everything that you can out of the valve train...
 
kurly154 said:
I took the head to Roberts Kart shop today. He checked my installed height and its at .955. He did not have any dual springs in stock so I'm going to have to order some and then recheck it. But with my installed height being close to what Tim Isky recommends the inner spring seems to coil bind it feels like. With the inner spring it the motor was harder to turn over and felt kinda binding. Turning it over by hand. With just the outer spring it felt more free and not binding. Thanks for the tip Mike.
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You may want to just try 1.2 rockers which is 338 lft instead of 1.3 which is 366 lift. 338 will still get the job done.
 
mikey56 said:
another thought that maybe you might want to check....if your hitting coil bind and valve float, maybe you need to check all your angles and measurements of the entire valve train. a high lift cam can cause all kinds of issues that you have to address one at a time. if your hitting coil bind and the pushrod looks like it wants to bend, then you need to look at shortening the pushrod. i used stock length puhrods in our motors at the start of the year. didn't think twice about them. then we noticed coil bind and the pushrods were flexing more than we liked, but it was race night and we needed to get to the track. i lost the intake rocker stud....my son lost the exhaust rocker stud and it bent the crap out of the pushrod. when we got home, we looked at everything and it was then that the light bulb came on.....we did everything we could EXCEPT take into account the higher lift that would put excessive strain on the pushrods and springs! so i ordered tow sets of short pushrods.....now we don't have any coil bind issues and everything is back in alignment....

jsut my thinking.....check this ...coil bind and pushrod length can lead to valve float because it's all out of kilter and your not getting everything that you can out of the valve train...
Click to expand...

I'll check everything again once I get some new springs. I am running the shorter pushrods since I have my head milled .070 maybe I will need to get the adjustable length or cut my own pushrods but all that will be new to me.
Thanks for all the help guys
 
Got the dual springs installed. Did not see any coil bind or see the pushrods bow. Will let everybody know how she does this weekend. Thanks again.
 
Well the dual springs solved the valve float. Turned it 9000 rpm today. Couldn't keep up with them stroker motors though. Thanks again guys
 
kurly154 said:
Well the dual springs solved the valve float. Turned it 9000 rpm today. Couldn't keep up with them stroker motors though. Thanks again guys
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Glad you got it fixed, those stokers are to hard to beat with a small motor. Yakattack your math was correct, that was one of my old small block Chevy calculator's for rocker arms.
 
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