Someone check my stupid please... valve springs

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jcmeyer5

jcmeyer5

Token Ford Guy
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Part of the issue I have been facing with the heads for the 340 has been the rockers contacting the valve springs (not the retainers). The springs are 1.50" diameter springs with 1.33" OD, 1.00" ID retainers. The springs can wander about laterally - the retainer doesnt do a good job of holding them on axis. I went out in search of a smaller diameter spring. I found one that I am tempted to try. Here are the vitals:
  • First, the cam is a Mopar purple .474"/.474" 280/280 hydraulic flat tappet.
  • The springs I selected are 1.400" diameter. They have a seat pressure of 80lbs at 1.700" installed and a spring rate of 293lbs/in. Coil bind is 1.125".
  • I would need to install them at 1.65". That would give me a seat pressure of 95lbs.
  • Open pressure would end up at 234lbs at 1.176" height (1.650" less the 0.474" lift).
  • That gives me a margin of 0.051" to coil bind.
Conventional wisdom (for street use) is 105-125lbs seat pressure, 220-250lbs open pressure. I am a bit low on seat pressure, and about mid-field on open pressure. I could possibly put a 0.015" shim under the spring, but that would only get me 5lbs. I dont know if that is worth it.

The reasons I like they are a) they dont contact the rockers, b) they locate much better than the larger springs on both the spring seat and the retainer, c) they were $70 for the set (Comp Cams 903), and d) I dont have to buy new retainers to go with them. Ideally I wanted to run beehives (I run them on my 351C), but the cost wasnt justifiable vs. this avenue.

So that is the game plan. For a street driven car that will be driven primarily by a 65 year old man, will these fit the bill? I feel like they will, but a small voice in the back of my head is making me doubt myself.
 
Wow, I think you are getting way off track. Who assembled the heads on the first get go? You or a machine shop that knows what to do? You have not mentioned rocker to valve tip. The valve springs and retainers need to be purchased as per cam specs.
Your problem is you need to set the push rod length, after all else on the valve assembly is as it should be.
 
No, wrong spring.

When it comes to hydraulic street/a trio cams...Look for a spring that yields 105-115lbs seat, 120 lbs seat if competition usage only.
Open pressure should be 265-275 with that cam .

235 open is too little .
 
See? That’s why I came here to check my stupid. I knew the springs were borderline, but I thought maybe they would work. I know the “recommended” spring is P4120249, but it’s diameter is no better than what I have. I also can’t find specs on that spring, other than it’s for .430 to .500 lift hydraulic cams.

I’ll keep looking. Thanks for the input.
 
You need to contact Mike at B3 engines and speak with him about locating your rocker shaft correctly. That will fix your problem and you can run the correct springs.
 
jcmeyer5 said:
See? That’s why I came here to check my stupid. I knew the springs were borderline, but I thought maybe they would work. I know the “recommended” spring is P4120249, but it’s diameter is no better than what I have. I also can’t find specs on that spring, other than it’s for .430 to .500 lift hydraulic cams.

I’ll keep looking. Thanks for the input.
Click to expand...
You should be good with a 1.437 spring. Plenty of those available.
 
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