Vavle Spring Questions
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Mountain Pass
Joined: May 2013
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From: Spanish Springs
Vavle Spring Questions
I'm running a Comp XE262H cam in my 390. I looked up the specs and Comp website recommends running the 926-16 or the 924-16 springs. Although, the machine shop sold me the 940-16 springs and I built the engine using these springs, trusting that they know what was best for my combination. I'm trying to figure out why they sold me these springs instead of the recommended springs?
Here's the links with this specs:
33-238-4 - Xtreme Energy
COMP Cams® - Specialty Valve Springs
And, I'm running the Silvolite 1130 pistons on stock D2TEAA heads and D4TE block.
Should I be using the recommended springs? Anyone have any idea why the machine shop sold me the 940-16's?
Here's the links with this specs:
33-238-4 - Xtreme Energy
COMP Cams® - Specialty Valve Springs
And, I'm running the Silvolite 1130 pistons on stock D2TEAA heads and D4TE block.
Should I be using the recommended springs? Anyone have any idea why the machine shop sold me the 940-16's?
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Based on this:
920-16:
137 @ 1.750 262 @ 1.250
940-16:
93 @ 1.900 237 @ 1.300
The 940's they are using are substantially weaker than what's suggested.
Seat pressure, from 137 to 93, and compressed from 262 to 237, that's quite a jump.
Unless they are installing them with a much lower height than spec'd, I'd be concerned. And even then, what about bind height?
They bind at:
920-16: 1.175
940-16: 1.200
Not only are they weaker, but they also bind at a higher height.
Strange, very strange indeed.
920-16:
137 @ 1.750 262 @ 1.250
940-16:
93 @ 1.900 237 @ 1.300
The 940's they are using are substantially weaker than what's suggested.
Seat pressure, from 137 to 93, and compressed from 262 to 237, that's quite a jump.
Unless they are installing them with a much lower height than spec'd, I'd be concerned. And even then, what about bind height?
They bind at:
920-16: 1.175
940-16: 1.200
Not only are they weaker, but they also bind at a higher height.
Strange, very strange indeed.
Thread Starter
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Mountain Pass
Joined: May 2013
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From: Spanish Springs
I appreciate the feedback. I guess that's not terrible news. Doesn't hurt to break in the cam with weaker springs. Didn't really want to contact the machine shop. I wasn't particularly pleased with some other stuff they did. Although, they did have really good customer service. Next time I will be using a different machine shop, though. Do you think this may be causing some performance issues for the engine? The reason I'm researching these issues is because the engine just doesn't seen right. I think the performance should be much better than what I'm getting.
Elder User
Joined: Nov 2009
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From: Mayfield, KY
I would be concerned with less than 100 lbs of seat pressure. It may cause problems when you push the pedal. I agree weaker is better for break in but you need more for
hot rodding I would think.
hot rodding I would think.
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Mountain Pass
Joined: May 2013
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From: Spanish Springs
Well, I called the machine shop to ask them about it. They sold me the different springs because of the installed height, in order to get the same pressure as the recommended springs. I'll have to do some more research and studying to fully understand it. Thanks for the feedback.
Elder User
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From: Mayfield, KY
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Mountain Pass
Joined: May 2013
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From: Spanish Springs
Well, I called the machine shop to ask them about it. They sold me the different springs because of the installed height, in order to get the same pressure as the recommended springs. I'll have to do some more research and studying to fully understand it. Thanks for the feedback.
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Thread Starter
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Mountain Pass
Joined: May 2013
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From: Spanish Springs
Well after going through my receipts, appears I'm the one who screwed up and bought the wrong springs from Summit. Not the machine shop's fault. Would still appreciate some feedback on which springs I should be using with the Comp XE262H cam on the stock 72 truck heads. I'm looking at the Comp 926-16 or the 924-16 springs. Can't find the specs for the 924's though. Anyone else using this cam setup? What springs would work best?
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Mountain Pass
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From: Spanish Springs
Well, calling contacting Comp Cams was good advice. I e-mailed their tech support.
Here's the e-mail response I got from Comp Cams Tech Support:
"This cam should have our 926-16 for a single spring or if you are going to machine the heads for a double spring, use our 924-16. The 940-16 are too weak in pressure to be able to spin any RPM for this engine. Install height need to be around 1.800". for the single springs to work. The dual can work with a 1.900 install height. Which would you prefer?"
Since I'm running stock heads, I'll need the single springs (926-16) and shims to get my installed height correct. Thanks for the feedback everyone.
Here's the e-mail response I got from Comp Cams Tech Support:
"This cam should have our 926-16 for a single spring or if you are going to machine the heads for a double spring, use our 924-16. The 940-16 are too weak in pressure to be able to spin any RPM for this engine. Install height need to be around 1.800". for the single springs to work. The dual can work with a 1.900 install height. Which would you prefer?"
Since I'm running stock heads, I'll need the single springs (926-16) and shims to get my installed height correct. Thanks for the feedback everyone.
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