Which valve springs for 383 w/ Comp HE275HL

[eagleone1983]

Hey guys,

So a while back I posted about my dyno results with the 383 and mentioned I was getting what I assumed was valve float at around 5k rpm. It was suggested to change my springs as I didn't do that when I bought my stealth heads all I did was upgrade the locks and retainers to the 10* type. It looks like there are two different types of springs I can get with this cam. The 924-16 dual spring or the 26120-16 beehive style. Which one should I go with? Are there any other items I should consider with this change? Thanks for any help.

 

[lewtot184]

i'd use the 924's. the other's are beehives and i think they have too much pressure for a small hydraulic.

 

[eagleone1983]

Comp recommends either with the cam so I don't think too much pressure would be an issue. I've never heard of beehive's before so I'm just now doing some research on it. All I know is I want my car to rev over 5K RPM

 

[texas69bee]

The stealth spring is only rated at 300, 924-16 is rated at 347 but the beehive is at 370

 

[eagleone1983]

So the higher the spring rate the better? would the 300 spring rate I have now be the cause of my valve float?

 

[lewtot184]

you don't need a 370lb rate spring for that cam. in fact i wouldn't use any of the comp springs. a set of edelbrocks would work fine. thats not a 6000rpm cam.

 

[eagleone1983]

You're right Lewtot it's rated to 5800. I'm not stuck on a specific manufacturer I just listed those springs because it's a comp cam. Any spring recommendations from anybody would be appreciated.

 

[mentor70]

i bought the 924s, you need to run enough spring to keep the valves from bouncing on the seats, but no so much as to wear out the rest of the valve train

 

[451Mopar]

Hey guys,

So a while back I posted about my dyno results with the 383 and mentioned I was getting what I assumed was valve float at around 5k rpm. It was suggested to change my springs as I didn't do that when I bought my stealth heads all I did was upgrade the locks and retainers to the 10* type. It looks like there are two different types of springs I can get with this cam. The 924-16 dual spring or the 26120-16 beehive style. Which one should I go with? Are there any other items I should consider with this change? Thanks for any help.

Do you know the manufacturer and part number of the new retainers and locks? They may be compatable with the 924-16 springs. The beehive springs would need different retainers and they are much more expensive.

 

[eagleone1983]

yeah they are comp cams, I got them off 440source so the part number they list is probably thier number not comps. I don't mind paying the extra money for new retainers if its a better overall spring.

 

[IQ52]

I think I would measure my present installed height and test the springs I'm presently running. Then I would compare them to the springs I'm thinking about using. The springs might not be the problem at all.

 

[66Satellite47]

You definitely need to measure the installed height with the retainers & locks you're using. The seat pressure needs to be high enough (120-125# or so) to avoid valve float, not too much (310-320??) avoid lobe wear. Comp 924's look right. Also be sure you're not getting coil bind for some reason, (retainer hitting the guide, dampers going solid or something).

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Also, the rate isn't as important as what the measured pressures are. The rate gives you an indication before you actually check the installed measurements.

 

[eagleone1983]

I'm going to measure my springs this weekend. I'm assuming i measure from where the springs contacts the head all the way to the top of the retainer while the valve is closed correct?

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Oh and another question, what do I measure with? Just a standard tape measure? I know dumb question...

 

[GTX MATT]

IMO the 924s wont provide a significant difference in seat or open pressure, theoretically they will have less pressure. Comp lists open pressures at far more lift than the cams that the springs are recommended for provide. Those springs would theoretically give you 119 lbs at the ~1.88 inch installed height your Stealths will be, and 301 lbs open at .525 lift. Comp is stupid with these springs, they recommend a dual which create confusion when their own 911 single springs are supposed to offer more pressure. I honestly don't know why they sell the 924. I called and asked they didn't know either (probably so you will buy a valve guide cutting tool from them).

The Stealths supplied springs are SUPPOSED to be 130 on the seat. According to the specs given by Stealth their springs are 333 lbs/inch. That should THEORETICALLY give you 305 pounds open. I don't know if I would trust the supplied specs 100%, I'd have them checked to be certain, but they should be close. To be honest the springs on those Stealths are very similar to the 911s Comp sells.

A buddy of mine replaced the springs on his 440 in the fall and the 924 was what was recommended. I recommended the 911s to him and they're working well.

IMO you shouldn't have encountered valve float with those springs at that RPM. Did you get custom pushrods for this engine? I would be looking more towards a lifter pump up/short pushrod/preload issue for the extra RPM. How much did your power/torque really fall off?

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You should measure your spring height with a valve spring height micrometer, which you can get for about $50. This, however, requires the springs to be off the heads.

I can tell you that my Stealths with 10 degree locks and standard retainers from Comp were 1.88 with the spring cups that cam installed on the heads. (440Source lists 1.875 as their installed height) You're going to be in the correct ball park. I really don't think spring pressure is an issue for you, and I don't think the .01-.02 or so your installed heights might vary are causing any spring pressure issues as that would only be about 4-8 lbs difference.

 

[IQ52]

I've been trying to hint and let you figure it out. The problem isn't the valve springs. I went back and reread your prior thread and reminded myself of your massive confusion on how to set the lifter preload. You must get that correct first. I gave you Comp's instructions for both types of lifters. Did you ever set the correct preload for the types of lifters you are using? EH?

I pulled two Stealth valve springs out of a box where I store the weakest Stealth springs that I take off. They were 136-138# @ 1.890" installed height and 300-308# @ .500" lift. that is plenty of pressure to control that cam to 5,800 rpm.

The 924 is listed 112# @ 1.900 and 129# @ 1.850". 285# @ .500" lift when installed a 1.900" and 303# @ .500" lift when installed @ 1.85". The springs aren't your problem. Look elsewhere.

 

[eagleone1983]

Thanks IQ52, I haven't checked the preload yet. Just so I understand you though it could be a sign there is too much preload on the lifter or too little?

The issue I had when doing the preload is it seemed when the rocker adjustment was turned all the way out (as loose as it could be) there was no up and down movement on the pushrod. So I had no way of telling when the adjustment was at zero preload, all I could do was spin the pushrod between my finger and thumb and try and guage when it seemed to feel a little snug. I would assume this would mean my pushrods are too long but all these measurements were verified by my builder. I'm assuming he knows what hes doing, I sure the hell don't.

 

[IQ52]

Thanks IQ52, I haven't checked the preload yet. Just so I understand you though it could be a sign there is too much preload on the lifter or too little?

The issue I had when doing the preload is it seemed when the rocker adjustment was turned all the way out (as loose as it could be) there was no up and down movement on the pushrod. So I had no way of telling when the adjustment was at zero preload, all I could do was spin the pushrod between my finger and thumb and try and guage when it seemed to feel a little snug. I would assume this would mean my pushrods are too long but all these measurements were verified by my builder. I'm assuming he knows what hes doing, I sure the hell don't.

From your description it would seem that the pushrods are too long. Builders have been wrong before. We still make mistakes. Our great fortune is that we have a dyno to run everything before it leaves the shop so we catch the problems before we deliver them to the customer.

 

[eagleone1983]

That sucks to hear, I've already bought two different sets of pushrods because I brought my car to another shop to look at and he said my rods were too long and to buy some different ones. So I bought the ones he suggested and I guess he was also wrong. Damn...wish you were closer I can just pay you to do it right the first time.

 

[GTX MATT]

Are you buying off the shelf stuff or custom length?

 

[eagleone1983]

they were off the shelf pushrods in the lengths that were recommended to me.