Valve spring help.

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smythge

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I just swapped my cam from a small stock cam to the Mopar performance .509/292 cam. the motor is a 67 440 and I am currently running bone stock 906 heads. I am planning on breaking in the cam with the current valve springs then swap out for the recommend springs. I have found a couple different sets that seem appropriate for my setup the first was a crane double spring, but this spring will require machine work to the heads (I am trying to avoid as I will be swapping the heads later on for a set of eddys) the second choice are the mopar performance springs (5249848), what I am wondering is if the heads will need to be machined to accept these springs? I tried to call Mopar with no luck, sent a question to the tech department with no answer. Below are the specs on the springs.

Number of Springs Per Valve: Single
Outside Diameter of Outer Spring (in): 1.554 in.
Damper Spring Included: Yes
Inside Diameter of Outer Spring (in): 1.130 in.
Inside Diameter of Inner Spring (in): 1.032 in.
Valve Spring Style: Standard

Valve Spring, Single, 1.554 in. Outside Diameter, .480-.540 in. Lift Range, .216 in. Wire Diameter, Each

As always any help is appreciated.

Greg
 
If the springs are listed as "single w/damper", then the original spring pockets should be fine, same with the umbrella valve seals. That being siad, I'm away from my MP catalog with the recommended springs for each cam. The Comp Cams Magnum 292 which is less aggressive than the MP unit, calls for dual springs witha damper. So, I'd have to think you need the double springs, and the associated mods to fit them. It doesnt mean it wont run, but it might have issues with coil bind, and will have probelms with controlling the valve events. So you will be down on power as soon as the springs are exceeded. Also, you always want (or I do anyway) to have MORE spring if possible. SO if there are 2 choices, you want to use the one that wont have to work as hard to gget the same performance. Let's say a single spring is rated for 120lbs on the seat and 320lbs at say .500 lift at an installed height of 1.850", and a double is 130lbs on the seat, and 360lbs at .500 lift at the same installed height. A cam manufacturer says they want 120 on the seat, 310lbs at .500 lift for that same installed height. The double will last much longer, and control the valve better, than the single, even tho technically, they both are "within spec" for that cam. I would choose the double, because heat generation is much higher in a spring near it's limit, and idle time means less oil dripping over them to help cool the springs. Heat is what fatigues a spring.
 
Maybe I should just break down and get the new heads now. I can't see paying $250.00 for parts and another couple hunder bucks for the machine work, for a temporary fix. Not to mention the time involved in taking the heads off again. Any suggestions on heads?
 
IMO, go with comp cams springs. call the tech line and tell them the specs for the cam. MP stuff is just chinese garbage anyway. my buddy and I tore apart his motor and all the parts that were MP were wasted (pushrods, lifters, springs, etc.) The consistency is just not there anymore, the quality of the metal they use. comp cams has better quality and better tech, period. I deal with bob mazzolini racing quite a bit and there are certain things of MP he doesn't sell because he has had comebacks on them. you never know, you might get lucky with stock stuff, but wth a cam over .500 I would go with better quality.
 
Don't put a double spring on that cam. It isn't needed. Too many people put springs that are too strong and all it does is waste horsepower. Crane sells a single w/ dampner that's around $70. Comp sells a single w/dampner for around $85. Don't plan on reusing the old retainers and locks. Those will set you back another $60-$70. Ideally you should get them installed so the seat pressures can be set. There's some more cash. The aerohead $500 specials are sounding pretty good around now, aren't they? good luck.

don
 
FYI dusterdood over on bigblockdart.com has a set of heads that you might be interested in. I think he still had them as of yesterday. Check a for sale ad for valvesprings.

don
 
Thanks for all your help, I already emailed dusterdood about his heads, they look like a great deal, does anyone have any experience with the aerohead heads?
 
dusterdon said:
Don't put a double spring on that cam. It isn't needed. Too many people put springs that are too strong and all it does is waste horsepower. Crane sells a single w/ dampner that's around $70. Comp sells a single w/dampner for around $85. Don't plan on reusing the old retainers and locks. Those will set you back another $60-$70. Ideally you should get them installed so the seat pressures can be set. There's some more cash. The aerohead $500 specials are sounding pretty good around now, aren't they? good luck.

don
Click to expand...
I got to agree with dusterdon. I'm running ported 902 (that's right 902) heads on my 383 with the .509" MP cam and this engine runs hard to 6000RPM. The springs I used are the Crane singles with dampeners and have had no valve floatation problems mind you I haven't taken it :burnout: past 6000 and don't intend to.

P6020032.JPG
 
I decided on Comp cam springs with 10* retainer and locks. got everything from summit, finished one side got to the other and 1 of the double grove locks was incorrectly machined and would not fit together properly. When I compared it I could see it was mis-shapen. I was changing the springs on the heads, so I had everything ripped apart hoping to get it back to the track on Sunday. I called Summit and they promptly over nighted me a new set, but suggested I call Comp cams to tell about the problem. I talked to a total *** on the phone at comp cams and he made sound like this is a common problem and they won't do anything to fix it. Just one more bad parts experience, I won't buy from comp cams again!
 
I like thier product, but I too found the tech guys a little sad. I can read the catalog and website pages too. He finally had to go and pull one of each part number I gave him, so I could explain my question with visual aids. Then he said "yep, they do look very much a like." I knew thye looked alike. But would one fit where the other didnt was the question...The catalogs didnt say yeah or no...
 
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