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Discussion Starter · #1 ·
As some of you may know, I have been rebuilding the race motors for my Cougar for a bit and the main hangup has been matching the race springs that came with the motors built by Kinetics. This will work on the 2.5L and 3.0L V6, I have finally found the solution for a spring that will handle well over 8,000 rpm and will work with the stock retainers. It does require a slight opening up of the spring pocket, but any decent automotive machine shop should be able to do this. Its the new Melling performance Valve Spring Part Number 466554. The closed rates are somewhat similar at stock 81 lbs versus 100 lbs for the new one, but the open rates climb a fair bit higher at stock 152 lbs versus 265 for the performance spring. This spring is very similar to the race springs that came with the Kinetic Race Engine which are a bit longer than stock, but they have a lower coil bind number, so can handle higher lift cams. Compared to the race springs, they are the same physical size, take the same retainers and are just a hair smaller in O.D.. I even think the rates are the same, but I won't know for certain until I measure them. What's even better, is that they are only about $7.00 USF a spring versus $15.00 USF for the custom PAC Springs.

Take this for what it is, advice, but after purchasing 3 other sets of springs, I finally have a solution that works for me. I am now going to go buy 2 more sets, 1 for the race 3.0 and one for the ex-Mirko motor. Good times.

Eric
 

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1999 3.0 SilFro
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Nice detective work; sounds like that's just what the doctor ordered.
 

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Discussion Starter · #4 ·
What is very interesting is that the 4.6l SOHC 16V motor uses stock springs with a 71 lb closed and 152 lbs open. This spring is considered to be the drop in replacement. So, with just a small pocket opening, we can use these in our motors. The race heads, had this done, so the pocket opening will work. The Melling spring is actually polished. Looks good and its cost effective.

I went through about 20 different specs of springs to find this one. PAC has a very similar spring, the 1214, but it runs about 50% more expensive. Now I just have to sell the other springs sets I bought.

Eric
 

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Discussion Starter · #6 ·
Stock spring OD is .945". The new spring is 1.06". My race heads had the pocket opened up to 1.08". I don't doubt my 3.0 heads can have the pocket opened up the same amount.

Eric
 

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Discussion Starter · #8 ·
Fyi, the spring actually fits inside the stock valve spring pocket. Its a tight fit, so I am going to need the pockets clearanced a hair.

Eric
 

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Discussion Starter · #10 ·
I think they could even self clearance with the tool steel spring against the aluminum.
 
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