I an trying to find out what GM valve springs and retainers to use with an original GM 396 375 HP cam. Thanks, Tim.

Should be the LS-6 second design dual spring PN 3970627 with steel retainer PN 3964264.

1.487" OD x 1.88" installed height with a seat pressure of 105 pounds and and it coil binds at a 1.28" height. It's rated at 450 #/"...

This information is from my 5th Edition of "Chevy Power".

Hope this helps..

pdq67

Definately use the LS-6 dual spring (same cam) the stock singles had a bad habit of breaking and making a real mess.

The best deal IMO is from Competition Products, www.competitionproducts.com. (http://www.competitionproducts.com.) GM #454-502 dual springs, 1.48 OD, 110 lb @1.88 inst hgt, 345 lb @ 1.32. Coil bind @1.27. Springs only are $39.95, or springs plus GM #3088 L-88 retainers, and GM #4338 3/8" valve locks all for $62.95. This is what I have and works well.

Mike, funny you should mention that. I had a '70 L-78 Nova and about 1971 it broke a spring but I couldn't figure out why it was hitting on only 7 cylinders. After driving it to work 2 or three days I finally found it. I was SO lucky no other damage was done. The damper was holding everything together. Luckily the locks never came out. I changed all the springs to aftermarket and all was well.

Tim, Chevy makes a lot of good stuff but i avoid their valve springs like the plague. I've seen a couple break with no damage and a one just got weak and pulled the top off of a valve, then the valve dropped and trashed a perfectly good piston, rod and head. Get a good aftermarket spring, preferably one that has good seat pressure along with open pressure similar to the factory unit. A thermal barrier coating is another thing that has great merit when it comes to springs as they operate in a hostile environment, (lots of heat). I personally don't feel that 110 pounds is enough seat pressure since the big block high perf. 2.19 valve is extremely heavy (about 150 grams). If you can't turn it with your hand you will probably be O.K., something in the neighborhood of 135-140 is better if you don't get to much open pressure. You will generally find that new valve springs lose quite a bit of seat pressure after they get hot a few times.

Use something heavier than the original stock type L78 springs, especially if you are doing any 6000+ shifts. At high rpm the stock springs were not strong enough to keep the valve in contact with the rest of the valve train and it would free fall shut. Eventually the keepers would pound through the retainer causing a dropped valve and lunched block. Not many L78 cars have their original engines for this very reason. L88 springs are probably all the extra pressure that you need. Seems to have worked for us.
We had the same problem as Von with a 396-360hp. Just a miss at low rpm. Caught it in time also.

Yes Keith, Thats exactly what i was refering to. It not the open pressure that causes this problem as the valve will follow the mild cam profile but the keepers move up and down in the keeper grooves from not having sufficient seat pressure and this is what pulls the tops off of the valves, it is the lack of seat pressure. I caught pulling valves twice in my 375-396. If your car starts to slow down about one to two MPH per run pull your valve covers and look at the tops of all your valves. More than likely one will have less margin at the top which means a valve is getting ready to drop. They are very strong engines if you watch the valves.

Harold, interesting. I only have maybe 115 -120 on the seat, and around 340 over the nose. never thought about the seat issue, but these springs have 30K on them ( I know it's time to swap them out), with no issues. But with good Ferrea (sp?) valves.

L88 springs have the same pressures as the 502 takeouts Von refers to. True L88 springs are dual with dampner, GM p/N 12495496 for 16, using retainer 3879613 ( X 16).

Short answer, if they show 115+ at 1.88 and 300- 330-ish at 1.340 " ( you have .540 lift at the valve, right?), then I would run them.

I bought some of those $40 specials and a few folks reiterated the " don't use a GM spring" mantra, so I sent them back.

At 7000 rpm, I don't want any errors.

I used the old ISKY 8005 spring with a Chevy ZL-1 Cam and Chevy steel retainers with the built in seals and it seemed to work fine. I like the extra seat pressure but this spring might flatten a street driven cam very quickly, mine wasn't streeted, only raced. "Wolfy" could probably give you some lower limits if asked. If you go back and recheck the springs after they have been run for awhile you will probably find the spring has lost about 10 percent of its original seat pressure.

The Isy 8005-A are pretty beefy. So far the best fit I find ( wish the heck I knew what I had on there now - they're perfect) are the Comp 925s or Crower 68398s.

TIM, I do have a set of Comp 924s that I got for a 12 pack of Pepsi from a Gold member here. Won't be using them. Too light for the 7000 rpm stuff, and a bit too heavy for the very low rpm motor I'll be building. Springs, locks, retainers.

My 1980 Isky cat. says the 8005-A springs are 135 pounds at 1.875" and 160 pounds at 1.812".


And that they have a 400 #/" rate and 1.160" coil bind height...

I suppose they are still the same??

pdq67

Yes pdq67, They were pretty strong but worked good in my application.

I installed Competition Products Manton Race, (single w/ damper), PN 2454 springs with my CC 282S solid cam.

Spec's are 135 # at 1.88" installed height and 350 # at 1.250" lift.

Rate calculates at 341 #/"..

I installed them using .050" taller keepers b/c I was a little scared to run that much seat pressure.. Now the caculated seat pressure is 123.2 # at 1.915" installed height since my heads aren't true 1.88" heads....

Pressure at an approx. .546" lift is only about 310 # which should do me fine since I'm only going to rpm up to say 5700 at most... Power peak is supposed to be at 5500 rpm is why..

pdq67