Valve Spring Part Number

[Bob S.]

Valve Spring identification?....and does it use the same damper as 3735381?

Hello - I checked the p/n 3735381 valve springs I received yesterday with my dial caliper, and find that one is clearly different. The dimensions that differ from all the rest (and the specs that Joe Lucia provided for 3735381) are: wire dia = .191" (vs .169"), spring O.D. = 1.277" (vs 1.228") .

Does anyone recognize this spring? And, more importantly, can anyone confirm this spring uses the same damper as 3735381? (One of the 3735381 springs came w/o a damper, and the mystery spring has a damper that I'll use if it can be confirmed to be the same....)

Thanks for any input!

Bob S.

[Duke W.]

Re: Valve Spring Part Number

Sounds like you got a mismarked part. Both the 381 and 068 springs should include a damper.

My suggestion is to return what you have and purchase a set of Sealed Power VS677, which are equivalent to the O68.

They can be found on the Web for about a buck a piece.

Most valve springs are also color coded with a splotch of paint.

The rate is proportional to wire diameter to the fourth power, so the .191 wire diameter spring is considerably stiffer. The oddball might be a 3927142 spring/damper for the 140 offroad cam. The OD is in the ballpark, but I don't have a spec for the wire diameter.

Duke

[Bob S.]

Re: Valve Spring Part Number

Thanks Duke. If the damper in the mystery spring is the same as the damper that 3735381 uses, would it possible to safely remove the damper from the mystery spring and insert it into the 3735381 spring without causing a stress concentration by nicking or gouging it?

Bob...

[Duke W.]

Re: Valve Spring Part Number

Probably, but I've never tried to separate a damper. Try it on and old spring and see how it goes.

The outside of the damper ribbon wire has a slight interference fit to the spring wire. The resulting friction is what generates the damping to help keep the spring out of surge mode.

Duke

[Timothy B.]

Re: Valve Spring Part Number

Is there anyone that can cross reference this TRW # for valve springs, (VS935). These are the springs installed in the cylinder heads for my 63.

Thanks for the help,

[Joe L.]

Re: Valve Spring Part Number

Is there anyone that can cross reference this TRW # for valve springs, (VS935). These are the springs installed in the cylinder heads for my 63.

Thanks for the help,

Timothy------


The TRW VS-935 is equivalent to the Sealed Power VS-677 which is equivalent to the GM #3911068. It's not exactly the correct spring for a 1963 but it very close to the original spring, GM #3735381, which is equivalent to Sealed Power #VS-521.

[Duke W.]

Re: Valve Spring Part Number

I recommend the 068 or equivalent for all SB restorations including base cam 283s with the ...929 (or equivalent) cam that replaces the obsolete original cam.

And pressed in studs are fine assuming they have no history of pulling.

L-79s used the 068 beginning in 1967, but used the earlier spring in prior years. The O68 was also used with the 30-30 cam Z-28 engines while the Corvette 30-30 cam engines used the earlier spring, so there are no compatibility issues with any OE production or OE replacement cam.

The fact that the 068 remained as the production spring for most SBs (including all mechanical lifter configuations) for the next two decades is proof that it's a good design.

With proper attention to installed height, it will rev to 6000+ with OE hydraulic lifter cams and 7000+ with OE mechanical lifter cams.

Duke

[Timothy B.]

Re: Valve Spring Part Number

Thanks Joe and Duke for the information. All this talk about valve springs got me to look at my old receipts. The 300 HP engine has a stock GM 929 cam and the springs mentioned above. All stock pressed in studs etc. it runs very strong. Only modification is .060 overbore and inital timing set at 10-12* with the stock 24* distributor and curve.

The problem is every time it's out for some reason it goes to the red line. I think there is something wrong with my foot.