SB valve springs....3911018 vs VS677

[Clem Z.]

then F/M needs to correct their catalog *NM*

[Clem Z.]

make sure you use a hardened shim

between the bottom of the spring and the head because the damper will cut into the cast iron

[Joe L.]

Re: VS 677

Jim and clem------

The Federal-Mogul VS 677 and the GM #3911068 valve springs have nearly identical specifications. They can be used completely interchangeably. The only difference I can find, at all, is that the OD is slightly different. The VS-677 is the 1.172" described by clem and the GM #3911068 is 1.241". I would consider that difference as irrelevent.

I can find no indication that the GM #3911068 spring is now or ever was available as a set of 16. However, I would not rule out the possibility. I doubt it, though. I also doubt that any GM dealer will be able to tell you if such a set is available (even if such set is actually available).

[Clem Z.]

i would check to make sure that the larger

GM valve spring retainer will fit inside the smaller diameter F/M springs

[Scott Marzahl]

Re: VS 677

Man, looks like everyone has conflicting data. The FM webiste says the Max O.D. is 1.238"

[Duke W.]

Re: VS 677

Catalogs including the GM Corvette P&A catalogs are notorious for errors.

I have a feeling that the VS677 is an exact replacement for the 3911068 spring/damper assembly and conforms to the GM drawing, but I guess at some point someone is going to have to procure at least one and find out.

Given GM's price, I would go with the VS677 from a convenient and competitively priced source.

I'm sure that GM sources these springs from a vendor, and that vendor may well be F-M, so GM may be selling the same part for several times the price.

I usually trust F-M OE replacement parts because in many cases, they may have built the originals - like the OE SHP forged pistons. We know TRW built them for GM and F-M bought TRW's automotive operations ten or so years ago, and now they are offered unders F-M's Speed Pro performance products line. They may also be sold by GM, but I'm sure the price is way higher than if you buy them through the aftermarket channel.

Duke

[Joe L.]

Re: VS 677

Duke-----

Once-upon-a-time, TRW did manufacture, at least, the forged slugs for the GM forged pistons. Someone else had to have done this; GM NEVER had any in-house aluminum forging capabilities, at all. However, I'm not so sure that TRW manufactured the finished pistons. The GM pistons of yesteryear were machined at the various engine plants from the slugs manufactured elsewhere. For most cast pistons, the slugs were manufactured at the GM aluminum foundry in Bedford, IN. For forged pistons, I think that the forged slugs were provided to the GM engine plants and they took it from there. This applies to both PRODUCTION and SERVICE pistons.

There are no forged pistons for 1972 and older applications which remain available from GM.

[Jim V.]

VS677 Have Dampers....

andy...do you know the dimensions...height, OD, & ID? Also, what retainers and valves did you use and with what cam...

Thanks

[Jim V.]

scott...FM online says

OD = 1.172. Where did you get the 1.238?

[Jim V.]

oh.....difference between

Speed-Pro and Sealed Power specs. Went to FM site and lookup up valve springs under both Speed-Pro and Sealed Power brands. Each shows the same part number ...VS677...with DIFFERENT OD specs. What a mess!!!! Looks like it is not enough to say VS677 given a spec differences between Speed-Pro VS677 and Sealed Power VS677. Yikes..........

Sorry Scott...you were right with the stated larger OD.

[Clem Z.]

go to for F-M spring diamentions

www.federal-mogul.com/fmeconnect/technicalservices/downloads/1255.pdf

[Jim V.]

Yepppp...wonder if...

Speed-Pro VS677 is really different or if the Speed-Pro spec is just flat wrong? Clem...are you aware of differences between identical part numbers branded Speed-Pro vs Sealed Power?

Thanks my friend...

[Clem Z.]

if i needed springs i would order just 1 and

check it out and then if OK order 15 more. i have gotten the wrong springs from GM,they had the wrong springs in the box. i once had ordered 3916164 and got 3989354 in some of the boxes marked 3916164 so with any valve spring you should check them on a RIMCO valve spring checker

[Andy #28359]

Re: VS677 Have Dampers....

Jim,

I thought I knew the dimensions when I researched this before the purchase. Now there seems to be conflicting information from different sources. In any event, I was led to believe that these were as close to the original springs as possible. They have been on my '65 for 3 months now, so I can't measure them for you. So far they are doing fine!

I'm using the original GM valves and retainers with the '929' 300HP cam.