LS5 build

[Justin S.]

I'm building my '70 LS5 to original specs. I'm using cam 3904359. Any recommendations for aftermarket valves and springs?

Thanks, Justin

[Joe L.]

Re: LS5 build

I'm building my '70 LS5 to original specs. I'm using cam 3904359. Any recommendations for aftermarket valves and springs?

Thanks, Justin

Justin-------

The GM parts are all discontinued.

For the valves, it's simple. Use the following Sealed Power valves:

intake: V1912

exhaust: V1911

The above will be, essentially, OE-equivalent valves. I've inspected these carefully and they appear to be identical to the GM valves.

For the valve springs it's more complicated. The valve spring originally used for your engine and, in my opinion, the best valve spring ever available from GM for street big blocks was the valve spring referred to as GM #3970627 (I say "referred to" because that part number was actually the part number for a spring + valve spring cap with integral valve stem seal). Unfortunately, this valve spring is GM-discontinued.

Sealed Power valve spring # VS-708 is IDENTICAL to the valve spring referred to as GM #3970627. As many folks on this board know, I am definitely not one to equate aftermarket parts with OEM. Frankly, I believe that in the vast majority of cases aftermarket engine parts are inferior to OEM. However, in this case I have carefully inspected NOS original GM #3970627 valve springs as well as the VS-708. These appear absolutely identical to me. As a matter of fact, I expect that some other manufacturer made them for both GM and Sealed Power (Federal-Mogul).

The big problem with using these springs is that they require valve cap (retainer) GM #3964264. This valve cap was discontinued by GM in August, 2013 and has NEVER been available in the aftermarket, either from Sealed Power or anyone else. Even Sealed Power says that it must be used with the VS-708 spring. It would be possible to have the valve guides machined down and use certain positive valve seals with the VS-708 spring but one would still lack a valve cap that properly aligns and centers the spring.

If you have the original valve caps from your engine, then you already have the GM #3964264 valve spring caps. In that case, you can re-use them with the VS-708 springs. If the seal component of the cap is deteriorated (as is likely), they can be replaced with Fel-Pro SS 72513. The latter is a kit of 16 special valve seals.

The only other thing I could suggest would be to use spring Sealed Power VS-657 with traditional umbrella seals and valve spring cap Clevite 2164115.

Below are photos of a GM #3964264 valve cap:


DSCN3267.jpgDSCN3268.jpg

[Justin S.]

Re: LS5 build

Joe, thanks s

[Justin S.]

Re: LS5 build

Joe, thanks so much. Would it be ok to reuse the original retainers with the VS-708?

Justin

[Joe L.]

Re: LS5 build

Joe, thanks so much. Would it be ok to reuse the original retainers with the VS-708?

Justin

Justin-----

If they are the original retainers as I've pictured, then, yes, you can absolutely use the VS-708 with these retainers. If you have any other retainers, then they are not original to your engine.

[Patrick B.]

Re: LS5 build

Are the Felpro SS 72513 duplicates of the plastic seal portion of the 3964264 or are they something else?

[Joe L.]

Re: LS5 build

Are the Felpro SS 72513 duplicates of the plastic seal portion of the 3964264 or are they something else?

Patrick-------


They're very close to being exact duplicates. They don't fit in the cap quite as well as the originals but they should be 100% equally functional.


DSCN3270.jpgDSCN3271.jpg

[Patrick B.]

Re: LS5 build

Thanks Joe

[Mark E.]

Re: LS5 build

Justin-------

The GM parts are all discontinued.

For the valves, it's simple. Use the following Sealed Power valves:

intake: V1912

exhaust: V1911

The above will be, essentially, OE-equivalent valves. I've inspected these carefully and they appear to be identical to the GM valves.

For the valve springs it's more complicated. The valve spring originally used for your engine and, in my opinion, the best valve spring ever available from GM for street big blocks was the valve spring referred to as GM #3970627 (I say "referred to" because that part number was actually the part number for a spring + valve spring cap with integral valve stem seal). Unfortunately, this valve spring is GM-discontinued.

Sealed Power valve spring # VS-708 is IDENTICAL to the valve spring referred to as GM #3970627. As many folks on this board know, I am definitely not one to equate aftermarket parts with OEM. Frankly, I believe that in the vast majority of cases aftermarket engine parts are inferior to OEM. However, in this case I have carefully inspected NOS original GM #3970627 valve springs as well as the VS-708. These appear absolutely identical to me. As a matter of fact, I expect that some other manufacturer made them for both GM and Sealed Power (Federal-Mogul).

The big problem with using these springs is that they require valve cap (retainer) GM #3964264. This valve cap was discontinued by GM in August, 2013 and has NEVER been available in the aftermarket, either from Sealed Power or anyone else. Even Sealed Power says that it must be used with the VS-708 spring. It would be possible to have the valve guides machined down and use certain positive valve seals with the VS-708 spring but one would still lack a valve cap that properly aligns and centers the spring.

If you have the original valve caps from your engine, then you already have the GM #3964264 valve spring caps. In that case, you can re-use them with the VS-708 springs. If the seal component of the cap is deteriorated (as is likely), they can be replaced with Fel-Pro SS 72513. The latter is a kit of 16 special valve seals.

The only other thing I could suggest would be to use spring Sealed Power VS-657 with traditional umbrella seals and valve spring cap Clevite 2164115.

Below are photos of a GM #3964264 valve cap:

Following Joe's advice, I ordered Sealed Power VS-708 valve springs from RockAuto. I RECEIVED Speed Pro VS-708.

I sent an email to RA asking them about the brand difference, and if they are equivalent. RA does not have a telephone, so I'm awaiting their reply.

Sealed Power and Speed Pro are each owned by Federal-Mogul. Is one of these a budget brand for F-M, and the line of parts across their brands different? Or are they equivalent?

[Joe L.]

Re: LS5 build

Following Joe's advice, I ordered Sealed Power VS-708 valve springs from RockAuto. I RECEIVED Speed Pro VS-708.

I sent an email to RA asking them about the brand difference, and if they are equivalent. RA does not have a telephone, so I'm awaiting their reply.

Sealed Power and Speed Pro are each owned by Federal-Mogul. Is one of these a budget brand for F-M, and the line of parts across their brands different? Or are they equivalent?

Mark------

In this case, Speed-Pro and Sealed Power are absolutely the same. In fact, in most cases, if not all, they are the same. For some reason unbeknownst to me, Federal Mogul just can't seem to settle on which one of their acquired brands they want to sell parts under. TRW is another brand acquired over the years and you'll sometimes see Federal Mogul parts under that brand. Keep in mind, though, that all of these brands are aftermarket brands, not OEM. Once-in-awhile, as in the case of these springs, the parts may be the same as OEM (but not usually).

Are all of the Federal-Mogul parts of whatever brand good parts? Yes, they definitely are. But, as I say, they are usually not the same as OEM.

[Duke W.]

Re: LS5 build

Sealed Power is F-M's brand name for OE equivalent replacement parts. Speed Pro is their "performance line", which includes some OE parts and some of non-OE designs. Camshafts come to mind. For example most OE SHP cams both hydraulic and mechanical lifters are sold under the Speed Pro brand, but they are manufactured to the GM blueprints. The base 300 HP cam, also manufactured to the GM print, is sold under the Sealed Power brand.

Yes, it's somewhat confusing, but in most cases if you can cross reference an OE part number to a Speed Pro or Sealed Power part number,' it's build to the GM print.

Duke

[Mark E.]

Re: LS5 build

Thanks Duke and Joe.

I'll go ahead and install these springs.

It is confusing to order brand X, then receive brand Y.

[Dick W.]

Re: LS5 build

Mark------

In this case, Speed-Pro and Sealed Power are absolutely the same. In fact, in most cases, if not all, they are the same. For some reason unbeknownst to me, Federal Mogul just can't seem to settle on which one of their acquired brands they want to sell parts under. TRW is another brand acquired over the years and you'll sometimes see Federal Mogul parts under that brand. Keep in mind, though, that all of these brands are aftermarket brands, not OEM. Once-in-awhile, as in the case of these springs, the parts may be the same as OEM (but not usually).

Are all of the Federal-Mogul parts of whatever brand good parts? Yes, they definitely are. But, as I say, they are usually not the same as OEM.

F/M is/was one of the suppliers to GM.

[Joe L.]

Re: LS5 build

F/M is/was one of the suppliers to GM.

Dick------

Yes, that is true. However, that does not necessarily mean that their aftermarket parts are the same as those supplied to OEM. Often times, the parts are not even made in the same factories.

For example, Walker was an OEM supplier to GM for mufflers and pipes, including, of course, for Corvettes. However, Walker's aftermarket mufflers for Corvettes were not the same as those they supplied to GM. They were not even made in the same factory.