1971 LT1 valve Springs availabilty

[Gary C.]

Hi,
Does anyone know where I can get a set of stock 1971 LT1 valve springs or an equivalent?
Thanks,
Gary

[Joe L.]

Re: 1971 LT1 valve Springs availabilty

Hi,
Does anyone know where I can get a set of stock 1971 LT1 valve springs or an equivalent?
Thanks,
Gary

Gary------


Very easy. GM #3911068. These are the valve springs originally used and they are still available today.

There are other valve springs available in the aftermarket, such as Federal-Mogul VS-677, which are claimed equivalent. They are a lot less expensive. Would I use them if I could buy the original 3911068? No.

[Duke W.]

Re: 1971 LT1 valve Springs availabilty

There is nothing special about the ...068 valve springs. They were used on virtually all small blocks from '67-up... everything from a 283/2bbl. to the LT-1. Exceptions were small blocks that had rotators on the exhaust valves. The rate and seat force is the same, but different geometry to accommodate the rotators.

The Sealed Power (Federal Mogul) VS677 is the same, built to the GM blueprint. In fact, I'm certain that what you buy from GM is the same Federal Mogul manufactured spring, and they can be found for as little 20 bucks a set on the Web.

Installed at minimum height to allow .090-100" coil bind clearance the valve train limiting speed with OE mechanical lifter cams is about 7200 and 6700 with OE hydraulic lifter cams.

Duke

[Mark E.]

Re: 1971 LT1 valve Springs availabilty

Wow. Knowing this can be a money saver.

I'm surprised small blocks did not use valve springs uniquely designed for different applications. I never researched it, but thought they came in a variety of heights, turns, rates depending on use.

[Joe L.]

Re: 1971 LT1 valve Springs availabilty

Nope. Only 3 different springs used from 1955 to 1991 for ALL small blocks. The 3911068 was used from 1967 to 1991 for all PRODUCTION small blocks except exhaust valve for those equipped with rotators, as Duke mentioned.

[Don L.]

Re: 1971 LT1 valve Springs availabilty

There is nothing special about the ...068 valve springs. They were used on virtually all small blocks from '67-up... everything from a 283/2bbl. to the LT-1. Exceptions were small blocks that had rotators on the exhaust valves. The rate and seat force is the same, but different geometry to accommodate the rotators.

The Sealed Power (Federal Mogul) VS677 is the same, built to the GM blueprint. In fact, I'm certain that what you buy from GM is the same Federal Mogul manufactured spring, and they can be found for as little 20 bucks a set on the Web.

Installed at minimum height to allow .090-100" coil bind clearance the valve train limiting speed with OE mechanical lifter cams is about 7200 and 6700 with OE hydraulic lifter cams.

Duke

True in many cases.

BEWARE - aftermarket, and by now, perhaps OEM replacement springs too, are being made using different materials and processes vs original parts. The material alone used today in OE has FAR higher performance than what was in our old cars when new. Today's "junk" material is sometimes a higher grade than the old production stuff. Evolution has seen several generations of wire since these SBC parts were first produced.

Aftermarket is a cut-throat business where price is king. China and India are popular mfg points. I'm in this business - ask me how I know.

Without a warranty, many shortcuts in mtl and in processes are "possible".

[Duke W.]

Re: 1971 LT1 valve Springs availabilty

Federal Mogul is a current Tier 1 supplier to the auto industry, and I have no doubt that they build their VS677 springs to the 3911068 print. I wouldn't bet that aftermarket cam grinders' springs are of equivalent quality, but I only recommend OE cams, cam lobes, and other OE valve train parts most of which are available from Federal Mogul in the Sealed Power Brand of OE replacement parts.

When Duntov designed his cam in 1956 he knew it would be tough to get through the release system with any different than regular production parts in the valve train, and he wanted that cam released NOW. So he increased duration, reduced net lift at the valve slightly, and the resulting milder dynamics increased valve train limiting speed by a good thousand revs.

Subsequent cam designs used the same philosophy, and when you buy replacement parts from OE suppliers that build the parts to the GM prints you're pretty much assured that they are of OE quality and durability.

When you consider that probably at least 10 million small blocks were built from '67 to '91 the demand for new valve springs is certainly in the tens if not hundreds of thousands per year, and high volume reduces production cost, so they are inexpensive.

Duke

[Don L.]

Re: 1971 LT1 valve Springs availabilty

Duke, not to debate, but while Federal Mogul is indeed a tier 1 supplier to the OEM market, they do not make springs. They also, to the best of my knowledge, do not supply springs at the tier 1 (OE) level. Certainly not for high volume production. There are now only a few names in this game and I know them all. I'm a competitor in this market.

Federal Mogul buys springs from third parties for aftermarket and replacement business applications. Aftermarket is an "international" supply base, meaning springs are sold to aftermarket accounts by many different manufacturers. Some are domestic/some are foreign. In the business, there's sometimes a marked difference between specs (and performance against specs) between OE supply and aftermarket. I have seen it. I've actually seen different part drawings with lower performance specs for aftermarket than their OE counterpart. Look at it this way - an OE component carries a warranty equal to that of the rest of the assembly it's in. When parts get old and need to be replaced, the aftermarket gets the sale. In the aftermarket, there's a far shorter, if any warranty. BTW, my reference to Federal Mogul is in no way a detriment to them. They are a fine supplier to the market. My reference was simply to share that while the may sell springs, they don't make them.

Getting back to Gary's initial question, there are numerous "stock" EVS (engine valve spring) parts available. Just how to define "stock" can be tricky. Wire used in 1971 is long ago obsoleted. Many of the manufacturing processes too have evolved over the years. Like most industries, the spring industry is far more capable today of making a precision part than it was 47 years ago. Aftermarket can be a hit/miss vs performance specs, depending on the house used. Beware of low cost, high volume catalog parts. I am certainly not plugging here, which is why I'm leaving my company's name anonymous in this thread. I would recommend a known high quality spring. A spring is no less important than any other significant part in the engine. I view a EVS as I do a fuse. In the valve train, it's a weak link. Why risk it?

Hope this helps...

[Gary C.]

Re: 1971 LT1 valve Springs availabilty

Thanks for your input eveyrone.

[Duke W.]

Re: 1971 LT1 valve Springs availabilty

I would recommend a known high quality spring..

So how does the average owner who wants to rebuild his engine determine a "known high quality spring" to replace the OE 3911068 without being an industry insider.

What brand/part number do you recommend for an aftermarket 3911068 spring that meets the seat force at installed height and rate specs and is of equal or better quality in terms of materials and durability as the originals installed at Flint.

Also, since GM still offers this spring, who manufactures it?

Duke

[Don L.]

Re: 1971 LT1 valve Springs availabilty

So how does the average owner who wants to rebuild his engine determine a "known high quality spring" to replace the OE 3911068 without being an industry insider.

What brand/part number do you recommend for an aftermarket 3911068 spring that meets the seat force at installed height and rate specs and is of equal or better quality in terms of materials and durability as the originals installed at Flint.

Also, since GM still offers this spring, who manufactures it?

Duke

I can't recommend a particular part number. Perhaps evolution has affected the number of offerings too. Specifics in the valve train (camshaft, rocker arm type and/or ratio, etc) may favor a different set up. The racing/high performance division of my company has a tech staff to aid in selection. There's toll free number to help.

I just re-did my L48 top end over the winter and used the PAC Racing #1909 (single spring with damper). See the attached charts for SBC and BBC details. I have rotators on the exhaust side. I have shims in the intake side that allows me to use the same spring throughout the engine. The line of thinking there is that if in the future, springs are removed for any reason, there will no risk of the repair technician mixing long and short springs, not knowing they are different.

As far as recommending a supplier, there are numerous. Comp Cams, Crane, Isky, Lunati, Manley, PAC Racing and Summit Racing are all good. Of these, only PAC Racing manufactures what they sell. Others are "private labeled", meaning they are produced by spring manufacturers on their behalf. These will all likely be more expensive than a FLAPS-bought spring. Risk for all the things I've shared above should be considered when choosing a replacement EVS.

I can't tell you who manufactures GM's service replacement springs. There could be numerous service replacement suppliers to GM. As an OE supplier, we are required to provide service parts for a set time period after end of production. For the 068 (and similar), that time period expired long ago.

I hope this helps.

[Duke W.]

Re: 1971 LT1 valve Springs availabilty

Thanks for the reply. My only interest was in a replacement for the OE 3911068. Its specs are listed in the GMPP catalog. Lacking industry insider knowledge all I can do is buy a trusted OE replacement brand like Sealed Power that I know is marketed by a Tier 1 OE supplier, and even if Federal Mogul does not actually manufacture the VS677, I have no choice but to assume that it does match the specs and quality of the springs manufacturer by GM back in the day when they were used on new engines.

The Sealed Power OE replacement for the ...068, VS677 has the same specs - about 80 pounds on the seat with a rate of 267 lb/in, so around 200 open with OE cam lobes. With indifferent installed height, valve train limiting speed is around 6000+ for an OE hydraulic lifter cam and close to 7000 with an OE mechanical lifter cam. With minimum installed height allowing .090-.100" coil bind clearance hydraulic lifter OE cam limiting speed is about 6700 and 7200 with an OE mechanical lifter cam.

So I have another question. Unless your L48 is modified, like an aggressive dynamics aftermarket cam, to produce useable power above the OE 5300 redline, why did you use such stiff springs?

Duke

[Don L.]

Re: 1971 LT1 valve Springs availabilty

Thanks for the reply. My only interest was in a replacement for the OE 3911068. Its specs are listed in the GMPP catalog. Lacking industry insider knowledge all I can do is buy a trusted OE replacement brand like Sealed Power that I know is marketed by a Tier 1 OE supplier, and even if Federal Mogul does not actually manufacture the VS677, I have no choice but to assume that it does match the specs and quality of the springs manufacturer by GM back in the day when they were used on new engines.

The Sealed Power OE replacement for the ...068, VS677 has the same specs - about 80 pounds on the seat with a rate of 267 lb/in, so around 200 open with OE cam lobes. With indifferent installed height, valve train limiting speed is around 6000+ for an OE hydraulic lifter cam and close to 7000 with an OE mechanical lifter cam. With minimum installed height allowing .090-.100" coil bind clearance hydraulic lifter OE cam limiting speed is about 6700 and 7200 with an OE mechanical lifter cam.

So I have another question. Unless your L48 is modified, like an aggressive dynamics aftermarket cam, to produce useable power above the OE 5300 redline, why did you use such stiff springs?

Duke

Hi Duke.

Feeling like this thread is now morphing to something other than the OP intended, but yes, I am aware of my higher-than-stock loads.

Some changes in my valvetrain set up were made during my recent project. My engine builder and valve train Engineers say that for me, it's safer to have more load than not enough. They didn't feel that the higher loads posed any extraordinary risk of cam damage, etc in my set up. My engine builder has been doing this for many years and has built some legendary race engines. I have trusted his recommendations throughout my project. I also know I now have 100% genuine USA produced parts in the entire valvetrain.

Getting back to the OP's query, I'd add that for those that might want to stay closer to the stock load, there are certainly lighter, high quality springs available through the aforementioned names.

Hope this helps.