L79 Camshaft (GM # 3853151); who makes what

[Duke W.]

Re: L79 Camshaft (GM # 3853151); who makes what

I apparently missed a couple of prefix digits in the NAPA part number - or my notes are old and the numbers changed:

NTP 103023X is an three way adjustable roller chain set. There are two listings for this part number. One says non-factory roller cam. (I'm not sure if this precludes its use for flat tappet cams.) The second listing says nothing about the type of cam

NTP 103023 is the OE replacement non-adjustable truck roller chain set

NTP 203001 is the OE replacement second design (narrow) silent chain used on pass. cars.

I suspect that all of the above are manufactured by Cloyes. NPT stands for "NAPA Timing Products", so they are probably all Cloyes manufactured products sold under NAPA's own brand.

That can be a problem - determining who actually manufactures a part in the "brand name" box.

Go to www.napaonline.com and type the part numbers into the search box. I don't think you need to type in the "NPT".

I e-mailed Tim Schuetz, a NAPA jobber in Wisconsin, and asked him to look at this thread and help us sort out the 103023X.

Duke

[Gary B.]

Re: L79 Camshaft (GM # 3853151); who makes what

Jack, Duke,

Thanks guys. I think you've figured it out.

Gary

[Steven B.]

Re: L79 Camshaft (GM # 3853151); who makes what

I'm looking at a Crane Cams Blueprint Series 327-350 hp camshaft Crane Cams part no. 967601 new in the box that I bought probably 20 years ago. I don't know about the cam produced now, but the box advertises Crane Cams, Incorporated, Daytona Beach, FL 32014, MADE IN THE U.S.A. I have used this cam before. When degreeing it, it was right on the money. It IMO it is an excellent cam. If the valves are adjusted by running the engine, backing off the adjusting nuts until just clattering, then tightening until the clatter just disappears then with the engine off, and the lifter on the base circle tightening 1/8 to 1/4 turn, the lifter will have less tendency to pump up and float the valves. I know that this is 70's technology, and there may be better current theory. Someone help me if there is a better current method. I'm not sure what benefit there would be pushing 7000 RPM unless you are racing.
The Cloyes chain sets from what I understand were OE for a number of manufacturers at least in the seventies. I have used the Cloyes True Roller set. They were the first true roller timing chain set in the early seventies. The sprockets were magged and tuftrided, and the chain was (I don't know about now) manufactured by Reynolds of England and was advertised to not stretch. IMO a good set. They probably make a more improved set currently.
Steve

[Duke W.]

Re: L79 Camshaft (GM # 3853151); who makes what

Tim said he would look into this further and probably put in a post. In the meantime here's what he said via e-mail. Note that he confirms that the NPT 103023X is manufactured by Cloyes.

"It will work fine. The primary applications takes it back into the late 50's. It is your typical [truck] Chev timing set with an adjustable crank gear. Pretty much standard issue.

...if no one knows, it is a Cloyes chain and gear set".

I suspect the the link in post #14 that describes the C-3023X as non-adjustable is incorrent.

So the NPT 103023X is the same Cloyes-manufactured set as the Cloyes C-3023X - just a different box, so buy on price and convenience.

The term "true roller" is just marketing hype. The only difference between the truck chain and the "true roller Cloyes" is the Cloyes has .25" rollers vs. .20" for the OE truck chain. For other than abusive drag racing the larger rollers provide zero benefit, so why spend 3-4 times the price? The funds are better spent elsewhere.

Crane is a quality manufacturer. In the past, and possibly still, today, they manufactured vintage SHP cams for GM that were sold through the GMPP catalog. The cams they've made to my designs were dimensionally correct and all were Parkerized, which aids breakin.

My first choice is Federal Mogul (Sealed Power, Speed Pro) and Dana Corp. (Clevite) cams. They are more widely distributed and probably lower priced, but it's really just a matter of price and convenience.

Adjusting hydraulic lifters is easier, cleaner to do with the engine not running. At TDC of the compression stroke on each cylinder back off the nut while wiggling the pushrod up and down. Once you feel clearance, tighten the nut until the clearance just disappears, then turn them down zero to one turn.

"Zero lashing" the will allow the engine to recover faster from valve float. This usually requires frequent relashing due to clearance developing and subsequent valve train noise. For normal road applications I usually recommend 1/2 turn down from zero lash.

Maximum valvetrain speed is obtained by setting up the valve spring installed height to allow .090-.100" clearance from coil bind. With the OE springs this will yield 6500-7000, but whether a L-79 cam will still be making useable power at that point is a function of how well the heads are massaged.

Duke

[William F.]

Re: L79 Camshaft (GM # 3853151); who makes what

Duke, with the real L79 cam being one of the all time best-almost the power of a mechanical and not having to adjust lash, why go to a mechanical unless you're determined to wind past 6000 in a car you really don't need to take a chance blowing up in the first place?

[Michael H.]

Re: L79 Camshaft (GM # 3853151); who makes what

Duke, with the real L79 cam being one of the all time best-almost the power of a mechanical and not having to adjust lash, why go to a mechanical unless you're determined to wind past 6000 in a car you really don't need to take a chance blowing up in the first place?

I agree. The 151/350 HP cam is one of my all time favorites.

[Duke W.]

Re: L79 Camshaft (GM # 3853151); who makes what

The extended rev range of the LT-1 cam means it produces more average power over the top 1500 of the rev band than either the L-79 or L-46 cams; 1500 is about how far the revs drop shifting at 6-7000. Higher average power over the top 1500 of the rev range means higher acceleration through the gears.

Some guys want to maximize acceleration performance while maintaining OE appearance. Others are not that concerned with maximizing performance, aren't comfortable with revving that high, or don't want to deal with periodic valve adjustments.

It's a matter of personal choice, and not everyone has the same criteria.

With current inexpensive rods that are vastly more durable than OE rods and proper OE replacement valve spring height setup, occasionally revving to 7000 with the LT-1 cam will not cause any durability problems, especially if it was originally a mechanical lifter cam engine with the big pan.

I do caution L-79/46 owners that the extended rev range of the LT-1 cam has a greater potential to cause oil starvation, which is about the only thing that can hurt these engines. The higher the engine revs the tougher it is for the oil to drain back down to the pan, so oil level should constantly be maintained at the full level or slightly above.

Up to the early/mid seventies when SCCA allowed dry sumps on production cars, Corvette racers typically ran the oil level a quart or more overfull. At high revs there are 2-3 quarts inside the engine trying to get back down to the pan, but the higher the crankcase windage, the tougher it is to find a way.

Duke

[Michael H.]

Re: L79 Camshaft (GM # 3853151); who makes what

For L-79s I recommend the L-46 camshaft
Duke

For L79's, I recommend an L79 camshaft.

[Duke W.]

Re: L79 Camshaft (GM # 3853151); who makes what

How about responding to the full quote:

"For L-79s I recommend the L-46 camshaft (Sealed Power CS-1095R, Clevite 229-1615) installed four degrees advanced with a [NPT 10323X] adjustable roller chain set. Installing this cam four degrees advanced brings the inlet POML back to 110 degrees ATDC (same as the L-79) from the as manufactured 114. The L-46 cam has two degrees more .050" duration and the same LSA as the L-79 cam, so from a practical standpoint it's the same as the L-79 cam except for the later phasing as manufactured.

The reason I prefer the L-46 cam is better lobe dynamics." [emphasis added]

Duke

[Michael H.]

Re: L79 Camshaft (GM # 3853151); who makes what

The rest of your paragraph wasn't at issue.

Personally, I think most of your cam recommendations are silly. You're trying to pretend that people are still racing these cars 50 years later.

Why can't a members old Corvette sound and run like an old Corvette?

Tell people what you want in your car but stop telling members what to put in their cars.

[Duke W.]

Re: L79 Camshaft (GM # 3853151); who makes what

I don't "tell' anyone what to put in their car, but I make recommendations based on their objectives. The L-79 cam doesn't "sound" any different than the L-46 cam - at idle or anywhere else in the rev range... same with the McCagh Special compared with the 300 HP cam; and The LT-1, Duntov, and 30-30 idle so similarly that no one for sure can pick any out. Some claim they can, but can't prove it.

All my recommended engine configurations are designed to "sound" and visually appear just like an OE engine of the owner's choice, but they offer broader road-friendly torque bandwidth along with higher top end power and revs. They are road, not racing engines. Some owners are okay with a stock rebuild, but some want to extract maximum performance within the limits of OE appearance and idle behavior. That's my specialty, and the results have been published in The Corvette Restorer, The Corvette Forum, and here on the TDB. I also do engine system engineering work on serious racing engines for vintage racers, which are configured very differently.

For rebuilds/restorations I often recommend later design SHP cams over earlier designs because they incorporate what Chevrolet learned about valve train dynamics through the sixties and my own design cams use OE lobes.

If you want to rant about cam selection you'll find a lot more to rant about over on the Corvette Forum where about 99 percent of the time the "experts" recommend some hot rod cam.

Duke

[Tim S.]

Re: L79 Camshaft (GM # 3853151); who makes what

The rest of your paragraph wasn't at issue.

Personally, I think most of your cam recommendations are silly. You're trying to pretend that people are still racing these cars 50 years later.

Why can't a members old Corvette sound and run like an old Corvette?

Tell people what you want in your car but stop telling members what to put in their cars.

If you do not like the suggestions given by Duke, there is no where here that requires you to read it. It is a well documented fact Duke's knowledge is often solicited. He has input and experience that most of us have not been exposed to. Let's keep the TDB on the up and up.

[Gene M.]

Re: L79 Camshaft (GM # 3853151); who makes what

If you do not like the suggestions given by Duke, there is no where here that requires you to read it. It is a well documented fact Duke's knowledge is often solicited. He has input and experience that most of us have not been exposed to. Let's keep the TDB on the up and up.

But it is the same stuff over and over and over. Anytime a posting on camshafts comes up it is the same reply with the same put down on "hot rod" cams suggesting the LT1 version. This is a RESTORATION web site, hydraulic lifter engines did not use LT1 solid lifter camshafts. And L79 engines only used L79 cams. Unrealistic talking about revving a L79 to 7200 RPM. These engines are all done making power way before 7200 RPM. This is not a drag racing web site.

[Joe L.]

Re: L79 Camshaft (GM # 3853151); who makes what

But it is the same stuff over and over and over. Anytime a posting on camshafts comes up it is the same reply with the same put down on "hot rod" cams suggesting the LT1 version. This is a RESTORATION web site, hydraulic lifter engines did not use LT1 solid lifter camshafts. And L79 engines only used L79 cams. Unrealistic talking about revving a L79 to 7200 RPM. These engines are all done making power way before 7200 RPM. This is not a drag racing web site.

Gene------


Yes, it's primarily a restoration discussion board. However, many other technical aspects regarding Corvettes are discussed here and are fully allowable under the rules of this discussion board. For folks that are committed to the strictest forms of originality and 100% correct restoration, I would suggest that they ignore discussions or information which departs from that. However, as I've mentioned previously, if folks are absolutely committed to 100% correct-in-every-way restoration, then they shouldn't use things like stainless steel sleeved calipers, non-original part numbered internal engine parts, over-bored cylinder blocks, undersize crankshafts, Timken wheel bearings, non-original part-numbered brake pads, o-ring calipers, waterpumps with non Delco bearing/shaft assemblies, or, even, current API rated engine oils. None of those things and many more are original and will not cause a car to be restored to its original, factory-deliverd condition.

[Gene M.]

Re: L79 Camshaft (GM # 3853151); who makes what

Gene------


Yes, it's primarily a restoration discussion board. However, many other technical aspects regarding Corvettes are discussed here and are fully allowable under the rules of this discussion board. For folks that are committed to the strictest forms of originality and 100% correct restoration, I would suggest that they ignore discussions or information which departs from that. However, as I've mentioned previously, if folks are absolutely committed to 100% correct-in-every-way restoration, then they shouldn't use things like stainless steel sleeved calipers, non-original part numbered internal engine parts, over-bored cylinder blocks, undersize crankshafts, Timken wheel bearings, non-original part-numbered brake pads, o-ring calipers, waterpumps with non Delco bearing/shaft assemblies, or, even, current API rated engine oils. None of those things and many more are original and will not cause a car to be restored to its original, factory-deliverd condition.

Yes but all those mentioned are attempts to save the original parts and mimic original configuration . Adding a solid lifter cam to a L79 is not in the spirit of restoration. It would be a deliberate modification. No different than the so called "hot rod" camshaft.

Joe, the post was in complement to Mike Hanson indicating the replied postings to the OP are the same over and over again.