Roller Cams

[Craig F.]

I am curious what some of you all are using for cams in new motor rebuilds. With the lack of Zink in new oils, (except Redline or using a zink additive) and the increased wear on flat tappet cams, I now need to replace the solid cam in my motor. Last time I ran the valves I had 3 that show large wear and it all points to the cam loab wear so far. Specifically, I am replacing the cam in a 400 SB and working on rebuilding my 327-365 motor. Both have solid flat tappet cams and really should be roller cams to be able to use newer oils. Has anyone found a roller cam grind that is just like the 30/30 cam used in 365hp motors?

[Joe L.]

Re: Roller Cams

I am curious what some of you all are using for cams in new motor rebuilds. With the lack of Zink in new oils, (except Redline or using a zink additive) and the increased wear on flat tappet cams, I now need to replace the solid cam in my motor. Last time I ran the valves I had 3 that show large wear and it all points to the cam loab wear so far. Specifically, I am replacing the cam in a 400 SB and working on rebuilding my 327-365 motor. Both have solid flat tappet cams and really should be roller cams to be able to use newer oils. Has anyone found a roller cam grind that is just like the 30/30 cam used in 365hp motors?

Craig-----


I am not aware of ANY roller cams currently manufactured which duplicate the profiles of older flat-tappet cams used in Corvettes. In fact, I don't think a roller cam which had equivalent characteristics to an older cam would have the same profile, at all. I've often wondered if such a cam could be designed and manufactured, though.

I'm a BIG fan of roller cams.

[Duke W.]

Re: Roller Cams

With the lack of Zink in new oils, (except Redline or using a zink additive)

I guess you don't read The Corvette Restorer

Duke

[Duke W.]

Re: Roller Cams

I've often wondered if such a cam could be designed and manufactured, though.

It's certainly possible to design/manufacture a lobe for roller lifters that yields the exact same lift-crank angle specification as any flat tappet cam.

But such a design would offer the exact same performance characteristics as the flat tappet cam, so there would be no point, given the higher cost.

Roller lifters can sustain higher lobe contact pressure, so a roller lobe can have more aggressive dynamics and lift with the necessary higher load valve spring to control the greater inertia forces without loss of durability. This facilitates similar top end power with shorter duration/overlap than a flat tappet cam, and the shorter duration/less overlap can yield better torque bandwidth and a more tame idle than the OE flat tappet SHP cams.

But now the engine, other than top end power, has significantly different performance/operational characterisitics. In short, it's a completely different engine.

It's like trying to have a cat act like a dog, but still be a cat.

Duke

[Craig F.]

Re: Roller Cams

I do read the Restorer, but must have missed an article that you feel answers my question on cam selection for solid lifter motors.

[James W.]

Re: Roller Cams

I recently had my 71 LS5 rebuilt using a roller cam and lifters, but not rockers. The profiles are not the same, but the idle is very close. I did not use roller rockers due to clearance problems. The engine dynoed at 427 HP and 485lb/ft of torque. I also had port matching and some pocket prting done, along with bench flowing the heads. Rotating assembly was balanced and engine was clearanced.

As far as the low zinc, etc levels, go to an oil made for deisel engines. They still have the additives. I use Mobil 1 deisel in my 90 ZR-1.

Jim

[Clem Z.]

Re: Roller Cams

i believe this guy should know. i think the problem came from aftermarket cam manufactures with wild ass lobe profiles, heavy spring pressures and no parkerizing of the cams to save money. to read the attachments go to "page" and then "Zoom" then to 150%

[Duke W.]

Re: Roller Cams

I do read the Restorer, but must have missed an article that you feel answers my question on cam selection for solid lifter motors.

It was an article about what type of motor oil to use for vintage flat tappet cam engines.

Duke

[Joe C.]

Re: Roller Cams

Craig-----


I am not aware of ANY roller cams currently manufactured which duplicate the profiles of older flat-tappet cams used in Corvettes. In fact, I don't think a roller cam which had equivalent characteristics to an older cam would have the same profile, at all. I've often wondered if such a cam could be designed and manufactured, though.

I'm a BIG fan of roller cams.

Very possible, but not probable. Roller cams must be machined of billet steel. Their extra cost, plus the cost of roller tappets, hardened pushrods (necessary if your originals are not case hardened), stiffer springs, head machining/modifications, guide plates, screw in spring studs, and ROLLER TRUNNION rocker arms (although not required, their elimination would negate 1/2 of the friction loss savings), and probable valve cover clearance issues make the conversion cost prohibitive. This, in light of the fact that reduction of friction loss at high RPM's might amount to less than 15 horsepower.

The only real advantage to roller profiles is that they allow wider lobe centers, less overlap, and earlier intake valve closing as compared to flat tappet cams................all contributing to flatter, broader torque curves and more stable idle with higher vacuum. The price to pay, however, is loss of top end power. If you choose a more aggressive, circle track cam with tighter centers, more overlap, and late intake valve closing, then your engine will sound very much like the 30-30 cammed smallblock, will develop massive horsepower, but will have extremely limited torque below 3500 RPM. Surprisingly, the best compromise, is the vintage SHP flat tappet cam profiles.

The closest I can find, to vintage profiles in roller cams, is a brand new series of Lunati solid rollers. These are new additions to their "Voodoo" series. I ran sims of their 60141 and 60142 cams. These are ground on fairly wide (by today's standards) LSA of 110. They will probably "sound" similar to the 30-30. They do not perform as well as the 30-30, however, developing less average torque and less average horsepower. Among other cams that I tested were the Lunati 501B1, and Isky 530A.

There is no roller cam on the market, which will exactly duplicate the operating characteristics of neither the 30-30 nor the LT1.

[Bob S.]

Re: Roller Cams

Craig, the article referenced above is on page 19 of the Summer 2008 Restorer.

I've just gone thru the same mental gymnastics on the rebuild of my L-79 engines, and decided to stick as close to stock as possible for the cam design, etc. One key issue is insuring the valve spring loadings also remain close to stock....many engine builders apparently promote high valve spring loads in the interest of "performance".

Another question you may wish to consider: While currently available oils for diesel engines ('CI' and 'CJ') may have sufficient amounts of ZDDP to support the use of flat tappet cams, how long will that continue to be the case? My source (I worked for 25+ years in product engineering in the diesel engine field) tells me the trend is now to roller cams in medium duty diesels (heavy duty diesels already have them across the board). Strikes me as inevitable that sooner or later diesel oils will likely contain reduced ZDDP levels too....maybe by then other solutions will be clearer (additives, suitable oils for flat tappet cams or whatever??), but for now, what I'm doing is to strictly limit my valve spring forces to what GM originally used.

Happy Holidays,
Bob S.

[Michael H.]

Re: Roller Cams

ROLLER TRUNNION rocker arms (although not required, their elimination would negate 1/2 of the friction loss savings), and probable valve cover clearance issues make the conversion cost prohibitive. This, in light of the fact that reduction of friction loss at high RPM's might amount to less than 15 horsepower.

We discussed roller cams/rocker arms here a while back and I think a few have forgot what I posted.
The true benefit of roller cams and rocker arms for newer cars doesn't really have anything to do with power. Not directly, anyway.
If there was actually enough friction to reduce engine power by 15 horse power, just exactly how long would a flat tappet lifter or rocker arm last? Not very long, at all. Enough friction to robb 15 HP would quickly destroy these components. Rocker arms and flat tappet lifters can last hundreds of thousands of miles and still be shinny on the contact surfaces when removed. That should tell us something about how much frictional loss is created at these points.

What it does have to do with is fuel mileage and emissions. While it's true that these components, by themselves, do not robb power, they DO require a lot of lubrication, which requires oil pressure, which gobbles up power. It takes a LOT of energy to spin an oil pump, especially at road speed RPM.
By reducing the amount of pressure required, the power required to turn the oil pump can be reduced.
Some Pro Stock engine builders go as far as using needle bearing cam bearings but not because there is any power to be gained because of less friction. It's because they require less oil flow/pressure. Less power loss at the oil pump.

Roller cams/lifters in race engines were used for two reasons. One, because of the incredible valve spring pressure required to prevent valve float at high RPM and... and two, because an longer duration, faster action cam profile was available with the roller design.
If you increase the duration of a cam lobe, you eventually get to the point where lifter to lobe contact no longer occurs on the face of the lifter. The point of contact would move off the face of the lifter.
There are two ways to correct the problem. Either use larger diameter lifters, (or mushroom lifters) or use roller lifters.
Roller lifters cured both problems which is another reason why so many racing engines used them.
However, in Nascar, for example, roller cams/lifters are not allowed so todays Nascar engines usually use wide base or larger OD lifters.

Here's a link to the original discussion.

https://www.forums.ncrs.org/showthre...leage&uid=5460

[Clem Z.]

Re: Roller Cams

with race cams and heavy springs you can reduce the oil temp 10/15 degrees going to roller rockers in a BBC

[Bill C.]

Re: Roller Cams

Gentlmen,
If anyone has an old bottle (prior to June 1st, 2007 ) of diesel oil, Rotella or Delo, compare the specifications met by the current version and the prior version, many specs for caterpillar, John Deere, etc are no longer met and the bottles now have "enviormentaly improved" or "emissions friendly" or similar verbage on them. What that means simply is the ZZDP has been reduced and its likely gauranteed to get lower as the Auto industry is squeezed to meet the requirements of standing behind emission systems and catalytic converters (currentley going on deisels also) for 100K miles and beyond. ZZDP is POISON to the cats and you can be sure the lobbyists will be doing all that they can to keep any additives out of the publics hands, as for sure as we need it for our flat tappets, JQ Public will for sure want to put it into his new SUV for "added" protection and soon his idiot light will come on indicating a problem that the manufacturer will have to remedy at their expense. Not hard to see whats happening, we are the minority in our needs for our old engines. Back on the same date, 6-1-08 GM stopped supplying the good old EOS assembly additive, which is rich with ZZDP ( which by the way, back in the 60's and 70's was called "engine oil additive" under the same #1052367 part # ,and GM recomended adding a pint at every oil change, and a full quart during first run break in) I still have some of those and can send pics for anyone interested. It was unavailable from June in its good form supplied in the black bottle GM part # 1052367, until around December of 2007 it was reissued using the same part # but now supplied in a white plastic bottle. You can be sure it is NOT the same formula but a reduced ZZDP version.
Why else would they reissue it? On top of that, the price more than doubled!
You will not find the ingredient levels on either bottle. There are currently some products available including in the driveline claiming to have the levels of ZZDP required as an additive. I am skeptical, again, why would the powers that be allow anyone to produce in this country or allow to be imported a product that potentially will cost them lots of warranty money and they can so easily condem it as being Enviormentally unsafe. Foolproof solution? Buy all the GM EOS part # 1052367 in only unopened BLACK plastic bottles you can find, add a pint to each oil change using a good Deisel motor oil such as Rottella or Delo as they have the highest levels currently. GM used to tell us to do that and then you are safe, gauranteed. Try your local GM dealers back shelves or sometimes can be found on ebay. Its in my opinion the only way I can sleep knowing my old cams are safe. Lastly, if memory serves, Mobil one full synthetic and compareable oils were released at about the same time (1984 ?) as the introduction of production car roller cams and the elimination of flat tappet cams, reading into the timeline, I would not recomend using synthetic in flat tappet cam motors. It is an excellent oil for sure but I am not sold on application in the older motors, although I have used Castrol syntec prior to summer of 2007 with good results. It will take some time unfortunately to see what happens but I aint waitin" !

[Joe L.]

Re: Roller Cams

Very possible, but not probable. Roller cams must be machined of billet steel. Their extra cost, plus the cost of roller tappets, hardened pushrods (necessary if your originals are not case hardened), stiffer springs, head machining/modifications, guide plates, screw in spring studs, and ROLLER TRUNNION rocker arms (although not required, their elimination would negate 1/2 of the friction loss savings), and probable valve cover clearance issues make the conversion cost prohibitive. This, in light of the fact that reduction of friction loss at high RPM's might amount to less than 15 horsepower.

The only real advantage to roller profiles is that they allow wider lobe centers, less overlap, and earlier intake valve closing as compared to flat tappet cams................all contributing to flatter, broader torque curves and more stable idle with higher vacuum. The price to pay, however, is loss of top end power. If you choose a more aggressive, circle track cam with tighter centers, more overlap, and late intake valve closing, then your engine will sound very much like the 30-30 cammed smallblock, will develop massive horsepower, but will have extremely limited torque below 3500 RPM. Surprisingly, the best compromise, is the vintage SHP flat tappet cam profiles.

The closest I can find, to vintage profiles in roller cams, is a brand new series of Lunati solid rollers. These are new additions to their "Voodoo" series. I ran sims of their 60141 and 60142 cams. These are ground on fairly wide (by today's standards) LSA of 110. They will probably "sound" similar to the 30-30. They do not perform as well as the 30-30, however, developing less average torque and less average horsepower. Among other cams that I tested were the Lunati 501B1, and Isky 530A.

There is no roller cam on the market, which will exactly duplicate the operating characteristics of neither the 30-30 nor the LT1.

Joe-----


Most hydraulic roller cams are manufactured from steel billets, but not all. The Federal-Mogul/Speed-Pro hydraulic roller cams are manufactured from austempered ductile iron cores. They wear as well as the steel billet variety. No special distributor driven gear is required with them. However, many other aftermarket hydraulic roller steel cams now use a pressed on, cast iron distributor drive gear so they are also compatible with standard distributor driven gears.

GM hydraulic roller cams DO NOT utilize a pressed-on distributor drive gear, though. They must be used with a special melonized distributor driven gear.

[Duke W.]

Re: Roller Cams

Gentlmen,
If anyone has an old bottle (prior to June 1st, 2007 ) of diesel oil, Rotella or Delo, compare the specifications met by the current version and the prior version, many specs for caterpillar, John Deere, etc are no longer met and the bottles now have "enviormentaly improved" or "emissions friendly" or similar verbage on them. What that means simply is the ZZDP has been reduced and its likely gauranteed to get lower as the Auto industry is squeezed to meet the requirements of standing behind emission systems and catalytic converters (currentley going on deisels also) for 100K miles and beyond. ZZDP is POISON to the cats and you can be sure the lobbyists will be doing all that they can to keep any additives out of the publics hands, as for sure as we need it for our flat tappets, JQ Public will for sure want to put it into his new SUV for "added" protection and soon his idiot light will come on indicating a problem that the manufacturer will have to remedy at their expense. Not hard to see whats happening, we are the minority in our needs for our old engines. Back on the same date, 6-1-08 GM stopped supplying the good old EOS assembly additive, which is rich with ZZDP ( which by the way, back in the 60's and 70's was called "engine oil additive" under the same #1052367 part # ,and GM recomended adding a pint at every oil change, and a full quart during first run break in) I still have some of those and can send pics for anyone interested. It was unavailable from June in its good form supplied in the black bottle GM part # 1052367, until around December of 2007 it was reissued using the same part # but now supplied in a white plastic bottle. You can be sure it is NOT the same formula but a reduced ZZDP version.
Why else would they reissue it? On top of that, the price more than doubled!
You will not find the ingredient levels on either bottle. There are currently some products available including in the driveline claiming to have the levels of ZZDP required as an additive. I am skeptical, again, why would the powers that be allow anyone to produce in this country or allow to be imported a product that potentially will cost them lots of warranty money and they can so easily condem it as being Enviormentally unsafe. Foolproof solution? Buy all the GM EOS part # 1052367 in only unopened BLACK plastic bottles you can find, add a pint to each oil change using a good Deisel motor oil such as Rottella or Delo as they have the highest levels currently. GM used to tell us to do that and then you are safe, gauranteed. Try your local GM dealers back shelves or sometimes can be found on ebay. Its in my opinion the only way I can sleep knowing my old cams are safe. Lastly, if memory serves, Mobil one full synthetic and compareable oils were released at about the same time (1984 ?) as the introduction of production car roller cams and the elimination of flat tappet cams, reading into the timeline, I would not recomend using synthetic in flat tappet cam motors. It is an excellent oil for sure but I am not sold on application in the older motors, although I have used Castrol syntec prior to summer of 2007 with good results. It will take some time unfortunately to see what happens but I aint waitin" !

This is one of the WORST posts I have seen on the TDB in some time - spelling, grammar, composition, layout, but most importantly - FACTS!

For those who have short memories, The Summer 2008 Corvette Restorer has a factual article on current motor oils.

It also lists a number of Internet references including the API 1509 document. I suggest that unless you want to make a fool out of yourself, read the article and references before you pontificate on motor oil. There's absolutely no excuse for anyone on this forum to be ill-informed about current motor oils.

Merry Christmas!

Duke