I was pulling my old engine apart this past weekend and was really upset with what I found. After about 6 years of running on the old roller cam it looked great, the original roller lifters looked great.
I ran this same cam another season, this past summer and pulled it the other night fully expecting it to be in great shape?
On lob was gone. A 1/8th deep groove was cut the width of the roller over the nose, 15 good looking lobes and lifters and one whiped lope and while the roller still moved smoothly the roller surface inself was badly pitted.
The Chain. I use Cloyes double roller, fits really tightly when new.
Couldn't believe the stretch. Lots of slop after about 20,000 miles. You could take the cam gear and rock the cam back and forth.
With the cam gear off and wrapping the chain around the cam sprocket you could grab a link on the back side from where you were holding it and pull the chain away from the sprocket quit a bit.
Makes me wonder about using a gear drive?? The problem with gear drives is they say you need block machining? I can't do that, I have an assembled short block and was going to degree the new cam in this weekend and I will not pull the block back apart.
I am not very impressed with our timing chains if this is an example of what I should expect down the line.
As for the whiped cam lobe I ran 175 pound seat pressure and 480 open with the old cam. The new cam runs about 200 seat and 550 open.
I have a set of the more expensive RED ZONE lifters and you can notice the larger wider roller wheel so I hope these lifter last longer then the other ones.
It is discouraging putting a good package together with what you feel is the best parts and it still comes apart.
The cam, lifters, springs and timing chain run about $1600 and you expect it to last.

 

any evidence that the roller lifter turned sideways some how and prevented it from "rolling" properly.... perhaps the locking mechanism for the lifter had too much play in it and the lifter rotated slightly????

 

While I can not help with the roller cam issues I might offer my experience with gear drives. I bought a Pete Jackson gear drive back in the 80's (before they even had a choice of "quiet" or "loud"). It went on smoothly and did not require any machining. Still looked like new when I pulled it a few years later. Used it again on another engine and it performed well. I did not care for the sound after a time so I sold it to a friend.

FWIW.

-Mark.

 

Which Cloyes?
P/N?
Inspect rollers "closely"... do the rollers have factory split? (many of even the best Cloyes do have OE split rollers).

Have had lotsa chain stretch with chains recognized as better/best with relatively SMALL solid flat tappet cams & springs in circle track motors. Also had chunks of roller chipped out at edge of factory splits on same sets.

Have had excellent results with "Rollmaster" brand (Australian) that has "IWIS" brand chain (that chain German-made & IWIS stamped into side plates and rollers do NOT have factory split) ... supposedly Cloyes was to incorporate IWIS into some of their sets but I have not seen it ... nor have I seen every one either.

CV Products near Charlotte NC sells Rollmaster.

Regardless of chain design/quality ... If end play on either cam or crank is excessive, it'll wreck a chain/lobe.

I will not use & do not recommend gear drive.

 

Both of my motors use the Crane billet timing sets. My timing set in my 383 has been rotating 195# seat 560# open through a couple of cams and sets of springs and up in the 20,000 miles.

It was still so tight that it's hard to install.


black nitrided 3.75 stroker crank 40 pounds, ARP main studs, with billet caps.

 

Funny our speed shop won't use them either.
About a month ago I was in the back of the shop watching them put an all alumiumum 570 or so mopar together. The block was a work of art and cost about $6000 for the bare block. A gorgous engine. Very pricy.
Last night I saw it destroyed, can be repaired but one head needs welding and one cylinder is totally destroyed.
A waste of a money and a beautiful piece of engine.

 

Gear drives had a bad rap about 10-15 years ago. Now you won't find a circle track car around here without one. But were not taking about some Pete Jackson cheap unit.

I personally don't like the whine.

Norval could you post a cam lobe picture? I'm really convinced that billet steel cam shafts are the way to go with roller cams.

 

I have several milodon gear drives, one on the vette and one on the truck and I have a spare one for replacement parts. They work fine and the one in the vette was still tight when I took it apart, the one in the truck has been there for quite some miles, never had a problem with them. They come w/ bushings to go between the cam gear and block, no machining was required.

 

The timing set's most likely worn from all the "metal" that's mixed and running in the oil.

The lifters (Isky's) aren't going to hang out to long either, not with that
"low" spring pressure. You don't have near enough for a solid roller setup.

Gear drives allow too much drivetrain vibrations up into the rollers, and these lifters will suffer for it also. I know you guys aren't going to believe this but we've got many BB units (with 300# closed, 800# open) up here that have nothing more than the old "Jenkins" inspired "nylon" Hi-Perf timing gear. The Hi-Perf ones are the wider pieces! I will add we change them (yearly) regularly on inspection. The same time we make the bearing changes. One unit is well over 1200HP (street-car) with no issues. Thanks, Gary in N.Y.

P.S. We have a unit heading for the dyno this week, some 11 degree
G.M. "splayed" heads, with 400# closed and 1100# open (not recommended for street use). You MUST keep the rollers on the lobes or you'll have upcoming issues. Pressure-fed or not, they will fail. I personally have some "Cranes" still running the streets up here with the same lifters from a 1990 build. No pressure-feds back then. Been through a dozen spring changes however. Belt drives are not street-oriented either!

 

+1

I use an older Erson Gear drive (single idler) that is similar to the milodon unit. A brass bushing between the cam gear and the block, and a torrington-roller nose button to control cam walk. The Erson housing is cast, but I'm not sure about the milodon unit.

You *will* notice the whine of the gear, so it depends on how loud you like your passenger compartment. Personally, I like the sound, but then again I'm in love with my car (and sold my soul to build it) so I'm somewhat biased.

 

Actually my oldest one is an erson one...they are indeed very similar

 

Norval, to help prevent unwanted wear on your timing set, you could drill a small hole, .030 or less in one of the oil passage plugs behind the timing gear. This would shoot oil directly on the timing gear and through the holes in the gear, and on to the timing cover. It will splash oil all over the timing set, lubing it way more than it would normally ever see. If your clearances are good and your oil pump adequate, you shouldn't have any noticeable reduction in oil pressure from that extra hole.