Silent Cam Gear

[CACorvairs]

Yes I remember seeing that gear at Palm Springs as he was very excited to show it to me.
It's from the early 2000's (old phone number).
I was puzzled why it had been drilled and tapped with two set screws onto the cam.
That made me think it was a very high RPM application but he insisted it was not.
Mine are made from high quality 6061 T6 billet aluminum and manufactured by an aircraft gear company
here in the US.
Approximately 600+ gears later it's good to know that's the only one of mine I've seen fail.
I ran out of stock due to a unusually large order earlier this month but more are in production now.

Jeff

[joelsplace]

Jeff, since you are having them made why don't you have them put the timing mark in the correct spot?

[erco]

I was puzzled why it had been drilled and tapped with two set screws onto the cam.

HTHRYCE

[RexJohnson]

To answer Jeff's question about the set screws. My previous cam gear came loose on the cam on the way to the 2018 Pittsburg convention with over 150k. I had variable cam timing with nothing to control it. So I didn't want to deal with that again. His gear was hooked to a 260 cam with an NOS (not rusty) crank gear. I don't race my car I just drive it across the country pulling my trailer.

[davemotohead]

Well I stand by the CA Corvair's gear, I have used them for years and built probably 30+ engines with them mostly 140's and some hot rod engines as well and have never had one fail yet, I do not set screw them either as I feel the bigger snout holds them to the cam better than the fail safe gears. I believe a lot of the Racers use them as well as the airplane guys if I remember correctly. I bought a bunch of them from Jeff years ago and still have some on the shelf for my next few builds. 1 failure out of 600+ gears is pretty good odds if you ask me compared to the failure rate of the other gears.

[martyscarr]

I agree that Jeff's cam gears are a quality product, and was very surprised when Rex had a failure. Maybe he had just gotten one that had slipped through quality control? I felt pretty bad as I had recommended he use that gear from Jeff.

Years ago, the air cooled VW engines had 15 different sized cams gears available to compensate for variations in the cam and crank centerline machining. There was the spec gear size, seven oversize gears and seven undersize gears. I don't remember how much difference they varied in size. I think there are also some variations in the machining of Corvair blocks that might lead to premature cam gear failure, but I don't have any evidence to support this.

As far as set screwing the gear to the cam, I always do this and think it is cheap insurance against having a failure at that connection.

links to vw cam gear info https://vwparts.aircooled.net/Stock-Cam ... 9-019g.htm
and https://shoptalkforums.com/viewtopic.php?t=54859


And regarding the original post, I had an old Volvo with a phenolic cam gear with a steel center, they decided to get divorced after about 120K miles. Went to the junkyard and got a good used gear for $7 and drove for another year or so.

[RexJohnson]

I'm not saying that these gears are bad at all. I have just had a 100% failure with the one I had. Even the best products can have bad ones. Time will tell if I'm the only one.

[Wittsend]

... As far as set screwing the gear to the cam, I always do this and think it is cheap insurance against having a failure at that connection.

Years have shown that the set screw method works but I was skeptical without milling the holes to tap that a drill would just walk off into the soft gear metal using a drill press. In the end my son fabricated a washer for me and he notch milled the bellhousing for the washer clearance. We then drilled and tapped the cam for a tapered head, flush surface hex bolt. There is a Cummings Diesel engine that also has a press fit cam gear and there is a bolt on washer available for it https://apexdieselperformance.com/product/443/. So, the concept seems sound. Permatex 64000 is used on the washer to gear surface, red Loctite on the bolt and there is a notch on the bolt to stake the washer to. So far, so good.

[Frank DuVal]

Fiber cam gears were common on older engines. Their advantage was they were quiet! Used typically up to the 1950's and then nylon and steel became more common, EXCEPT for competition use where big cams and high RPM caused fiber gear failures.

The fiber cam gears in OEM engines lasted longer than the 50s. A friend's 1974 or so Capri V-6 quit on I-95 while we were going to work one day. Got it towed home and the huge fiber cam gear had shredded. I'm not sure when the 230/250/294 Chevrolet sixes finally stopped using them, but it too was into the 70s.

[66vairguy]

Fiber cam gears were common on older engines. Their advantage was they were quiet! Used typically up to the 1950's and then nylon and steel became more common, EXCEPT for competition use where big cams and high RPM caused fiber gear failures.

The fiber cam gears in OEM engines lasted longer than the 50s. A friend's 1974 or so Capri V-6 quit on I-95 while we were going to work one day. Got it towed home and the huge fiber cam gear had shredded. I'm not sure when the 230/250/294 Chevrolet sixes finally stopped using them, but it too was into the 70s.

True enough. The Volvo four used them for a long time. I was referring to the majority of American engines sold that were V8's by the 1960's. By the mid 60's GM finally came out with a new I-6, but I recall the old stovebolt six stayed in production for trucks a while longer.

[erco]

A Corvair fiber cam gear. That is a new one on me. Buy it as a novelty item.

Price drop for novelty collectors and thrillseekers!

[Dennis66]

Fiber cam gears were common on older engines. Their advantage was they were quiet! Used typically up to the 1950's and then nylon and steel became more common, EXCEPT for competition use where big cams and high RPM caused fiber gear failures.

The fiber cam gears in OEM engines lasted longer than the 50s. A friend's 1974 or so Capri V-6 quit on I-95 while we were going to work one day. Got it towed home and the huge fiber cam gear had shredded. I'm not sure when the 230/250/294 Chevrolet sixes finally stopped using them, but it too was into the 70s.

True enough. The Volvo four used them for a long time. I was referring to the majority of American engines sold that were V8's by the 1960's. By the mid 60's GM finally came out with a new I-6, but I recall the old stovebolt six stayed in production for trucks a while longer.

Chevrolet had the 235 CID up until 1963, in 63 they switched over to the 230. They may have offered the 194CID in '62 in the Novas. In '64 they offered an optional "Performance 230" that had 155 HP (vs the normal 140HP). This was offered in the Chevelles, maybe Novas. These cars had a pair of checkered flags bracketing a "230" on the front fenders behind the tires. Under the hood they sported a chrome valve cover, air cleaner top, oil dip stick, fuel and vacuum lines, and a special cam. All factory. I had one in my '64 Chevelle 2 door wagon. In 67 they upped to a 250 CID and somewhere in there offered a 292 in the trucks. Dennis

[jfreez]

The 194 came out in 62 specifically for the chevy II, (nova is actually a trim level, I tend to call them all Novas as well)
at least in the first generation all the 194s had the fiber cam gear. I had to replace the one in my 63SS

[Dennis66]

My bad. Like calling all Corvair's "Monzas" . Let's not forget the 153s either. Have a friend with a 153 powered Chevy II. He want's to build it up (V-8). I'm trying to talk him into keeping it original. Dennis

[Frank DuVal]

Oops, I mean 292, not 294 in above comments.

The fiber gear lasted into the 70s in Chevrolet sixes (I guess GM sixes, since Buick also used them along with Olds and Pontiac in the "ChevyII" based bodies.

1962 was the introduction of the 194, aka modern Chevy straight six, it came in the Chevy II. The base engine was the 153 4 cylinder.

1963 the full sized cars got the 230 and it was also available in trucks, along with the 235 (?) and the 292 in large trucks.

1964 the stove bolt (235, 261) was long gone. Only 153, 194, 230 in cars. Same for 1965.

1966 the large cars got the 250.

The 283 was not available in the Chevy II until into the 64 model year. I have a friend with a 64 Nova and the 194, early production. I've rebuilt it twice, he now only drives it as a special car. Approaching 300K. His '03 Malibu has over 400 K on it.

I've had a 64 Biscayne and a 65 Bel Air with the 230 and a 66 with the 250 (Impala).

I've also rebuilt a '69 Nova 153 with the non-shifting Powerglide. Took four sleeves the block was so worn. Speaking of chrome, this 4 in this Nova had chrome valve cover and air cleaner top. Real tiny snorkel, way smaller than the Corvair air cleaner snorkel. The 153 engine was also the Mercruiser 4.

[American Mel]

Had a '76 chevyvan10 w/250 straight six with fiber gear.
It was drove hard and put away wet many times, and was still seen running around town into the late eighties with the original engine, cam, and gear-set.