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intersting cam gear retention method
Posted by: martyscarr ()
Date: July 24, 2022 04:50PM

I've not seen this method of retaining a cam gear before, I'm not so sure it really does much? Comments? Oh, and the seller says this cam is new, but I don't think it looks new sad smiley

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Re: intersting cam gear retention method
Posted by: American Mel ()
Date: July 24, 2022 05:09PM

No, that doesn't look new.

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WA. state, 1 mile south of the Canadian border, I am not at the end of the world, but you can see it from here.

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Re: intersting cam gear retention method
Posted by: cnicol ()
Date: July 24, 2022 08:26PM

If the cam were new, none of the lobes would have wear marks. That camshaft has evidence of long term use on every lobe plus discoloration on the gear. While the cam is probably ok, I wouldn't trust the gear for a minute.

Craig N. Coeur d'Alene ID.
66 Black Monza 4dr, 4.2L V8 49k
61 Seamist Jade Rampside 140 PG
65 Canadian Monza 4dr 110/PG 40k
66 Sprint Corsa convt - First car! Re-purchased 43 years later
2+2 gnatsuM 5691

+17 Tons of parts




Edited 1 time(s). Last edit at 07/25/2022 10:31AM by 1966-Corsa-GT-180.

Re: intersting cam gear retention method
Posted by: wittsend ()
Date: July 25, 2022 03:36PM

As a first time Corvair owner the concept of the cam gear coming loose was a concern. I had my son make up this washer and he also notched the bell housing to clear the washer. I can't remember exactly but it was about .170 thick. The thickness was a matter of how much I felt safe to take out of the bellhousing and the amount of remaining clearance factoring for cam end play.

Your bolt is a lot smaller. It seems to have done its job (needed..., or not). I initially put a notch in my bolt to stake but instead I used a Permatex retaining compound 6400 on the washer and Loctite Red 27140 on the bolt threads. Many will think it is overkill but it was just "father & son time" and cost us nothing.

In my research I found that a certain Cummins's diesel with a press on gear also had a problem of coming loose. The solution was similar to the cam you have and what I did (2nd image below). So, it isn't like others aren't doing it.

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***'61 Lakewood, a "Freebie" in hibernation for 27 years - In the process of applying CPR.***



Edited 1 time(s). Last edit at 07/25/2022 03:38PM by wittsend.

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Re: intersting cam gear retention method
Posted by: SpyderMan ()
Date: July 25, 2022 05:51PM

I don’t think this method of cam retention would have stopped my recent cam grear failure. Mine was slowly wolowing out until it got so bad a tooth bound and broke. I don’t see how this would keeping a gear from trying to turn separate from the cam.

Sam Russell
Durham NC
1962 Monza Wagon Ted Brown EFI Gen II
1964 Spyder coupe


Re: intersting cam gear retention method
Posted by: wittsend ()
Date: July 25, 2022 08:11PM

The washer is not intended to keep the gear from rotating on the camshaft. That is what the key is for. The washer is intended to keep the gear from walking forward on the camshaft thus preventing it from as you say "wollowing" loose, eventually losing its perpendicular relationship to the camshaft and having a negative effect on the gear teeth.

There are literally billions of cars on (or have been on) the road where the cam gear (or pulley) slides onto the camshaft by hand and is retained typically with one or three bolts and does not have the loosening issues that the Corvair has (even if the problem is more exaggerated than actual). GM could have easily created an extra 1/4" to make the gear a bolt removable item reducing the cost of replacement - and enhancing the ability to make timing alterations.


I often hear here (or read in publications) to "check your cam timing." OK, the checking part is reasonable, but if it is found to be off what are you going to do??? Split the case, press off your brand new (now no longer usable) gear, purchase a new gear and an offset key and HOPE that whatever inconsistencies were in the first gear remain the same in the second? Some have said they use an old gear that is modified to slip on/off easily just for checking. But, are the gears checked to make sure they match?

To me the irony is that the reason to check cam timing in the first place is because inconsistencies are known to exist. But follow that to its logical conclusion it has the POSSIBILITY of a very expensive dog chasing its tail. From what I've seen here the 'press on' cam gear (its difficulties and issues) just seems to be accepted by most and I have difficulty understanding that acceptance when a bolt on gear was feasible from the start. And yes I am aware then many have never had a cam gear issues and for those with the funds that the American Pi gear exists. This is not an argument about what people on the CC Forum do, it is about GM's design in the first place.

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***'61 Lakewood, a "Freebie" in hibernation for 27 years - In the process of applying CPR.***



Edited 1 time(s). Last edit at 07/25/2022 08:13PM by wittsend.

Re: intersting cam gear retention method
Posted by: corventure Dave ()
Date: July 25, 2022 08:41PM

Basically, have to keep in mind that Gm built the Corvair as a cheap economy car. They put tons of engineering dollars into just launching this car. Engineering enhancements such as a cam gear retailer and many other things we have developed over the decades, just was not an issue for a car that was only intended to last a few years. Well... maybe 10!!! winking smiley

Corventure Dave

Re: intersting cam gear retention method
Posted by: joelsplace ()
Date: July 26, 2022 08:08AM

GM saved quite a bit of money with this design and I doubt it was any issue for them under warranty. No bolt(s) washer, threading, extra assembly steps

Joel
Northlake, TX
5 Ultravans, 138 Corvairs and counting...

Re: intersting cam gear retention method
Posted by: RobertC ()
Date: July 26, 2022 09:46AM

joelsplace Wrote:
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> GM saved quite a bit of money with this design and I doubt it was any issue for them under warranty.

Curious question?

How many cam gears failed at less than 100,000 miles?

I know from threads here that there was a batch of "poor" replacement gears that shattered / broke.

A lot of effort / thought / different solutions has gone into "pinning" the gears.

My Corvair mechanic used 3 socket head screws - 90 / 180 degrees from woodruff key.

Of course, there are the failures from incorrectly installed cam gears, also.

Re: intersting cam gear retention method
Posted by: joelsplace ()
Date: July 26, 2022 10:21AM

I'll guess they had no warranty failures. I'm sure they had a good process to install them.

Joel
Northlake, TX
5 Ultravans, 138 Corvairs and counting...

Re: intersting cam gear retention method
Posted by: RexJohnson ()
Date: July 26, 2022 12:10PM

The reason that GM used the press on gear for the Corvair and straight 6's is because it was simple, cheap and worked well. The reason that the V8 engines have a bolt on cam gear is it would be hard to put the timing chain together and or take it apart if you couldn't get the gear off.

RJ tools
Salem,Oregon

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