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Identify Cam
Posted by: SkidRo ()
Date: January 17, 2018 12:11PM

All,

I have a 66' Corsa. Back in the 90's the entire car was restored by the PO. I pulled the power pack recently to replace the clutch etc. I noticed the cam gear had set screws in it along with the woodruff key. This was interesting to me but I didn't think anything else about the set up until now. The engine sort of lopes like it has a mild cam so it has me thinking that it may have one. Is there any way to determine if it does that does not require opening up the engine?

Thanks,
Rory

Rory
66 Corsa
Silver Spring, MD

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Re: Identify Cam
Posted by: MattNall ()
Date: January 17, 2018 12:16PM

Is the bellhousing still off? Aftermarket cams are usually marked on the gear end as I recall!





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Re: Identify Cam
Posted by: SkidRo ()
Date: January 17, 2018 12:35PM

Matt, Everything is back in the car and I am driving it. I pulled the PP last summer!

Would my timing change with a different cam?

Rory
66 Corsa
Silver Spring, MD

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Re: Identify Cam
Posted by: MattNall ()
Date: January 17, 2018 12:59PM

Timing change? Not really... but with a different cam...a different advance curve may be needed to get the MOST out of the setup...

Time for a Dyno tune ...





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Re: Identify Cam
Posted by: RobertC ()
Date: January 17, 2018 02:25PM

Since you do not remember any markings on the end of the cam, I would guess that it is the GM "304" - the replacement cam for 140 / turbo. Not quite as "radical" as the original "891" cam.

The history of your car may give a clue to the source of the set-screwed cam gear.

A northern CA Corvair mechanic (70's / 80's) put set screws in the cam gear in an attempt to stop cam gear failure - where the cam gear eventually slipped ("wore") the key way and the steel crank gear stripped the cam gear.

I would assume other Corvair mechanics around the country employed a similar technique.

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Re: Identify Cam
Posted by: SkidRo ()
Date: January 18, 2018 09:43AM

Thanks Matt and Robert for the info. I vaguely remember some markings and I thought I took a picture of them. But I can't find any pictures of the cam so it will remain a mystery.

Rory
66 Corsa
Silver Spring, MD

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Re: Identify Cam
Posted by: texas yenko dude ()
Date: January 18, 2018 09:54AM

RobertC Wrote:
-------------------------------------------------------
> Since you do not remember any markings on the end
> of the cam, I would guess that it is the GM "304"
> - the replacement cam for 140 / turbo. Not quite
> as "radical" as the original "891" cam.
>
> The history of your car may give a clue to the
> source of the set-screwed cam gear.
>
> A northern CA Corvair mechanic (70's / 80's) put
> set screws in the cam gear in an attempt to stop
> cam gear failure - where the cam gear eventually
> slipped ("wore") the key way and the steel crank
> gear stripped the cam gear.
>
> I would assume other Corvair mechanics around the
> country employed a similar technique.

We have been double set screwing cam gears for the race cars since the early 70's. You can slip a cam gear pretty easy.


Some people pin the crank gears (Pinned gears can walk loose.) We have a guy that welds them to the crank. And yes, his welds are so tight and clean, we can get them off if needed and put a new gear on.

If you had a picture of the end of the cam, we likely could tell you what you have.

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