Corvair DiagramCorvair Photo
Corvair Center
home forum corvairs calendar links Corvair Podcast
California Corvairs
Clarks Corvair
Clarks Corvair
“Performance
“CORSA"



Chevy Corvair License Plate
Chevy Corvair Chrome Wheel
Corvair Center Forum :  Corvair Center Phorum The fastest message board... ever.
Corvair Center 
Degree a Cam without a Cam Card.
Posted by: v8vair ()
Date: August 06, 2017 05:46AM

This is great info to find out if your cam is what the cam card tells you it is.
[nitroimage.proboards.com]

Options: ReplyQuote
Re: Degree a Cam without a Cam Card.
Posted by: JimBrandberg ()
Date: August 06, 2017 06:05AM

I printed off the information for next time. I do most of that except I don't get into lobe seperation angle and valve overlap, I should though.
I'm told that many Corvair cams are not what they used to be. Some don't come with a Cam Card when new.
I'd like to start a file. No shortage of things to do. This will help with document consistency.
Jim Brandberg
Isanti, MN
CorvairRepair.com

Options: ReplyQuote
Re: Degree a Cam without a Cam Card.
Date: August 06, 2017 06:31AM

That's a great write-up. The one thing the author doesn't tell you is how to find lobe centerline, and people do it differently, but most engine builders find peak lobe lift, back up until the dial indicator drops either .010" or .050", go a tick past, so you can come back to the number under preload in the direction of engine rotation as the author says, and use the same lift value on either side of the peak lobe lift. Note your degree wheel at each point, and add each and divide by 2 to get the average, and that is the lobe centerline. Due to differences in opening and closing ramp rates, it may not always be centered in between your opening/closing @ .020" and .050" events!

On a side note, cam grinders have come a long ways with CNC machining in the last decade. I had a custom V8 cam ground by a big name grinder in 1997, and had never installed it in the engine. I had a similar cam ground last year from the same vendor and checked them on our Cam Doctor at work against their respective cam cards. The one I had ground in 1997 had lobe separation 4 degrees off! It actually works out OK, because that was what I was going to have ground currently.smiling smiley Sometimes stuff just works out...

---------------------------------------------------------------------------------------------
You're unique, just like everyone else...

Johnny B
Central WI

Wife's '68, 3.0L, twin-screw compressor and fuel injected in the works...

Project Pressurized Pancake


Options: ReplyQuote
Re: Degree a Cam without a Cam Card.
Posted by: JimBrandberg ()
Date: August 12, 2017 06:21AM

I write down the degrees for every .050 of lift as I'm going and also run forwards and backwards up the closing side. I can then check several different places to verify the centerline.
I don't know if that makes sense the way I wrote it. I would record degrees for .050, .100, .250, .300 and note maximum lift. Then run the math 4 times to see if they all come out the same, say 106 degrees Intake centerline as an example.
Again I'm checking with lifters that have a bolt epoxied in to stick up out of the lifter bore and a dial indicator with a magnetic base.
I have a cam gear for checking that has been reamed for a slip rather than press fit so I can decide on an offset woodruff key ahead of time. Of course I would recheck with the pressed on gear alleged to be final.
Again and agin things check out good with maybe some variances on the cam or gear but last year I had one that was way out of whack, turned out the gear on the crank had turned with a sheared woodruff key. The crank had looked good through Magnaflux and polishing while staying Std.
I digress from the topic but I love this sort of stuff, especially since cams these days are sometimes not what they're supposed to be.
Jim Brandberg
Isanti, MN
CorvairRepair.com

Options: ReplyQuote
Re: Degree a Cam without a Cam Card.
Posted by: v8vair ()
Date: August 12, 2017 11:31AM

[www.faliconcranks.com]
This one is a little better

Options: ReplyQuote
Re: Degree a Cam without a Cam Card.
Posted by: v8vair ()
Date: August 12, 2017 11:42AM

The main reason you want to check any cam is the fact that they are all different.
Your buddies stock 110 runs way better than your stock 110.
Of course you want to make sure the cam you ordered is really what the card says it is.
A cam and gear that's 8 degree retarded due tobad grind,gear mark off is going to be lazy.
As long as your close to 0 or maybe a degree advanced your good.
Advancing or retarding doesn't make more hp just changes its rpm range.
The more advanced the close the intake comes to the piston.
A Ray Sedman adjustable cam gear makes dialing in your cam easy and interesting.
Mike



Edited 1 time(s). Last edit at 08/12/2017 11:44AM by v8vair.

Options: ReplyQuote


Sorry, only registered users may post in this forum.
This forum powered by Phorum.