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Do I really need to degree the cam?
Posted by: Chasgee ()
Date: October 06, 2019 06:16PM

I’m just being lazy! The crank key is at 9:00, cam key at 6:00, and the cam gear mark is at the top. Is this fool proof for a street car or should I degree the cam?

Chuck Gee
Carlsbad, CA

1963 Monza 102 - in the family from new
1966 Corsa 140 Coupe - new project

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Re: Do I really need to degree the cam?
Posted by: Frank DuVal ()
Date: October 06, 2019 07:06PM

I've built many an engine just doing it that way, go by the picture in the shop manual of the two keyways. Stock crank and stock cam with stock cam gear, usually. I'm not building race engines.winking smiley

Of course you do want to not use a 140 powerglide crank gear on a manual transmission 140 or any other horsepower engine/transmission. Heard it causes strange issues.

Frank DuVal

Fredericksburg, VA

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Re: Do I really need to degree the cam?
Posted by: joelsplace ()
Date: October 06, 2019 07:41PM

I've heard of some cams and gears that have incorrect keyways. As much trouble as it is to change I would do some kind of sanity check.

Joel
Northlake, TX
5 Ultravans, Lost count at 100 Corvairs...

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Re: Do I really need to degree the cam?
Posted by: vairmech ()
Date: October 07, 2019 04:37AM

I have found the only thing to really watch is the "NEW" timing marks on the aftermarket cam gears. What do I mean about that? The aftermarket gears are mis-marked and make lining up the timing mark ambiguous and in the wrong spot.

What do I mean by this? The place the timing mark is put will make it look good on either side of the crank timing mark. One way is correct and the other is advanced by 14 degrees. The engine will run but not very well.

I have posted about this before. I know about checking the angles but screw that, that is to hard. It is very simple, make your own mark with a sharpie just to the left of the stamped mark at the root edge of the tooth marked. That is the ORIGINAL timing mark spot and that will line up perfectly with the crank timing mark.
Here is an aftermarket gear and the timing mark, see how they put the "0" in the middle of the tooth? It's an easy place to put it but it is wrong! This mark below is closer than most I have seen but still off!



Now here is a GM gear and how they were marked. Gosh the timing mark is on the root edge of the tooth just to the left of the picture above just where I said to put your mark. This mark lines up perfectly with no question as to if it is lined up correctly. Just remark the timing gear and put it together, I don't degree or check street engines.



Ken Hand
Handy Car Care
248 613 8586

Vairmech@aol.com

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Re: Do I really need to degree the cam?
Posted by: zarfnober ()
Date: October 07, 2019 04:39AM

Check it! If you dont have a degree wheel, you can compare the new one to the old one, just lay it on top, align keyway, and see if dot matches up.. I'd only check it this way with against an original GM gear though. Otherwise get out the degree wheel, there are quite a few incorrectly made gears out there.

Rocco

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Re: Do I really need to degree the cam?
Posted by: JimBrandberg ()
Date: October 07, 2019 04:52AM

I always check the cam timing and get to wondering why sometimes, lining up the keyways like in the CORSA Tech Guide is great. Last year I discovered a crankshaft where the gear had sheared the woodruff and slipped. It looked fine from the end. The crankshaft was from an unknown place but had been Magnafluxed and either polished or ground .010/.010.

I think getting the stuff out and checking cam timing is cool and fun but I'm weird that way.

Jim Brandberg
Isanti, MN
CorvairRepair.com



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Re: Do I really need to degree the cam?
Posted by: corventure Dave ()
Date: October 07, 2019 07:36AM

For decades I have checked the cam timing gear mark against an OEM cam gear.
Usually do this right when a new gear arrives in the mail.
So there actually is a reason to keep that old removed original cam gear laying around.eye rolling smiley

Corventure Dave

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Re: Do I really need to degree the cam?
Posted by: 66vairman ()
Date: October 07, 2019 08:17AM

I've seen GM cam gears with the timing indicator in the same spot as the "NEW" cam gears. I wouldn't say it's "wrong", more like the Corvair timing marks on the cam and crank gear are too far apart making for a poor alignment process. The best way is to draw a centerline through the cam timing gear to line up with the "notch" on the crank gear.

I had to install a new crank gear, cam gear, and a new cam shaft. It was well worth the effort to index the camshaft because of so many new parts and a chance for error. Fortunately the center line I put on the new cam gear worked per verification by indexing the cam.

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Re: Do I really need to degree the cam?
Posted by: vairmech ()
Date: October 07, 2019 04:54PM

66vairman Wrote:
-------------------------------------------------------
> I've seen GM cam gears with the timing indicator in the same spot as the "NEW" cam gears. I wouldn't say it's "wrong", more like the Corvair timing marks on the cam and crank gear are too far apart making for a poor alignment process. The best way is to draw a centerline through the cam timing gear to line up with the "notch" on the crank gear.
>
> I had to install a new crank gear, cam gear, and a new cam shaft. It was well worth the effort to index the camshaft because of so many new parts and a chance for error. Fortunately the center line I put on the new cam gear worked per verification by indexing the cam.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

With your straight line shown above is that supposed to be the alignment mark? It won't line up properly. The original 0 in your pic will line up perfectly with the crank mark. The center of the tooth is not the correct timing mark spot.

Ken Hand
Handy Car Care
248 613 8586

Vairmech@aol.com

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Re: Do I really need to degree the cam?
Posted by: Chasgee ()
Date: October 07, 2019 07:27PM

Thanks for all of the input. I might as well check it, but I’ll have to make some tools to get it done. I’m used to doing it on cast iron blocks, so my mag base sticks without extra tooling. Guess I better get to work fabing some new tools!

Chuck Gee
Carlsbad, CA

1963 Monza 102 - in the family from new
1966 Corsa 140 Coupe - new project

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Re: Do I really need to degree the cam?
Posted by: ROD ()
Date: October 07, 2019 10:00PM

This is where you mark the gear with a line. otherwise you won't see it up by the "0" behind the crank gear

Rod Tetrault
El Cajon , CA
65 Corsa Yenko Clone / 65 Corsa EO Creampuff Vert
66 Corsa "JIMISH" Mid engine Turbo LS1 currently 2nd fastest Corvair in the USA
Class 5 Corvair powered Baja
Corvair powered Buggy x 3
Enough hidden parts to build a space ship

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Re: Do I really need to degree the cam?
Posted by: JimBrandberg ()
Date: October 08, 2019 04:41AM

It's also good to check the installed cam timing in case you have to take it into consideration later on if it doesn't run quite like you anticipated. If it's a little doggy getting underway or wheezy at high RPMs you can spend a lot of time goofing around with carburetors and ignition timing while wondering if the cam timing is okay. It's a lot more difficult to check with the valvetrain installed and the engine in the chassis. I will always do it but then I have all the stuff and enjoy doing it.

Jim Brandberg
Isanti, MN
CorvairRepair.com



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Re: Do I really need to degree the cam?
Posted by: Chasgee ()
Date: October 13, 2019 07:33PM

Ok, so I made the tools and checked it out. Looks like the cam is 4 degrees advanced from what the cam card says. There is a note on the card that says this grind is run 2-6 degrees advanced in most applications, so I’m right there.

I’ve never seen a note like that before and have always degreed cams to the intake centerline. Strange the cam grinder just didn’t make the card reflect the advanced numbers. Oh well.

In case anyone is wondering, the cam is an Isky 270 grind from California Corvairs.

Chuck Gee
Carlsbad, CA

1963 Monza 102 - in the family from new
1966 Corsa 140 Coupe - new project

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Re: Do I really need to degree the cam?
Posted by: MattNall ()
Date: October 13, 2019 08:03PM

Look at the Cam's KEY.... is it offset...?

MODERATOR
Sea Mountain, between Charleston Harbor and Coos Bay! SW Oregon Coast
Click HERE for My Website...Click HERE for My TechPages!
..............................110-PG.................................................Webered-Turbo

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Re: Do I really need to degree the cam?
Posted by: Chasgee ()
Date: October 13, 2019 08:15PM

No it’s not. All the marks line up like they are supposed to as well.

Chuck Gee
Carlsbad, CA

1963 Monza 102 - in the family from new
1966 Corsa 140 Coupe - new project

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Re: Do I really need to degree the cam?
Posted by: MattNall ()
Date: October 13, 2019 09:16PM

Grinder did you right!

MODERATOR
Sea Mountain, between Charleston Harbor and Coos Bay! SW Oregon Coast
Click HERE for My Website...Click HERE for My TechPages!
..............................110-PG.................................................Webered-Turbo

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Re: Do I really need to degree the cam?
Posted by: Chasgee ()
Date: October 13, 2019 09:59PM

I agree!

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Re: Do I really need to degree the cam?
Posted by: JimBrandberg ()
Date: October 14, 2019 04:10AM

I just did a Isky 270 and came up with 104 instead of 108, just like your's. Since the Failsafe cam gear was already installed I just went with it and expect it to be good.

Jim Brandberg
Isanti, MN
CorvairRepair.com



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Re: Do I really need to degree the cam?
Posted by: v8vair ()
Date: October 14, 2019 05:54AM

Ole Blues cam was advanced about 5 degrees, It ran Great. I mean really good. I was replacing the crank seal when I noticed the crank gear had spun and that's when i figured out why it was so responsive. Now that I repaired the crank im gonna have to advance the Cam to get it back where it was.
Ray Sedman has a Cam Doctor and he told me hes checked 100s of factory cams and no two were alike. Maybe that's why some stock motors seem to run better than others.
So in my opinion i would always set up a Corvair motor with atleast a few degrees of advance like GM did with the PG 140. So yes check that cam timing. Mike

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Re: Do I really need to degree the cam?
Posted by: JimBrandberg ()
Date: October 14, 2019 07:46AM

My understanding is the 140 PG cam is retarded if anything.
The 891 cam as installed in 110 and 140s has a 108 Intake center.
The 889 cam as installed in 95 HP has a 104 Intake center.
The 889 cam as installed in 140 PG has a 108 Intake center.
This is my understanding and if I'm incorrect I'm happy to learn about it.
Part of my understanding comes from a Bob Helt book, I think it's in Corvair Secrets.
My understanding may be more from the "facts" than hands on since installing an original cam and checking the cam timing doesn't come up very often these days. If I've done it I didn't save the data in the place I'm now saving it. Perhaps I will get organized one day. HA.
I would also totally believe that the same configuration engines will vary somewhat.
I checked a 140 Manual with 891 cam that someone else put together which was reported to not run so good. I came up with 112 Intake center. I'm putting an Isky 280 in it but haven't started with it yet. I don't think it had a 140 PG crank which would explain the 112. I'd have to check my notes to see if I checked it with a different used 891.
A lot of times in the past, checking with me has been sort of quick to verify that it's not off a tooth which is about 14 degrees, not necessarily to check for a few degrees. I've gotten more careful lately since it's interesting.

Jim Brandberg
Isanti, MN
CorvairRepair.com



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