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beertracker
Cochise

414 Posts

Posted - 06 Dec 2018 :  2:54:14 PM  Show Profile  Reply with Quote
I just bought a Edelbrock 350-7812 timing set for Pontiac 455. https://www.jegs.com/i/Edelbrock/350/7812/10002/-1

The ad states it supports;

Maximum Advance/Retard at Camshaft 2 degree
Maximum Advance/Retard at Crankshaft 4 degree

The cam gear only has one keyway.

The crank gear has three keyways; one at 0, one at 4 Adv. and 4 ret.


Edited by - beertracker on 16 Dec 2018 7:57:43 PM

cortcomp
Coyote

USA
5455 Posts

Posted - 06 Dec 2018 :  4:04:56 PM  Show Profile  Visit cortcomp's Homepage  Reply with Quote
The cam gear would have one, and the crank has the three. You're basically moving the crank -4, 0 or 4. IIRC the cam has marks on them to match the different symbol you choose to use on the crank.
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Corncob2061
Cochise

USA
411 Posts

Posted - 06 Dec 2018 :  6:59:04 PM  Show Profile  Reply with Quote
Usually have to use offset keys to get things closer. Mr. gasket makes a 2 degree for the cam key

https://www.summitracing.com/parts/mrg-987g?seid=srese1&cm_mmc=pla-google-_-shopping-_-srese1-_-mr-gasket&gclid=EAIaIQobChMIqMGHvaSM3wIVmZOzCh2uygSpEAQYASABEgKL3vD_BwE
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beertracker
Cochise

414 Posts

Posted - 06 Dec 2018 :  11:41:42 PM  Show Profile  Reply with Quote
Here is a review of the Mr. Gasket offset key from the link above.

quote Crank key degree change of 4 actual degrees.

Summit RacingSummit Racing Verified Purchase MRG-987G
FYI: Two degree offset keyway actually changes the degree reading on a degree wheel by four degrees, not two. Too bad they don't make a one degree key way. Otherwise, a good product. end quote


Dec. 16, 2018

I think the reviewer above is using the key on the cam gear and not the crank gear. If 2 deg key is used on the cam gear this will give 4 deg offset on the crank gear since 1 turn on the cam gear equals 2 turns on the crank gear (a 2x multiplier). It depends where you specify the reference.



Edited by - beertracker on 16 Dec 2018 7:55:43 PM
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Corncob2061
Cochise

USA
411 Posts

Posted - 07 Dec 2018 :  10:00:54 AM  Show Profile  Reply with Quote
IRC, that key fits on the cam, not the crank. I have mostly used the mopar peformance keys sets, they are getting difficult to find, but had a 1 degree cam key. Which changes the timing 2.

https://www.ebay.com/p/Mopar-Performance-Offset-Cam-Keys-P4286500-La-Smallblock-340-360-318-273/1336839291

I have had the +4, 0, -4 adjustable timings sets change the timing 8 degrees on most all of timing sets I have used. IRC, I used the mr gasket 2 key to move back a 8 degree advance to 4, same a using 0 key and +4. Might not have been a Pontiac though. Billet Cloyes looks like a nice set. I do not know if the 2 setting is an actual 2 or 4 though. Have not used that set before. Someone needs to help us out and make a 1 degree key!
Jay

Edited by - Corncob2061 on 07 Dec 2018 12:21:33 PM
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Corncob2061
Cochise

USA
411 Posts

Posted - 07 Dec 2018 :  11:54:04 AM  Show Profile  Reply with Quote
Straight up, mark to mark, zero degree keys and using 0 timing keyway should be 4 degrees advanced and match the ICL number listed on the cam card. If a cam has a 110 lsa, the icl should be 106. Which is termed as 4 degrees advance for what your describing. The 6 degrees advance is allowing for the slack and drag on the chain and gears. Which makes the timing 104 when you check it, 104 is the target if you want a cam to run on 106. When the engine is running slack in the chain and gears is equivelant of retarding 2 degrees. Some cams come with the 2 degree extra advance built in to allow for the slack in the chain, some do not. They can also sometimes be off a couple degrees anyway, so it is difficult to predict what key or adv/ret is needed. Typically 2-4 adv is required. Anything less than 2 when you measure, it is close enough.
Jay
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tjs44
Crazy Horse

USA
591 Posts

Posted - 07 Dec 2018 :  12:27:37 PM  Show Profile  Reply with Quote
When I order a custom cam I have no adv built in.We then do what we think we need.Tom
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Corncob2061
Cochise

USA
411 Posts

Posted - 07 Dec 2018 :  12:55:01 PM  Show Profile  Reply with Quote
Tom have you ran into the adj 4 degree key ways moving the timing - or + 8 before? I have always wondered if different timings sets used different references, some from the crank, some from the cam.

Nice thing about customs cams, you can have them ground however you want.
Jay
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tjs44
Crazy Horse

USA
591 Posts

Posted - 07 Dec 2018 :  5:56:31 PM  Show Profile  Reply with Quote
In recent years we have only used the lower sprocket which is 3 degrees.Have not used a offset cam keyy in a lot of years.Im sure if you want to get gnats ass you could use a combination of both.Tom
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