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I have not done this yet but it just accured to me . that if you move 1 tooth on the cam gear = 9 degrees .than if you moved one tooth on the crank gear it would = 4.5 degrees because the crank gear being half the tooth count of the cam gear . does this make sense to anyone or do i have it wrong.

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91 colt gl 4g37/5m22 from 94 T/E/L mustang 5.0

The cam gear has 40 teeth which is 9* per tooth.
The crank has half as many teeth therefore each tooth is 18*
You still end with a 9* advance or retard.
As for emissions, i recently moved to Arizona and passed with flying colors.

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http://members.cardomain.com/socrateez
04' Olds Alero
91' Colt GL hatchback
4g15 12valve 5spd.
4g37 TB, MAF & Injectors. 4g37 ECU
Ported & polished & custom CAI w/K&N filter
5* Cam retard, 7*Ignition advance
2-1/4" catback w/flowmaster muffler
89 GT brake and suspension swap
Lots of little s#@t

360 divided by 40 = 9 cam degrees to get crankshaft degrees you have to divide 720 by 40 witch is 18 crank degrees are we trying to retard by crank degrees or cam degrees

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91 colt gl 4g37/5m22 from 94 T/E/L mustang 5.0

Ok now im confusing myself . i need some help sorting this out . one rotation of the crank only moves the cam 20 teeth . two rotations of the crank move the cam one rotation or 40 teeth. one tooth at the crank will move the cam a half of a tooth and one tooth at the cam will move the crank two teeth. help my brain is going to exploed

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91 colt gl 4g37/5m22 from 94 T/E/L mustang 5.0

OK, if one crank tooth is 18* and you move it one tooth(18*)then it will move the cam HALF the same distance(9*)or one cam tooth. Remember the ratio between the crank and cam is 2:1

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http://members.cardomain.com/socrateez
04' Olds Alero
91' Colt GL hatchback
4g15 12valve 5spd.
4g37 TB, MAF & Injectors. 4g37 ECU
Ported & polished & custom CAI w/K&N filter
5* Cam retard, 7*Ignition advance
2-1/4" catback w/flowmaster muffler
89 GT brake and suspension swap
Lots of little s#@t

yes with no belt on the car move the cam one tooth you are moving your cam 9 . but my point is, in proper terms you are retarding your cam 18. its the relationship to the crank that matters . and that if you jumped the belt one tooth on the crank pulley you would only have to back the cam up a half a tooth to take up the slack in the belt. however if you jumped one tooth on the cam pulley you would have to rotate the crank two teeth to take up the slack ,leaving you with a cam to crank relationship of 36 degrees retarded in my terms

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91 colt gl 4g37/5m22 from 94 T/E/L mustang 5.0

to further clearafiy jump the belt at the crank pulley and get 18 degrees retard in relationship terms and the cam moves 4.5

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91 colt gl 4g37/5m22 from 94 T/E/L mustang 5.0

How is everyone retarding their cam gear? Do you have to take all of the belt covers off and loosen the tensioner to do it, or is there an easier way?

No easier way, you have to loosen it to play with it. (No pun intended!)

Hrm... first the Turbo Fluid Exchange Convention, now loosening of tensioners to play w/ pulleys...

The "easiest" is also the most expensive: Use adjustable cam degree sprockets.

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Age is a number; attitude counts.

I have a spare 12v steel sprocket, PM if you want it. I fitted mine in about 10mins. Removed the top belt cover, took off the old pulley and slid on the new. Turned the timing around to maximum BTDC, probably running about 15degress. Got the cold air intake and for an old 4G15 it flew!!!

It was getting high mileage though, and needed a full rebuild. Got fed up with it's lack of power, wanted a turbo car, it went to the scrapper, got 30 dollars for it Had a mandrel bent exhaust manifold on it too.

Do you mean to say that instead of loosening the belt tensioner, I can simply unbolt the cam gear and retard it one tooth?
Loosening the tensioner sounds like a lot of work in a very cramped space...

If you look at my www link, you can see a lot of stuff I did to my 4G15, I even drew a diagram. I personally think 9 degrees is a bit too much. I set mine at 4.5 degrees.

I have an undrilled cam sprocket, if anyone wants it, I take paypal. It'll go in the bin otherwise. I don't have my 4g15 anymore, damn good engine though.

Apologies for unearthing this a second time, but I'm going to do the 9 Degrees of Retardation mod when I change my timing belt, and there is a point of inconsistency that I'd like clarified.

I read somewhere in this thread that the cam pulley should be turned one tooth counterclockwise, but wouldn't that be advancing it one tooth, rather than retarding? I'm going back to Autos 1 in high school when the topic of discussion was distributors.

If the above is true, that would explain why socrateez experienced the timing advance jump. When the belt slipped a tooth, it had the same effect as turning the cam backwards.

So the dyno simulator numbers are better when the cam is retarded 9 deg., but which gave better results in practice, advance or retard?

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