SuzukiSavage.com - Cam Timing, Part Deux

Armen

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Cam Timing, Part Deux
10/15/16 at 11:04:09

So, I'm scratching my head trying to figure a simple way to make small adjustments in the cam timing. I start to write a program to poke more holes in the cam sprocket (only the teeth are hardened, the rest can be drilled). Figure I'd do three sets of holes for 1, 2, and 3 degrees of cam timing-which would correspond to 2, 4, and 6 degrees of crank timing. Of course, there are three holes-two for the cam bolts, and one for the locating pin.
But, I am shiftless and lazy.
So, I buy another crank sprocket and take a look. Sure enough, there are 19 teeth for the cam chain and 22 teeth for the crank splines.
WooHoo!
360 degrees divided by 19 teeth is 18.947 degrees per tooth for the chain sprocket.
360 degrees divided by 22 splines is 16.364 degrees per tooth for the crank splines.
So, if you advance the chain timing on the crank sprocket by one tooth, and retard the crank sprocket 1 tooth on the crank splines, you end up with 2.58 degrees of advance. A nice amount if one is dialing in the cam timing. Not good enough for a race engine, but good enough for a street bike.
Especially if you are dealing with a used cam chain. Might be the ticket to bring the cam timing back to stock.
Wink

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verslagen1 YaBB Moderator ModSquad Online Where there's a will, I want to be in it. Posts: 28760 L.A. California Gender:	Re: Cam Timing, Part Deux Reply #1 - 10/15/16 at 11:10:21 Nice... and you can check that with a degree wheel against the top of the head.
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LANCER Serious Thumper Alliance Member Offline Savage Beast Performance Parts Posts: 10603 Oklahoma Gender:	Re: Cam Timing, Part Deux Reply #2 - 10/15/16 at 11:48:34 So are you drilling new holes for the pin ? I have a few extra cam gears, would you be willing to drill some for me for some $$ ?
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Armen Serious Thumper Offline Half-Witted Wrench-Jockey from Jersey Posts: 1431	Re: Cam Timing, Part Deux Reply #3 - 10/15/16 at 11:53:53 Hey Lancer, Nope, I'm not touching the cam sprocket. Or doing any machining. All the changes are done by moving the crank sprocket. The chain is advanced one tooth on the crank sprocket, and the sprocket itself is retarded one spline on the crank. Make sense? Told you I'm shiftless and lazy
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norm92de Serious Thumper Offline SuzukiSavage.com Rocks! Posts: 1180 El Paso TX Gender:	Re: Cam Timing, Part Deux Reply #4 - 10/15/16 at 11:56:40 Nice discovery. Ain't science wonderful. How much did you decide .070" of cam chain stretch retards the cam timing?
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Ruttly Serious Thumper Offline Thumpers Rule Posts: 4997 Manteca , CA Gender:	Re: Cam Timing, Part Deux Reply #5 - 10/15/16 at 12:08:40 Armen , Curious with your finding and have a question. If you did that to a brand new engine with no wear would that still have a good result.
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Ruttly Serious Thumper Offline Thumpers Rule Posts: 4997 Manteca , CA Gender:	Re: Cam Timing, Part Deux Reply #6 - 10/15/16 at 12:15:19 Armen, Next question. Will ignition timing need to be adjusted as well ?
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LANCER Serious Thumper Alliance Member Offline Savage Beast Performance Parts Posts: 10603 Oklahoma Gender:	Re: Cam Timing, Part Deux Reply #7 - 10/15/16 at 13:24:26 Are you doing this based on having a stock camshaft ?
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norm92de Serious Thumper Offline SuzukiSavage.com Rocks! Posts: 1180 El Paso TX Gender:	Re: Cam Timing, Part Deux Reply #8 - 10/15/16 at 14:31:58 Armen, I just did a few calculations and I think your figures are off. The total advance of the cam is 10.765 degrees. A bit too much to correct for a worn cam chain.
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norm92de Serious Thumper Offline SuzukiSavage.com Rocks! Posts: 1180 El Paso TX Gender:	Re: Cam Timing, Part Deux Reply #9 - 10/15/16 at 14:40:57 Armen, My numbers are correct except for the direction. The cam is retarded 10.765 degrees!
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Armen Serious Thumper Offline Half-Witted Wrench-Jockey from Jersey Posts: 1431	Re: Cam Timing, Part Deux Reply #10 - 10/15/16 at 16:20:19 Hey Norm, How did you get to those numbers?
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Armen

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Re: Cam Timing, Part Deux
Reply #11 - 10/15/16 at 16:21:28

Answers:
Verslagen figured out the cam timing change with a stretched chain. I'd ask him.

Don't think I'd change the ignition timing.

As far as doing this on a stocker, advancing the timing usually moves the power band lower in the rev range. Considering how early the motor signs off, I doubt you'd want to lose any more top end.
Try it and see. Just do the usual piston-to-valve clearance checks.

Lancer-I was offering this as a way to make a relativley small change in cam timing. Either with a stock or hot-rod cam.

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Armen

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Re: Cam Timing, Part Deux
Reply #12 - 10/15/16 at 16:34:25

Norm,
Just so that we are on the same page:
On the crank sprocket, move the chain one tooth to advance the timing. There are 19 teeth on the crank sprocket.
360 degrees divided by 19 is 18.947 degrees per tooth.
Retard the crank sprocket one tooth on the crank splines.
There are 22 splines on the crank.
360 divided by 22 is 16.364 degrees.
By advancing the timing 18.947 degrees and retarding it 16.364, you have a net advance of 2.58 degrees.
Measured at the crank, which is how most cam timing is given.
Unless I had another brain fart Shocked

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norm92de

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Re: Cam Timing, Part Deux
Reply #13 - 10/15/16 at 17:39:21

Armen,
We are indeed talking at cross purposes.
What I thought you said was advance the crank sprocket one spline, then retard the cam chain one tooth.
What you have just described is different. Advancing the cam chain one tooth. Then retarding the sprocket one spline will indeed result in an advance in timing of 2.56 degrees at the crank and an advance at the cam 1.28 degrees.

I think you have achieved what you wanted. It will be more than enough to compensate for a worn chain.

Congratulations. We on this site are sure doing things Suzuki never thought of.

Norman.

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Dave YaBB Moderator ModSquad Offline SuzukiSavage.com Rocks! Posts: 17815 Camp Springs, Kentucky Gender:	Re: Cam Timing, Part Deux Reply #14 - 10/16/16 at 03:03:57 Well done!
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