# adjustable cam gear - how much to compensate for a 0.030" head shave?



## theuean (May 11, 2000)

Just as the topic states. How much should I advance/retard the cam timing (degrees) to get it back to stock after having the head decked?
-Sean


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## john green (Aug 4, 2000)

*Re: adjustable cam gear - how much to compensate for a 0.030" head shave? (Speedemon)*

set it to 0. You aren't changing anything except compression.


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## Butcher (Jan 31, 2001)

*Re: adjustable cam gear - how much to compensate for a 0.030" head shave? (john green)*

Wrong answer. Try an automotive class or at least a book, because any time you change the distance from the cam to the crank and leave the belt [or chain] the same length you are changing the cam timing. 
Instead of asking some of us clowns who do not know what they are talking about, why don't you just measure it out yourself and let us know [but then maybe I would not trust your answer either].


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## gearhead455 (Oct 30, 2001)

*Re: adjustable cam gear - how much to compensate for a 0.030" head shave? (Butcher)*

A simple "no" would have been OK. These posts are getting too hostile! Do you talk to people like that in person? 
If I went around talking like that to strangers, I would get socked in the face quite often.


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## theuean (May 11, 2000)

*Re: adjustable cam gear - how much to compensate for a 0.030" head shave? (gearhead455)*

Hmm. I was all excited to have three replies to this topic.........
Oh well thanks anyway. Anyone else?


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## A1Rocco (Oct 6, 2001)

*Re: adjustable cam gear - how much to compensate for a 0.030" head shave? (Speedemon)*

It has been posted before(don't know who) that .044" shave equates to a 1*degree retard. If you have taken .030 off you will probably not feel that in cam timing but your compression will go up to 10.5:1.
2mm shave =.080"=1.3 of a comp. point. I wouldn't take off more then 2mm.
You need a KS for more then 10:1.
Knowing what timing is ground into the cam you will use is also important. My present swap is a JH 1.8 with 8.5:1 comp. and a shaved 2mm 83 head. That's about 9.8:1 comp. The cam will be a .405 lift from my stock 81 Scirocco 1.7. It's much bigger then the stock 83 cam and should work well in the JH head with big valves, but that cam has 3* of retard ground into it and the 2mm shave will add almost 2* more so if I advance the cam 5* I should be around 0.


[Modified by A1Rocco, 10:34 PM 7-23-2002]


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## john green (Aug 4, 2000)

*Re: adjustable cam gear - how much to compensate for a 0.030" head shave? (Butcher)*

quote:[HR][/HR]If you have taken .030 off you will probably not feel that in cam timing but your compression will go up to 10.5:1.[HR][/HR]​ - A1Rocco
my post isn't that far off big chief. When you shave your cylinder head .030....you don't need to retard the timing b/c the distance is so minimal, whether you set it at 0 or retard the thing a degree....it isn't going to make much difference. Considering the fact that he doesn't know how far to compensate and considering the fact that there is some room for error....my recommendation is to set it a 0....go from there if you have to, but a cut that small......?
Now....why don't you add something to the conversation and measure for me the distance differences and equate that to degrees in timing measurment.


[Modified by john green, 11:07 AM 7-24-2002]


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## gearhead455 (Oct 30, 2001)

*Re: adjustable cam gear - how much to compensate for a 0.030" head shave? (john green)*

If the distance from the crank to the head decreased than the can sprocket would rotate counter clockwise which is retard. So to compensate the timing would need to be advanced...
So if the distance decreased by .03" and the radius of the cam pulley is "?" and it rotates .03" to the left than the cam (center of the pulley) rotates "X" inches which is "X" degrees? Does this sound correct?
Does anyone know the diameter of the cam sprocket off hand?


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## john green (Aug 4, 2000)

*Re: adjustable cam gear - how much to compensate for a 0.030" head shave? (gearhead455)*

quote:[HR][/HR]...So to compensate the timing would need to be advanced...[HR][/HR]​Yes, advance not retard........my bad!


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## theuean (May 11, 2000)

*Re: adjustable cam gear - how much to compensate for a 0.030" head shave? (john green)*

A little follow up.
Regarding compression and how much to shave... I needed (for my plans) to bump up from 10:1 - 11:1. If 2mm = 1.3comp pts, how much do you need to shave to increase it one point? Easy enough, 1.538mm or 0.060". As stated above, every 0.030" = 0.5comp. pts.
I knew I had seen this number (0.060) somewhere. I just remembered wrong at 0.030








Further question, and since this is my thread I have no problem piggybacking it







*At what point does the 8v engine become an interference engine?* My cam has a lift of 0.449" (TT 280/276), combined with the 0.060" I'll be taking off.
Many thanks for answering all my questions








-Sean


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## john green (Aug 4, 2000)

*Re: adjustable cam gear - how much to compensate for a 0.030" head shave? (Speedemon)*

quote:[HR][/HR]At what point does the 8v engine become an interference engine[HR][/HR]​Hopefully not now after shaving the head and buying the cam!!!!! I don't have the tech knowledge to give you an answer but I am sure that Gearhead could give you a pretty good calculation as to whether or not you are already treading thin water or not. My guess is that the cam profile should be directly calculated with the deck of the head. Did you do any calculation? I hope you didn't cut too deep....then again, it's fairly easy to change your camshaft PRIOR to hearing your valve(s) tap the piston face!


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## gearhead455 (Oct 30, 2001)

*Re: adjustable cam gear - how much to compensate for a 0.030" head shave? (Speedemon)*

Can't say for sure, It's going to be close. When I assemble an engine or install a camshaft, I always approach the job as if the engine is interference even though it may not. I always install the cam with the crank 90 degrees before #1 TDC (lowers all of the pistons in the cylinders), set the cam timing and then rotate the engine clockwise to set TDC. 
Just make sure not to break a timing belt.


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## kickster (Aug 15, 2000)

*Re: adjustable cam gear - how much to compensate for a 0.030" head shave? (gearhead455)*

I shaved the head about 0.031" When I placed the 1.8 8v head on 2.0 ABA block the cam timing was off by 4 deg!!!!
I had to advance it 4" to bring it to zero. What gives here?
Am I adjusting it correctly? I set it by the TDC marking on plastic part and the O-T marking on cam gear.


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## brinskan (Jan 21, 2000)

*Re: adjustable cam gear - how much to compensate for a 0.030" head shave? (kickster)*

as much as we love to argue here, it is refreshing to find a forum where the only discussion is about floormats.... thanks guys for keeping my 4am reading informative


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## john green (Aug 4, 2000)

*Re: adjustable cam gear - how much to compensate for a 0.030" head shave? (brinskan)*

quote:[HR][/HR]as much as we love to argue here, it is refreshing to find a forum where the only discussion is about floormats.... thanks guys for keeping my 4am reading informative[HR][/HR]​








I think that you meant to say quote:[HR][/HR]it is refreshing to find a forum where the only discussion is *NOT* about floor mats[HR][/HR]​







http://****************.com/smile/emthup.gif


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## brinskan (Jan 21, 2000)

*Re: adjustable cam gear - how much to compensate for a 0.030" head shave? (john green)*

it was 4am.... give me a break, i am only an editor for a magazine







DOH


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## john green (Aug 4, 2000)

*Re: adjustable cam gear - how much to compensate for a 0.030" head shave? (brinskan)*















http://****************.com/smile/emthup.gif


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## PowerDubs (Jul 22, 2001)

*Re: adjustable cam gear - how much to compensate for a 0.030" head shave? (john green)*

Good thread!!! http://****************.com/smile/emthup.gif http://****************.com/smile/emthup.gif


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## der_panzer (Apr 28, 2003)

*Re: adjustable cam gear - how much to compensate for a 0.030" head shave? (Butcher)*


_Quote, originally posted by *Butcher* »_Instead of asking some of us clowns who do not know what they are talking about, why don't you just measure it out yourself and let us know [but then maybe I would not trust your answer either].

Who whizzed in your Cheerios this morning? Order de-caf next time! This is supposed to be a list where we all help each other out, not chastise someone for their lack of knowledge. If they knew everything, they wouldn't be here in the first place, nor would you!
Answer: It will retard the cam timing, but not even enough to feel (1 degree or so.) Considering the pickup that you'll get from the shave, you'll never miss it. Depending on your setup, it might even benefit you. (Some folks think that the only way to make power is to move that cam gear way over into the "+" range.)


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## ABA Scirocco (May 30, 2001)

*Re: adjustable cam gear - how much to compensate for a 0.030" head shave? (kickster)*


_Quote, originally posted by *kickster* »_I shaved the head about 0.031" When I placed the 1.8 8v head on 2.0 ABA block the cam timing was off by 4 deg!!!!


I came across the same sort of thing yesterday, a ABA head shaved .075" on an ABA block, the cam timing was out by 6 degrees, it was too advanced (go figure







) It was an aftermarket cam reground on a VW stock billet so, perhaps the cam was reground off center. 
Does anybody know how accurate the timing marks are on a VW? I know improperly positioned TDC and timing marks is a bit of an issue on some older North American cars maybe it's a problem with VW's too. BTW, I'm the guy who calculated the one degree per .044", I'm quite certain that is an accurate number.
The upshot of all of this seems to be that it would a good idea, check the timing marks and measure the zero on your cam if you a have the opportunity, especially is the head's been shaved, or if the cam as been replaced.



_Modified by ABA Scirocco at 10:50 PM 6-5-2003_


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## ABA Scirocco (May 30, 2001)

*Re: adjustable cam gear - how much to compensate for a 0.030" head shave? (ABA Scirocco)*

Somebody IM'd me to explain how to zero a cam, I did it a few weeks ago but I can't find the thread so here goes again. 
1- Turn the engine to TDC on the #1 cylinder's compression stroke
2- Place a short heavy straightedge on the camshaft balanced on both lobes of the # 1 cylinder, as in the picture below (Cam gear removed for clarity)
3- determine distances "A" and "B" as per the picture
4- adjust your cam gear until these distances are the same, be careful to make sure you don't turn the crankshaft.
5- you camshaft should now be zeroed, if you wish, mark this zero position and advance or retard your cam as desired.
One added note, this method only works for symetric cams so if you are using something like one of the Shrick asymetric cams, consult the manufacturer or vendor for zeroing instructions.











_Modified by ABA Scirocco at 11:24 PM 6-5-2003_


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## speed51133! (Aug 5, 2002)

*Re: adjustable cam gear - how much to compensate for a 0.030" head shave? (ABA Scirocco)*

you know, when you shave the head, or you add thicker gaskets, you DO change the cam timing.
you can say not enough for you to notice, but the fact is you are changing it.
people answer "snippy" because all too often there is misinformation spread. 
You tell 1 guy that shaving the head doesnt change the timing, then he tolls a bunch others, then everyone thinks its a fact, shaving the head doesnt affect cam timing.
truth is it does


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## ABA Scirocco (May 30, 2001)

*Re: adjustable cam gear - how much to compensate for a 0.030" head shave? (speed51133!)*

Right you are! Anything that changes the distance from the crank to the cam will change the cam timing so, non stock thickness head gaskets, shaving the head, decking the block all change the cam timing. And, based on my and Kicksters observations, it appears that some aftermarket cams can also throw off the cam timing. Checking the cam timing the way I described above is good practice anytime you make a significant change involving the head and/or valve train.


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## PowerDubs (Jul 22, 2001)

*Re: adjustable cam gear - how much to compensate for a 0.030" head shave? (ABA Scirocco)*

Ok,....anybody know how to check this on a 16v?


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## ABA Scirocco (May 30, 2001)

*Re: adjustable cam gear - how much to compensate for a 0.030" head shave? (PowerDubs)*


_Quote, originally posted by *PowerDubs* »_Ok,....anybody know how to check this on a 16v?









I was wondering that myself, but I guess this is the wrong place to ask.


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## PowerDubs (Jul 22, 2001)

*Re: adjustable cam gear - how much to compensate for a 0.030" head shave? (ABA Scirocco)*


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## hejso (Feb 2, 2004)

*Re: adjustable cam gear - how much to compensate for a 0.030" head shave? (PowerDubs)*

wow, old ass thread. im responding so it's in my watched topics. i have a feeling Ill need some of this info soon.


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## wantacad (Apr 4, 2003)

*Re: adjustable cam gear - how much to compensate for a 0.030" head shave? (hejso)*


_Quote, originally posted by *hejso* »_wow, old ass thread. im responding so it's in my watched topics. i have a feeling Ill need some of this info soon.

Thanks for bumping this, I was scrolling down and reading thinking the same "I'm going to need this info soon!"


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## theuean (May 11, 2000)

*Re: adjustable cam gear - how much to compensate for a 0.030" head shave? (wantacad)*

Sweet!
As a follow up to all this, I did end up building that motor and had it cc'd for compression. Bang on 11:1 after a 0.060" deck of the head, stock headgasket, and RD 10:1 block.
Just some more FYI for this super old thread... I gotta buy another rabbit, that was freaking fun (fast) car.


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## streetwhore91 (Feb 28, 2006)

*Re: adjustable cam gear - how much to compensate for a 0.030" head shave? (Speedemon)*

http://****************.com/smile/emthup.gif


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## salz2135 (Sep 18, 2006)

Is the autotech 270 cam symetric? Also, what's a good straight edge to use for zeroing the cam?
Thanks.


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## jackfrost1031 (Oct 19, 2004)

*Re: (salz2135)*

http://www.not2fast.com/turbo/...me=15


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