LD9 cam timing after maching / headgasket thickness change? - Performance Forum

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LD9 cam timing after maching / headgasket thickness change?
Saturday, February 27, 2010 2:58 PM
When I put my motor together the first time I used a Victor Reinz replacement headgasket because Cometic wasn't making them yet and I wasn't going to o-ring the block/head to use copper. So now I've gone in and changed to a Cometic .040 thick gasket and made a cam/spring change.

I've got everything ready to button backup but I'm off by half a tooth on my crank gear and my buddy has my cam degree wheel locked up in his garage and he and the family are on vacation 'til next Friday. So,tell me if I'm just over thinking this...

When I got the block/head machined they took off .005 from the block and .010 from the head moving the cams .015 closer to the crank,the new headgasket was .052 thick versus the GM stock @.047 so I wasn't to concerned when my timing mark @ the crank was actually a little past TDC when everything was going back together ( less then 1/4 tooth). Now that I've put the thinner headgasket in the cams have moved further towards the crank and I'm off timing @ the crank by half a tooth.

If I put the timing mark on the crank gear before the timing mark on the block I would be Advancing the cams,RIGHT? If I put the timing mark on the crank gear after the timing mark on the block I'll be retarding the cams,RIGHT?

So,the crank gear has 19 teeth,cam gears have 38. 360* divided by 19 = 18.947* per tooth divided by 2 (revolutions of crank vs. cam) = 9.473* per tooth divided by 2 (half a tooth off) = 4.736* crank,advanced/retarded. RIGHT???

So,I'm thinking it would be better to set the crank timing mark BEFORE TDC so the cams are Advanced...

Discuss






"The FACTS are always subject to CHANGE once the TRUTH is applied"
"In the entire history of man the only stupid questions are the ones that don't get asked"

Re: LD9 cam timing after maching / headgasket thickness change?
Saturday, February 27, 2010 4:21 PM
Wow Gary, you got me there.

The only thing I know is when I went with a .030 gasket from a .074 MLS gasket I know it was hard as heck to line up my timing marks. I thought for sure the cams got too close to the crank and I had too much slack. All I know is that my did on the crank gear the dot was slightly past the align mark on the block. Car ran fine lol. I will see how it goes again when I put my engine back together.

I know I didn't answer anything you wanted to know, just wanted to share










~2014 New Z under the knife, same heart different body~
______________________
WHITECAVY no more
2012 numbers - 4SPD AUTOMATIC!!
328 HP
306 TQ
Re: LD9 cam timing after maching / headgasket thickness change?
Saturday, February 27, 2010 6:49 PM
i was off half a tooth per cam also... but my head is shaved .020, knowing that for ever .020 shaved retards timing by 1 degree, i set them half a tooth advance 15 k miles ago on the old build... my timing marks from 15 k miles in the timing housing survived the heat from the powder coat and so i lined them back up the same way again



Re: LD9 cam timing after maching / headgasket thickness change?
Sunday, February 28, 2010 5:02 PM
wow... too much math for me :S

time for mcmoney's cam gears, eh gary? lol



Re: LD9 cam timing after maching / headgasket thickness change?
Sunday, February 28, 2010 7:19 PM
I'm thinking a lot of it's timing chain stretch. I was trying to do the the math of the gear dropping .025 closer to the crank. Should only be about 2.25* at the crank (less than 1/4 tooth). I could always take the cam gears off and redrill offset dowel and alignment holes after I get my degree wheel back and see just how far I'm really off.





"The FACTS are always subject to CHANGE once the TRUTH is applied"
"In the entire history of man the only stupid questions are the ones that don't get asked"
Re: LD9 cam timing after maching / headgasket thickness change?
Sunday, February 28, 2010 9:16 PM
how many miles does the chain have?

cant imagine too much since the rebuild... 10k?



Re: LD9 cam timing after maching / headgasket thickness change?
Monday, March 01, 2010 4:57 AM
Somewhere around 18k. I like to drive it when I can .





"The FACTS are always subject to CHANGE once the TRUTH is applied"
"In the entire history of man the only stupid questions are the ones that don't get asked"
Re: LD9 cam timing after maching / headgasket thickness change?
Thursday, March 04, 2010 6:42 AM
Went to ORLY's last night and picked up a new Cloyes timing chain (the one that was on was a Morse),put it on this morning and now I'm just (guessing) around an 1/8 of a tooth cam retarded,7/8th of a tooth advanced. After I get my cam degree wheel back I'll mess with it this weekend and get everything to run straight up and try to get on the dyno next weekend...






"The FACTS are always subject to CHANGE once the TRUTH is applied"
"In the entire history of man the only stupid questions are the ones that don't get asked"
Re: LD9 cam timing after maching / headgasket thickness change?
Thursday, March 04, 2010 7:33 AM
Gary what new things you got on the car this year? Cams, springs, and Intake mani?










~2014 New Z under the knife, same heart different body~
______________________
WHITECAVY no more
2012 numbers - 4SPD AUTOMATIC!!
328 HP
306 TQ
Re: LD9 cam timing after maching / headgasket thickness change?
Thursday, March 04, 2010 7:54 AM
Ya,that's about it. I figure with the cam and spring change it should be over the 400hp mark on a DynoDynamics 480ish DynoJet. Might have to throw some bigger injectors in or run a secondary injector setup to get enough E85 pumpimg into it. I'm so busy here at the shop I probably won't have as much time to play as I want to...





"The FACTS are always subject to CHANGE once the TRUTH is applied"
"In the entire history of man the only stupid questions are the ones that don't get asked"
Re: LD9 cam timing after maching / headgasket thickness change?
Thursday, March 04, 2010 8:17 AM
Nice, can't wait to see better numbers. What brand injectors are you running and what cc's are they?









~2014 New Z under the knife, same heart different body~
______________________
WHITECAVY no more
2012 numbers - 4SPD AUTOMATIC!!
328 HP
306 TQ

Re: LD9 cam timing after maching / headgasket thickness change?
Thursday, March 04, 2010 10:10 AM
I'm running Delphi 95lb. (998cc) low impedance right now. If I have to go bigger I might consider some Moran adjustable 150lb-210lb. , but that's $750 for 4 injectors,ouch...






"The FACTS are always subject to CHANGE once the TRUTH is applied"
"In the entire history of man the only stupid questions are the ones that don't get asked"
Re: LD9 cam timing after maching / headgasket thickness change?
Thursday, March 04, 2010 6:35 PM
Oh I didn't know you were running low imp, cool to know that we can with the 99 and up. 750 for some injectors?? Dang they better self tune themselves then










~2014 New Z under the knife, same heart different body~
______________________
WHITECAVY no more
2012 numbers - 4SPD AUTOMATIC!!
328 HP
306 TQ
Re: LD9 cam timing after maching / headgasket thickness change?
Thursday, March 04, 2010 7:05 PM
adjustable injectors?! what the....



Re: LD9 cam timing after maching / headgasket thickness change?
Thursday, March 04, 2010 7:53 PM
just do 2200cc injector dynamics but they are $1000 for 4 but you'll never need another injector again and they are high imp.




R.I.P. Brian Klocke, you will never be forgotten
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