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Finding Intake cam lobe center, degreeing cam
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- Опубликовано: 12 авг 2024
- L28 engine, installed head, Erson cam 280N grind, finding cam intake lobe center to determine if properly installed to mfg specifications.
I'm changing out the race grind cam in my '72 240Z. I'm going to a more street performance cam with a smoother idle and better vacuum with some more low and mid range torque. I am concerned that the new Comp cam is timed correctly. I will try to verify TDC at the crank timing mark first. Then I'll see that the ICL is correct or pretty close anyway. The timing chain only has 1800 miles on it so it shouldn't need any advancing adjustment on the sprocket. Thanks for the great videos.
Well, good luck, glad I could help...didn't see much on this subj for overhead cam engine so I took a whack at it
@@joem6859 Well it was a pretty darn good whack.
@@novakenss thanks again, good luck
I did get my cam changed from a Comp Cams road race grind to a street performance spec grind. I had to resurface the rocker arms first. I tried many ways to verify the Intake and exhaust lobe centerlines. I tried .050" on both sides of the valve opening/closing but the numbers I was getting seemed off by about 14 degrees from the spec of 110*. I then tried .050" on either side of the tip of the lobes and got about the same results. I was concerned that the cam was way off. Then I read about symmetrical vs asymmetrical cam lobes, noting the uplift ramp is very different from the down ramp which allows for a more gentle valve closing to be nice to the valve seats. The rocker arm ratio changes throughout the cycle and the asymmetrical lobes help to accommodate that also. I finally ended up just looking for the maximum lift point of both intake and exhaust and presto, I was getting 110* just like on the Comp Cams spec sheet. I poured on the cam, a bottle of zinc oil from Comp Cams and did a break in run for 30 minutes at 2500 rpm. I have triple Weber 40 DCOE's and now it idles way better and is easier to jet and set the idle speed. I'm having my distributor rebuilt and recurved by Advanced Distributors in Minnesota so I can't drive it until it gets back to me. Now on to the next upgrade; Electric Power Steering. My wide wheels and tires require it. I do like working on my Z.
@@novakenss very cool, good luck.
Hey Joe, New Subscriber here and no apologies needed for the video of you verifying and validating your L28E Camshaft. Great video, well explained how to obtain the necessary measurements and esp the necessity of repeatability. I too am an engineer (flight test manufacturing engineer) in commercial aviation. I’m curious as to where you acquired the light weight Vlv springs to index your cam. Monkey see Monkey Do principal, you know Thanks again. Nice Shop by the way! Cheers
You can find the lighter springs at your local engine shop, they might have to order them but they're specifically designed for this exercise.
thanks for the kind words
got a question for u ..i got a 1990 k5 blazer 700r trans 2000 to 2400 torque converter in it and im thinking about buying this race motor it has 12.5 to 1 sbc 355 030 over with elgin e-1090p solid flat tappet cam with scorpion 1.6 rockers for total lift of 573intake 594 exhust can i use the torque converter i have on this engine,,..i no i got alot of things to change because it is a tbi fuel injection
sorry, don't know too much about sbc's and what trannys will work or not work
Hey Joe M !
I'm back from the future, it's Dec 2020! What ever happen to the Z.???
Hey... just finished the build and troubleshooting of a Megasquirt 3 EFI unit, working on the power feed, relays, wiring now. Build engine run stand for it as well, maybe fire it in a month?? maybe...
Time machine has come back around...where is your build at today April 30th.
Are you on Facebook with updates like " Church of L-series group" or S30- Life Group "??
Hey... how you doin? Yeah, I'm in the process of trying to start the motor shortly, maybe next 2 weeks. Have some debug to go thru with the MegaSquirt 3, a few other things to check, then we'll try to light it off!! And yep i'm in the Church as well. May post to both YT and the Church. Thanks for asking. How's your project doin?
Ok, in your book it said 109.....then you added and divided by 2 and had 106.5, and you said it was good? 109 isn't 106.5 What am i missing?
I was just trying to check it, to see if I my installation was way off, looks like the timing is slightly advanced by approx 2 degrees, I decided to leave it. The error could just be my measuring setup, or my finding TDC.
If it's truly advance it might result in a little more bottom end. I did the video because there were no vids for this type of procedure on this engine, thought it might help. I"m definitely not an expert....
After you found max lift, why add 50 thousandth?
that's how the cam maker specs it, at 0.050" lift, pretty common way of doing it