Degreeing a Cam, or not.....

Would you run it or take it apart and correct it?

  • Total voters
    34
-
Without an infinitely adjustable timing set(like a Cloyes hex-a-just), you’re often stuck with only getting within a degree or so of where you’d ideally prefer it to be.
I usually have a 2* window I’m trying to reach.

For the combo being discussed here, I’d be shooting for 107.5-109 ICL.
 
Finally got the tools to correctly degree the cam. I removed the driver's side rockers so I could measure the pushrods directly. After finding top dead center with a TDC stop. I first measured .050 inch lift on intake at 13* btdc, Cam card says 15*. Then I measured exhaust lift .050 at 51*abdc, matching the cam card. This gives me 15+51+180=244* duration (246 on cam card). Exhaust .050 open 62 bbdc, matching cam card, close 11.5* cam card 10*
To check intake center line I took reading at 3 different points .025 .040 .050 or so before (I am not sure about the order or exact number, but I am sure that I was the same before and after) and after max lift.

Intake center line
78.5*+137.5*=216/2=108 Perfect
62.5+153.5=216/2=108 yeah
140.5+75.5=216/2=108 trifecta

For exhaust center line
162*+69*=231/2=115.5 close to cam card 116
151.5*+78.5=230/2=115 sorta close
145.5+84.5=230/2=115 ok for me

108+115/2=111.5 lobe separation cam card says 112*

Final check was lobe lift, intake .339, exhaust 353. Cam card was .344 and .358

What did I learn? First and foremost, Degree in your cam or you just do not know where it is.
Second, you can do a good measurement of your cam without pulling the timing cover off to check where you are. My measurements before removing the pulleys indicated the need for an 8* advancement of the camshaft to get it to spec. After advancing it 8 degrees and doing a proper cam degree, I was able to get it to spec.

If there is anything I missed, please advise me before the weekend when I will close it up.

I did not go back and check all the initial measurements. One day I might. But for today, I am happy to have corrected my mistake and I have it right. Next step, reassembly, valve lash, ignition timing and drive.

Lastly, Thank you everyone for the help, guidance, wisdom and encouragement to get me through this process. Glad to have a great group of guys who care about helping others without attitudes and negativity.
 
First ride today. My seat of the pants assessment is that I have hit the jackpot. I do not have a racetrack to test it this year, but I have a backroad that works for some runs. Previously we could go up to 100 before having to shut it down. Today, I went to 106 in much shorter distance and looking at the datalog, I did not even give it full throttle and the time was about 10 seconds of acceleration. That is way faster than ever before. Now I want to drive it a bit so that the Sniper tunes itself and then get it on a Dyno. The previous runs only indicated about 350 HP. to run 12.3 seconds. next step is to assess the valve lash settings from a different thread.
 
Kent mosby said:
First ride today. My seat of the pants assessment is that I have hit the jackpot. I do not have a racetrack to test it this year, but I have a backroad that works for some runs. Previously we could go up to 100 before having to shut it down. Today, I went to 106 in much shorter distance and looking at the datalog, I did not even give it full throttle and the time was about 10 seconds of acceleration. That is way faster than ever before. Now I want to drive it a bit so that the Sniper tunes itself and then get it on a Dyno. The previous runs only indicated about 350 HP. to run 12.3 seconds. next step is to assess the valve lash settings from a different thread.
Click to expand...

Sounds like progress Kent!
 
Kent mosby said:
First ride today. My seat of the pants assessment is that I have hit the jackpot. I do not have a racetrack to test it this year, but I have a backroad that works for some runs. Previously we could go up to 100 before having to shut it down. Today, I went to 106 in much shorter distance and looking at the datalog, I did not even give it full throttle and the time was about 10 seconds of acceleration. That is way faster than ever before. Now I want to drive it a bit so that the Sniper tunes itself and then get it on a Dyno. The previous runs only indicated about 350 HP. to run 12.3 seconds. next step is to assess the valve lash settings from a different thread.
Click to expand...

Glad you got to the bottom of it, we all had a lot of fun following along, and learned some things to.

You climbed that Mountain, good on you for staying with it.

☆☆☆☆☆
 
Just for ***** and grins can you do a compression check and post it for us to have before and after degreed numbers please?
 
162 prior to degreeing the cam 172 after degreeing the cam. I tested 3 or 4 cylinders and were all similar
 
One last thing about this. Ignition timing. To sum up where we are. I verified that the Crankshaft 0* mark is at the top dead center with the piston. That did not change. I adjusted the camshaft 8* advanced to match the cam card. I re-assembled and left the ignition timing where it was. Now my question.

I did not change the crankshaft pulley, just re-installed it so my TDC did not change. So my timing marks on the crank should be accurate,,,,correct?
Finally, how would what I did affect ignition timing? I have not checked it and I will this weekend. I should have before starting it but I did not. The sniper controls the timing advance and I just need to set the initial timing.

It would seem to me that advancing the cam, I would also be advancing the timing since the distributor is driven from the camshaft. My brain is struggling with this one. I will check and post where I am at now this weekend but any advice welcomed.
 
Your crankshaft at Top Dead Center has not changed.

You advanced the cam 8 degrees and this advanced the ignition timing at the same time being the distributor is driven off of the camshaft.

Your new valve timing events are bringing in the fuel charge earlier.

Would think you would still want your initial ignition timing at around 15 degrees advance, not at the 23 degrees advance as it is set now. As an example ^^^^^.

The fuel charge is in the cylinder, when do you want to fire it? Too much advance and it is fighting itself as the piston is trying to get over the top, then back down the other side to do the work.

Take a timing light to see where it is set now, then back it down to your original desired settings.
 
George Jets said:
Your crankshaft at Top Dead Center has not changed.

You advanced the cam 8 degrees and this advanced the ignition timing at the same time being the distributor is driven off of the camshaft.

Your new valve timing events are bringing in the fuel charge earlier.

Would think you would still want your initial ignition timing at around 15 degrees advance, not at the 23 degrees advance as it is set now. As an example ^^^^^.

The fuel charge is in the cylinder, when do you want to fire it? Too much advance and it is fighting itself as the piston is trying to get over the top, then back down the other side to do the work.

Take a timing light to see where it is set now, then back it down to your original desired settings.
Click to expand...

Thanks, That is what I thought but needed to be sure. Sniper is really easy to set timing. I will set it this weekend.
 
You must log in or register to reply here.
-

Back
Top