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Degreeing Cam - Dot to Dot!
https://www.slantsix.org/forum/viewtopic.php?t=16918		 Page 1 of 3
Author:  bwhitejr [ Wed Apr 05, 2006 4:31 am ]
Post subject:  Degreeing Cam - Dot to Dot!
I assumed that if my camshaft and crank gears are aligned dot-to-dot that my CompCams camshaft would be set up on the intake centerline. Is that true?

The reason for the question is something my machinist said when I asked him about degreeing the cam. He said he set it up and it was 110 degrees. I noticed that the dowel was in the stock hole in the Cloyes double roller cam gear and no offset bushing was present. The cam specs say lobe separation 110 degrees and intake centerline is 106 degrees. So. Did he just dot-to-dot the thing (and said he degreed it) or did he really set it up at 110 degrees? If so how did he do it?

bwhitejr
Author:  Charrlie_S [ Wed Apr 05, 2006 6:14 am ]
Post subject: 
If he said it is 110*, he either measured it, or is just BSing you. If he just did "dot to dot" he would not know how many degrees it was. If it is really at 110* the cam is installed 4* retarded. Ask him why he installed it 4* degrees retarded.
Author:  Dart270 [ Wed Apr 05, 2006 6:20 am ]
Post subject: 
110 deg is a BAD idea. Depending on the cam, I would run between 98 deg and 104 deg, but not more than 104. Degreeing takes some time, but it's worth it.

As a rule of thumb, my experience is that you should advance any cam spec'd for a 225 by 4 deg over the cam company's recommendation. For example, if they say 106 deg centerline, then you should degree it at 102 for better performance.

Lou
Author:  SlantSixDan [ Wed Apr 05, 2006 6:27 am ]
Post subject:  Re: Degreeing Cam - Dot to Dot!
Quote:
I assumed that if my camshaft and crank gears are aligned dot-to-dot that my CompCams camshaft would be set up on the intake centerline. Is that true?
The only thing you know if you line up the dots is that the dots are lined up. That goes for any cam from any maker, not just the ones from "sometimes we almost tell the truth about our cams" Comp. You gotta degree it with a wheel!
Author:  bwhitejr [ Wed Apr 05, 2006 6:46 am ]
Post subject:  Degreeing Cam - Dot to Dot!
So how would I change the timing of the cam unless I used offset bushings?

bwhitejr
Author:  SlantSixDan [ Wed Apr 05, 2006 7:00 am ]
Post subject: 
No, no, you would use offset bushings. That part's no problem. The problem is guessing or lining-up dots instead of measuring to determine which offset bushing to use, in which direction.
Author:  bwhitejr [ Wed Apr 05, 2006 7:09 am ]
Post subject:  Degreeing Cam - Dot to Dot!
OK... So I would degree the cam with a wheel knowing I will need some offset bushings to set it up, even if I am going to put it on the factory intended 106* intake centerline. Or at some other timing.

What is the probability that I am at 106*, already?

bwhitejr
Author:  Charrlie_S [ Wed Apr 05, 2006 7:24 am ]
Post subject:  Re: Degreeing Cam - Dot to Dot!
Quote:
What is the probability that I am at 106*, already?

bwhitejr
1 out of 360

Like everyone is trying to tell you, you MUST use a degree wheel and indicator, to know where the cam timing is. guesing does not cut it. If you spent the money for a performance cam, spend the time to get the performance out of it. If you paid the machinist to degree it, take it back, and tell him to do it right. 110* is not right.
Author:  sandy in BC [ Wed Apr 05, 2006 7:25 am ]
Post subject: 
one in three hundred and sixty.
Author:  dusty7t4 [ Wed Apr 05, 2006 12:08 pm ]
Post subject: 
I have looked around for a degree wheel, but I can't find one that says it can do a slant. am I just not finding the right one or is there one out there that will do the job but isn't labeled right? (or one where I can get close enough)?

I ask because everything is labeled a v-8 wheel

-dave
Author:  emsvitil [ Wed Apr 05, 2006 12:20 pm ]
Post subject: 
Actually it's better than 1:360.......

Probably

90% it's 106 +/- 4
98% it's 106 +/- 10
Author:  SlantSixDan [ Wed Apr 05, 2006 12:35 pm ]
Post subject: 
Quote:
I have looked around for a degree wheel, but I can't find one that says it can do a slant. am I just not finding the right one or is there one out there that will do the job but isn't labeled right? (or one where I can get close enough)? I ask because everything is labeled a v-8 wheel
There is no such a thing as a V8 degree wheel, slant-6 degree wheel, etc. Degrees are degrees. There are 360 of them in a circle.
Author:  dakight [ Wed Apr 05, 2006 12:42 pm ]
Post subject: 
On a related note... is there any suitable substitute for a timing tape on a /6. I know the harmonic balancer will not accept a conventional timing tape.
Author:  bwhitejr [ Wed Apr 05, 2006 12:51 pm ]
Post subject:  Degreeing Cam - Dot to Dot!
Let me see if I understand how I got here.

The machinist was lazy and didn't really degree the cam. Or he did and didn't bother to set it up at 106*. So what I am dealing with is a collection of production tolerances? If it really is 110*.

I have the Mopar Degree wheel at home. Is there a way to check the degreeing without taking the whole front of the engine off. And can it be done like that with sufficient accuracy.

By the way. I got Cloyes to send me the drawings for the double roller gears, so I could check the dot-to-dot alignment. Good info!

bwhitejr
Author:  Dart270 [ Wed Apr 05, 2006 2:04 pm ]
Post subject: 
You can just set up a dial indicator on the pushrod sitting on #1 intake lifter or on the cam end of that rocker arm, then use a 3/4" NF thread bolt/nut to fasten the deg wheel onto the crank, then screw a piston positive stop into the #1 spark plug hole, then follow standard procedure for degreeing cam. You do not have to even take the balancer off if you just want to check cam timing.

If you are <106 or close, then it may not be worth taking the motor apart. What is this cam and what is your intended usage?

Lou
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