Posted By: BTTG
simple cam degreeing question - 02/08/11 01:19 PM
If you purchase a high quality camshaft and high quality timing set do you just use the 4 degree offset available on most crank gears to move the cam ±2 degrees relatively (while degreeing it) and call being within 1 degree of card specs a day? This would adjust for something that initially was off by 3 degrees (bringing it in to 1 degree off). I assume being 3 degrees off initially would be on the large side allowing the 4 degree crank offset to take care of most problems? Also assume this is the case as adding an offset bushing is not a simple task necessarily and in all that I have read is never discussed, but at the same time I never see discussed how to bring the timing to within spec.....usually it just says adjust and recheck with degree wheel without describing the "adjust" part.
Posted By: Dodgeguy101
Re: simple cam degreeing question - 02/08/11 01:58 PM
I would still check initially. You don't know if it is off by the 3 or 4 degrees from the getgo. Nothing to do with the camshaft, it IS SUPPOSED to be right, but I would want to check the timing set. By then you already have everything set up, go ahead and check it. I have a quality timing set, I thought, and it was 4 degress off. I had to use the 4 degree advance notch to get it installed straight up. Then I had to use a bushing to get it set at the proper centerline. Bottom line, don't guess. My 2 cents.
Posted By: Magnum
Re: simple cam degreeing question - 02/08/11 03:37 PM
Even the crank indexed to the keyway can be out.
Just slam the production stuff together but if you find yourself asking if it should be checked. Then it should be checked.
Posted By: BTTG
Re: simple cam degreeing question - 02/08/11 04:04 PM
I am not trying to take the easy way out and just throw it together by lining up the dots. I want it perfect and will degree it with an index wheel.
I am just trying to figure out if the degree wheel says it is off by 2 degrees how do I correct that to zero? I would think not many drill out their cam gear, elongate the attaching bolt holes (3 hole attachments), and buy a $20 offset bushing. Do they (I really don't know but would think not)? To much room for error or wrecking the timing set in my opinion. If this was common practice then offset bushings would be available on affordable timing sets as overboring the dowel hole and including even a single 2 degree offset bushing would cost manufacturers only pennies.
that leaves 2 options I can think of:
using the crank key way to adjust 2 degrees at cam (half of the 4 degree change at the crank) (installing cam gear/chain then reestablishing TDC effectively shifting the cam relative to the crank 2 degrees) or shifting cam gear ahead/behind by one link on the chain. Guessing that would change things only a degree or 2?
This is my whole point everyone says do it right with a degree wheel but then you read instructions (I've read 2 recommended assembly books and several manufacturers instructions) and they don't actually tell you how to bring it to within spec they just tell you to "adjust" and recheck......
Posted By: Dodgeguy101
Re: simple cam degreeing question - 02/08/11 06:38 PM
Once you figure out what you need, just get the bushings. They come with 0,2,4,6,and 8 I think. Drill out the hole that the cam dowel goes in. Put teh bushing in that you need , make sure you line it up right. It takes a little thought, did for me, first time I've done this, and make sure you put the offset the correct way and recheck it. I have a roller cam so I have the plate and roller button set up from Mancini, so I drilled the hole all the way through, but if you have a solid cam, just drill the hole far enough so the bushing fits in and can't come out the other side.
Go to the comp cams site, it explains it pretty well on how to degree it in. That is what I used. Hope that helps.
Posted By: RapidRobert
Re: simple cam degreeing question - 02/08/11 10:44 PM
What Dodgeguy101 said. Drill the pin hole out (not all the way) to .406" (13/32). Find exact TDC then degree it & see what bushing you need/install it/degree it again to check it/stake it & to elim some confusion although you are degreeing the cam which turns half speed of the crank these degrees are CRANK degrees as you are measuring off of the degree wheel/pointer on the CRANK.
Posted By: BTTG
Re: simple cam degreeing question - 02/15/11 09:35 PM
Obviously, I am not thinking about this correctly.Say the original dowel hole was 0.30" (hypothetical I did not measure) in the cam gear and the dowel rod on the cam was 0.298" so the cam dowel slid right through the cam gear dowel opening. If you bore the dowel hole on the cam gear all the way through to 0.40" that obviously is bigger than 0.30". Bigger is required as the bushing must go in that hole (bushing is larger than its dowel hole opening thus allowing the cam to be slightly advanced/retarded by changing the placement of the offset) (done through use of different offset bushings. The bushing has a hole for the dowel of the same original diameter (0.30"). Since the dowel hole is the same diameter in the offset bushing as well as the original cam gear the dowel on the camshaft cannot be inserted all the way except if the offset is 0 (because this is the only time the 2 would be aligned). if you offset it say 2 degrees (offset bushing) then the hole in the cam gear (remaining after not boring all the way through) and the offset bushing will be out of line and the camshaft dowel cannot go on all the way....right????
Sorry this is tough to describe.
Posted By: GARAGEMAN
Re: simple cam degreeing question - 02/15/11 10:02 PM
Posted By: Magnum
Re: simple cam degreeing question - 02/19/11 07:31 AM
Security against what?
I do it for the simply reason that it's easy to break a pin if you load the end. If you try to shear it, hard to break.
Since the cam sproket is thick than the bushing. If you drill all the way through. The bushing will not rotate but it is free to walk forward against the cam bolt washer. When if floats to the rear, that's a good thing. It places the camshaft dowel in a shear load. Strong.
When if floats to the front. You are now driving the camshaft with the tip of the dowel.
So drill the hole only deep enough to keep the bushing near the back of the sproket. I'm sure this has been overlooked a million times but shear load is why I only drill part way through.
