Cam Degreeing Results, and Questions

[1980_Cj7]

Bought an extra lifter removed the spring, and stacked some washers in it to make it a "solid". It must have ended up a little short though, as we couldn't get all the slop out of the rocker, so we lost the rocker and put the dial indicator on top of the push rod. Here's what we came up with with the timing set installed straight up:

Intake opens at 6 degrees BTC (cam specs call for 4)
Intake closes at 30 degrees ABC (cam specs call for 34)

Wondering what to do now. This is our first attempt at degreeing a cam, so I'm not sure if it's us, or the cam is really off. For example, why isn't it off the same amount on both ends??? We have the RollMaster, so there is plenty of adjustibility.

That seems awful early for the intake to close, so retarding the cam 4 degrees probably would help. (We want to run pump gas.) What do you more experienced guys think? As a reminder, we're running KB 354 pistons (9.5:1) and are .040 over.

Very anxious to get this thing back together, but sure don't want to get in a hurry and make any mistakes. Can't afford to go thru this a THIRD time.

Thanks for the help.

[AMX69PHATTY]

Yeah I know what ya mean about a 3rd time.
Wiped out a cam lobe on my new motor and get to do it again.

Those figures are at .050 lift right ?
Did ya check the Intake Lobe Centerline Angle ?
This is what most folks "set" to a cetain degree.
Retarding the cam moves powerpand up in rpm range
Advancing cam moves it down in rpm range.

Did ya run your cam specs at KB Silvolite to see
what inatke closing angle would give you 8:1 Dynamic CR ?
He he, a stock timimg set is easy, only one choice.
The RollMaster creates all kinds of "opportunities".
Did ya already post your cam card ?
Maybe call and talk to the tech at the cam company ?
Ain't it fun ?

[1980_Cj7]

Yes, checked the Intake C/L and got 104 degrees. Specs call for 105.

All our checking has been at .050, but that brings up another question. I was reading in the cam degreeing kit instructions that you need to know whether the specs are based on the lifter or the valve, due to the multiplication factor the rocker introduces, and measure accordingly.

I didn't even get a cam card with this cam, and it is brand new. All I have is what I could pull off of the Clevite web site. If I can find that, I'll post it again.

Found it, it's number 2 under the V8 section.

http://mywebpage.netscape.com/SketchKT/AMC+401+Ross+Pistons+Clevite+Cam+Info.jpg

[82Waggy]

It's not uncommon for the duration to be off a bit from the card - mine was also.

If you are sure you want it at a 105 LCA, then I would leave it at 104 and let break in wear and chain stretch take care of retarding the difference.

When I checked my LCA, I measured at .050 before and after the max lift reading and split the difference on the degree wheel to find LCA. Trying to find LCA at the max lift reading was troublesome for me because it held max lift for a few degrees of rotation.

It is hard to say exactly what LCA you should use. I'd run it and see what you think. If it is good and strong but pings you could retard the cam a notch or back out some timing. If it does not ping but you would like it to be more responsive you could advance it a little.

I'm buttoning mine up at 106LCA to start off with.

[1980_Cj7]

When I checked my LCA, I measured at .050 before and after the max lift reading and split the difference on the degree wheel to find LCA. Trying to find LCA at the max lift reading was troublesome for me because it held max lift for a few degrees of rotation.



Yep, that's exactly how we did our LCA too. Guess I'll run these numbers on KB's calculator and see what I come up with.

[1980_Cj7]

Correction, the 104 we measured was the intake centerline, not the LCA. Our LCA is supposed to be 110 degrees. We didn't figure that yet. We'll have to get the numbers on the exhaust valve first.

[82Waggy]

Correction, the 104 we measured was the intake centerline, not the LCA. Our LCA is supposed to be 110 degrees. We didn't figure that yet. We'll have to get the numbers on the exhaust valve first.

LCA=Lobe Centerline Angle
LSA=Lobe Seperation Angle

I know some use LCA to describe the Lobe Seperation Angle -too confusing.

[1980_Cj7]

I'm going to put more washers in the lifter tonite to get rid of the lash, and check again with the valve spring load on the lifter and see if that makes any difference. I'm hoping the load on the valve train might delay the timing of the valve events slightly. They aren't that far off.

[1980_Cj7]

Well, I think we're finally getting somewhere. Here's what we came up with:

Intake opens 7* BTC (should be 4* BTC)
Intake closes 32* ABC (should be 34* ABC)
Intake centerline 103* (should be 105*)
Exhaust opens 48* BBC (should be 44* BBC)
Exhaust closes 6* BTC (right on)
Exhaust centerline 117* (should be 115*)

After some figuring, it looks like if we retard the cam 2*, we'll get:

Intake opens 5* BTC (1* early)
Intake closes 34* ABC (right on)
Intake centerline 105* (right on)
Exhaust opens 46* BBC (2*early)
Exhaust closes 4* BTC (2* late)
Exhaust centerline 115* (right on)

Now, how to get the blasted RollMaster timing set off to reposition it. The crank gear is really tight. There's no way to use a puller without it contacting the chain, and I don't want to mess that up. Anybody know any tricks???