Need advice--Camshaft degree issue (maybe??)

[QBuff02]

Ok, so bear with me here to be sure I understand this. Let's use the numbers I had (just for my sake ). When I did the positive stop in each direction, the two numbers added together & divided by 2 equaled 83. My degree wheel was sitting at 84 degrees.

Now I have to go 83 degrees on the degree wheel to be true TDC. So what you are saying is I should rotate that 83 degrees to get my true TDC, and then bend the pointer to the TDC mark on the degree wheel? (Or bend the wire that 1 degree right there and then rotate to TDC on the degree wheel?)

Is that correct?

For the sake of strictly finding TDC, you want the degree wheel and pointer to be as close to tdc as can be when you start the process. Install your piston stop so the piston will come up just shy of tdc and get your number on the wheel, then rotate the crankshaft the opposite direction back to the piston stop and get your number on the wheel. Note-Your number being so high is because your piston is so far down in the hole with the piston stop set up the way you originally had it. Your shooting for the pointer to be at exactly zero on the degree wheel when the piston comes to true tdc with the piston stop removed. So, when you install the piston stop so the piston is closer to tdc the numbers you see will be smaller on the wheel in each direction. So if by your numbers you went one direction and came up with 82 degrees in that direction and then rotated the opposite way to the piston stop and your wheel was then sitting at 84 degrees. (i'm assuming you were 82 degrees and then 84 degrees respectively to come up with 83 from your math- 166 right?) that tells me your pointer was 2 degrees off because of the fact it was 82 one way and then 84 the other, so you only need adjust the pointer half that distance, or ONE degree. so adjust the pointer that one degree to 83 degrees on the wheel and don't touch (loosen or adjust) the wheel. Now with the pointer moved that one degree from 84 to 83, if you rotate the crank you should now come up with 83 degrees in either direction. Right? If you're with me so far.. This shows you have located the wheel in the correct relation for true tdc. If you did correctly, then NOW if you remove the piston stop, Zero degrees on your pointer/wheel should be exactly TDC on both the piston and the degree wheel. And you can double check that with your dial indicator, if it's correct, then you can proceed to degreeing the cam to check it's installed location. Hopefully that makes a little better sense now?

 

[OldBlueDually]

@QBuff02 I believe I understand your method now, I did exactly what you suggested and ended up with the same result of TDC, and cam centerline of 105.5 degrees. So I am still off of 102 by 3.5 degrees. ****.

I adjusted my stop too, so I was matching 34 degrees each side of TDC by moving the pointer.

So your method is moving the pointer, rotate each way to check gave me the same result of me getting the two numbers, adding & divide by 2 and then moving the degree wheel to that spot, then set TDC on the degree wheel.

I am just baffled here why I cannot get this cam centerline of 102 like the specs say I should.

 

[OldBlueDually]

Okay, so my point being that you moved the gear that's supposed to change timing by 4° and you ended up with 8° from your initial reading in either direction. Something don't add up.

Just a thought. Cams rotate at 1/2 engine. Since the discrepancy is double what the markings suggest, is it possible that there's a misinterpretation of the specs in terms of cam degrees vs engine degrees?

Man, I am not sure on that one?? I have it back at stock setting now. Getting sick of re-doing the same damned thing over and over and getting the same effing results.

 

[OldBlueDually]

Also, when you change the cam timing with the sprocket are you also then re-zeroing and rechecking your tdc and pointer and starting over from scratch? Or, for argument sake are you pulling the wheel, leaving the pointer in place, changing the sprocket, reinstalling the wheel at zero and proceeding? because you've now advanced the cam 4 degrees and if you're putting the wheel back on at zero on the pointer with the cam now advanced an additional 4, in my head it would be off by 8 degrees during a recheck.

Ok, thought about this more. YES....I was setting my degree wheel back to 0 and starting over. Should I set the degree wheel to also be 4 degree advanced?? Then start the process?

This is the first time I have ever degreed a cam before, so still learning here. Watched a whole bunch of youtube video's and read the comp cams instructions many times over.

 

[QBuff02]

Ok, thought about this more. YES....I was setting my degree wheel back to 0 and starting over. Should I set the degree wheel to also be 4 degree advanced?? Then start the process?

This is the first time I have ever degreed a cam before, so still learning here. Watched a whole bunch of youtube video's and read the comp cams instructions many times over.

https://www.lunatipower.com/how-to-degree-a-cam


You're so close you can taste it.. lol and it does get frustrating sometimes! so if you check your cam timing using the method above on the link from Lunati, what do you come up with? Just for arguments sake..


Sent from my iPhone using Tapatalk

 

[OldBlueDually]

https://www.lunatipower.com/how-to-degree-a-cam


You're so close you can taste it.. lol and it does get frustrating sometimes! so if you check your cam timing using the method above on the link from Lunati, what do you come up with? Just for arguments sake..


Sent from my iPhone using Tapatalk

So close, yet so far! For the hell of it I put in my stock timing set, that came out to 98 degrees so it is 4 degrees advanced!

I think what I should do instead of continually pissing around with this is buy another new gear/chain set that has more adjustment to it. Right now my lower sprocket has the 3 keyways for 4 degree advance/retard. I am thinking of buying this set here that has the 3 keyways on the lower gear for 4 degree advance/retard, and it has 3 holes in the upper gear for 2 degree advance/retard. I feel this would get me a hell of a lot closer...or spot on if I am lucky.

https://www.summitracing.com/parts/cca-2113

 

[OldBlueDually]

So close, yet so far! For the hell of it I put in my stock timing set, that came out to 98 degrees so it is 4 degrees advanced!

I think what I should do instead of continually pissing around with this is buy another new gear/chain set that has more adjustment to it. Right now my lower sprocket has the 3 keyways for 4 degree advance/retard. I am thinking of buying this set here that has the 3 keyways on the lower gear for 4 degree advance/retard, and it has 3 holes in the upper gear for 2 degree advance/retard. I feel this would get me a hell of a lot closer...or spot on if I am lucky.

https://www.summitracing.com/parts/cca-2113

Well ****, went to comp cams to compare prices and used that part number......a different damned timing set is pictured here at comp. I already have this set.....

https://www.compcams.com/magnum-double-row-timing-set-for-65-83-oldsmobile-260-455.html

Not sure why summit would show a different one, I guess thats why they have that statement on their site "Image is a representation of this item. Actual item may vary."

 

[OldBlueDually]

https://www.lunatipower.com/how-to-degree-a-cam


You're so close you can taste it.. lol and it does get frustrating sometimes! so if you check your cam timing using the method above on the link from Lunati, what do you come up with? Just for arguments sake..


Sent from my iPhone using Tapatalk

I said screw it, I am done effing with this thing, I called up Competition Products (where I bought my timing set I am using) and they happened to have a Cloyes double roller timing set, 9 keyways in the bottom gear, and 3 holes in the top gear!! NOW when this arrives I will get this dam thing degreed in properly!

You must be registered for see images attach

 

[MikeB]

So close, yet so far! For the hell of it I put in my stock timing set, that came out to 98 degrees so it is 4 degrees advanced!

Actually, that's probably perfect! I know that most, if not all, of Comp's small block cams are drilled to be 4 degrees advanced with a stock timing set. So I'm assuming the same is true for your Olds cam.

Good article here: https://www.onallcylinders.com/2016...facturers-grind-advance-into-their-camshafts/

Also, do you understand that your Thumpr cam is designed mainly (if not strictly) for a rough idle to impress people at the drive-in? So, if 4 degrees advance is built into your cam, retarding it to "straight up" will essentially retard it from what Comp had in mind. That typically moves the power band higher a couple hundred RPM, which will lower cylinder pressure and could make the idle even worse. Just curious here, because you said the truck will be used for cruising and highway driving.

 

[shiftpro]

Actually, that's probably perfect! I know that most, if not all, of Comp's small block cams are drilled to be 4 degrees advanced with a stock timing set. So I'm assuming the same is true for your Olds cam.

Good article here: https://www.onallcylinders.com/2016...facturers-grind-advance-into-their-camshafts/

Also, do you understand that your Thumpr cam is designed mainly (if not strictly) for a rough idle to impress people at the drive-in? So, if 4 degrees advance is built into your cam, retarding it to "straight up" will essentially retard it from what Comp had in mind. That typically moves the power band higher a couple hundred RPM, which will lower cylinder pressure and could make the idle even worse. Just curious here, since you said the truck will be used for cruising and highway driving.

Yes now we getting closer to the truth... he got the wrong cam for a truck, period.

 

[OldBlueDually]

Actually, that's probably perfect! I know that most, if not all, of Comp's small block cams are drilled to be 4 degrees advanced with a stock timing set. So I'm assuming the same is true for your Olds cam.

Good article here: https://www.onallcylinders.com/2016...facturers-grind-advance-into-their-camshafts/

Also, do you understand that your Thumpr cam is designed mainly (if not strictly) for a rough idle to impress people at the drive-in? So, if 4 degrees advance is built into your cam, retarding it to "straight up" will essentially retard it from what Comp had in mind. That typically moves the power band higher a couple hundred RPM, which will lower cylinder pressure and could make the idle even worse. Just curious here, because you said the truck will be used for cruising and highway driving.

This cam is ground with a lobe separation of 107 degrees, and you are to degree it in at 102 degrees. So the LSA-Cam Degree=5 degrees of advance built into the cam.

If you add my stock gears with another 4....holy crap that is 9 degree total. So if I degree it within 1.5 degrees either side of 102 centerline (or dead nuts on would be nice!!!) I would be golden.

YES....this baby is made to "thump" & shake for showing off at car cruises. Just to add to it I am putting on a set of electrical 3" exhaust cutouts to dump pipes behind the front tires too (unnecessary, but fun). Either way, I want it to be set how the spec card says it should be set.

Yes now we getting closer to the truth... he got the wrong cam for a truck, period.

I will have to disagree with you on that I am building this thing for fun and cruising and at idle, why not sound badass

 

[MikeB]

Just read your last post. If LSA is 107 (214 at the crank), then "straight up" would be 107 ATDC. So with intake center line at 102 ATDC, that's 5 degrees advanced, as you said. But using a stock timing set you would still get 5 degrees advanced, not 9 degrees. Where am I wrong here? Is there +5 degrees built into the stock timing set?

As for the Thumpr cam, be sure to get a larger gas tank and very low axle ratio.

 

[OldBlueDually]

One more thing: Don't expect duration @ .050" tappet rise to exactly match the timing card. Last time I checked a Comp cam it was 2-3 degrees short, compared to a cam from Jones Cam Designs that was right on the money. You may also discover lobe lift to be +/- a few thousandths, probably minus.

After I get the cam degreed properly I will be reviewing the rest of those items to verify all is good, and hopefully close to target.

No matter what cam I were to put in this, I would be doing the same exact thing to make sure it is all good.

 

[shiftpro]

This cam is ground with a lobe separation of 107 degrees, and you are to degree it in at 102 degrees. So the LSA-Cam Degree=5 degrees of advance built into the cam.

If you add my stock gears with another 4....holy crap that is 9 degree total. So if I degree it within 1.5 degrees either side of 102 centerline (or dead nuts on would be nice!!!) I would be golden.

YES....this baby is made to "thump" & shake for showing off at car cruises. Just to add to it I am putting on a set of electrical 3" exhaust cutouts to dump pipes behind the front tires too (unnecessary, but fun). Either way, I want it to be set how the spec card says it should be set.




I will have to disagree with you on that I am building this thing for fun and cruising and at idle, why not sound badass

Torque is more fun than sound my friend.

 

[jeff406cid]

Had to do a double-take, I thought I was looking at my engine! Just degreed mine a few days ago it came up at 107.750 on a 108 desired Centerline.