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

[OldBlueDually]

I am working on my '69 455 Olds right now, degreeing the camshaft on it. I need your advice on the results. Comp cams advice is "leave it as you have it and run it". The camshaft is supposed to be at 102 degrees and my results are not that.

This is for my 76 GMC crew/dually, I will not be drag racing or trying to get a tenth of a second off a quarter mile run. I will be cruising with it, driving/highway...etc. Just for fun is all this build is for. May do an occasional burnout & goof off, that's it.

Here is what I have for parts;

I have the new timing gear/double roller chain set for it. The crank gear has 3 keyways, 0 is stock setting, A is 4 degree advance, R is 4 degree retarded.

The camshaft is the comp cams thumpr; https://www.summitracing.com/parts/CCA-CL42-600-5

I made a positive stop, I am using a dial indicator & pushrod (also used no pushrod, same results each time).

My results are: (trying to achieve 102 degrees)

Stock timing marks: Result was 105.5 degrees (multiple times) so I am retarded by 3.5 degrees. (this is the one comp cams stated to leave it & run it).

Advanced 4 degrees: Result was 97.5 degrees (multiple times) so now I am advanced by 4.5 degrees (they said do not run it advanced like this).

Retarded 4 degrees: Result was 113 or some crazy crap.....

What do you guys suggest?.....

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[Blue Ox]

Your pictures make it look like you're degreeing to BDC. You want to elaborate a little more on what you're measuring? The link you posted does not have the specs for valve opening and closing. Are you using the correct lift spec to measure it and are you measuring in the correct place. I @$$ ume it's at the lifter, but it doesn't hurt to verify.

 

[QBuff02]

Where's the cam card? The specs on that cam when looked up on the link you provided say it has a centerline of 107 so why are you trying to get to 102? Unless the cam card is different than the advertisement in the link provided? Is the cam also ground advanced? Also, I was taught and have always been of the mindset when finding tdc you want the positive stop to stop the piston somewhere between .250-.500 below deck when zeroing your degree wheel. And then rotate in each direction to determine correct pointer location before proceeding with degreeing. And then check centerline rotating the engine in both directions. The cam I put in my 454 called for a 106 centerline and checked it twice in each direction and it was 105 1/2 one way and 106 1/2 the other way. Accounting for a small amount of play in the timing chain set or maybe the pointer off juuuuust a touch, or which of the two of us's eyes looked at it, I called it good enough. Based off what info I got from the cam application and what number you came up with installed "straight up" i'd leave it at the 105.5 and run it as well. BUT that's based off the 107 LSA on the specs online. So if the cam card calls out an ICL of 102 and the LSA is 107 then the cam is ground 5 degrees advanced. Almost all "street" cams (that's what we'll call them for arguments sake) are ground advanced to some degree (no pun intended). And I wouldn't want to advance it another 4, so i'd either leave it where it is or go through the process from scratch again. Which i'd probably do because i'd like to see the numbers closer as well. And then if you get the same results a second time, run it. I'm still curious what the cam card you got says though. I forgot to add where you are checking with your dial indicator? If you don't have a solid lifter and are using a hydraulic lifter you want the dial indicator to rest on the outer lip of the lifter and not down on the plunger, because that could also have an effect on the reading on your degree wheel as well if the plunger happens to depress/collapse slightly while going through the motions.

 

[OldBlueDually]

@Blue Ox I am degreeing starting with TDC where my pointer is (coat hanger). What I did was make that positive stop a couple inches down the cylinder to roll the engine each direction, write my numbers down, add them & divide by two. With that result, I would then roll the engine back that amount to find true top dead center. My stop is dead nuts in the center of the piston too.

From there I would degree the cam centerline now (102 degrees).

@QBuff02 the lobe separation is 107 degrees, the cam centerline is supposed to be 102 degrees. I forgot to post the cam spec card, here it is below.

Here is what I did. As stated above I used the positive stop to find true top dead center. I then set my degree wheel at TDC.

I then setup my dial indicator on the deck with a magnetic base, I used my #1 pushrod set into the hydraulic lifter on cylinder #1 intake lifter, set my dial indicator square to the world & pushrod. I rolled the engine in normal rotation until I reached max lift on the intake cam lobe. Dial indicator was then set to 0". I then rolled the engine backwards until the indicator read .100", and then rolled it normal direction until the dial indicator read .050" and at this point I wrote down the degree number from my degree wheel.

Now I continued to roll the engine in its normal rotation until the dial indicator went back to 0" and then back to .050", looked at my degree wheel & wrote down that number. I added the two together & divided by 2. That number was 105.5 each time (3.5 degrees retarded).

So when I set my lower gear to 4 degree advance I did the same procedure each time, came up with 97.5 (4.5 degrees advanced).

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[Wumbo]

I rolled the engine in normal rotation until I reached max lift on the intake cam lobe.

What was the degree wheel reading at that point?


Nevermind, re-read what you posted.

 

[Blue Ox]

Just for entertainment, could you install the gear on the advance keyway and see what kind of readings you get?

Based on what you're describing my guess would be that the gear may be defective.

 

[OldBlueDually]

Just for entertainment, could you install the gear on the advance keyway and see what kind of readings you get?

Based on what you're describing my guess would be that the gear may be defective.

See my first post my friend (it was 97.5 degrees, so 4.5 degree advanced).

 

[QBuff02]

@Blue Ox I am degreeing starting with TDC where my pointer is (coat hanger). What I did was make that positive stop a couple inches down the cylinder to roll the engine each direction, write my numbers down, add them & divide by two. With that result, I would then roll the engine back that amount to find true top dead center. My stop is dead nuts in the center of the piston too.

From there I would degree the cam centerline now (102 degrees).

@QBuff02 the lobe separation is 107 degrees, the cam centerline is supposed to be 102 degrees. I forgot to post the cam spec card, here it is below.

Here is what I did. As stated above I used the positive stop to find true top dead center. I then set my degree wheel at TDC.

I then setup my dial indicator on the deck with a magnetic base, I used my #1 pushrod set into the hydraulic lifter on cylinder #1 intake lifter, set my dial indicator square to the world & pushrod. I rolled the engine in normal rotation until I reached max lift on the intake cam lobe. Dial indicator was then set to 0". I then rolled the engine backwards until the indicator read .100", and then rolled it normal direction until the dial indicator read .050" and at this point I wrote down the degree number from my degree wheel.

Now I continued to roll the engine in its normal rotation until the dial indicator went back to 0" and then back to .050", looked at my degree wheel & wrote down that number. I added the two together & divided by 2. That number was 105.5 each time (3.5 degrees retarded).

So when I set my lower gear to 4 degree advance I did the same procedure each time, came up with 97.5 (4.5 degrees advanced).

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So if i'm understanding you correctly when you checked for tdc in each direction and divided by two.. that's actually the amount you have to adjust the POINTER on the degree wheel without moving the crankshaft at all. But you rotated the engine to split the calculated difference instead of adjusting the pointer? So for theoretical numbers if rotating clockwise the pointer stopped at 10 degrees one way but 5 degrees the other way that's a difference of 15 degrees, of which you would adjust the pointer in theory 7.5 degrees on the degree wheel towards the difference and that will then net you true TDC on the degree wheel. And then once you adjust the pointer those 7.5 degrees, rotate it in each direction to make sure that when it hits the piston stop it's truly still at zero in each direction. or say, if it's 8 degrees one way and 4 degrees the other way the difference to adjust the pointer on the degree wheel would be 6 degrees to make it zero in each direction. Also, are you factoring in the additional 4 degrees? because if you come up with 105.5 and then advance the cam 4 you should end up with 101.5 not 97.5. I'm trying to figure out how you only advanced the cam 4 degrees but by your numbers provided you ended up advancing the cam 8 degrees? The 102 is a fixed variable machined into the cam and doesn't change unless you manipulate it by adjusting the crank sprocket. Most recommendations are if you are within one degree either way to not change it, but if you come up with 105.5, by then advancing the cam sprocket 4 degrees your cam should now be at 101.5 when you recheck it. For arguments sake i'd reset the piston stop up higher in the bore closer to true tdc and that might take your margin of difference down when calculating the amount to move the pointer on the degree wheel. You didn't state whether you had the head installed and were checking this off of the valve retainer? If that is the case you need to factor in your rocker ratio as well otherwise your numbers will be off by a few degrees. so take your .050 and X it by your rocker ratio to get the number to look at for your valve timing events. For example, using a big block chevy with a 1.72 ratio rocker .050X1.72=.086 so the .086 would be the number to look at for degreeing. But if you're not and measuring direct off the lifter then using the standard .050 is correct.

 

[OldBlueDually]

So if i'm understanding you correctly when you checked for tdc in each direction and divided by two.. that's actually the amount you have to adjust the POINTER on the degree wheel without moving the crankshaft at all. But you rotated the engine to split the calculated difference instead of adjusting the pointer?

With my timing gear marks lined up (as pictured above) I set my degree wheel to TDC (I should have said this earlier!). I then rotated the engine to install my stop. Then I rotated the engine in each direction until it hit my stop & recorded the numbers. I added them two numbers together & divided by two.....which 83 degrees was my number. My degree wheel pointer was showing at the 84 degree mark. So what I did is I backed up the engine 83 degrees, I then rotated my degree wheel to the TDC.

So did I do the above wrong? I hope not.

Also, are you factoring in the additional 4 degrees? because if you come up with 105.5 and then advance the cam 4 you should end up with 101.5 not 97.5. I'm trying to figure out how you only advanced the cam 4 degrees but by your numbers provided you ended up advancing the cam 8 degrees? The 102 is a fixed variable machined into the cam and doesn't change unless you manipulate it by adjusting the crank sprocket. Most recommendations are if you are within one degree either way to not change it, but if you come up with 105.5, by then advancing the cam sprocket 4 degrees your cam should now be at 101.5 when you recheck it.

I thought the same, if I had 105.5 and advanced 4 degree I "should in theory" get 101.5, but I did not get that. I did this process 3 times to verify from scratch and ended up with 97.5......

I will do what you suggest, I will put my piston stop closer to TDC & re-do all of this. To start I will leave my timing marks at the factory setting.

This whole damned thing has me scratching my head.

 

[Blue Ox]

See my first post my friend (it was 97.5 degrees, so 4.5 degree advanced).

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?

 

[QBuff02]

With my timing gear marks lined up (as pictured above) I set my degree wheel to TDC (I should have said this earlier!). I then rotated the engine to install my stop. Then I rotated the engine in each direction until it hit my stop & recorded the numbers. I added them two numbers together & divided by two.....which 83 degrees was my number. My degree wheel pointer was showing at the 84 degree mark. So what I did is I backed up the engine 83 degrees, I then rotated my degree wheel to the TDC.

So did I do the above wrong? I hope not.



I thought the same, if I had 105.5 and advanced 4 degree I "should in theory" get 101.5, but I did not get that. I did this process 3 times to verify from scratch and ended up with 97.5......

I will do what you suggest, I will put my piston stop closer to TDC & re-do all of this. To start I will leave my timing marks at the factory setting.

This whole damned thing has me scratching my head.

Generally how I do it is I put the timing set on and then rotate the #1 piston up to tdc as close as I can by eye and then install the degree wheel and the makeshift pointer on tdc, i'd then back the piston about halfway down the hole and install the piston stop roughly .500 below the deck and bring the piston back up to the stop and get a reading and then rotate the engine the opposite way and get my reading once it hits the stop, once I calculate the number I split the difference by moving the pointer instead of the wheel. You've got a smaller margin of error that way even though the piston is moving X amount of degrees no matter what. I basically want the degree wheel tdc mark to be pointing as close to actual tdc of the piston as possible, and maybe for me its just more of a visual thing. 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.

 

[OldBlueDually]

@QBuff02 I took your words here & will reply....

Generally how I do it is I put the timing set on and then rotate the #1 piston up to tdc as close as I can by eye and then install the degree wheel and the makeshift pointer on tdc Yes, this is exactly what I did.

i'd then back the piston about halfway down the hole and install the piston stop roughly .500 below the deck and bring the piston back up to the stop and get a reading and then rotate the engine the opposite way and get my reading once it hits the stop, once I calculate the number I split the difference by moving the pointer instead of the wheel. Ok, I am further down the hole than .500, I will try your way with around .500. I do NOT move my pointer either. This doesn't make sense to me, I was told never to touch the makeshift pointer.
You've got a smaller margin of error that way even though the piston is moving X amount of degrees no matter what. I basically want the degree wheel tdc mark to be pointing as close to actual tdc of the piston as possible, and maybe for me its just more of a visual thing.

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? Yes, I start from scratch. Even if I were to accidentally bump the pointer or tweak my degree wheel I would start from square 1.

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. I pull the degree wheel, leave the pointer on the block, remove gears/chain, put lower gear at 4 degree and re-install. I then verify the new marks on the gears are lined up, put my degree wheel back on to TDC to the pointer. Then start the process from square 1 with the positive stop.

 

[WesN]

I have never set up a Comp Cams mainly Crane and comparing your card and the last Crane I installed they show the Crane at .050 and the Comp at .006 could this throw things off?

 

[QBuff02]

Ok, I am further down the hole than .500, I will try your way with around .500. I do NOT move my pointer either. This doesn't make sense to me, I was told never to touch the makeshift pointer.

Because depending on the wheel you use there's more risk involved by breaking the bolt loose to try and nudge the wheel a few degrees one way or the other. I have an old Moroso one that gets sandwiched to the crank snout with washers, where some of the newer ones use a threaded type pincher that you can loosen it and slide the wheel one way or the other on the snout more easily. if that makes sense? So once you determine location with the style I have it's easier to bend the wire a few degrees left or right to center it on zero. That's probably why most people and cam companies recommend a coat hanger or mechanics wire instead of a solid type of object as a pointer. It's also the way I was taught. Because if everything is correct you shouldn't have to move the pointer more than a couple degrees one way or the other to "zero" it. So lets throw a couple numbers out there.. say you get everything setup and locked down and then turn the crank clockwise and the wheel lands on 24 degrees when the piston hits the piston stop, but you turn the wheel counter clockwise and when the piston hits the stop it lands on 20 degrees. that's a difference of 4 degrees, so to make it end up an even 22 degrees in each direction either side of tdc, the pointer OR the wheel only needs adjusted by 2 degrees. So you tweak the wire by 2 degrees and now when you recheck it, it's 22 degrees in each direction stop to stop and you now know where true tdc (0) is. You can remove the piston stop and begin to degree the cam.

Not to muddy the waters but when I degreed my cam, I used a piston stop that had a threaded hole with a bolt in the center of it, BUT I have 30cc domed pistons, so I could've removed the bolt and just relied on the dome to contact the stop directly and it would've worked just fine. But I didn't remove the bolt so the center of the dome contacted the bolt on the stop so it ended up about half inch in the hole. The numbers once tdc is located come out the same when you get to degreeing the cam, but they're a bigger gap before you get there. A lot of people will check for finding tdc .050-.100 each direction in the hole. But the closer you are to tdc the better off I think you'll be. With your dished pistons you could probably get away with just a bolt and nut/jam nut through your tubing for a solid piston stop.

 

[OldBlueDually]

Because depending on the wheel you use there's more risk involved by breaking the bolt loose to try and nudge the wheel a few degrees one way or the other. I have an old Moroso one that gets sandwiched to the crank snout with washers, where some of the newer ones use a threaded type pincher that you can loosen it and slide the wheel one way or the other on the snout more easily. if that makes sense? So once you determine location with the style I have it's easier to bend the wire a few degrees left or right to center it on zero. That's probably why most people and cam companies recommend a coat hanger or mechanics wire instead of a solid type of object as a pointer. It's also the way I was taught. Because if everything is correct you shouldn't have to move the pointer more than a couple degrees one way or the other to "zero" it. So lets throw a couple numbers out there.. say you get everything setup and locked down and then turn the crank clockwise and the wheel lands on 24 degrees when the piston hits the piston stop, but you turn the wheel counter clockwise and when the piston hits the stop it lands on 20 degrees. that's a difference of 4 degrees, so to make it end up an even 22 degrees in each direction either side of tdc, the pointer OR the wheel only needs adjusted by 2 degrees. So you tweak the wire by 2 degrees and now when you recheck it, it's 22 degrees in each direction stop to stop and you now know where true tdc (0) is. You can remove the piston stop and begin to degree the cam.

Not to muddy the waters but when I degreed my cam, I used a piston stop that had a threaded hole with a bolt in the center of it, BUT I have 30cc domed pistons, so I could've removed the bolt and just relied on the dome to contact the stop directly and it would've worked just fine. But I didn't remove the bolt so the center of the dome contacted the bolt on the stop so it ended up about half inch in the hole. The numbers once tdc is located come out the same when you get to degreeing the cam, but they're a bigger gap before you get there. A lot of people will check for finding tdc .050-.100 each direction in the hole. But the closer you are to tdc the better off I think you'll be. With your dished pistons you could probably get away with just a bolt and nut/jam nut through your tubing for a solid piston stop.

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?