Aligning crank timing sprocket with Camshaft front gear - Team Camaro Tech
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post #1 of 27 (permalink) Old Mar 30th, 10, 10:48 AM Thread Starter
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Question Aligning crank timing sprocket with Camshaft front gear

What is the best way to align the crank timing sprocket with the camshaft gear. I would like to get both as inline as possible to prevent timing chain problems? Do you normally have to shim the sprocket or the gear to mke this alignment.

Thanks for all replies ahead of time.

John Lighthart
James Island, SC
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post #2 of 27 (permalink) Old Mar 30th, 10, 06:30 PM
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Re: Aligning crank timing sprocket with Camshaft front gear

I suppose you mean fore and aft movement on an early motor. Most times this can be determined with the condition of the timing chain, ie. new vs. used or single vs. double row chain. This can also be achieved with after market torrington type bearing and wear plates between cam gear and block. But on an early motor the flat tappet cam wants to walk forward and if you dont have a cam gear button or some device to keep the cam from doing so, your gear alignment is apt to go forward as far as the timing chain will allow or eventually wear thru the timing cover in severe cases. . Late model motors with the cam retaining plate keep this from happening but they are also factory rollers. Flat tappet cams are off center a little to keep lifter spinning in lifter bores to keep the wear patterns down.

If its a later model motor ie. one piece main seal type factory rollers, they have a bolt on wear plate to the block that is specific to that cam. Keep in mine early cams differ from late model cams. Hope this helps. Some one else may chime in here if they have found something else.

Don
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Last edited by zdld17; Mar 30th, 10 at 07:50 PM.
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post #3 of 27 (permalink) Old Mar 30th, 10, 08:23 PM
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Re: Aligning crank timing sprocket with Camshaft front gear

Quote:
Originally Posted by zdld17 View Post
But on an early motor the flat tappet cam wants to walk forward and if you dont have a cam gear button or some device to keep the cam from doing so, your gear alignment is apt to go forward as far as the timing chain will allow or eventually wear thru the timing cover in severe cases. . .
Don - I always thought the flat tappet cam lobes were ground kinda like this
\ / \ / \ / \ / etc. to keep the cam from walking forward and the lifters keep it in place. I don't recall that the factory used anything in the way of a cam button on the flat tappets, solid or hydraulic.

I was under the impression that since a roller cam can't be ground like that since the roller has to be square to the lobe, that a cam button or a retention plate was used to keep the cam in place. I've been wrong before, however, so please correct me if I am here.

(Maybe you meant to say "roller" above?)


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post #4 of 27 (permalink) Old Mar 30th, 10, 09:16 PM
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Re: Aligning crank timing sprocket with Camshaft front gear

If your aligning dot to dot, it's pretty straight forward. Place the cam sprocket and rotate the cam accordingly to align the crank dot, rotate one full turn, if they are off by the slightest bit after one full turn, take the sprockets off and retry, if this is what you are talking about?

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post #5 of 27 (permalink) Old Mar 30th, 10, 10:23 PM
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Re: Aligning crank timing sprocket with Camshaft front gear

BPOS you are wright, you can add a cam button but there is no need. Line on both sprocket shoud align unless installing a use wear timing chain.
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post #6 of 27 (permalink) Old Mar 31st, 10, 05:35 AM
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Re: Aligning crank timing sprocket with Camshaft front gear

Quote:
Originally Posted by BPOS View Post
Don - I always thought the flat tappet cam lobes were ground kinda like this
/ / / / etc. to keep the cam from walking forward and the lifters keep it in place. I don't recall that the factory used anything in the way of a cam button on the flat tappets, solid or hydraulic.

I was under the impression that since a roller cam can't be ground like that since the roller has to be square to the lobe, that a cam button or a retention plate was used to keep the cam in place. I've been wrong before, however, so please correct me if I am here.

(Maybe you meant to say "roller" above?)
You are correct in your thinking on both, I have alway made it a habit on using some type of button or roller bearing on either cams.

Don
TC # 349
Zdld17:69 Z/RS,306, NOR141111, 9N554XXX, 12A, X3G, 59/59,723, AFR 195,CCC282/290HR, TKO 600, BU1122B1E Owner since Dec 1968

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post #7 of 27 (permalink) Old Mar 31st, 10, 06:42 PM
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Re: Aligning crank timing sprocket with Camshaft front gear

John,
If both sprockets are manufactured properly and the front of the block is not worn, there should not be an issue with the alignment. I have only used a cam button on roller cams and have never had a problem.

Bill Koustenis
Owner
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Waldorf Md
1971 Chevelle "Heavy Chevy" original owner


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post #8 of 27 (permalink) Old Mar 31st, 10, 07:32 PM
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Re: Aligning crank timing sprocket with Camshaft front gear

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Originally Posted by BillK View Post
John,
If both sprockets are manufactured properly and the front of the block is not worn, there should not be an issue with the alignment. I have only used a cam button on roller cams and have never had a problem.
same here

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post #9 of 27 (permalink) Old Mar 31st, 10, 11:35 PM
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Re: Aligning crank timing sprocket with Camshaft front gear

Fwiw many years ago the guy (Hamner Perfromance) that machined/ built my 400 block used a cam button w/ the flat tappet cam and a matching timing cover.
He installed a bb oil pump with a Canton racing oil pan. He also epoxied screens in gally holes. Roundy round thing I think I dunno.

I figure it can't hurt a bit having the cam button and the other mods too.

1967 convertible T-1
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post #10 of 27 (permalink) Old Mar 31st, 10, 11:59 PM
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Re: Aligning crank timing sprocket with Camshaft front gear

Assuming you are referring to a Flat Tapped Camshaft, if you look at the push rods, they spin in the direction in which the Lifter Rotates on the bevel of the Cam Lobe. For a SBC the lobes order on the cam, from of the front are EEIIIIEEEEIIIIEE and with lobes beveled \ / \ / ...etc. I believe all the Push Rods rotate Clockwise on the Driver Side and Anti-Clockwise on the Psgr Side or Visa-Versa - Been awhile since I`ve ran a FT Cam ;o)

There is no need for Cam Buttons or Wear Plates with FT Cams as the Bevel will hold the cam in position relative to the Lifter Bore Locations. If a Push Rod does not rotate, it's a sign that the Lobe maybe be flattening.

A Roller Cam in a Retro-Fitted FT Cam Block is another Story.

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Last edited by Z15CAM; Apr 1st, 10 at 12:13 AM.
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post #11 of 27 (permalink) Old Apr 1st, 10, 12:15 AM
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Re: Aligning crank timing sprocket with Camshaft front gear

Quote:
Originally Posted by Z15CAM View Post
Assuming you are referring to a Flat Tapped Camshaft, if you look at the push rods, they spin in the direction in which the Lifter Rotates on the bevel of the Cam Lobe. For a SBC the lobes order on the cam, from of the front are EEIIIIEEEEIIIIEE and with lobes beveled / / ...etc. I believe all the Push Rods rotate Clockwise on the Driver Side and Anti-Clockwise on the Psgr Side or Visa-Versa - Been awhile since I`ve ran a FT Cam ;o)

There is no need for Cam Buttons or Wear Plates with FT Cams as the Bevel will hold the cam in position relative to the Lifter Bore Locations. If a Push Rod does not rotate, it's a sign that the Lobe maybe be flattening.
I'm confused now... I don't understand what you mean by \ / \ / and I'm pretty sure you can rotate the push rods both counter and clockwise.
Since the firing orders are the same, the roller should also have the same order of lobe, but the egg shape is harder to keep the cam from walking?

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post #12 of 27 (permalink) Old Apr 1st, 10, 02:56 AM
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Re: Aligning crank timing sprocket with Camshaft front gear

Quote:
Originally Posted by Z15CAM View Post
Assuming you are referring to a Flat Tapped Camshaft, if you look at the push rods, they spin in the direction in which the Lifter Rotates on the bevel of the Cam Lobe. For a SBC the lobes order on the cam, from of the front are EEIIIIEEEEIIIIEE and with lobes beveled / / ...etc. I believe all the Push Rods rotate Clockwise on the Driver Side and Anti-Clockwise on the Psgr Side or Visa-Versa - Been awhile since I`ve ran a FT Cam ;o)

There is no need for Cam Buttons or Wear Plates with FT Cams as the Bevel will hold the cam in position relative to the Lifter Bore Locations. If a Push Rod does not rotate, it's a sign that the Lobe maybe be flattening.

A Roller Cam in a Retro-Fitted FT Cam Block is another Story.
Seems like I recall the engine builder (http://www.hamnerracingengines.com/) said there is still some room for the camshaft to walk forward even on a flat tappet camshaft but like I said I figure it can't hurt anything with a cam button on a FT, and this guy builds lots of race winning motors in circle tracks so I told him to do what he thought best for my 400.

I realize also that it is not needed in FT's but it can't hurt.

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post #13 of 27 (permalink) Old Apr 1st, 10, 08:25 AM
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Re: Aligning crank timing sprocket with Camshaft front gear

Quote:
Originally Posted by HOGDADDY View Post
Seems like I recall the engine builder (http://www.hamnerracingengines.com/) said there is still some room for the camshaft to walk forward even on a flat tappet camshaft but like I said I figure it can't hurt anything with a cam button on a FT, and this guy builds lots of race winning motors in circle tracks so I told him to do what he thought best for my 400.

I realize also that it is not needed in FT's but it can't hurt.

Long ago, Jenkins and Smokey wrote articles about this topic. Good enuff for me. Also too much movement forward changes dist/cam gear wear patterns. But then many of us have motors in our older cars that ran many miles the way GM designed them orginally.

Don
TC # 349
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post #14 of 27 (permalink) Old Apr 1st, 10, 08:57 AM
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Re: Aligning crank timing sprocket with Camshaft front gear

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Originally Posted by ace's68 View Post
I'm confused now... I don't understand what you mean by / / and I'm pretty sure you can rotate the push rods both counter and clockwise.
Since the firing orders are the same, the roller should also have the same order of lobe, but the egg shape is harder to keep the cam from walking?
John -

The / \ / \ on a flat tappet means that half of the lobes have a slight incline toward the rear of the block, and half have a slight incline toward the front. Not enough that you see just by looking, but it's there. The result is that they kind of work against eachother, keeping the cam from moving fore or aft (more or less.) That slight incline aslo causes the lifters to spin in their bores.

Rollers need to be dead nuts straight up and down, because the roller wheel would cause a train wreck if it spun in its bore. Hence the need for a cam button or a retaining plate to prevent the cam from walking.

I never knew these old things were so sophisticated......


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post #15 of 27 (permalink) Old Apr 1st, 10, 01:06 PM
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Re: Aligning crank timing sprocket with Camshaft front gear

Quote:
I realize also that it is not needed in FT's but it can't hurt.
YES you can Destroy a FT Cam using an Anti-Cam-Walk Device, as it is difficult to locate the Neutral Position of the Cam determined by the Lobe Bevel against the Spinning Lifter observed by the rotation of the Push Rod. If you install an Anti-Cam Walk Device with a Forward Walk Stop/Back Kick Wear Plate to limit Fore-Aft movement, by say .004", in the wrong location it can cause undo pressure and wear on the Lobe Bevels of the cam against the Lifter.

DO NOT use Anti Cam Walk Devices on FT Cams PERIOD. By design Anti-Cam-Walk devices on FT Cams are NOT REQUIRED. The Alternating Bevel machined into each Lobe of a FT Cam is the Anti-Cam-Walk Device and if not Machined within tolerances by cam Mfgr's is probably, in my opinion, the main culprit for FT Cam Failure as apposed to ZDDP content in Oil.

Roller Cams Walk Forward due to the inherited misalignment of the Lifter Bores in Retro Fitted FT Chevy Blocks - was not considered critical due the the Anti-Cam-Walk Bevel Machined into the Chevy Cam Lobe (I believe Backward in Fords) and Anti-Cam Walk Devices ARE Required. If the Lifter Bores are Machined True, as they are in modern Roller Blocks, over sized Lifter Diameters are usually used in FT Blocks. This will Eliminate Cam-Walk and undue pressure on Roller Pins but does not Eliminate the need for Anti-Cam-Walk Devices due to Harmonic Kick.

I was a Teen in the 60's with my head under the hood of every Muscle Car and build my 1st Engine when I was 11 - a 54 Straight 6 Pontiac ;o)

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Last edited by Z15CAM; Apr 1st, 10 at 02:11 PM.
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