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New timing gears - changed design?


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Posted

I was looking around to get a timing gear set and noticed the new double row ones like mine have squared off valleys in the teeth. Seems like the originals fitted tighter with rounded teeth/valleys. Does anybody think there will be a quality difference? I don't think mine wore like that.

Timing gear comparison.jpg

Posted

Just a different design between manufacturers. Nothing to worry about. However, it makes it very important to get your sprocket and chain set from the same supplier because of this. Another member here discovered this recently when he got a miss matched set and the chain wouldn't work properly with the sprockets. 

  • Like 2
Posted (edited)

The one thing that tossed me for a loop was after I mounted the thing in place I noticed that the two gears were NOT in the same plane. I had to order shim stock and jet cut some shims to move out the crankshaft sprocket a little to have both gears dead flat on the same plane. All new gears and chain.

 

When you start mixing crankshafts, camshafts and new gears, sometimes something is not going to line up.

 

JamesPerfect.jpg.2b4e4be0eb2dd0ec77a8c2f4b7baa587.jpg

Ten_and_Three_Thou_Shims.jpg

Thirtey_Three_Thou_Shims.jpg

Edited by James_Douglas
  • Like 1
Posted (edited)

As Merle said, I doubt it matters whether the sprocket has square or round valleys, as long as the chain and sprockets are matched to each other.  I have sprockets that are square bottomed and others that are round bottomed (different engines, but both flatheads and they worked fine).

 

I have pics of a double row crank sprocket with square bottoms and another with round bottoms.  Í just got a new phone and am having trouble posting them, but let me know if you want to see them and I'll get them posted.

 

Oh, and I'm the guy Merle was talking about who was having trouble with the mismatched timing set, so I've gained some familiarity with these parts.  Still working on that, but I'm sure we'll get it worked out.

 

Edited by Matt Wilson
  • Like 1
Posted
On 1/6/2022 at 8:29 PM, James_Douglas said:

The one thing that tossed me for a loop was after I mounted the thing in place I noticed that the two gears were NOT in the same plane. I had to order shim stock and jet cut some shims to move out the crankshaft sprocket a little to have both gears dead flat on the same plane. All new gears and chain.

 

When you start mixing crankshafts, camshafts and new gears, sometimes something is not going to line up.

 

James

James, I wonder if you have a later camshaft hub on your camshaft, paired with an earlier crankshaft or crankshaft sprocket.  It was recently pointed out to me in a separate thread in the truck forum that there was a change of part numbers at a certain point in time. 

 

I have what I believe to be an earlier camshaft and sprocket hub and a later camshaft and sprocket hub in my possession, and they are nearly identical (and certainly appear that way visually), but the later hub is a little thicker in the bolt flange than the earlier one, and this seems to result in a greater distance from the back of the thrust plate to the front of the hub flange, by about 0.010 -0.012".  This would place the sprocket forward by that amount.  Is this about the amount you had to use when shimming, in order to get the two sprockets to line up?

 

I'm putting together a later block and cam with what I think may be an earlier crankshaft, so I'm wondering if I'll need to swap hubs from the earlier cam to the later cam to get the sprocket spacing correct.  Of course, I'll do a test of the parts as they are currently before making such a swap, but I'm trying to get a heads-up to be a little more informed.

 

Thanks.

Posted

I think is was a lot more on the order of 30 thousands. I have a photo that is labeled "thirty-three-thou". In any case I would mount what I was going to use and do what I did which was take a long straight edge and place it on the large gear and see if the small gear is on the same plane. If not, shim it out until it is. The shims do not rotate separate from the gear or the shaft to once on they will never wear or cause any other issues. Having the chin not have any side thrust is a very good idea!

 

James

Posted
20 minutes ago, James_Douglas said:

I think is was a lot more on the order of 30 thousands. I have a photo that is labeled "thirty-three-thou". In any case I would mount what I was going to use and do what I did which was take a long straight edge and place it on the large gear and see if the small gear is on the same plane. If not, shim it out until it is. The shims do not rotate separate from the gear or the shaft to once on they will never wear or cause any other issues. Having the chin not have any side thrust is a very good idea!

 

James

Yes, absolutely, you don't want those sprockets to be misaligned... very bad way to run.  I'll be sure to check what I've got first, before changing anything.  Where did you get the shim stock?  I suppose it can be found on Amazon, but maybe there are better sources.

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