+003 Timing Gear

[Biggles]

One of my aluminium timing gears is stamped "+003".
Has it been drilled to give 3 degrees advance to the camshaft, or what?

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[Mart]

Hi Neil. As it is quoted in thou rather than degrees would it be more intuitive to assume it might be to cope with a block that has been line bored and has had the crank bore raised by .003"?

Just guessing, mate, but while I do believe gears exist for such a scenario, I don't know how they would be marked.

Mart.

 

[Charlie ny]

Big,
The pitch diameter of the gear is .003 over the mean size. This would perhaps
'tighten up' excessive lash..........maybe.
Charlie ny

 

[flatjack9]

It is .003 oversize.

 

[Mart]

That does make more sense.

Mart.

 

[Tim Ayers]

Seems odd that this even exists. So the crank gear is worn so you put on a larger cam gear?

 

[flatheadmurre]

Yep i have them in .006 to...easier to change to a oversize camgear then change the gear on the crankshaft...

 

[Tim Ayers]

Yep i have them in .006 to...easier to change to a oversize camgear then change the gear on the crankshaft...

I guess so.

 

[Biggles]

Thanks, Barners.

 

[Kube]

It is .003 oversize.

This is correct. These were quite common many years ago.

 

[Ol' Ron]

Back in the day, blocks were milled over the Main bores to fit new caps, then line bored to a standard size, THus the Smaller gear. When I did this, I made a fixture to cut the caps. I took .005" off the cam and aligned the block, cutting only a few tents from the block. Then you could use a standard timing , Willbe using it soon have a Good block with no caps????? gear