I am running a large cap dizzy with a hyd. roller cam and would like to change the dizzy gear to the factory 1991 melonized gear.



Are the large cap and small cap SBC distributor gear sizes the exact same?

 

Not sure about the sizes but you are generally better off with a harder gear.

 

They're all the same.

 

Thanks. What would be the difference between the .500 and .491 sizes I am seeing?

 

Aftermarket distributors use a heavier .500" shaft.

 

The small cap distributors need a tiny 0.427" shaft gear

 

So I'm assuming a stock GM melonized dizzy gear from say the 1991 model year probably won't fit an eBay special large cap dizzy?

 

91 is when they started using the small cap with the externally mounted coil. The small GM small cap is a computer controlled distributor with no weights or springs inside it.

A small shaft sized gear for a small cap won't fit on a large cap or aftermarket distributor. I suppose if you had a lathe or milling machine to accurately enlarge the hole, it would work. Cheaper to just buy the proper gear.

 

The Corvette only used the big dist. The new gm gears are support to melonized. I got a bronze one for my small dist. Crane makes them.

 

hmmm....thanks for the information Setphen.


So is there a GM melonized gear that would fit onto the large cap dizzy I have? I've found some on Summit's site but don't know my exact size....I still see the .500 and .491 sizes which I do not know the difference between.

I cannot justify 50+ bucks for a dizzy gear when the GM melonized one (that probably won't fit) is less than $30.