Re Curving the Proform Distributor Timing Advance

[Gregski]

So three years ago I bought myself a Proform HEI distributor, with vacuum advance. My truck is a '74 so it predates the factory HEI but I did not intend to keep its points distributor alive. Figure this will be an upgrade.

So just to level set, Proform makes four different black cap HEI distributors for the Chevy Small Block, but as you will see it's really only two styles (cheap and cheaper, lol).

The first style is their cheap line and it has three products in it, same cheap guts just different finishes etc.

PART# 66941BK - BK is for black (this is the one I got)

PART# 66941BKU - same as above but the U is for unpolished

PART# 66941BKM - same as the first one but the M is for Mechanical advance only, so in other words no vacuum can, not so good for street use, so I passed on this one.

The second style is a more expensive GM factory replacement unit with better guts, a melon sized gear (LOL) you know what I mean, and an adjustable vacuum can

PART# 141-682

and this is their Advance Spring & Weight Kit PART# 66948C