GM HEI on 258?

Thanks for that.

Check out my Skip White HEI notes post
It takes some setting up with springs, vacuum limiter and replacement module for a good performance ignition for pretty cheap - but it's exactly as farna described - engineer yourself and save!
It doesn't seem like much more work or money than getting all the parts for the TFI swap
I love the simplicity of this fat cap HEI on my 258. Looks clean and mean
One issue that was tricky is the mech advance is physically limited by the slots for the weights at 22 degrees
If you want initial timing in the 10-15 range, with total timing 32-40, you might want 26 max mech which has to be accomplished by drilling the slots out 1.2 32nds of an inch, or about .3 per degree. I did 1/32" and got it up to 25
40 seems like a lot of timing for I+M but actually there's a sweet spot around 9.5 compression that benefits from that much. I think I have about that with the way the engine builder put on the 4.0 head. I did 2 different tests that suggested about 43 total timing before vac advance
Once you max out mechanical and initial advance for your sweet spot, vac advance must be severely curtailed.
There are a lot of articles about this for any performance engine with the HEI you want to get it down around 12. This means turning the screw in the can outwards 9 out of 10 turns, and using the Crane vac limiter in the 1st or 2nd most extreme position

mitchito wrote: the Skip White website

A "real" GM module will work. I seem to recall there being two types with different connectors... a four and a five pin?? Can't recall details now, but I'm sure someone with more GM HEI knowledge will chime in.

Needs a late model AMC V-8 drive gear.