68 caddy hei distributor

[anviltester]

Finally finished building a new motor for this 68 caddy.  used a 70 500ci block bored 30 over with a bunch of cad company parts inside.  Using a march serpentine front drive.  My question is what her distributor can i use with the motor?  I think i will need a "small cap" to clear the front drive but unfamiliar with them (i usually do sbc and bbc for older trucks of which we use a regular her distributor).  Does small cap just mean an external coil?  Any help is welcomed. Thanks.

[Scot Minesinger]

A small cap with external coil is going to be the way to go, as timing adjustment will be limited.

[bcroe]

HEI is certainly an upgrade, generally the alternator is converted to internal
regulator type as well.  You ought to check belt clearance for the serpentine
belt setup. 

My own preference is to use the large cap with coil if possible.  This will
allow more plug voltage without arc over, and eliminates some potentially
troublesome wiring to a coil.  A beauty of the HEI is cleaning up the
whole spark generator to one component.  Running out of timing adjustment,
it can be moved a tooth engaging the cam for a better position.  Bruce Roe

[TJ Hopland]

I can't find any good pictures of the March setup but the photos I do see if they are actually of a Cadillac motor it looks like that big top bracket gets near the distributor so that would be where your clearance issue may be. 

Factory there was just points and the coil in cap HEI.  IF you want or need a small cap you would have to do a Pertronix sort of thing or go with an aftermarket one which I would assume Cad Co has.   I know MTS has a small cap electronic one.  If you were going coil in cap DUI builds a Cad one. 

A Chev dizzy can apparently be modded to fit a caddy.  Basically the difference is how deep it goes into the motor so a little machining and some collars it can be done.

[Dave Shepherd]

Dui makes a Cad specific Hei dist.

[DeVille68]

My 68 472 had a 74 or later type HEI installed. (big cap).
I now bought a used original distributor and sent it to David Ray: https://www.davessmallbodyheis.com/
It came back beautifully restored. Since my engine is still in the works, I could not test this unit yet. But sure looks very nice.
Aside from the larger HEI terminal spark plug wires, no one can tell.

(if you look closely you see the differences, but just popping the hood no one will notice..)

[mario]

Dave built my points dizzy. Turned it into a small body hei.  Using standard wires and stock coil. Been running it for 15 years, trouble free.
Ciao,
Mario caimotto

[anviltester]

i found a small cap with external coil specifically for the caddy motor.  im going to machine a bracket to bolt to the existing holes in the edelbrock intake to place the coil on so should be clean and easy to get to.  Thanks for all the help.  Now if i can solve the timing issues like having to fig out which of the 6 pointers fir this motor so i can time it properly.  Think this is a call for cameron at cad co

["Cadillac Kid" Greg Surfas 15364]

It seems strange that they developed a serpentine belt system that didn’t accommodate a HEI.
Greg Surfas

[TJ Hopland]

Sounds like a poorly thought out kit if it doesn't come with the proper timing indicator or like Greg says accommodates one of the more popular GM distributors.    All that fancy machined aluminum they couldn't come up with a little piece of plastic or sheet metal for a timing mark?    How has the rest of the fit and finish been on the kit?   Can you post some pictures?   

If you really want to find TDC on a mostly assembled engine you need to get a piston stop.  You end up making 2 marks on either side of TDC where the stop hits the piston then find the center between the 2 marks and that is your TDC.    You don't just try and find TDC direct because there is a few degrees of dwell time as the crank comes over center that the piston isn't moving.