Inliners International Forums General Discussion Engines Question: differences in pre & post 75 HEI distributors

Normally I am a very methodical person who keeps written notes and tags parts. Katrina is responsible for my doubts in this case. The 250 CID pre 75 distributor has a longer shaft and a different drive gear than does the 75 and the post 75. The gears are in a different location on the shafts as well. Am I correct? I am not sure where or when I obtained the pre 75 but am 99% sure that the post 75 is off the block I just rebuilt. Are there any other differences of which I should be aware? On the same subject but a different incident; I remember in the distant past replacing a points distributor with a HEI and having trouble with the cap jamming against the block/head. My notes indicate I filed the cap slightly to gain the needed clearance. If I am correct this info may be of use to others who read this post as well as to me. Thank you in advance for your help. Ray 3450

I have NEVER had a Need to file any HEI going in place of a Old Point unit. even a 80s dist will work In a Points dist. Place. So not sure what or where your problem came in.

I have both the 74-75 HEI (external coil) and the later coil in cap putting both side by side I see very little difference in the lenght. The problem of the cap jamming up against the side cover or block does exist. I've mentioned that in previous posts. Filing the cap is one solution. You can also reposition where number 1 is, by moving the distributor gear backwards or forwards on the cam gear. Then turn the oil pump drive with a long screw driver till the distributor drops in. It takes some trial and error, but you should be able to find a spot where you get at least 0-10 degrees movement. I thought this was only a problem with 292s.
Larry

Now that 292's are mentioned, I did have a PU with a 292. As I mentioned, I have lost a lot of my info but the clearance problem may have been on a 292. I clearly remember the problem, but not many details. Since I have no clear idea where I came across the distributor I classisfied as pre 75, it may be something else from a vehicle I helped someone else work on. I generally do not fool with anything but Chevy.Ray