MCfan Posted February 29, 2012 Share Posted February 29, 2012 I'm looking for answers and advice on rebuilding and swapping a stock GM HEI distributor into my '70 402 car. Specifically, I need to know how much shaft end play is acceptable and what certain numbers mean that are stamped on the internal parts. Although I have an Accel points eliminator in my stock distributor (came to me that way), I have been contemplating the swap of a stock GM HEI unit. I picked up one in a parts swap recently and have been cleaning and rebuilding it. I've never played with an HEI before so I downloaded instructions from the internet on the basics of removal, disassembly, reassembly and installation. I also took pictures of the unit and tracked parts carefully so I wouldn't assemble it incorrectly or leave parts on the bench. Well, it all looks correct except that there is .085" of vertical shaft end play (see photo below). That amount of end play was there when I disassembled it so I didn't leave any shims out, but it just doesn't seem right. With the helical drive gear, it seems like excessive end play could affect the radial positioning of the rotor relative to the fixed housing, introducing a variation in the timing. I recently disassembled my stock Delco Remy distributor and it had enough flat shims in place to virtually eliminate shaft end play. Does anyone know how much shaft end play is acceptable or recommended for a GM HEI? Also, I am wondering if the numbered internal parts will be correct for my 402. In the photo below, the mechanical advance weights are each stamped with "106", the spring post retainer is stamped with "361" and the tongue of the vacuum advance is stamped with "624 20". I think the "20" means 20 degrees of maximum vacuum advance, but I haven't a clue what the other numbers mean. I assume the mechanical advance curve is set with springs of various tensions like the my original distributor. Finally, are there any other electrical components (i.e. ballast resistors, etc.) than need to be deleted, replaced or added to make this swap? Many thanks for any answers or advice! Quote Link to comment Share on other sites More sharing options...
Leghome Posted February 29, 2012 Share Posted February 29, 2012 I do not have any answer for your questions. My 72 came with an HEI but it has an MSD box so the only thing in my HEI is the rotor, big coil on top and the pickup coil in the bottom. It works good but thought about eliminating the MSD box and going with a total electronic MSD ignition that my son in-law has. Quote Link to comment Share on other sites More sharing options...
Mo's70MCs Posted February 29, 2012 Share Posted February 29, 2012 Dennis, On my daily driver I vowed to quit sinking big money on the old blue streak points, I used to buy quite often. So in searching for an inexpensive HEI setup I stumbled on this Ebay seller and I thought hell it can't be, it must be a cheap unit. Well much to my surprise it's been working trouble free for almost two years. It's beaten the amount of mula I've sank in the past for a decent set of points. Not to mention how it just woke that old 350 up.. like night & day. Have you considered buying an inexpensive unit? I was pleasantly surprised. linky I couldn't buy a used unit & re-built it for that much..I haven't touch it since I dropped it in. Only disappointment made in CHINA. Quote Link to comment Share on other sites More sharing options...
stangeba Posted February 29, 2012 Share Posted February 29, 2012 Haven't done mine yet but I do know you need a 10 gauge wire running 12 volts NO RESISTOR. Your vac can is 20 degrees max advance but I don't know how much vacuum it takes to get it there, attach a hand pump and test it. Good luck Bruce Quote Link to comment Share on other sites More sharing options...
monte70car Posted February 29, 2012 Share Posted February 29, 2012 We rebuilt a HEI dis over the weekend in the kit it came with an adjustable vacuum advance can, also new weights and three different springs. For a big block they say to use black springs which starts the curve at 600 rpms and is good up to 4500rpms. Quote Link to comment Share on other sites More sharing options...
black07ss Posted February 29, 2012 Share Posted February 29, 2012 Dennis, On my daily driver I vowed to quit sinking big money on the old blue streak points, I used to buy quite often. So in searching for an inexpensive HEI setup I stumbled on this Ebay seller and I thought hell it can't be, it must be a cheap unit. Well much to my surprise it's been working trouble free for almost two years. It's beaten the amount of mula I've sank in the past for a decent set of points. Not to mention how it just woke that old 350 up.. like night & day. Have you considered buying an inexpensive unit? I was pleasantly surprised. linky I couldn't buy a used unit & re-built it for that much..I haven't touch it since I dropped it in. Only disappointment made in CHINA. Good to know Rod!! I saw that HEI last year and I thought it was a scam or a piece of junk Quote Link to comment Share on other sites More sharing options...
Mo's70MCs Posted March 1, 2012 Share Posted March 1, 2012 Good to know Rod!! I saw that HEI last year and I thought it was a scam or a piece of junk Bob, Not to hijack the thread.. I was also apprehensive at first but after seeing the price. I said to myself...you've thrown away more money at buying a decent work-tool (Klein) and been pleasantly disappointed. Quote Link to comment Share on other sites More sharing options...
Big Jim Posted March 1, 2012 Share Posted March 1, 2012 My car has a similar distributor made by Proformance. I think I paid $75.00 for it similar source. No problems so far. Quote Link to comment Share on other sites More sharing options...
wallaby Posted March 3, 2012 Share Posted March 3, 2012 Here's a pretty good write-up on the procedure: LINKY Quote Link to comment Share on other sites More sharing options...
70mcarlo Posted March 4, 2012 Share Posted March 4, 2012 That's a very good write-up, Mark. I printed it out for future reference. Thanks! Quote Link to comment Share on other sites More sharing options...
jacob Posted March 5, 2012 Share Posted March 5, 2012 hope it woks good Quote Link to comment Share on other sites More sharing options...
MCfan Posted March 5, 2012 Author Share Posted March 5, 2012 Here's a pretty good write-up on the procedure: LINKY Many thanks for the link to that excellent HEI document, Mark! That is exactly what I needed! Certainly confirmed my suspicions about excessive end play causing timing variations. I will get one of those shim kits and tighten the end play up to no more than .010" before I try to install it. Also, great photos and information on heat conducting grease, performance coils/modules, 10 ga solid copper lead wire and proper timing suggestions for street versus track. I still need to get a new rotor and a set of wires before I can even try it. This information should keep me out of trouble. Thanks again for sharing such a useful document! Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.