Later year HEI distributor on my ‘69 350

Discussion in 'Small Block Tech' started by Entropy11, Oct 15, 2018.

  1. Entropy11

    Entropy11 Active Member

    Hi there. I’ve read mixed things everywhere online. Is there anything preventing me from dropping in a later model year HEI distributor (ie: a 1978 LeSabre 350) into my ‘69 Special Deluxe 350 (2bbl)?

    I ordered all the parts for the Pertronix Ignitor 3 (conversion module, coil, wires,...)
    Only to find the module DOA.

    I’d like to skip that idea (mixed reviews everywhere) and drop in a HEI from a later year. It’s cheaper, I get a new/reman distributor, and I can ditch the separate coil (I’m not overly concerned with stock appearance). “Conversion” distributors also seem to have mixed reviews unless I get into the $400 DUI and MSD territory. This seems like an easy fix for $100 or so with (possibly) better reliability than a $250 conversion distributor or another $100 ignitor 3.

    Did anything change with the later distributors when the smog stuff took over the engine? I already have a 12v ignition switched lead that I’m supplying from my battery via a relay fed by my resistance wire.

    Thanks for any help.
    Nailhead Ronnie likes this.
  2. gsgnnut

    gsgnnut Well-Known Member

    Any buick 350 Hei dist with a vac can should work.
    Nailhead Ronnie likes this.
  3. alec296

    alec296 i need another buick

    Plug wires are different, you really should take resistance wire out of loom and disconnect r terminal from starter. Hei vacuum advance is ussually ported vacuum, and 68-69 can be manifold vacuum. So there would be more mechanical advance built into distributer on the 68-69 distributer. So remember that as you tune timing.
    Nailhead Ronnie likes this.
  4. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD"

    Any Buick V8 HEI will work, it has to have the early 4 pin module. At some point, GM went to a 7 pin with electronic spark control, and those won't work. The Buick 455 was made up to 76 and the Buick 350 to about 79? The amount of mechanical advance built into the HEI's from various years is all different, so if you think you can just stab one in there and run book initial timing, you can't. The big cap HEI can have interference from the front of the intake manifold, the upper radiator hose, and as mentioned use different spark plug wire connections at the cap. An HEI requires battery voltage. The points wiring has resistance which won't work with the HEI. It requires rewiring.
    Nailhead Ronnie likes this.
  5. Entropy11

    Entropy11 Active Member

    Great points from all of you, thx so much.

    I totally forgot about mine being manifold vac and later models possibly switching to ported.

    The plug wires also escaped me... thx.

    I guess my biggest concern was the possible variation in mechanical advance... but that was adressed to. You guys are great and I thank you.

    I guess I’m just back to the drawing board. I thought the pertronix was going to be a quick fix/upgrade, but it showing up doa on top of my reservations of using it based on various feedback has left me searching for a better option. On top of that, after swapping out my faulty vacuum advance during the install, the current distributor has seen better days. When I pulled the shaft out of it I found some decent scoring on it and one of the arms on the mechanical advance portion is tweaked and sits further in at rest than it should. I’m slowly finding all the little things that are making my “new to me” car run horribly and be a pain to time correctly.

    I have my old parts back in now after pulling the pertronix out, but was hoping to have new parts in before I run my cars up to my storage building for the winter.

    I was thinking possibly a DUI unit and just installing it in the spring. I seem to see good things on them (provided I don’t have clearance issues). I’m open to any good suggestions though.

    Thanks again everyone.
  6. Waterboy

    Waterboy Well-Known Member

    Hey Entropy,
    I agree with all said above me. Why did you mention a 78 HEI in the first post? That's what I put in my 68 350 and it works perfect! Got it from the junkyard for cheap. Bought all new electronic parts. It's advantage is 12* initial timing and 20* mechanical timing. Works perfect for me!!! I'm not positive, but I think I read on this forum that if you buy a re-manufactured one it might not be set up with the same mechanical timing.
  7. Entropy11

    Entropy11 Active Member

    Haha- if you had a post somewhere on here I’ve probably read it! I’ve been searching through posts forever because I hate to ask something already covered.

    Funny thing was I saw several posts on various sites mention ‘78 in particular, while other posts and even a Hemming's Motor News article

    mention swapping any post ‘74 Distributor I believe.

    Glad you posted here... I guess I’m throwing this idea back on the table. Lol.

  8. alec296

    alec296 i need another buick

    The hei isn’t a bad idea. Just know what your timing situation is going to be. Look up the distributer number you obtain to know the amount of advance it has. So you can figure what you need and how to tune your engine.
    I used the Mallory conversion kit in stock distributer myself. You can also send your distributer to Everyday Performance for rebuild/conversion. With a recurve. Ken is a member of v8buick. And a Buick owner. He does a nice carb rebuild to gain performance also. .
  9. Mark Demko

    Mark Demko Well-Known Member

    Years ago I swapped in a GM HEI in my 71 GS, best thing I did, yes there are a few minor clearance issues with the big cap but nothing that isn't easily remedied.:D
  10. MrSony

    MrSony Well-Known Member

    Whatever used unit you get, make sure it doesn't have successive amounts of endplay. The shaft can walk up and down causing erratic timing.
  11. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD"

  12. partsrparts

    partsrparts Silver Level contributor

    I have a 68 350 in my 76 skylark with a HEI from TA Performance, it comes with 20-22 mech adv. I have no clearance issues and it is installed with the vac canister pointed forward for plenty of timing adjustments. The dist is set up per Larry's timing thread
  13. 69GS400s

    69GS400s own amusement ride!

  14. Entropy11

    Entropy11 Active Member

    So much great info from everybody agin- thx

    I scrolled through the catalog last night and must have skipped right over that page... dang.
    Looks like it would have been perfect and I’d trust TA more than some no-name place.

    I ended up grabbing a ‘78 HEI dist, cap, rotor, coil, and plug wires (all Delco parts). I just referenced a ‘78 LeSabre V8 350 5.7 in every parts listing I sourced. The important part was VIN code “X”. The only other option was “R”. R appeared to be the Oldsmobile 350 option while the X was the Buick option. The distributor is a Remanufacture of course.

    Parts list in case it all works out/parts to avoid if it doesn’t:

    - 30-1896 Distributor

    - ACDelco D505A GM OEM Ignition Coil

    - ACDelco D336x Ignition Distributor Cap

    - ACDelco D448X Ignition Distributor Rotor

    - ACDelco 9088U Spark Plug Wire Set.

    Looks like three wires off the coil... one black with a ring terminal, one red and one white with spade terminals.
  15. Entropy11

    Entropy11 Active Member

    This should have been my best route I’m assuming but with the time crunch I’m in I was scrambling for an immediate solution.

    I have a feeling I might ship this new one out to him if the mechanical curve is off!

    Things were so screwed up from the start with the one in there now. I know the vacuum advance had issues and that was also replaced when I did the (failed) conversion. I had to be 16-18° advanced at idle to run right and that would skyrocket to 44° at about 2,500-3,000rpm.

    After just a quick startup following reassembly with the old parts (points, condenser, coil) it was already sounding a little better with the new vacuum advance. I figure I’ll try my plan B and see if I can get things 100% before storage. If not, a quick reassembly with the old parts and a time should at least get me to my storage place.
  16. Waterboy

    Waterboy Well-Known Member

    Wow, I'm NO expert, but I argue with my buddy who was a mechanic for 40 years, but 44* degrees is not bad at that RPM if you have no load. You should see the service manual for the vacuum advance at cruising speed. It is way up there with no load.
  17. Entropy11

    Entropy11 Active Member

    Thanks I didnt know that. I was just trying to follow what I was reading about timing and was getting worried because I kept seeing mention of 32° and such.
  18. MrSony

    MrSony Well-Known Member

    Did you check your total timing with the vacuum advance disconnected and the port on the carb plugged? That's how it should be. See what it is without it, then add the advance, and see what it is. What you have after - what you had before will give you how much vacuum advance you have.
  19. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD"

    Vacuum advance needs engine vacuum to operate. Under light load, small throttle openings, the engine can tolerate more advance, the benefits are cooler running and better fuel economy. The vacuum advance canister has a spring inside that opposes advance addition. Engine vacuum has to overcome the spring to advance timing. Engine vacuum is an excellent indicator of engine load. Under cruise light load, the engine develops high vacuum which adds advance. At high throttle openings and heavy load, engine vacuum drops off and will be at or near zero at wide open throttle. The spring in the canister will pull out any vacuum advance under those conditions. Best wide open throttle power needs about 30-34* of Timing. Mid 40’s or more cruise timing gets you best fuel economy.
    MrSony likes this.
  20. Entropy11

    Entropy11 Active Member

    Yep- disconnected and plugged at the carb/manifold port. I was getting no difference with it connected or disconnected that pointed me to the pinhole/crack in the vacuum advance diaphragm. It almost seemed to run better blocked off so maybe the vac leak from the hole was doing that? Or maybe it was all in my head lol. Strange part was that it seemed even with no vac to it, it still had some engagement (as in the little arm wasn’t all the way out where it should have been). Again, nothing I could measure, but it seemed sort of “locked” in position yet not fully out.

    When doing the pertronix conversion I decided to pull the distributor so I could replace the vacuum advance. After dropping the gear off the bottom and pulling the shaft was when I saw the scoring (maybe nothing major, I don’t really know enough) on the shaft. The shaft also has considerable up/down play (1/8-3/16”). I think that play can be shimmed from what I’ve read (?), but the overall condition of the entire distributor is what pushed me to find something entirely new.

    Maybe just having the new vac advance and a fresh vac line made the car sould a little better upon startup, even without timing it. The old vac line held suction, but was hard and I’m guessing the ends (even when I cut them fresh) still were not getting a 100% seal.
    Last edited: Mar 17, 2019

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