another electronic ignition in a '73 Riviera


Active Member
RE: Another '73 Boattail electronic, high-energy ignition done!!

Alright, there were a few stumbles in this one. After installing the accel 71105 distributor with their best high-current 35366 ignition module, accel 8.8mm spiral-core wires, regapped AC-Delco R45TS 0.065" gapped plugs, a hidden 12V ignition switch wired and fused directly to the battery (this makes for a cheap security system) and another Jacob's Ultra Coil (one of the best performance/dollar parts I've come across), it wouldn't run. Matching up the slot on the top of the oil pump shaft wasn't that hard (about four tries, using a regular flat screwdriver), although when I did, the rotor wasn't aligned with my orientation marks. I was so frustrated, after trying to get the distributor seated correctly, that when I did, I didn't want to remove it and reinstall it. I thought if I made sure that the rotor pointed to same plug wire tower#, I could adjust the timing to get the engine running. WRONG!!

Finally I had to take it to a mechanic, who said the #1 cylinder at TDC approach would have to be used. Reading various methods to do that by taking off one valve cover and checking when both intake and exhaust vales were closed by cranking the crankshaft didn't seem overly complicated. But I was working on the car just by myself with no one to crank the engine. Another method mentioned was using a screw-in 30" tube filled with oil in the #1cylinder spark plug hole, and watching and measuring the fall and upward movement of oil in the tube, which corresponds to the movement of the piston also seemed somewhat daunting.

But in the end, even if I had done all those things, they still wouldn't have worked. The mechanic told be the air gap between the magnetic pick-up and the reluctor was way off (it's supposed to be 0.002"-0.005"). I thought on a new, expensive distributor that would be preset Now, I know I need to buy some feeler gauges.

I guess it's all apart of the learning curve. With every mistake or overlooked item, you do learn something in the process for the next time

**Let me tell you what HUGE difference this system has made in the performance of my second '73 Boattail and the weak GM HEI in my '76 Riv. It was running alright with points and a less powerful jacob's coil for points. The old spark plugs were remarkably clean. And some sources I read said that high-performance ignitions are overkill because the ignition only uses enough spark energy to cross the spark plug gap, and the rest of all these advertised high-output coils and ignition boxes is unneeded. What this doesn't take into consideration is using bigger spark plug gaps, which jacob's electronics say is the key to to extracting any benefits to a hi-energy ign.system. Because normal GM HEI's used 0.060" gaps, I thought I'd try 0.065" gap, which worked out GREAT, because my ign. components produce more spark energy at low and high rpms than GM's stock HEI's. Also, unlike points, most e-ignitions take the full 12V all the time. Now the idle is silky smooth, throttle response is much more responsive, and general engine performance is improved. I'm just amazed what a great ignition system can do to for a street car; the difference is startling. Hopefully mpg will improve. jacob's actually guarantees it. Beffore I was getting 8.9mpg when I checked the initial timing before taking out the points distributor ( It was set at 0 degrees BTDC!!No wonder why my gas mileage was so poor!) I bumped it up to 10. In my '74 Buick service manual, there are two timing spec's for 455's---4 +/-2 degress BTDC for the stock 455 and 10 +/-2 degress for the Stage 1 L75 engine. At 10 degrees BTDC, it seems to run much better. I've read somewhere to use as much intial timing as possible, until pre-ignition occurs.

So was it worth it? Yes. Even though I needed some mechanic's help at the end, it was worth it to learn something.


Active Member
And I highly recommend the following instead of GM's HEI:

--MSD has a new line of Buick ready to run distributors (finally!!!), for 400/430/455's and even nailheads, that just need a good coil with < 1ohm resistance. your points coil won't work because they have higher resistance; and on a electronic ignition a >1ohm coil will cause the ign module to overheat.
--Accel 71105 Buick Billet distributor with one of the most powerful ign modules in it (I bought the same one for my '76 Riv's HEI at Summit for $70)
---the old jacobs' Ultra Coil-which looks like a huge box with blue anodized heatsinks. The coil will fire almost any spark plug. In my '63riviera with an Ultra Coil, whose carb runs rich, I found the plugs to be clean from carbon deposits, even after 20,000miles.

--I feel the conversion kits just are just not worth the time and money, when you can drop in a new electronic distributor in less time. I've used many Mallory Unilite modules that have had premature failure, leaving you completely stranded. Accel's and MSD's magnetic pick-up principle has been used and perfected for years.

--Many people do modify GM HEI with good results. Everyone knows the inherent flaws with HEI-- decreased spark energy above 4500rpm. It had a compromised design, which, although integrated, could have been improved with better, external coil. But after buying a new high kVolt in-cap or external coil, ign. module, wiring harness, capacitor, reluctor, advance weights, a quality dist. cap and rotor with high dielectric properties and restoring the shaft, which may have some wobble due to worn bearings; the price can easily approach a quality electronic distributor like the MSD or Accel units. I know, because I've done both methods. And sometimes saving time is worth the extra money that self-contained new distrutors cost. New e-distributors are usually made of close-tolerance, machined billet, have smoother shaft bearings and higher-quality parts.

---Spark plug wires. There are a lot of good ones out there--MSD, Accel, jacobs, Taylor, etc. Just make sure they're spiral core and not suppression core. You definitely can't use solid core wire because of the EMI/RFI interference with the electronic parts in the system

---spark plug gapping--an often overlooked part of ignitions. Even if you buy all this expensive ignition equipment, you won't get the full benefits unless you increase the gap to make a hotter/stronger/longer spark.

Most of this stuff can be found on ebay cheap.
Last edited:
Sounds great Steve! I don't know if you saw the bit I wrote about timing your engine here

Another thing about spark plug gap and wires is that as you increase your plug gap you encourage the spark to find another route to ground, often through crossfire or directly to ground through poorly routed plug wires. Wires should be at lease 1/2" apart when running parallel and when the cross as close to 90 degrees as possible. When proper clearances are in question, don't be afraid to add some of that plastic wire loom that you get from your auto parts store to any areas in question.:thumbsup: :thumbsup: