This page grew out of my Buick HEI Conversions page. As I learned more about what Buick distributor housings would fit into the various engines and about the later model computer controlled HEI distributors, I realized that it should be possible to create a computer controlled HEI distributor for the Buick V8 engines that were never offered with EFI. This page documents the research I've done on this conversion in preparation for being able to put a TBI style EFI system on one of my Buick 455 engines using all factory parts. Much credit for the basic information on this particular page goes to Jürgen Sadil who wrote in to give me details about the computer controlled HEI conversion work he did for his vehicle and what pitfalls he ran into along the way. Without his help, I would have been scratching my head for quite a while longer than I already have been to get this all figured out.
This swap works because pretty much every Buick V8 engine built after the Nailhead series of engines (300, 340, 350, 400, 430, 455, and likely the 215 as well) and all V6 engines until they switched to using a Distributorless Ignition System (DIS) in the '80s (with the possible exception of the pre 1964 V6 engines, similar to the 215 V8's) used the same basic distributor housing. The distributor gear varies with the 400, 430, and 455 units being different than the rest, but that can be interchanged easily enough to make this swap a reality. The HEI units are taller and larger than their older points style cousins, but they do fit. This is a condensed form of the information found on my Buick HEI conversions page - if you want more details on the interchange and how the basic process works, you should read that page first, then come back here and finish reading this page. Note that you may not be able to get this swap to work on the early "odd fire" V6 engines unless you can get the right "odd fire" magnetic pickup to work in this conversion. I have not researched if it is possible to use a pre-computer controlled magnetic pickup with the computer controlled HEI module. If you find out that does work, please email me and let me know.
Starting in the early 1980's GM started putting computer controlled electronic fuel injection on various engines. To make that work, the computer needed to be able to control the timing, and thus GM had to change the standard HEI style distributor a bit to get this to work. The changes were minor and common to all of the HEI systems - similar to the pre-computer controlled HEI units, they were all identical under the cap and all that differed was the part of the distributor that went into the engine. The changes consisted of removing the mechanical and vacuum advance pieces, using a new HEI module with 7 pins (connections) instead of the earlier 4 (or sometimes 5) pins, and adding a separate 4-wire connector on the distributor to connect to the computer. The magnetic pickup unit inside the distributor was similar in design, but slightly different in execution.
The basic idea is to combine the later model V6 distributor housing/shaft with your existing distributor gear, then add Chevy V8 style electronics/internals from the same year as the donor distributor, and if you do it right you should get a EFI-ready distributor for your early Buick engine made will all GM factory perfect GM parts. As always, the trick is getting all the right pieces and getting it all to work right when you're done.
Buy or Build
Doing this conversion is conceptually straightforward, but one detail makes it impossible for the average shade tree mechanic to complete it at home for V8 engines. The magnetic pickup wheel that needs to be changed from a V6 to a V8 unit is pressed onto the main shaft and cannot be removed without special tools than I do not have. If you look closely in the photos below, you can see that the shaft is splined so that the pickup and rotor mount cannot move relative to the shaft. I also do not know how the V8 magnetic pickup wheel needs to be installed - it must be "phased" correctly relative to the shaft - or where to purchase one from. Since V6 conversions do not have this problem, they can be successfully converted at home using simple replacement parts available from any well stocked auto parts store.
If you wish to purchase a rebuilt unit with this conversion work already done, I have been informed by Jürgen Sadil that Philbin can custom rebuild V6 units and convert them to V8 usage if you ask for it. Their part number on the V6 unit is 1671 - see http://philbingroup.com/rebuilt/catalog/part/15-1671.html for details on what it fits. They offer a ton of rebuild distributors for all kinds of engines - see their catalog page for details.
I'm still researching if there are any local distributor rebuild places that can do the conversion on my donor distributor for less money.
Assuming you can overcome the challenges, getting a donor distributor from a computer controlled Buick V6 engine is the first step, and it is a close as eBay. There are usually a couple for sale at any given time for reasonable prices. Your local salvage yard is another good source.
Next is buying the new parts you need. Internally, you need the module, wiring, and pickup - I think the pickup is the only thing that differs between the V6 and V8 units. You also need a new cap and rotor, and a new coil is a good idea too. This may also a good time to change your spark plug wires. If you are converting from a points style distributor, then new HEI style wires are a mandatory replacement item as the connection at the distributor cap is different.
Then you need to follow a pretty standard process to tearing down the V6 donor distributor, cleaning all of the reusable parts, painting/detailing the housing as needed, and then reassembling the distributor with the new parts you already bought. Note that you may need to drill out the hole for the distributor gear roll pin in some cases. Be sure to use a new roll pin, and be sure to lubricate
Here are some pictures of a Buick V6 computer controlled HEI distributor that I bought used and disassembled to research this conversion.
Comments? Kudos? Got some parts you'd like to buy/sell/barter/swap? Nasty comments about my web page so far? See Contacting Us.
Page last updated 12/27/2011 10:23:21 AM