I was looking to convert a Cadillac 4.5 distributor to vacuum advance and found they do not have aftermarket options, but thankfully the answer is on the Pennock’s forum. A few members here figured out converting the Caddy distributors to vacuum advance in order to run carburetors, which is great but their threads lost the pics years ago because they were links to Photobucket, etc. I will upload photos of the process in the hope they stay searchable for others. Credit for the original solution to BubbaJoeXXX, Capt Fiero and anyone else that helped.
The conversion is cheap and fairly straight forward. I purchased a new Oldsmobile OLDS V8 HEI Distributor for 260 307 350 403 455 Engine 1968-1976 on eBay for $50 to use for parts. The only other things I needed were screws and spacers, which I already had packs of. The photos should say it all, key things being to not lose the 'C' clips, then mark and cut the Caddy distributor with cutting disc, then cut Olds shaft and drill roll pin hole for drive gear. I used #8 & #10 self tapping screwing to set the vacuum module and #6 for the 4 pin ignition module. I swapped to straight screws with 5/16 nuts as spacers and lock washers to secure it. Here are detailed pics in series, I’ll post a link to the full swap thread once its up.
Cheers
[This message has been edited by 81 4.9L X-11 (edited 05-11-2025).]
You do good work but will you consider staying with MPFI that optimizes mileage, efficiency , longevity and power? You could be adapting this distributor to a Holley Fuel injection system. That system is state of the art and self adjusting.
------------------ " THE BLACK PARALYZER" -87GT 3800SC Series III engine, custom ZZP /Frozen Boost Intercooler setup, 3.4" Pulley, Northstar TB, LS1 MAF, 3" Spintech/Hedman Exhaust, P-log Manifold, Autolite 104's, MSD wires, Custom CAI, 4T65eHD w. custom axles, Champion Radiator, S10 Brake Booster, HP Tuners VCM Suite. "THE COLUSSUS" 87GT - ALL OUT 3.4L Turbocharged engine, Garrett Hybrid Turbo, MSD ign., modified TH125H " ON THE LOOSE WITHOUT THE JUICE "
You do good work but will you consider staying with MPFI that optimizes mileage, efficiency , longevity and power? You could be adapting this distributor to a Holley Fuel injection system. That system is state of the art and self adjusting.
Hi Dennis, I've been down the Sniper path for my 65. It has a PMD 400 with Edelbrock heads BUT with a 1969 manifold & Q-jet. Originally, I went with the std points and condenser until I got stranded 1/2 mile from work due to a shorted Chinese condenser. Since, I converted to a GM HEI & SI alternator using an MH converter harness. I rebuilt the HEI using NOS GM module & coil with an AC Delco alternator. Even though the Q-jet has great drivability, I started to consider the Sniper for the reasons you mentioned. On another PMD board, I started to search out opinions on the Sniper & other EFI set ups. Way too many stranded / reliability comments for me, like my Chinese condenser. If I were to further consider EFI, I would go with the Edelbrock system, at least with that, you can locate the ECM in the passenger compartment out of the under-hood heat. For the 4.5, not likely there is an Edelbrock system so for EFI I would stick with the GM system. As retirement approaches, I'll be looking for an 88 of any type to round out my collection.
Thanks guys. I have several 4.9 swaps, this one is budget oriented and probably the best for novice first attempts - working on swap post that has the details. I plan to upgrade the ignition, but needed this to get started and wanted to document it for others. I've been driving it for a couple weeks now and it works well.
You do good work but will you consider staying with MPFI that optimizes mileage, efficiency , longevity and power? You could be adapting this distributor to a Holley Fuel injection system. That system is state of the art and self adjusting.
Hey Dennis, I will work out MPFI on another build - need to figure out/ fab a distributor option with 7 + 1 hall effect pick up to run the Aces sequential port kits.
I'm taking the 4.9 Skylark to Carlisle for GM Nationals in June, let me know if you'll be there and we can compare notes 8)
Cheers, Robert
[This message has been edited by 81 4.9L X-11 (edited 05-16-2025).]
Hey Dennis, I will work out MPFI on another build - need to figure out/ fab a distributor option with 7 + 1 hall effect pick up to run the Aces sequential port kits.
I'm taking the 4.9 Skylark to Carlisle for GM Nationals in June, let me know if you'll be there and we can compare notes 8)
Cheers, Robert
I will be at Carlisle and very much look forward to meeting you. Have done six swaps of different types, ECM/PCM tuning with GM parts, and hopefully some of my info may be useful to some. As a tinkerer, find chatting with other engine swap guys very interesting and technical. Will send my cell number to you in a PM. Paula will probably be with me so I could be floating around a bit but she is going for some surgery next week so its 50/50 at this point. Call or send a text and will come over to where you are.
------------------ " THE BLACK PARALYZER" -87GT 3800SC Series III engine, custom ZZP /Frozen Boost Intercooler setup, 3.4" Pulley, Northstar TB, LS1 MAF, 3" Spintech/Hedman Exhaust, P-log Manifold, Autolite 104's, MSD wires, Custom CAI, 4T65eHD w. custom axles, Champion Radiator, S10 Brake Booster, HP Tuners VCM Suite. "THE COLUSSUS" 87GT - ALL OUT 3.4L Turbocharged engine, Garrett Hybrid Turbo, MSD ign., modified TH125H " ON THE LOOSE WITHOUT THE JUICE "
