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Posted By: BobShingledecker 63 GMC 305 v-6 distributor question - Mon Apr 19 2021 03:19 PM
I have a 63 GMC pickup with a 305, and have noticed there seems to be 2 types of distributors for this engine. Mine has the externally adjustable points (window like v-8 distributors). I think I have seen pictures of other 305s with distributor caps that resemble in line 6 type. Anyone know if there’s a year or model changeover point? Or am I mistaken?
Posted By: John Milliman Re: 63 GMC 305 v-6 distributor question - Thu May 20 2021 12:35 PM
Bob -- Sorry no one knew the answer to this. It may be an after market cap? My '65 305 did not have that window. Just a straight, solid cap.

How do you get to it??? On my truck, access to the side of the distributor was very limited and made harder by the location of the distributor in the first place. Is the idea that you can adjust the points with the engine running? So you have to lay across a hot, running engine and hope you don't get any flaming backfires through the carb right in your belly? Yikes.
Posted By: Justhorsenround Re: 63 GMC 305 v-6 distributor question - Thu May 20 2021 12:57 PM
John, regarding your “How do you get to it” question. Before starting the engine you would raise the side cover of the distributor, it should stay up on its own. Then start the engine and connect up your Dwell/Tach Meter. There was a specialty tool made to insert into the adjustment screw attached to the points. It was a long spring with a screwdriver handle on one end and the proper size Allenhead wrench on the other. A regular Allen wrench could be used but it was a real pain. You would then turn the driver left or right to adjust the points thus setting the dwell. The tool (I still have one) was about 10” long. Then pull the tool and close the little sliding door.
Posted By: bartamos Re: 63 GMC 305 v-6 distributor question - Thu May 20 2021 08:29 PM
To follow up, He asked his question over on 6066GMCCLUB and got the answer.
Posted By: fixite7 Re: 63 GMC 305 v-6 distributor question - Tue Jul 20 2021 10:07 PM
Martin over 50 years ago I just made an allen wrench distributor key and carried it with me,adjusted a lot of those.
Posted By: Hotrod Lincoln Re: 63 GMC 305 v-6 distributor question - Tue Jul 20 2021 11:01 PM
There's a shade tree trick on those external-adjust distributors when a dwell meter isn't available- - - -with the engine idling, turn the adjustment screw clockwise until the engine stumbles or stalls, then back off 1/2 turn. The dwell is set within specifications. I've also got one or two of those flex cable adjusters stashed away somewhere.
Jerry
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