Distributor questions

[purzell]

Truck: 1966 GMC with 351E V6

Guys, please be gentle on me. I am a total automotive noob and I'm just learning this as I go along, using the manual, the web and this forum.

I wanted to put the basic tune up into my truck. Bought cap, rotor, plugs, wires, points. Using my newly acquired GMC truck service manual, I opened up the distributor today to try to replace the rotor and points. I think I have a distributor from another car or truck. I found that the rotor is what the Napa guy called a Buick type (round and takes up the top of the cap) and the points are uni-points. Looked nothing like what was in the book. So I got the somewhat right parts from Napa for this distributor, but the wiring inside doesn't quite match up and the red wire is actually missing it's covering and exposing copper wire.

My thought is that the distributor should just be pulled out and rebuilt. But in that case, am I better off getting the "correct" distributor for my motor?

I was toying with the Pertronix ignition mod but if I can avoid the expense that would be nice. But if rebuilding or replacing the distributor is close in cost to the Pertronix, and I can put the Pertronix kit in my existing distributor, well that might be the right way to go?

I guess I need to know:
- what distributor should have been in my motor
-can I still get one for it, or
-what crosses over and fits on this motor, or
-if I can just put the Pertronix kit in this existing distributor
-what direction does the metal piece face on the rotor, I stupidly did not document it prior to removal. Pointing to drivers or passengers?

Thanks in advance for any assistance.

[purzell]

Here are some pics. In the first one you can see the red wire that is damaged.

[purzell]

Well, either my question is so stupid that no one wants to answer me....

...or I have stumped the pros!

I am guessing not the second answer...

[64fleetside]

The regular GM points can usually be replaced w/the unitized set, its just a diff way of doing it. The ground wire is usually a bare wire originally.

Does it fire? I usually prefer the unitized points, just stick an Allen wrench in there & set the dwell easliy.

[neto]

I wonder if someone already put the buick distributor for HEI system but changed it to points?

[purzell]

Does not fire. But perhaps I have the rotor oriented wrong. As I mentioned I photographed everything I did except the direction the rotor was facing before I disassembled it.
Also, how do I find out what this distributor originally came in?
Does anyone have the part number for the original distributor?

[64fleetside]

That V6 stuff is hard ta find, dunno if you will find a new dist for it. The rotor should only fit on one way. You have 12volts @the coil? You can adjust the dwell/point gap while cranking using an Allen wrech.

[Ledslinger]

I think your distributor is correct and your parts guy thinks you have an inline 6 motor. The points, condensor, and rotor for the GMC V6 are the same as a V8, the cap is unique to V6 GMC as far as I know. rockauto.com has all these parts and you can use their site to get part numbers.

The only wire I see looks like a ground from the points plate to the distributor body, you need a wire that goes from the terminal on the points to the coil, a primary lead. The rotor only goes on one way, there are projections on the bottom of the rotor, one is round and one is square to go into holes on the rotor shaft.

Send me a PM and I will reply with my phone number and I can help you further.

[dthela]

the original distributor has a small rotor which just slips over the top of the distributor shaft. parts are readily available. the one thats in there has the weights that change the timing when it spins they open up (things with springs on top).

[Corts60]

OK. First of all. That is the correct distributor for the truck.

Second of all, you do not have a push on type rotor, it is bolt on and as ledslinger said, it only bolts on one way. You can see the round alignment hole and square alignment (next to the actual bolt holes) in the pictures you have provided.

Also as suggested above, use rockauto.com for your parts sources. Chain store counter clerks get confused all the time over the V-6's because 90% of the people out there don't know they exist.

You need to set the gap on your points to .016 for initial start up and ensure that you are getting 12 volts to your coil + side. The - side of your coil hooks to the points in the distributor (possibly the wire you said was broken) and also the condenser gets attached to the same spot on the points as the ground wire from the coil.

Try these steps out and let us know what you find.

[HEI451]

There are two differemnt design distributors used in the V6 big blocks. Both are points type.

One is the type that has two clips to hold a smaller diameter cap, and the mechahnical advance UNDER the points plate.

The later type is what you show in your pictures, commonly refered to as a "window type" for the point adjutment window in the cap, and the two "bent nail" hold down pins.

They both use different point sets. The window types use the same points/condenser as the 1957 through 1974 points type V8 distributors use, with separated condenser, and the same rotor as the V8 distributor. BTW, YOU NEED TO STAY WITH THE SEPARATED CONDENSER, NOT THE 'UNITIZED' WITH THE CONDENSER ATTACHED TO THE POINT SET. The Unitized points have real issues with the quality and microfarrad rating of the condenser, and the problem of the ground from the point set and condenser as one piece.

For your distributor, the V8 window cap point style vacuum advances arfe a bolt in, along with the Crane 99601-1 adjustable vacuum advance kits.

The only specific part for the distributor for the late V6 is the cap. Any good auto part store can get the right cap, just make sure it has the window in it for point adjustment.

Setting the point dwell is the same as the window type V8, dwell metger to negative post on the coil, run engine at idle, adjsut points through the window, set to 30 degrees, dwell meter on 6 cylinder scale, done.

Also, the currently available V8 window/point type aftermarket distributor curve kits work in these distributors as well.

My 1965 305E V6 had the small diameter distributor in it. I wasn't aware at that time that the later wihndow type was available for them, so, since I build small body real HEI's into point distributors, and do them for the window type V6 4.3 Chevy (from a V8 distributor), and lots of the GM V8's, I proceeded to cut and paste a window top to a small distributor, to create virtually what you have already, the right thing to use.

I then converted the now right to use distributor, to a real, live small body HEI, with GM 4 pin HEI module, magnetic pickup and remote stock round oil filled coil, as I do for a lot of window type distributors. This ain't an ad, just an explanation that it can be done. .

[dthela]

Both mine had original bent nail caps with windows and small rotor.

[HEI451]

Windows/bent nail uses the same larger V8 rotor, the one that screws down to the point cam holder. The smaller distributors use a smaller rotor, that simply slips over the point cam holder, with one slot for alignment, no screws holding it.

The large rotor window cap disttributors use a mechamical advance under the large rotor. The small rotor/cap distributors have the mechanical advance UNDER the points plate.

[purzell]

This is great guys, thank you.

I had the rotor on correctly but still not sure it was the right one he gave me.
Checking Rockauto.com under the 4.6L V8 motor I see the ignition parts (none under the 351 V6) so I will order up the points and correct rotor and try again.

The parts I got at Napa actually look pretty accurate except that the rotor was a slightly larger diameter, but still fit in the cap.

I hear some dispute amongst the forum regarding unitized vs non-unitized points...

[Ledslinger]

Purzell, I didn't word it very well, but when I said points, condensor, and rotor was the same as for V8s, I meant most 60's GM V8s. Use a 1965 283 Chev when looking up these parts.

[HEI451]

No, actually, you hear that they are the best things since holes in donuts from some. And, then, from those that have worked with them EVERY DAY, seen first hand the problems they have, the issues in condenser workling correctly, point faces having short lived from condensers not working correctly, outright failures, timing issues, and the poor quality of them, the Unitized point sets are exactly what they are, JUNK.

[purzell]

Guys, thank you. Got the correct points and condenser, hooked everything up, put on the new Holley 4412, it runs!
Just need some carb tuning now.
Posted via Mobile Device

[Ledslinger]

Way to go!

[HEI451]

Great to hear it is up and running. And, the Holley is definitely a benefit over the stock carb.

[purzell]

Hey sorry to revive this older thread. We have been working on the tuning since asking these last questions. The truck runs pretty darn well once it is warm but it's very hard to start cold. I think I will replace the coil as it is old, and I have to redo the wiring to it anyhow as it's in really bad shape. I also have to address a vacuum issue at the front of the carb where the Mr. Gasket adapter mounts the Holley to the intake. I am assuming the vacuum leak is contributing to the cold starting but not sure where else to look besides also replacing the coil.

My question is this: is the coil the one that would go with that 283 v8 as recommended by Ledslinger earlier for the other ignition parts? Napa is still having a hard time finding parts for my 351 V6 motor?

Any other advice regarding the cold starting issue?

Thanks guys!

[100%Chevy]

Yes,it will work.
Mike.

[Corts60]

Cold starting is going to be a carb issue, not electronic. I would first ensure that the choke is working properly and if you do have a vacuum leak, that could also contribute as well because it is leaning out the air/fuel mixture. Cold engines like a rich mixture when they start, hence the choke.

Good luck!

[NCD1966]

well looks like you fixed your problem. I know nothing about the gmc v6s, but I did install a Pertronix kit in a 1953 ford tractor that was converted for 6 volt to 12 volt. It was always burning up the points. PITA
Its an easy kit to install, at first I thought there was some parts missing until I read the instructions.
Never had a problem with points again. I would highly recommend Pertronix kit to anyone still running points