Cannot install distributor to factory position

[Randy H.]

Re: Cannot install distributor to factory position

Some aftermarket cams appear to have the gear indexed improperly, requiring the dimple to be rotated 180 degrees from the correct OE position, but we usually can't ID them because they are in the engine, someone else rebuilt the engine, and there are no records.

Index the engine at about 10 deg. BTDC #1. Install the wires per the OE indexing, and reinstall the dist. starting with the rotor pointing forward. (Tweak the oil pump drive with a paint mixing stick is necessary to get it to drop in.)

As the gears mesh the rotor tip should end up oriented about 20 degrees right of engine centerline.

Rotate the housing until the points just barely begin to open. The VAC should be about halfway between the coil bracket and manifold interference points, and the cap window should be approximately normal to engine CL. If this is not the case, remove the distributor, reorient the gear 180 degrees and repeat the installation.

Duke

Duke,

My name is Randy Hebert and I purchased a 66-327 -350HP a couple of months ago. It ran pretty good but as a little rough. I decided to check the dwell and timing. Dwell was a little off, easy fix. Then I checked the timing and it was way off. Like seeing the mark at the top of the ballancer.
At least 30deg off the scale,Advanced.
I had the Vac line disconnected and pluged. I tried to adjust the distributor
and could not. I reindexed the dist a gear forward then went backwards. If I got the car running it ran like crap.

I checked the ballancer, Key way lined up with grove. Also verified top dead center, rotor position, and where the ballancer showed TDC. all was good.
I was begining to wonder about the motor as did Randall McCauley. A good friend of mine John Maggiore suggested I check the forum.

Well he sent me in the right direction. I read your reply to Randall.
I checked my car against your instructions and my point's werent even close to opening at all as your instructions indicated. I removed the gear as you instructed 180deg put back together. Then the point's were opening.

Started car and everthing fell into place. I was able to time tha car 10deg BTDC. It now runs great!!!

Thanks you for your post it bailed my butt out. Lost about 3 nights sleep
thinking about what was wrong. Your number 1 in my book.

Randy Hebert (24824)

[Duke W.]

Re: Cannot install distributor to factory position

Glad it worked out for you. I have never seen anything about the dimple orientation in any service literature. It's only on the distributor assembly drawings.

The "fix" has always been to start moving around the wires on the cap. That's what the "experts" told me when I couldn't get the timing right without the VAC hitting the manifold after disassembling my distributor back in 1966 when I was a ME undergrad.

After a couple of tries I gave the gear a close inspection and realized that with 13 teeth there were two possible indexing positions, and I also noticed the dimple. When I rotated it back to pointing the same direction as the rotor tip, reindexed the wires back to OE as shown in the '63 Shop Manual, the installation went perfect.

There are still probably thousands of Corvette distributors installed improperly with resultant poor operation.

I doubt if everyone will ever understand this simple issue.

When faced with a screwed up distributor installation, the best way to correct it is go back to zero and do it "by the book" just like GM did with the initial assembly of the distributor and engine.

1. Be sure the gear dimple is pointing the same direction as the rotor tip.

2. Be sure the wires are indexed per the service manual

3. Install as I recommended.

4. If you can't get the proper timing then the engine may have a cam with an improperly indexed gear in which case the dist. gear should be reoriented to the dimple pointing opposite the rotor tip.

5. Aftermarket distributor gears may have no dimple at all, so you have a 50-50 chance of getting it right the first time, but Murphy's Law says the chance of getting it right the first time is zero.

Duke

[Randall M.]

Re: Cannot install distributor to factory position

Duke,

I met you at the NCRS National Convention last summer. I just wanted to let you know that the steps you listed above were spot on. It turned out to be #4 - it was a inproperly indexed gear. I fixed it by reoriented the gear on the distributor 180 degrees. The car runs great- much better than before. Also, I followed your recommendation on using CJ4 rated Diesel Engine Oil to protect the solid-lifter valvetrain. I really appreciate you sharing your wisdom with me.

Thanks
Randall McCauley