63 340HP Distributor Orientation

[Norm B.]

I acquired some ignition shielding recently from a friend and was trying to install it on my car. Even though I have never had the shielding the brackets have always been on the engine. From what I can tell the coil bracket was either bent or shoved backwards at some time to allow room to turn the distributor when timing the car and now I cannot get the top shield to fit properly. I managed to get a good used coil bracket rather cheaply at Carlisle but before I embark on changing it out I am wondering if maybe the distributor is not installed correctly. I think that even with the new bracket I am still going to interfere with the distributor. It just doesn't look right to me and I have a gut feeling that the distributor may be out by one tooth.

From the pictures can anyone comment on whether or not the distributor orientation looks correct? Can anyone provide me with a picture of what is correct?

[Timothy B.]

Re: 63 340HP Distributor Orientation

Hi Norm,

What is the initial timing setting with the distributor in that position. If it's at 10-12*BTDC and the coil bracket is indexed into the intake manifold you may be fine. Closer to the coil bracket is easier on the tach cable but if you are not happy with where it is remove the distributor and rotate the lower gear 180* and that will move the vacuum advance more centered.

There is a dimple on the lower gear which indexes with the rotor tip but if the cam was ever changed that factory position may not hold true.

[John D.]

Re: 63 340HP Distributor Orientation

At Flint here's how the distributor was installed on the line. Cap was on with all the black wires dangling. The installer lined the bottom gear dimple up with the seam on the distributor case. Then when he put the distributor in the block he took his rubber mallet and smacked the distributor vacuum advance on the passenger side to get that one tooth thing.
That's why you see dings in original vacuum cans.
Learned this at Dr. Mike's Down on the farm after the NCRS National Meet in Warren, Flint in early 90's. Mike had the assembly line worker give a seminar at his farm. Right Doc??? JD

[John L.]

Re: 63 340HP Distributor Orientation

Looks ok to work with shield - but your right, may be one tooth out or your base timing is set way high. Points adjustment door would be almost straight toward the front and cap clips at 15 deg from clockwise to rear of engine.

[Edward J.]

Re: 63 340HP Distributor Orientation

Norm,, I think both the Johns have you on the right track, The cap window is close to front and the tach. cable points to the rear. If you cannot achieve this the pin holding the drive gear may have to be rotated 180, This exactly what I had to do, because of a Napa's 097 look a like camshaft.

[Norm B.]

Re: 63 340HP Distributor Orientation

Thanks guys. Looks like I have 3 or 4 rainy days ahead of me so I guess it is time to get busy out in the garage. I think I will start with a basic timing check and go from there. The car is a little overdue for some TLC anyway.

[Peter H.]

Re: 63 340HP Distributor Orientation

Good morning norm..if you need any help i,m available on sunday .... Peter ...

[Norm B.]

Re: 63 340HP Distributor Orientation

Thanks for the offer Peter but we are going to the Chihuly exhibition at the ROM on Sunday. You know, "Happy wife, happy life". I shouldn't get in over my head on this one but if for some reason I do I may shout out to you later.

[Rich Y.]

Re: 63 340HP Distributor Orientation

........he took his rubber mallet and smacked the distributor vacuum advance on the passenger side to get that one tooth thing. That's why you see dings in original vacuum cans.....

I have a very original and unrestored '63 340.
This explains the dent in my vacuum can.

[Norm B.]

Re: 63 340HP Distributor Orientation

Great pictures Richard. It looks like the window at the front on yours is virtually perpendicular to the center line of the car. It also appears your coil is oriented pretty much straight up and down where mine leans towards the rear of the car. More and more I am thinking that I may be out by a tooth but I am definitely going to check the timing first before pulling the distributor. The car starts and runs too well for the timing to be out very far.

[Duke W.]

Re: 63 340HP Distributor Orientation

I have a very original and unrestored '63 340.
This explains the dent in my vacuum can.

This is how a properly assembled and installed distributor should be oriented on all C1 and C2 small blocks - cap window normal to engine centerline or very close depending on initial timing value, and the VAC near the middle of the interference points with the inlet manifold and coil bracket.

Back in '65 when I was trying to figure out why the ignition on my 340 HP engine was breaking up as low as 4500 I removed and disassembled the distributor to try to find out what was wrong. Upon reassembly and installation, I couldn't get my initial timing without the VAC hitting the manifold or coil bracket with two adjacent tooth engagement orientations. All the "experts" I consulted said to move the wires one position, which only made the problem worse.

Finally about the third time I removed the distributor I noticed the dimple on the drive gear. And given that the gear has 13 teeth I realized that depending on the orientation of the gear it was equivalent to half a tooth. At that time the gear was installed with the dimple facing 180 degrees from the rotor tip, so I rotated it 180 degrees so the dimple pointed the same direction as the rotor tip, reindexed the wires back to the OE position shown in the '63 shop manual, and Voila! all was back to normal.

The distributor disassembly/assembly in the shop manual says NOTHING about the dimple orientation, and I'm not aware of any Chevrolet service information that discusses it, but it is mentioned on a distributor assembly drawing I have. The dimple orientation and even awareness of the indexing dimple is still a source of confusion and problems even among some professional mechanics who have been working on these cars for decades.

I still have the OE 201 15 VAC, and it has a gouge as yours does. However that VAC turned out to be the problem that caused idle instability and stalling that I was experiencing. The "experts" said disconnect it, but I finally realized that the Duntov cam's typical 12" Hg idle vacuum was not enough to pull the VAC to the limit and it "dithered", which resulted in loss of idle advance, which reduced idle speed resulting in loss of more advance until the engine finally stalled.

So circa '66 I replaced it with the 8" 236 16 VAC from the 365/375 HP engines along with the weights and springs, which brought in all the centrifugal at 2350 instead of 4600. The result was a stable idle at about 850 with a slight lope and noticeably more low end torque. No more stalling at idle!

Thus I came up with the "Two-Inch Rule" for VAC selection!

But the ignition still broke up as low as 4500, so I replaced the single point with the TI form the "12-mile L-88" that I helped disassemble in 1967-8 during my last year in ME at the U. of Washington. It failed in 1970 when corrosion caused a wire from the main power transistor to pop off the board that I successfully resoldered, and again in 1975, due to corrosion in terminals that connect to the amp.

At that point I had figured out how to "blueprint" the single point. I replaced the wobbly breaker plate, shimmed up the end play to the two to seven thou spec, and installed a set of 32 oz. points. Testing on a Sun distributor machine showed it to be dead on at up to 3500 revs, which is 7000 at the crank.

So I removed the TI, and installed the single point. Bench testing the TI eventually revealed the connector corrosion issue that I corrected, and after successfully bench testing I put it all in a box.

Thirteen years later, circa 1988, I sold the TI system to David Burroughs who owned the 12-mile L-88 at the time. I was pleased to see it go back on the car from which is came as this was about the point that fake L-88s began to show up, and I did not want to see the system fall into the wrong hands.

Duke

[Norm B.]

Re: 63 340HP Distributor Orientation

So the plot thickens. First I checked the initial timing and it appeared to be at about 12 deg. advanced. Next I pulled the distributor and sure enough the dimple on the gear was 180 deg. from the contact on the rotor. So I drove the pin out, turned the gear, and reinstalled the distributor. I also replaced the coil bracket with the recently acquired good straight one. But now I have made it even worse. Where previously I had to get the vacuum can against the coil that was pushed back towards the washer motor to get the timing close to being right now I can't even come close to getting the distributor to where it is supposed to be. The first picture is the position of the rotor before I changed the gear and the second picture is after I changed it. You can see how far out they are when the vacuum can is in the same position. The distributor will only go in one of two ways due to indexing of the pin on the oil pump so I can't have installed it out by one tooth. Number one plug wire is on what I believe to be the correct tower, being the first one on the passenger side from the window.

So I pulled the distributor again and had a closer look. The tag is 1111069 which is Late 64 & 65 365 HP engines. So here are my next questions;

1. Is the 1111069 distributor oriented differently than the 1111024 distributor that should be on this car?
2. If they are the same does anyone have any idea what may be causing this situation?

I have been trying to get in touch with the person that owned the car in 1966 and did have the engine apart back then to see if he remembers changing the distributor or cam or anything else but so far I have been unsuccessful. In the meantime anyone have any ideas or suggestions?

[Richard M.]

Re: 63 340HP Distributor Orientation

With the cap off, it's quite clear that you have a electronic ignition conversion of some sort. I have not seen that system before and have no idea who makes it. I would think that its orientation and installation placement may be outside the normal points configuration placement and affecting orientation and operation.

Since you do not have a stock setup, IMO...all bets are off for a normal configuration until you get to a baseline configuration, i.e. conversion back to points. If you can get information on the electronic conversion and potential adjustments of the stator and rotating trigger actuator, this may allow you to adjust for proper distributor placement with respect to the VAC clearances.

[Stuart F.]

Re: 63 340HP Distributor Orientation

I too noticed the electronic conversion right off; however, in my experience with several different kits, I've not seen one that should affect the orientation. I may be wrong, but this looks like one that uses the hall effect with a single wire and a two part chopper wheel (a popular brand). At any rate, it should not need to be re-converted to points to orient it right. You still have eight cylinders and therefore, eight make/break sensor blades.

Stu Fox

[Richard M.]

Re: 63 340HP Distributor Orientation

Stu, I agree he doesn't have to go back to points permanently, just to get a baseline. Then figure out the electronic system and if it can be adjusted.

Rich