Spark Plug Wire Orientation

[Dan D.]

I'm still trying to dial in some of the details on my car. I have a 1963 327 with a 375 FI unit. I don't have the 63 documentation and I would like to know the spark plug wire orientation on the distributor cap.

Right now I have #1 pointing 2 distributor teeth (55*) CW from the front of the engine. I don't think this is correct. I'm thinking it should be 1 tooth, but not sure.

14* initial advance puts the VAC close to the coil bracket, but not touching it. I have an aftermarket cam. The dimple is OEM and lines up with the rotor tip. And yes, Duke, when I get the distributor back in I am going to set the timing your way - 36 to 40* with the centrifugal all in.

This has been noted before, but it is next to impossible the adjust the points regardless of the cap orientation. There just is not enough clearance to the FI plenum to get a wrench in the door. Right now I have the distributor out and I jury rigged a set-up on the bench. Holding the distributor in a vice, driving it with a drill motor. Made a coupling out of a piece of nylon rod - cut a slot in it to fit in the distributor gear. Hooked up a coil, ballast resistor, 12 volt supply and the dwell meter. Real easy to do, and really nice easy way to set the points. Maybe someday I will go electronic. Assuming I will answer this thread I will take a photo and paste in it the thread - for your viewing pleasure.

Some clarification on the wires would be most appreciated. Perhaps a photo if anyone has one handy.

Thanks,

-Dan-

[Richard G.]

Re: Spart Plug Wire Orientation



Is this what you are looking for?
Be sure the plugs wires have the required 90 deg boots..

[Duke W.]

Re: Spark Plug Wire Orientation

The #1 plug wire MUST be in the terminal just to the right (perspective of sitting in the driver's seat) of the cap window edge. Then clockwise for the remaining firing order ...8436572. There is a diagram in the 1963 Corvette Shop manual and later CSMs.

Prior to removing the dist. you should have indexed the crank at the approximate initial timing value BTDC #1. If not, remove the #1 spark plug and rotate the engine until you feel compression with your finger over the plug hole. Continue to rotate the crank until the balancer notch is at the initial timing point on the tab.

Observe the orientation of the oil pump drive shaft slot. Now hold the dist. above the hole with the rotor pointing slightly to the right of engine centerline. Rotate the bottom forward and observe the orientation of the oil pump drive. Is it the same as the pump shaft slot? If not, use a paint mixing stick to rotate the oil pump drive slot to engage.

Now with the rotor pointing approximately along engine C/L slowly drop the dist. down the hole. As the gears engage the rotor will move clockwise. If the dist. doesn't fully seat the oil pump drive shaft is not properly oriented and needs to be tweaked. This can be a little tricky if you have not done it before, but with a little practice you will be an expert.

Once seated the rotor should be pointing at #1, about 20 degrees right of engine C/L.

Snug the hold down bolt just enough to keep the dist. seated, but can still be rotated by hand. Now rotate the dist. until the points just begin to open. This is called "static timing" the engine. With practice you can do this visually, but for more accuracy use an ohmmeter connected between the coil negative terminal and a good ground. The proper point is when the meter goes from zero to infinity. (An old analog meter is best for this.) The window should be approximately normal to engine C/L and the VAC should be about halfway between the interference points. if not, there's something wrong with the installation or the camshaft gear is not indexed IAW GM drawings.

Start the engine and set total WOT advance (VAC signal line disconnected and plugged) at 38-39 a few hundred revs above the RPM that max centrifugal is all in, and tighten the hold down bolt to 10-12 lb-ft, which is not that much for a bolt of that size, and do final total WOT timing check to ensure it's in the proper range. Connect the VAC signal line, check total idle advance (near 30 plus or minus a few) at about 900 and total cruise advance (low/mid 50s a few hundred revs above the RPM of max centrifugal).

You can check initial timing (VAC signal line disconnected and plugged) if you wish, but on engines with high overlap cams it can be very difficult to lower engine speed below the start of point of centrifugal and have it run stably long enough to actually measure before the engine stalls. If this is the case don't worry about it. If you properly executed the total WOT advance method to set the distributor and the total idle advance and total cruise advance are in the range previously stated, then the initial timing is in the ballpark.

Duke

[Dan D.]

Re: Spark Plug Wire Orientation

Thank You Richard. This is what I thought - I am too far CW. My wires are R-angle boots, but they are carbon from Lectric Limited, about the time frame when they were no good. So far they are working, but I am keeping close tabs on them. I measured the resistance of all 8 when they were new and I have that data, so I will be able to tell if they go high R or open.

Duke, I did index the distributor before removing it. I always do this before I remove a dist., and static time it after it is in. Otherwise it's extra work to find #1 TDC. Not a big deal, but I prefer to locate TDC before I remove the dist.

This is FI so I can tighten down the dist. hold down and still rotate the cap and body, and yes it is better to use an analog meter because the refresh time of digital meters is too slow. I am running a mild aftermarket hydraulic cam so I can idle it down pretty well, and I want to ball park the initial first so I can check the position of the VAC. I may have to rotate the dist. gear 180*. Once I am happy with it I will set the timing by your WOT method. Also I am using a B28 VAC right now (with full manifold vacuum), which may be too aggressive, as it is all in at 8". I have to measure idle vacuum first, but the B26 may be a better choice, as long as meets your 2" rule.

You say #1 MUST be just to the right of the cap window. Why is this a MUST? What happens if it is not? Just curious is all.

Don Hooper - thank you for the photo. That helps me with wire dress too.

Lastly, the promised photo of my 'high tech' dwell set-up. It works!

[Dan D.]

Re: Spark Plug Wire Orientation

Something got messed up earlier. This should be my complete message.

-Dan-

[Don H.]

Re: Spark Plug Wire Orientation

Didn't think you needed it.
Here you go,

[Richard G.]

Re: Spark Plug Wire Orientation

Below is a picture, from their website, of the lectriclimited.com/spark-plug-wire-set for a 63 Corvette.
The picture indicates the wires have straight ends at the distributor.
The 90 deg. boots along with the dates are what separates these wires from the rest of the vendors.
Seems the picture is a file picture and not what you would receive if ordered?
Rick

[Duke W.]

Re: Spark Plug Wire Orientation

[QUOTE=Dan Dillingham (49672

You say #1 MUST be just to the right of the cap window. Why is this a MUST? What happens if it is not? Just curious is all.


[/QUOTE]

If the gear dimple is not properly indexed and/or you don't index the wires on the cap as I stated, which is IAW the 1963 Corvette Shop Manual then you will likely not be able to set the initial timing to the proper value before the VAC hits the manifold or coil bracket interference points. Lots of guys have fallen into this trap, and there are likely a lot of Corvette SBs out there that still have this problem.

Been there, done that back in the mid-sixties. All the "experts" I talked to back then were clueless. I finally figured it out myself.

Duke

[Dan D.]

Re: Spark Plug Wire Orientation

Richard, I am not sure just what I bought, it was several years ago. They were from Corvette Central, which would have been L/L wires. They are right angle, and the lengths are about right. I made sure they were right angle before I bought them because of the additional height of the FI distributor. The cap is a fuel injection cap also; they are lower profile than the standard cap. I'm just hope they hold up is all.

-Dan-

[Dan D.]

Re: Spark Plug Wire Orientation

Okay Duke, I understand, thanks. I will be entering this phase soon, and the aftermarket cam is another variable for me. But I will move the dist. back one tooth, or 27.7* and re-position the wires to match. Then I will determine if the gear has to be rotated 180*. I can do this okay - I've crossed this bridge before.

-Dan-

[Richard G.]

Re: Spark Plug Wire Orientation

I need to get a wiring question correct for a 63 340hp car.
My understanding is the FI cars required the 90 deg boots because of the extra height of the distributor. Same reason the FI cars had the shorter cap on the distributor. However, it is my understanding, the plug wire on all Non-FI cars had plug wires that came straight up out of the cap.
Do I have this correct? Sure makes it difficult to get the distributor shielding on if this is correct. On might have to pull the slack out of the wires at the top to make getting the shielding installed a little easier.
Thanks
Rick

[Dan D.]

Re: Spark Plug Wire Orientation

Rick, you are correct. Straight-on connectors on FI cars would interfere with the top shield. 250/300/340 cars used straight-on connectors, and as you say, I think that would be marginal. So if you are not having it judged, then why don't you use the R-angle FI wires? If you are going to have it judged, the owner is required to remove the top shield so the coil & wires & so forth can be judged. Therefore you need the straight-on wire set. Perhaps using the lower profile FI dist. cap and straight wires would be better, and may fool the judges.

FYI, I found the invoice for my wires. Turns out I did not buy them from C/C - I bought them direct from L/L. Part number 1224-631. That's why I could not find the invoice right away. L/L has both wire sets listed on their web site, and with photos.

-Dan-