1963 Distributor to Coil Wire and Bare Wire to Vacuum Advance

[Frederick H.]

The black wire is goes from the coil to the points, just confirming the bare wire is the ground from the base plate to the B28 vacuum advance.
- I can't find the proper routing for the black wire in the Assembly manual but don't think it should be touching the block - routed beneath the tach cable).
- Also, I have seen the posts about replacing springs with the black ones from the Mr.Gasket kit - anyone familiar with the yellow ones?
Thanks in Advance.

[David H.]

Re: 1963 Distributor to Coil Wire and Bare Wire to Vacuum Advance

The black wire is goes from the coil to the points, just confirming the bare wire is the ground from the base plate to the B28 vacuum advance.
- I can't find the proper routing for the black wire in the Assembly manual but don't think it should be touching the block - routed beneath the tach cable).
- Also, I have seen the posts about replacing springs with the black ones from the Mr.Gasket kit - anyone familiar with the yellow ones?
Thanks in Advance.

Frederick

Above in "Sticky Threads" - Database of Restoration Documents, is a Tuning and Timing presentation by Duke Williams given at 2012 Nationals. That link is below.

Worth studying all, but, relevant to your specific question on springs are slides 27/28/29.

Dave

https://www.forums.ncrs.org/attachme...1&d=1499167975

[Frederick H.]

Re: 1963 Distributor to Coil Wire and Bare Wire to Vacuum Advance

Yep - read through it briefly - pretty detailed but great info. Will revisit - thanks.

[Timothy B.]

Re: 1963 Distributor to Coil Wire and Bare Wire to Vacuum Advance

Frederick, Someone added the bare ground wire because the factory wire probably broke. The Factory wire is spot welded to the points plate and attached to the vacuum advance screw plus it is insulated. The primary ignition circuit's ground path is through the points then through that ground wire to engine block back to battery negative.

[Frederick H.]

Re: 1963 Distributor to Coil Wire and Bare Wire to Vacuum Advance

Excellent - thanks for the info Timothy. I'll check the AIM for a part number. I probaby won't go to trouble of spot welding but would like to get an insulated wire.

[Duke W.]

Re: 1963 Distributor to Coil Wire and Bare Wire to Vacuum Advance

Frederick, Someone added the bare ground wire because the factory wire probably broke. The Factory wire is spot welded to the points plate and attached to the vacuum advance screw plus it is insulated. The primary ignition circuit's ground path is through the points then through that ground wire to engine block back to battery negative.

Actually the ground wire is crimped/soldered to the breaker plate. You won't find this is the AIM because the dist. was part of the engine assembly. You WILL find info and an IPB on overhauling the distributor in the 1963 Corvette Shop Manual and later CSMs.

This ground wire will eventually fail because it is constantly stressed by action of the VAC. I discussed this in threads that I started both here on the TDB and the Corvette Forum, SWCDuke, that includes a p/n for a NAPA/Echin repair part, but it's pretty easy to fab your own replacement.

My tuning seminar, previously referenced, will give you starting points for optimizing the spark advance map, which does NOT include a B28 VAC assuming your engine has an OE or OE equivalent "300 HP camshaft".

Duke

[Frederick H.]

Re: 1963 Distributor to Coil Wire and Bare Wire to Vacuum Advance

Thanks as always Duke. I do not have the cam specs for the engine from when it was rebuilt 30+ years ago but it is a 340HP with a bore of .30 over (no blueprint unfortunately). I saw some of your posts regarding the NAPA/Echin replacement numbers for points but do not recall the segment on the ground wire. Will do some searching for that one.
Thanks.

[Peter H.]

Re: 1963 Distributor to Coil Wire and Bare Wire to Vacuum Advance

Frederick. The Napa/Echlin # Is LW 42. Peter 🇨🇦

[Frederick H.]

Re: 1963 Distributor to Coil Wire and Bare Wire to Vacuum Advance

THank You Peter - will save me some time.

[Frederick H.]

Re: 1963 Distributor to Coil Wire and Bare Wire to Vacuum Advance

Although part of another thread, I meant to add I referenced your other posts regarding use of the B28 vs the OE advance that was previously installed (you called it a boat anchor) and based my current use of the B28 on your discussion as I recall. One of the shops that I had tasked with other items decided to mess with the timing - bottom line I had to move the VA where it was hitting the manifold to run so it was indexed incorrectly. Another Corvette shop had to pull the distributor and remove the pin and rotate 180 (as discussed in previous posts) to get it to index correctly which incates it is probably not the OE-type cam. They said timing is set at 14 at idle and 34 total. Dwell is at 20 which I want to re-check - should be at 30 but car starts and runs fine. Will reset to 30 and check timing.

[Leif A.]

Re: 1963 Distributor to Coil Wire and Bare Wire to Vacuum Advance

Although part of another thread, I meant to add I referenced your other posts regarding use of the B28 vs the OE advance that was previously installed (you called it a boat anchor) and based my current use of the B28 on your discussion as I recall. One of the shops that I had tasked with other items decided to mess with the timing - bottom line I had to move the VA where it was hitting the manifold to run so it was indexed incorrectly. Another Corvette shop had to pull the distributor and remove the pin and rotate 180 (as discussed in previous posts) to get it to index correctly which incates it is probably not the OE-type cam. They said timing is set at 14 at idle and 34 total. Dwell is at 20 which I want to re-check - should be at 30 but car starts and runs fine. Will reset to 30 and check timing.

Absolutely re-check timing after setting dwell correctly at 30. Moving dwell affects timing...moving timing does NOT affect dwell.

[Duke W.]

Re: 1963 Distributor to Coil Wire and Bare Wire to Vacuum Advance

Although part of another thread, I meant to add I referenced your other posts regarding use of the B28 vs the OE advance that was previously installed (you called it a boat anchor) and based my current use of the B28 on your discussion as I recall. One of the shops that I had tasked with other items decided to mess with the timing - bottom line I had to move the VA where it was hitting the manifold to run so it was indexed incorrectly. Another Corvette shop had to pull the distributor and remove the pin and rotate 180 (as discussed in previous posts) to get it to index correctly which incates it is probably not the OE-type cam. They said timing is set at 14 at idle and 34 total. Dwell is at 20 which I want to re-check - should be at 30 but car starts and runs fine. Will reset to 30 and check timing.

You didn't state what engine you have but the 8" B28 VAC should be used on '63 340 HP engines. It can also be used on the 340 HP FI engine, and I recommend changing them to full time vacuum advance since OE is ported. The 250/300 HP engines with manual trans should use a 15" B22, but if the car has AC used the Two-Inch Rule with the compressor engaged to select between the B22 and 12" B26. If PG use the B26 with or without AC.

Given the age of these cars and the fact that very few have accurate documentation of changes over the decades, I always recommend checking idle vacuum and using the Two-Inch Rule to select a VAC even if you think you know what cam is installed.

As previously stated timing does not effect dwell, but dwell DOES effect timing. Always check and adjust dwell if necessary BEFORE you check and adjust timing.

Duke

[Frederick H.]

Re: 1963 Distributor to Coil Wire and Bare Wire to Vacuum Advance

Absolutely - I always check dwell before timing but a reminder never hurts, especially now that I am nearing retirement and hope to have more time to work on it. It is a 340HP (sorry, thought I mentioned in previous post but no matter).

Thanks!