Pertronix ignition swap from points

[Tom E.]

Re: Pertronix ignition swap from points

Your Holley?

Jeff,
I must not have had enough coffee when I wrote that, main jets would be running at that engine speed but my point was he could have a lean condition causing the surging.
Tom

[Frank D.]

Re: Pertronix ignition swap from points

IMO - the owner needs to get back to a "baseline", timing and curb idle/mixture set up properly, correct heat range plugs, a physical examination of ignition components, check the vacuum/centrifugal advance functions and the advance map in general. And I'm betting when he "undoes" whatever that shop thought they were doing the car runs fine.

[Tom E.]

Re: Pertronix ignition swap from points

IMO - the owner needs to get back to a "baseline", timing and curb idle/mixture set up properly, correct heat range plugs, a physical examination of ignition components, check the vacuum/centrifugal advance functions and the advance map in general. And I'm betting when he "undoes" whatever that shop thought they were doing the car runs fine.

[Edward J.]

[Richard M.]

Re: Pertronix ignition swap from points

A stock 63 300hp uses the Carter AFB.

Another way to test spark is to use your inductive timing light on each plug wire.

Just the other day I had missing going on on a engine. Only running on 8, sometimes 9.

Timing light, no flash on 3, sometimes 4 of the 12. Pulled plugs. All fouled from too much idling diagnosing other issues.

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[Todd L.]

Re: Pertronix ignition swap from points

Thanks so much to everyone for the suggestions. I have since taken the timing to 12* at 700 RPMs with vacuum advance plugged off, changed the plugs to R45S, and changed the condenser for good measure. None of this changed anything. The engine idles great, has great throttle response, but as soon as you put it in gear under load it sounds like an old tractor. Once you bring the RPMs up, it does fine. I am going to order a replacement coil and try that once I get back in town next week.

It is a Carter AFB carb, and at 700 RPMs, I have 14.5"-15-1/4" of vacuum at idle with vacuum plugged.

[Richard M.]

Re: Pertronix ignition swap from points

Coils usually fail dead, hot.

I suspect VAC unit. May be faulty or leaky. Check with a MityVac ang gauge to see if bad.


I wouldn't rule out your rebuilt AFB too. Been down that road with our 63 300 PG.

Rich

[Duke W.]

Re: Pertronix ignition swap from points

Thanks so much to everyone for the suggestions. I have since taken the timing to 12* at 700 RPMs with vacuum advance plugged off, changed the plugs to R45S, and changed the condenser for good measure. None of this changed anything. The engine idles great, has great throttle response, but as soon as you put it in gear under load it sounds like an old tractor. Once you bring the RPMs up, it does fine. I am going to order a replacement coil and try that once I get back in town next week.

It is a Carter AFB carb, and at 700 RPMs, I have 14.5"-15-1/4" of vacuum at idle with vacuum plugged.

Hold off on buying a coil, but if you don't have a 1963 Corvette Shop Mnaual (ST 21) don't open the hood until you obtain one. Rather than throwing parts at the problem, let's do some diagnostics and adjustments.

The OE VAC is stamped 201 15, and takes about 15.5" Hg to pull to the limit. What is installed? Test it with a vacuum pump and report the start and stop points. You may have to loosen the dist. cap and move it aside to see the number stamped on the VAC bracket.

Idle vacuum MUST be measured with the VAC connected idling in neutral with a manual and DRIVE with an automatic, and in either case if equipped with AC the compressor must be engaged. Your measurement does not appear to be taken under valid conditions.

With an OE equivalent cam a manual should idle smoothly in neutral, 500 @ 18-19" Powerglides should idle in DRIVE at 450-500 at somewhat less vacuum, but I'm not sure what it should be.

Here's what I suggest you do.

1. With the engine fully warmed up but off, gently seat the idle mixture screws in half turn increments and note how many turns each is out from the seat, then turn them both out 1.5 turns. Use a tee with a short piece of 1/8" tubing at one end of the cross bar and attach it to the VAC. Attach the other end of the crossbar to the VAC signal hose and attach the vacuum gage hose to the base of the tee.

2. Start engine in Park with the brake set and at least one wheel firmly choked or someone in the driver's seat with the foot firmly on the brake. Set idle to 500, observe and record vacuum reading.

3. Increase idle speed to 700 and shift to DRIVE, set idle to 500 and move the idle screws first in and then out in quarter turn increments up to a half turn and select the setting that yields the highest idle vacuum speed, and idle quality (smoothness). Note and record final vacuum reading.

4. If idle speed ends up much different than 500 reset it to 500 or even try 450 and go through the mixture adjustment procedure again. It's a iterative process so continue until you feel the setup is optimized.

Report your results, which should give evidence of whether the engine has an OE cam or something else. The OE 201 15 VAC may not be functionally the best. The '66 and '67 300 HP engines had a 12" VAC, which was probably a better choice for a Powerglide and should pass the Two-Inch Rule. The 201 15 may not. The currently available B22 VAC is a 12" type equivalent to the '66-'67 355 16. The VAC was changed from the 201 15 in both '64 and '65, but made things worse. They finally got it right for '66, so it only too them four years from '62.

Few understand the importance of the VAC and why one is needed that is "functionally correct" for the specific engine transmission/combination and the GM calibration engineers back in the day apparently didn't fully understand either.

Duke

[John P.]

Re: Pertronix ignition swap from points

I have to repeat the great advice given to me by Joe Lucia for my 65 roadster, some years back. After all the typical meandering, testing, replacing, having professional carb rebuilds (a service replacement from many years ago)-he finally told me : ditch that carb and get a new Holley. Some of the best advice I ever received, and a difference maker.

[Todd L.]

Re: Pertronix ignition swap from points

Thanks for that advice. I am trying to keep this car as original as possible, since it is all numbers matching and 98% correct. After several comments here about the carb, I will definitely look into that though, when I get back in town in a couple weeks. Thanks to everyone for the insight, I appreciate the wisdom being shared here.

Todd

[David M.]

https://www.forums.ncrs.org/showthre...ailer+hitching

[Todd L.]

Re: Pertronix ignition swap from points

The distributor was rebuilt and has .030" end play. I have found a local "old school" mechanic that is going to come out and help me, just trying to coordinate schedules. I will keep you all posted on what he comes up with. Thanks for the continued recommendations.

[John D.]

Re: Pertronix ignition swap from points

Todd, Don Baker sets the end play at '.015 or less.
Meanwhile if you need a new VA buy a B22 from NAPA. Supposed to be the same as a 201 36. Duke will tell us if it isn't.
Sounds like you could have a carburetor issue. Say this was a fuel injecion car and you had this surging Todd. I would think the FI had an issue.
How is the 4657 fuel pump? By they way you are using ethanol make sure the hoses for the fuel pump are for ethanol.
Is you AC GF90 filter OK?
NAPA sells a nice inexpensive heavy duty distributor cap. RR168. Black with copper. Used to be made in USA but isn't now.
Glad you changed the ice cold spark plugs. John

[Duke W.]

Re: Pertronix ignition swap from points

Todd, Don Baker sets the end play at '.015 or less.
Meanwhile if you need a new VA buy a B22 from NAPA. Supposed to be the same as a 201 36. Duke will tell us if it isn't.

The OE VAC is stamped 201 15. The B22 has virtually the same nominal specs, start at 8", 15 (crank) @ 15.5." I recommend the 12" B26 for 300 HP engines with an automatic transmission.

Duke

[John D.]

Re: Pertronix ignition swap from points

Thanks for the reply on the '63 VA.. I don't know why I typed 210 36 Just checked an original and its stamped 210 15 as you said. Thanks again,
John