1966 L72 427/425 hp K66 Transistorised Ignition Question.

[Bill M.]

My 66 L72 came from the factory with the K66 Option (Transistorized Ignition) which was mandatory for this engine. The original window sticker shows this option also.

The K66 Pulse Amplifier (little black box) is still wired and installed where it should be.

The issue I have is that the alternator should be #1100696-42 amp but instead it is 1100693-37 amp (427-390hp). The date code month on the 1100693 is the same as the engine date.

The distributor should be 1111093-Transistorized Ignition but it is 1111141 (427-390hp)

The car runs excellent with no problems.

Any thoughts or feedback on why the previous owner(s) may have made this change.

Everything else on the car appears to matching numbers.

Bill-Parma Ohio
#67549

[Mark L.]

Re: 1966 L72 427/425 hp K66 Transistorised Ignition Question.

Bill, to confirm your understanding of the original window sticker it may be wise to have it Document Validated. On the other hand if you've owned the car since new you can forget that check. Unless you are going to have it judged, and it runs well, I'd drive it and forget it. Welcome to NCRS.

[Duke W.]

Re: 1966 L72 427/425 hp K66 Transistorised Ignition Question.

1111141 is the single point distributor for the L-36, and ...142 is the TI version. Both single point and TI distributors used the same housing, so it's easy to convert one to another. You need to remove the distributor cap to determine what's inside. Also report the data stamped on the VAC bracket.

All engines with TI also got a higher rated alternator due to the higher current developed by the TI system. Those early TI systems were not very reliable so an easy "fix" for one that failed was to simply install a single point distributor and ballast leaving the amp and TI harness in place, but not connected.

Duke

[Keith B.]

Re: 1966 L72 427/425 hp K66 Transistorised Ignition Question.

also a 37 amp alt is more common and way cheaper then the correct 42 amp one.

[Bill M.]

Re: 1966 L72 427/425 hp K66 Transistorised Ignition Question.

Thx. My Vette is a real nice, inside, out and underneath. Not a trailer queen but a real nice driver. Widow sticker is real (faded/glue marks etc) which includes the cars serial number on it. Matches the Protecto Plate. Engine was rebuilt and pics taken of all numbers/dates/codes from the top, inside and bottom of the engine. Carb/intake dates match the engine also.

It is just perplexing that with all that info someone would use other non matching equipment. I spoke with some folks who said "back in the day" is what cheaper to buy off the shelf as numbers did not matter to them..only cost savings. I am unsure where the black box (pulse amplifier) wires go so I will check them out later.

Right now I am happy with the start up and go and like you said I will drive it and forget it.

Thx Bill

[Keith B.]

Re: 1966 L72 427/425 hp K66 Transistorised Ignition Question.

a L72 ranks right up there with most faked cars ever. I would make sure what you think is real before thinking it is just because it looks old.

[Mark F.]

Re: 1966 L72 427/425 hp K66 Transistorised Ignition Question.

...It is just perplexing that with all that info someone would use other non matching equipment. I spoke with some folks who said "back in the day" is what cheaper to buy off the shelf as numbers did not matter to them..only cost savings. I am unsure where the black box (pulse amplifier) wires go so I will check them out later....

https://www.corvetteforum.com/forums...-and-coil.html

[Richard M.]

Re: 1966 L72 427/425 hp K66 Transistorised Ignition Question.

Many owners disconnected their TI, removed the TI distributor and ran a points distributor and coil and associated hardware. This also means a Ballast resistor must be used and wired between IGN 12v feed and the ignition coil + terminal.

It's quite possible that's what has happened to your car Bill. Not to doubt your cars heritage, but for reassurance you may want to verify a few things.....

Coming out of the firewall grommet to the right of the wiper motor, when facing it, is the Pink ignition feed wire. A TI system will have a black plastic terminal plug which connects to a White Resistor wire in the TI harness. Points systems use the Ballast resistor mentioned above. Normally the Ballast is attached to the firewall with a large Phillips head screw, locating a dimple in the mount area and drilling a hole when built. TI will have the dimple present with no hole. It's view may be obstructed by a factory applied waterproofing sealant.

eg 1
P1270046mod.jpg

Your car should not have a Ballast resistor in the circuit if TI is functional, or if one exists as you suspect, hopefully it's not mounted with a hole in the dimple and is located nearby. I once restored a 1967 L71(mandatory K66 as your L72), and it had a 283 SB in it put in by the original owner after he blew up the 427, and did a Points ignition conversion from TI long ago. The ballast was attached using the steering column reinforcement hardware. The dimple was left there.
pa180155.jpg

Also a small often unnoticed item in a TI system is a small rubber coated harness clip located under the driver's side female hood latch, held in with a small hex head screw. The actual location varies greatly as the builders in St Louis simply drilled a hole in that area to "get it in there". If it's located precisely in the AIM specified location I'd be surprised.

1966 AIM K66 A3 Note View C
1966_K66_A3.jpg

eg 1
P1270089.jpgP1270090.jpg

eg 2 TI harness gone and clip used for w/s washer hose. This one on that L71 with the 283 conversion.
pa180153.jpg

Same L71(283) car after 427 redux and TI Harness routing.
P3030012.jpg

To help trace your TI wiring. A 67, but 66 same.
TI_1_mod.jpg

Yes.... best to enjoy, but you asked about your unusual situation so I decided to give you some hints and things to help solve your mystery and research. Hopefully it all makes sense.

Rich

[Lawrence S.]

Re: 1966 L72 427/425 hp K66 Transistorised Ignition Question.

Rich, great info! Thanks for posting.

[Bill M.]

Re: 1966 L72 427/425 hp K66 Transistorised Ignition Question.

Thanks for all your info. Wish I had half the knowledge you do. When the weather breaks here in Ohio I am taking the car in to have the carb rebuilt. I am taking your info and all the other notes I have. Hopefully a lot will be answered, also the incorrect distributor (427/390hp) appears to be newer in appearance

Again, thx for your reply and info.

Bill

[Bill M.]

Re: 1966 L72 427/425 hp K66 Transistorised Ignition Question.

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