1966 427 425HP coil?

[Joe T.]

I have a 1966 427 425 HP with transistorized ignition. My VIN is 19404 built mid April. Should I use a 1115231 or 1115261 coil. The judging manual list both as acceptable.

[Donald A.]

Re: 1966 427 425HP coil?

I use the 261 coil (repro, original long gone) in my Feb 01 L72, and I have read various opinions on the 231 vs 261, some say early vs late etc but I have not seen any official NCRS opinion on this, and as you noted, either is OK in the 5th Edition Judging Guide. The 6th Edition is apparently coming out this year (is what I hear anyway) maybe they will have an update on this. Anyway both are electrically equivalent so either is fine IMHO but as always check coil resistance before putting in use to make sure it meets specs. TISpecialty.com lists the correct TI coil specs

[Jim D.]

Re: 1966 427 425HP coil?

I would be cautious using one of those "GM licensed reproduction coils". It seems that many have had problems in that they test fine when cold but fail when they get warm. Unfortunately, I just paid big bucks for one and now after further research, I'm hesitant to install it.

[Donald A.]

Re: 1966 427 425HP coil?

I would be cautious using one of those "GM licensed reproduction coils". It seems that many have had problems in that they test fine when cold but fail when they get warm. Unfortunately, I just paid big bucks for one and now after further research, I'm hesitant to install it.

Yes have seen reports of some problems with some of the repro GM licensed coils. I put my 261 in prior to recent judging and no deducts for that. I also checked it hot and cold and it seems to be OK. However that doesn't mean it won't quit tomorrow!! So I have an old spare 207 coil that I keep ready just-in-case

[Joe T.]

Re: 1966 427 425HP coil?

Well, I have tried 3 coils.. One 1115261 and two 1115231. All three GM restoration made in China. They all performed well with a cold engine. All three failed when hot and opened up to 0 ohms. T.I. Specialty recommends 2.5 to 7.0 volts, 7.5 amps and 0.41 to 0.51 ohms. One was 4 volts, 6 amps and .4 ohms cold and 0 ohms hot. One was 6.5 amps, 3.6 volts .3 ohms cold and 0 ohms hot. The last was 1.5 ohms on initial reading which was way over the recommended 0.4 to 0.5 ohms. All three failed and my 427 425HP died when hot. It has taken over two months replacing coils, checking grounds, new TI box, new distributor, wrapping fuel lines for vapor lock and finding three defective made in china coils. Although, I have heard some people have had good luck with these coils.

[Donald A.]

Re: 1966 427 425HP coil?

Joe sorry for your coil problems. Here's my opinion FWIW... I looked into obtaining an NOS 207 coil and original 261/231 coils previously, either unobtanium or ridiculously expensive. I found an old used 207 and keep it for a spare. Yesterday I found a couple in the Driveline, emailed about one, was told seller did not know primary or secondary resistance and if the coil works, it works, and for $500. Not for me. I spoke to the guy who restored my distributor, he has been selling GM Restoration coils for 10 years, has had very few failures he said. And some of those he felt were due to people not leaving an air gap at the bottom of the coil, letting it mount right up against the manifold, and thus gets too hot. So options are expensive 50 year old originals, or variable year 207 service replacements which won't pass judging, or new Repro which are imported and hit/miss. I am going to stick with my repro one since it is working well. I hope you can find a coil that works for you.

[Walter R.]

Re: 1966 427 425HP coil?

Joe,
Did you ever find a coil that worked?

[Jim D.]

Re: 1966 427 425HP coil?

I would be cautious using one of those "GM licensed reproduction coils". It seems that many have had problems in that they test fine when cold but fail when they get warm. Unfortunately, I just paid big bucks for one and now after further research, I'm hesitant to install it.

An update on the reproduction coil I bought. I lent it to a fellow member who was having coil issues and it failed when warm. I returned it for a full refund. I have an old untested 207 that I'll try when the car is back together.

[Joe T.]

Re: 1966 427 425HP coil?

I did. Using a refurbished 1115207 original GM coil.. Works great. No problems!

[Walter R.]

Re: 1966 427 425HP coil?

Where did you get coil?

[Joe T.]

Re: 1966 427 425HP coil?

Chicago Corvette.