C3 SB coil bolt question

[Don L.]

I recall reading a thread here not too long ago about the 2 ignition coil bracket mounting bolts, and that there was something different between them. I have tried the search without success.

Sorry to ask about this again, but can someone tell me how the two bolts should be? I think the thread was discussing that there's a difference either in headmark or paint treatment, but cannot recall exactly what it was and want to check mine now that the thaw is here.

[Steven G.]

Re: C3 SB coil bolt question

Don, Are you asking about correct 2 coil bracket bolts for a 72' ? If so, they are hex. cadmiun plated bolts using star washers, with recessed heads revealing an outer edge. I will have to do some looking to give you an accurate head marking discription that is if they were consistant in usage. Steve

[Terry M.]

Re: C3 SB coil bolt question

One of the bolts -- the inboard -- was installed at the engine plant and thus on those manifolds that were painted orange it was also painted orange. The original coil bracket had a slot for the inboard mounting fastener. At St Louis the coil installer slipped the bracket under the bolt that had already been installed and added the outboard bolt. We sometimes see different head marks on these two bolts.

Too bad you can't find the original thread since some of us posted pictures of the fasteners with head marks. We all sometimes veer off the topic of the original poster and in these cases it is next to impossible to find the thread later. I don't remember if that is what happened in this case, but it is something to keep in mind -- although I doubt it will stop the free-wheeling discourse on this board.

Both my coil mounting screws have anchor headmarks on the early 1970 LT1.
Many other headmarks would be acceptable. There is no one-size-fits-all when it comes to headmarks in most applications.

[Jeffrey S.]

Re: C3 SB coil bolt question

Don:
One of the screws (the one farthest to the right) is listed in my AIM (Section 6 page B6) as "Part of Eng." which means it was painted orange at Flint. The other has part number called out so it was installed at St. Louis and was, most likely, cad plated. The head markings would more than likely be different because the chances of the same supplier sending screws to both factories is not high although not impossible. BTW: did the washer pump work?
Jeff

[Don L.]

Re: C3 SB coil bolt question

Thanks, Jeff. My AIM [B6] shows BOTH bolts, the bracket and the coil too. How weird is that? I gather from Terry's advice that the inboard bolt came from Flint, therefore, should be orange. I really think what I was trying to recall was if the bolts were same/different headmarks. From the good adivce I got from you folks, I'm good with one painted bolt, one natural bolt , 2 star washers and possibly mis-matched headmarks. I'm on track.

Jeff, BTW - to the w/s washer pump! Had to sort out why the wipers wouldn't come on again, but found it to be that I needed to re-adjust the limit switch after having the actuator off for seal R & R. Just counting threads on the actuator stem 'aint enough...

[Patrick H.]

Re: C3 SB coil bolt question

Thanks, Jeff. My AIM [B6] shows BOTH bolts, the bracket and the coil too. How weird is that?

Don,

It's weird enough to indicate that the process in 1972 was different from previous years. I'm not home now to double check my AIMs, but if they're both shown then they were both St. Louis installed and should not be painted. Note the pictures below, and my 72's have never had paint on them, inboard or outboard.

Patrick

[Don L.]

Re: C3 SB coil bolt question

Patrick, please do check your AIM when you can. I should have mentioned in my earlier post that although the 2 bolts, the coil and the bracket are all shown in the AIM, there is no part number detail, at least that I can find for any of them. There is a note on B6 that tells that the distributor was installed at the engine plant, but I can't find anything about the coil and/or hardware.

Additionally, your two bolts appear to have differing headmarks. True? A potential indicator of separate installations???

I love these forensics...

[Steven G.]

Re: C3 SB coil bolt question

Don, the star washers are captured and should be on the bolts, I have an early 70' L-46 with orange inboard bolt and a 72' base engine unpainted orange inboard bolt, that an observation of cars I own and I am thinking are original. Steve

[Don L.]

Re: C3 SB coil bolt question

Thanks to all for the advice and direction. It is apparent from Jeff's, Terry's, Patrick's and Steve's original cars that the inboard bolts were installed and painted in 1969 and 1970 engines, but not installed prior to engine paint by 1972. 1971 is unclear from this thread. Hopefully, if there are disagreements, they'll be shared via reply.

I'm still puzzled, however, as to why I can't find/confirm the assembly information for the bolts and bracket in the '72 AIM. I'm hoping that I just missed it. Anyone see it?

[John H.]

Re: C3 SB coil bolt question

I'm still puzzled, however, as to why I can't find/confirm the assembly information for the bolts and bracket in the '72 AIM. I'm hoping that I just missed it. Anyone see it?

Don -

It should be in UPC 6 - the coil and plug wires were released in the same group (6Y4) by Engineering; may be on the same sheet as the plug wires.

[Terry M.]

Re: C3 SB coil bolt question

I'll check the AIMs when I get home. I have them stored where the sun don't shine, and it has turned cold again -- but for you guys ....

Since I kind of started it I guess I better see it through.

[Terry M.]

Re: C3 SB coil bolt question

OK class here is the story -- All you 1972 owners who can't read the AIM listen up. You guys had the answer all along, but didn't get it. Now I am going to go through this slowly.

1968 to 1972 AIMs UPC6 (thank you John) Sheet B6 -- yes it is on the same exact page in ALL of them, and I should have remembered because this is one of my favorite pages -- for EXTRA credit: start another thread and explain what the distributor timing marks mean on all these pages.

On the 1968-1971 pages ALL of them show the inboard screw as "part of engine" with a line pointing to that screw. There is also a triangle around a number pointing to that screw as well as the outboard screw – looking at the bottom of the page at the same symbol will give you the torque value for these screws. From this information one can reasonably conclude the inboard screw was installed at the engine plant but tightened at St. Louis.

Now for the interesting stuff for 1968 the outboard screw was part number 274430
1969 = 3848408
1970 = 9431963
1971 = 9431963

"Now ain’t that special" said the Church Lady.

Now for what you 1972 owners would have seen, if you had looked and read the signs:
For 1972 -- drum roll please -- There is no part number for the screw NOR for the coil. There is a note pointing to the coil that says: "coil assy [ ]" That square has a diagonal slash and is half darkened. That is the symbol that means "installed by others," so the coil assembly is "part of engine." Got it now class??
For 1972 the coil was installed at the engine plant -- at least for small blocks.

I'll let you guys who own big blocks work on this some yourselves. After all we tell you what books to buy, but then we have to go read them for you too.

[Don L.]

Re: C3 SB coil bolt question

Thannnkkk youuu, Terrryyyyy!

S'pose you have solved it then. Another weird thing is that as I read your post above, I kinda imagined myself sitting on your lap, in awe, just listening to you tell us/me the story. Looks like everyone here's gonna live happily ever after.

As my reply to Patrick shows, I indeed had the clue in front of me, seeing that it was all shown in B6, without part number detail, which tells us that it came in as part of the engine, but I got sucked into thinking the '72 bracket and coil were installed @ St. Louis, 'cause they were in '69, '70 and '71.

I'm enlightened...and appreciative. Really. Thanks.

[Terry M.]

Re: C3 SB coil bolt question

I was kind of holding my breath when reading your post Don. In fact it was your post that gave me the momentum to go look at the AIMs -- thanks. You posted enough to give me a clue. It was the square symbol that was the key, and not everyone notes that symbol or knows its meaning.

[Steven G.]

Re: C3 SB coil bolt question

Patrick, I found what I believe are original coil bracket bolts for 72', #3187, They are matching head headmarkings , BHT, has 2 circles and semi circle on top half. Just another example of bolts being used during this 72' production. Matching head markings are very interesting. Steve