70 LT1 Interesting Requirement!

[Ralph B.]

Regarding the (2) coil bracket bolts which hold the bracket onto the intake manifold, I find this unusual but intersting;

Assuming I understand the JM correctly the (2) bolts are finished differently i.e. ----- the inner bolt head is supposed to be painted aluminum and the outer bolt head is to be black phosphate.

My questions are:
1. Did I interpret this correctly?
2. As to why, do you suspect the factory wanted the outboard bolt to be colored the same as the intake bolts for matching purposes?
3. And finally are these bolts supossed to have washers?
Thank you in advance,
Ralph

[Dave S.]

Re: 70 LT1 Interesting Requirement!

Regarding the (2) coil bracket bolts which hold the bracket onto the intake manifold, I find this unusual but intersting;

Assuming I understand the JM correctly the (2) bolts are finished differently i.e. ----- the inner bolt head is supposed to be painted aluminum and the outer bolt head is to be black phosphate.

My questions are:
1. Did I interpret this correctly?
2. As to why, do you suspect the factory wanted the outboard bolt to be colored the same as the intake bolts for matching purposes?
3. And finally are these bolts supossed to have washers?
Thank you in advance,
Ralph

Ralph,
Your interpertation seems correct. Just to add confusion to that information I've attached a photo of the coil bracket from my 70 LT-1. I'm the second owner but it is a low mileage original car. It appears that both bolts still have their original paint on them and both have star washers and the head markings are the same. There are other 70 LT-1 owners that frequent this board and I'm sure they can add to this discussion.

[Terry M.]

Re: 70 LT1 Interesting Requirement!

Regarding the (2) coil bracket bolts which hold the bracket onto the intake manifold, I find this unusual but intersting;

Assuming I understand the JM correctly the (2) bolts are finished differently i.e. ----- the inner bolt head is supposed to be painted aluminum and the outer bolt head is to be black phosphate.

My questions are:
1. Did I interpret this correctly?
2. As to why, do you suspect the factory wanted the outboard bolt to be colored the same as the intake bolts for matching purposes?
3. And finally are these bolts supossed to have washers?
Thank you in advance,
Ralph

Ralph:
1) Yes as regards the LT1 with the silver painted manifold.
2) Same paragraph in the TIM&JG (but you do have to turn the page in the 4th edition) top of page 66, first line: "The bolts often have different head markings due to their installation at different plants."
3) Yes star external tooth washers. You can just see them in the photos below. These are of my 1970 LT1 which happens to have the same head mark on the coil bracket fasteners. That is not usually the case.

[Mike E.]

Re: 70 LT1 Interesting Requirement!

Don't remember the head markings on my 30k mile 71 LT-1 convert, but I know one is cad plated and the other black oxide/phosphate.

[Joe L.]

Re: 70 LT1 Interesting Requirement!

Ralph:
1) Yes as regards the LT1 with the silver painted manifold.
2) Same paragraph in the TIM&JG (but you do have to turn the page in the 4th edition) top of page 66, first line: "The bolts often have different head markings due to their installation at different plants."
3) Yes star external tooth washers. You can just see them in the photos below. These are of my 1970 LT1 which happens to have the same head mark on the coil bracket fasteners. That is not usually the case.

Terry-----


I think the reason for the difference is that one of the screws was installed at the engine plant and the other one installed at St. Louis. So, there were likely different part numbers used---one of which was black phosphate-finished and the other zinc plated. Why the screws were installed at different locations I have no idea.

[Keith L.]

Re: 70 LT1 Interesting Requirement!

Would it be safe to assume the one where the slotted end of the bracket is is the one put in at the engine plant? Then all they had to do is slide the bracket under and put the other bolt in.

[Joe L.]

Re: 70 LT1 Interesting Requirement!

Would it be safe to assume the one where the slotted end of the bracket is is the one put in at the engine plant? Then all they had to do is slide the bracket under and put the other bolt in.

Keith----


The "inner" bolt was the one installed at the engine plant.

[Terry M.]

Re: 70 LT1 Interesting Requirement!

Would it be safe to assume the one where the slotted end of the bracket is is the one put in at the engine plant? Then all they had to do is slide the bracket under and put the other bolt in.

That is what we were trying to say in the TIM&JG. The difference becomes far more obvious on cast iron manifolds where the bolt installed at the engine assembly plant got painted orange with the rest of the engine.

One should also note that many replacement coil brackets do not have the slot for the inboard fastener. An observant judge will make a deduction for both configuration and installation in that situation.

[Keith L.]

Re: 70 LT1 Interesting Requirement!

I wish this had been posted a couple days earlier. I took mine off Saturday. Looked at them today. One anchor like Terrys pic above. One with a circle with an E and three lines from the circle at 3,6 and 9 oclock. I don't know which one came from which side. Both have rust but the bottom appears brite zinc. (shiney silver) Ayone have these markings and which one is which? As many pics as I have taken none show the head markings before removal.