70 Heat Shield/Shields and wire support bolts

[Bill L.]

I am looking for a little clarification regarding the bolts. Should they have star washers, lock washers, or flat washers?

When attaching the rear RFI shields should there still be a thick washers on any of the exhaust manifold bolts in addition to the L bracket to which the RFI shield is held in place via the wing nuts?

What type of head mark and bolt was used to attached both spark plug wire supports to the rear of the block?


Kindest Regards, Bill

[Joe L.]

Re: 70 Heat Shield/Shields and wire support bolts

I am looking for a little clarification regarding the bolts. Should they have star washers, lock washers, or flat washers?

When attaching the rear RFI shields should there still be a thick washers on any of the exhaust manifold bolts in addition to the L bracket to which the RFI shield is held in place via the wing nuts?

What type of head mark and bolt was used to attached both spark plug wire supports to the rear of the block?


Kindest Regards, Bill

Bill-----


The bolts used to retain the spark plug heat shields and the lower rear spark plug supports were the same. They were a 1/4-20 bolt with a captive external tooth lockwasher. They were zinc plated and had an untrimmed (i.e. "indented") head. I believe the length was 1/2" or very close to that. Typical headmarkings were "L", "EL", or an anchor.

[Terry M.]

Re: 70 Heat Shield/Shields and wire support bolts

I went to look at my car, but I couldn't see a single one of those bolts without taking something apart. Maybe if I could get the car on the lift I might be able to see the bolts in the heat shields, but I have a feeling that is a big maybe.

[Bill L.]

Re: 70 Heat Shield/Shields and wire support bolts

I keep seeing "heat shield bolts" for sale and some have the flat washer and some have the star washer. I am starting to think maybe they used both? I have also observed 5 different head marks advertised. Sems, Anchor, E, E., and EL. One person claim that his one is held on with an "A" head mark.

Does anyone have an unmolested 70 they might be able to take a look at.

Like Terry said, it is really difficult to see the bolts from up top. I am thinking maybe the bolts that hold both the heat shield and the spark plug wire clip might be visable from down below.

Kindest Regards,



Bill

[Steven G.]

Re: 70 Heat Shield/Shields and wire support bolts

I AM WORKING ON #3187, 72, 350. SPARK PLUG WIRE HEAT SHIELDS HAVE E head marking, with split lock washer ONLY. spark plug wire bracket (rear block) ELH WITH STAR WASHER, ALSO, BACK UP LT. SWITCH SHIELD (4-SPEED) HAVE DOUBLE CIRCLE SURROUNDING ELH, WITH STAR LOCK WASHER. HEAD MARKINGS MAY BE DIFFERENT FOR 70 ? but washers should be the same. I hope this helps until someone offers better info. for 70.

[Alan S.]

Re: 70 Heat Shield/Shields and wire support bolts

Hi Bill,
I'm not sure just where you are in area code 301, but, you're more than welcome to come take a peek at some of these things on my 71 which apply to your 70 also.
My wife might even serve eggnog!!!
Regards,
Alan

[Robert S.]

Re: 70 Heat Shield/Shields and wire support bolts

On my 74' (L48) the bolts that hold the ignition wire looms on the left and right side at the rear of the block are as described by others - 1/4-20 recessed head by just under 1/2 inch long as I recall and have the external star lockwasher design. As my car was missing all the heatshields I purchased the bolts and heatshields from Corvette Central and the bolts came with lockwashers and not star washers (as I had assumed they would) but otherwise look like the wire loom bolts. The heatshield bolts are easily seen from underneath but can be installed from up top or underneath but are most easily tightened from underneath. Three go in rather easily. The 4th - passenger side front is a real bear as the bolt hole in the block is near the motor mount as I recall. At any rate it took me several hours to get it started enough to tighten from below. This bolt of course has to go through not only the heatshield but also the spark plug wire two wire clip.

As for the bolts and spacers on the exhaust manifold bolts they are shown in the AIM and in several vendor catalogues.

[Bill L.]

Re: 70 Heat Shield/Shields and wire support bolts

Hi Alan,

I am in Damascus, MD just south of 108. I would love to take a look. It is interesting and it looks like either star washers or split lock washers are correct. The only other thing to determine is if the head marks are the same as the mid year which means the "E." headmark would be fine.

The other parts for the shields I need are the L brackets as mentioned. I was looking at Long Island Corvette and if mid year is same as C3 brackets, they claim theirs are 100% correct. Do you by chance have any knowledge in that area as well.


Kindest Regards,




Bill

Hi Bill,
I'm not sure just where you are in area code 301, but, you're more than welcome to come take a peek at some of these things on my 71 which apply to your 70 also.
My wife might even serve eggnog!!!
Regards,
Alan

[Steven G.]

Re: 70 Heat Shield/Shields and wire support bolts

Bill, I Have Purchased Repo's Brackets From 2 Sources. Comparing To Know Original's, Both Repo's Are A Bit Thicker In Guage And 1 Source Had Stamping Made In Canada + Cmi. The Other No Stamping. Please Post Bolt Head Markings If You Are Able To Get A View From Alan's Car. Thanks, Steve

[Terry M.]

Re: 70 Heat Shield/Shields and wire support bolts

I think the CMI and "made in Canada" was on the last ones that were available over-the-counter in the "good old days" when the Chevrolet dealers still had Corvette parts. Those might just be correct for the later 1970s cars, but are something the 1968-'72 judges look for and deduct for (although it is a minor deduct).

[Bill L.]

Re: 70 Heat Shield/Shields and wire support bolts

Well I have purchased what look to be NOS GM heat shields for 3 of the 4 pieces. I try and look for those old GM stickers since the older the NOS the more likely to be correct.

I found some really nice original RFI shielding except for the cover. I have an original that is missing one of the clear rivets and needs to be re-flash chromed. I may get a repro for non NCRS events since the chrome is much nicer and it is easy to change out. Same for the air cleaner top.

I am hoping they do not have the made in Canada on them.

I should have them any day now.


Bill

[Terry M.]

Re: 70 Heat Shield/Shields and wire support bolts

I expect if one is crafty the "made in Canada" and the rest could be removed or filled in and the brackets replated. The plating doesn't last long next to the exhaust manifold bolts anyway. I guess it is all a matter of how much effort one wants to expend for a very few points. You know, the usual story.