More On 65-66 BB Spark Plug Heat Shields

[Michael H.]

Looking for input from owners of original or correctly restored 66 cars with 427. I have paperwork that shows the shield was removed from production on 2-4-66. Does anyone have a March or later car that they feel has it's original shields? I'll try to post the paperwork. Thanks,

Michael

[Michael H.]

3871266 Removed 2-4-66

The 3871266 shield along with attaching hardware was removed on 2-4-66.

[Peter M.]

Re: 3871266 Removed 2-4-66

Michael - I have an original , documented 427/425hp L72 - build date is 1st week April 1966. The engine was assembled March 31, 1966. The heat shields are original unrestored and inplace.

[Joe L.]

Re: 3871266 Removed 2-4-66

Peter and Michael-----

The 2-4-66 date is the date that the drawing was revised to delete the shields and associated hardware. There's no way that the change would have occurred on the production line in St Louis as of that date. Usually, it took 6 weeks, and sometimes considerably longer, for the change to affect production.

[Michael H.]

Re: 3871266 Removed 2-4-66

Yes, exactly Joe. That's why I requested info on cars built in March or later. Actually, the date of change on the assy line was, at times, very close to the date on the paperwork. If there was a safety issue or some other important reason why an immediate change was required, it may have occured within days of the print or AIM date. On "ADD" items, there was more of a lag in the time span due to material arrival at the line but with a "DELETE" item, the change would probably have occured much closer to the ECR date.

[Joe L.]

Re: 3871266 Removed 2-4-66

Michael-----

Safety-related things did get action much more quickly. However, during the 60s there really weren't too many of these. Just a handful. In this case, it appears that it was at least 2 months before the change was made. That's a little longer than I would expect for it to take, but it's "in the ball park".

[Michael H.]

Re: 3871266 Removed 2-4-66

There were many reasons why some part numbers were removed or changed during the model year and the time span between the date of change in the AIM, and the physical change on the line would often depend on the importance of the change. It went far beyond just safety issues. Many warranty problems in the field traced back to an assembly procedure or part configuration could call for an immediate change on the line. If an assembly procedure, the actual change in production could have occured BEFORE the date in the AIM ECR.

If, for example, a squeak complaint was received from the field and the problem traced to a screw holding a small bracket under the IP, the screw part number may have been changed but the physical change on the assy line might not actually appear for months. If, however, the right door was falling off when opened because of a faulty hinge pin design, the change, as you can well imagine, would be immediate. You can see this in the parts disposition sheets. Subtle non critical design changes in parts will state "mix with" or "use existing stock". Other more critical part number changes will show "disposition of stock: SCRAP".

This is one of the reasons why certain options sometimes become temporarily unavailable during the model. If a major problem is found and a part design change is required, it may take several weeks for this redesigned part to actually show up at the assembly plant. If the problem is something that can be corrected on the line with a slight modification to the existing part, the option may continue using the "patch" until the new design part arrives.

There's really absolutely no time span or rule that can be used for determining the length of time between ECR and the actual on line change. I know that many people assume that if the AIM calls for purple heater hoses to replace green heater hoses on AIM date xxx, all units built from that date on will have purple hoses. It's just as inaccurate to assume that the on line change occured two, four or six months later. That's why it's so important (to me at least) to gather as much information as possible while there are still unrestored cars left, which brings us back to my origina post, the point of which was to try to determine what the real world time of change was.

Michael

[James W.]

Re: 3871266 Removed 2-4-66

Is it possible that the factory continued to install them after the 2-4-66 date in an attempt to deplete the then current supply that was on hand?

Just a thought.

Regards,

James West
Omaha, NE.

[Joe L.]

Re: 3871266 Removed 2-4-66

Michael------

One other thing: in your original post you said that the shields were removed from PRODUCTION on 2-4-66. What I was commendting on in my response was that they were not removed from PRODUCTION on that date. They were removed from the AIM drawing on that date.

[Michael H.]

Re: 3871266 Removed 2-4-66

James,

I'm sure the installation continued after the date on the paperwork, at least for a short time. However, I don't think it had anything to do with using up existing stock at the plant. Generally, when there was a supply of parts that had been removed from the assembly process, the entire lot would be scrap. This would exclude major expensive components but everything else was disposed of. It was actually more cost efficient to scrap parts than it would be to ship back to source or parts distribution centers to be boxed for service sales. If I were to post some of the "scrap orders" I have on parts, it would bring tears to the eyes of any Corvette owner.

I don't know the exact reason why the shield was removed from 66 production but it didn't seem to have any affect on anything.

Michael

[Richard S.]

Re: More On 65-66 BB Spark Plug Heat Shields

Michael,
I have an original engine 427/390 convert. built in St.Louis, late in the day on Friday,June10th,1966. Engine was assembled Tuesday,May 31st,1966 in Tonawanda,NY. Block(942)was cast, Sunday(yes,Sunday)May 20th,1966. Conv. body S-7597 was built in St.Louis on Thursday,June 9th,1966. This engine did not have spark plug heat shields when I acquired it. Hope this helps your research in this area.

[Michael H.]

Thanks Rick *NM*