Fire wall heat shield?

[Chester]

White or black? What I'v determined is they are the whitish colored ones. But were they installed before or after the black-out stage to the engine compartment /firewall area? I've also read that the 68 does not have the "after market" transmission/tunnel fiberglass foil shield. Wait maybe it was the tunnel collar shield. The 68 does come with a under body foil/fiberglass some what "L" shaped per side shields? Like or positioned under the seats but under the car, then or with the spiked tabs bend them over.--was this done with the body on or off-- the guy at the shop said it is easier to do it with the body on so that you can line up the holes etc. Page 100 0f Dr. rebuild catologe says there are 2 stamped steel under body heat shields ( under seat area) My bodies north and I'm assuming these are still on the car. I know the large "L" shape are hhhhistory. Do these 2 stamped steel plates pinch the insulation between the body and themselves?

Thanks..

[Jack H.]

Re: Fire wall heat shield?

You're in a grey area here, Chester. '68 is a big challenge since it was first of new body style and there were MANY running changes. Folks will have their own opinions THEN there's what's right. What's right is what and how YOUR car was built....

I'm saying beware of getting single input(s) no matter how knowledgeable the source. You need to blend some detective work on this car with what's in print and/or known.

Here's what I'd do. Buy the '68 AIM (I think you said you have one), then buy the '69 AIM. Why? Lots of changes made during the year don't get documented until the next release of AIM. They're treated as non-critical temporary deviation exceptions.

Now, you're questioning things like tranny tunnel insulation/air dam and firewall/floor heat sheilds. You're into an area where we know designer's were 'drinking from a fire hose' of customer feedback (not always good). We also know things on '68 got added as well as deleted. Last, all the items you question are St. Louis build items (not purchased assy's like engine tranny), so they WILL be documented in the AIM.

Take the tranny tunnel insulation pad. Thumb through your '68 AIM and find where the part is called out going onto the car. See if there's one or more ECR (engineering change records) notes. These will be numbers in circles on the drawing near the part number field.

Now, look down at the bottom of the dwg where the ECR block is. You'll see notes and dates as to when change(s) on that particular item (when it came on, when it phased out, when there were major form/fit/function changes). Then, do the same thing with your '69 AIM.

You'll get a running history of what/when. These ECR notes only tell us when GM Engr at the Tech Center actually got around to modifying the dwg. They don't say if there was some kind of pilot run before formal adoption or if there was some kind of emergency release prior (threat to life limb property). Plus, the effective date doesn't say when (if ever) the change Detroit authorized actually got up & running at the St. Louis factory....

But, you'll be able to make more informed decisions in your restoration (and back them with 'proof') this way. If your car was built comfortably before a major ECR took place, odds are good it didn't have the item. If your car was built shortly on/after an ECR release date, you're in a very grey area (do more primary research). If your car was built comfortably after an ECR date, it probably incorporated the change.

[Gene M.]

Re: Fire wall heat shield?

Chester, Jack's summary on '68's was pretty true to form. I can help you out with early production '68's. My '68 (vin 4235) came with tunnel insulation but never showed and evidence of a collar insulator. The sheet metal shields all appear as expected but never any signs of fire wall nor floor insulation. I've owned it since '71 and I restored it as I found it. Hope this helps you.