Exhaust blackout, help me understand!

[Jim P.]

Re: Exhaust blackout, help me understand!

I love the smell of burnt paint in the morning.

[Michael G.]

Re: Exhaust blackout, help me understand!

It's my understanding that the same guy who sabotaged all the build records at St Louis (in area 51) also had the foresight to add a big block hood to many small block, as he felt that this would ease their later "restoration" to 435 HP cars. My guess is, he threw a few used black mitts into cars after he used them to smudge all the build records with black paint. This, of course, confused owners who thought the mitts had somehow been used to "black out" part of their cars, hence the "mitting" rumors.

[Dennis C.]

Re: Exhaust blackout, help me understand!

Wow,

Now I'm really confussed I am in prosses of trying to restore a 1959 and I have been told the NCRS technical is a guidline. The statement I made about the mittens came from that manual. Help me understand.

Thank you
Cliff

Cliff,

To complete your restoration, you will need to blackout your entire exhaust system except the clamps and hangers.

Regards,

Dennis

[Cliff P.]

Re: Exhaust blackout, help me understand!

Thank you all

Cliff

[John H.]

Re: Exhaust blackout, help me understand!

This was also mentioned in Noland Adams' C2 book, further adding to the confusion.

Paul -

Noland (bless his heart, I know him very well) didn't have the opportunity to be in the plant when he wrote the '63-'67 book; it was done after the plant closed.

[Mike E.]

Re: Exhaust blackout, help me understand!

It's my understanding that the same guy who sabotaged all the build records at St Louis (in area 51) also had the foresight to add a big block hood to many small block, as he felt that this would ease their later "restoration" to 435 HP cars. My guess is, he threw a few used black mitts into cars after he used them to smudge all the build records with black paint. This, of course, confused owners who thought the mitts had somehow been used to "black out" part of their cars, hence the "mitting" rumors.

Perhaps that's how the C3 LT-1 was born with a big block hood, it went over so well.

BTW Mitting is also mentioned in the '1965 JM in the Exhaust System section. I realize it's been completely debunked.


Mike

[Peter G.]

Re: Exhaust blackout, help me understand!

My pass experience in living with Corvettes during the 1975 era that my new 1976 did have the muffler and tailpipe blackout done. I do not remember seeing a '77 or later C3 with blackout.

[Troy P.]

Re: Exhaust blackout, help me understand!

C5's also had it.

[Troy P.]

Re: Exhaust blackout, help me understand!

Wait a darn minute. Since the blackout was sprayed on after the exhaust system was installed the hangers and clamps should be painted too. (Recall the point of the balckout process is so the cars wouldn't have any rusty parts when sold.) I have recently observed this on an unrestored 54 with 2331 miles on it. Also examining the photos of the car that was disassembled and documented in the UK (C1 registry) when it was new also shows the hangers and clamps black.Hall 54 043.jpg

[Paul J.]

Re: Exhaust blackout, help me understand!

Paul -

Noland (bless his heart, I know him very well) didn't have the opportunity to be in the plant when he wrote the '63-'67 book; it was done after the plant closed.

I was'nt being critical, John. I purchased his book 25 years ago and I bought it because of the amount of research and knowledge in it. It is still one of my favorite reference books. Several years ago this topic came up on this forum and I cited the reference in his book. You corrected me.

Paul

[Michael G.]

Re: Exhaust blackout, help me understand!

After reading this thread a few times, its clear that on C2s the blackout was applied just before body drop. I think I'm reading that the frame was still inverted, but an earlier discussion here showed paint dripping off of the bottom of the pipes, as though they had been painted from the top.

Given the above, its not quite clear if the chassis had been flipped into an upright position for body drop, before the spray that John described. Can you weigh in on this John H.?

Thanks,

[John H.]

Re: Exhaust blackout, help me understand!

After reading this thread a few times, its clear that on C2s the blackout was applied just before body drop. I think I'm reading that the frame was still inverted, but an earlier discussion here showed paint dripping off of the bottom of the pipes, as though they had been painted from the top.

Given the above, its not quite clear if the chassis had been flipped into an upright position for body drop, before the spray that John described. Can you weigh in on this John H.?

Thanks,

Mike -

The frame was flipped to right-side-up by the frame turnover device at the end of the Frame Upside-Down Line which transferred the frame to the beginning of the Chassis Line, and it remained right-side-up through the full length of the Chassis Line, all the way to Body Drop. The turnover device is shown in the foreground of the photo below.


66SLFrameLine.jpg

[Troy P.]

Re: Exhaust blackout, help me understand!

John, it looks like the number of body shims has already been determined. How the heck did they figure that out so early in the game?

[John H.]

Re: Exhaust blackout, help me understand!

John, it looks like the number of body shims has already been determined. How the heck did they figure that out so early in the game?

Troy -

The frame was measured for shim count in the very first station on the Frame Line, which was a precision fixture that clamped the frame down upside-down against zero datum points; each body mount bracket surface pushed down against a spring-loaded plunger, and the depth of plunger movement showed the shim count required at that location, which was then marked on the frame. Later in the C3 era, shim determination was moved to the Chassis Line, just prior to Body Drop, using an overhead "spider" fixture that did the same thing.


ShimGage (2).jpg

[Rick B.]

Re: Exhaust blackout, help me understand!

John, I'm sorry, I may be a little slow here, for clarity, for C1's, did blackout occur at the Frame Upside-Down Line or at the Chassis Line? This was prior to engine drop, correct? Also front suspension components, did they receive the blackout process or typically only from trans rearward?

thanks again John, I know you have been through this a thousand times

Mike -

The frame was flipped to right-side-up by the frame turnover device at the end of the Frame Upside-Down Line which transferred the frame to the beginning of the Chassis Line, and it remained right-side-up through the full length of the Chassis Line, all the way to Body Drop. The turnover device is shown in the foreground of the photo below.


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