1972 BB exhaust system - judging deduction

[James B.]

After reading other postings regarding point deductions of Gardner, Allen and CC exhaust systems, it prompted me to ask:

How much point deduction should I anticipate to receive on a complete NOS exhaust system (pipes and Walker mufflers) for my 1972 (with 454)? I've welded the mufflers to the rear pipes and I'm using NOS muffler hangers, brackets, u-bolts, heat riser, etc.


Jim

[Terry M.]

Re: 1972 BB exhaust system - judging deduction

Depends on NOS when? NOS 1972 you might receive little or no deduction depending on the quality of the welds. Oh and did you add a little stop sign shaped tab to the top of the outlet pipe to locate the tips?

NOS 1980s may have issues with the embossing on the mufflers, and you might have to cut an extra bracket off the back of the muffler.

You see, there is NOS and then there is NOS.

The clamps could also be an issue depending on the same date situation.

[Edward J.]

Re: 1972 BB exhaust system - judging deduction

Terry, Weren't the factory pipes welded to the muffler at the end plate, as the nos mufflers will have a part no stamped and no W stamp. and on the nos stock mufflers have a extension on the end plate so the weld will not be in the same spot. I guess it still a confiuration issue.

[James B.]

Re: 1972 BB exhaust system - judging deduction

I had orderd and purchased the entire exhaust system from a Chevrolet dealer in the early 80's.

The mufflers do have the pipe extentions on the inlet side. So, the welds I had performed to connect the pipes to the mufflers, would not be fashioned as factory original. However, I figured it would look more factory original without the large clamps to connect the mufflers. As for the muffler outlets, for the record, there aren't any welded tabs on my NOS units. Yes, there still remains an extra bracket on the back of each muffler. Any idea how much point deduction would the extra brackets add? Has anyone welded the tabs to the mufflers and can comment?

Jim

[Terry M.]

Re: 1972 BB exhaust system - judging deduction

OEM 1972 mufflers have no stamping on them other than the W. If yours duplicate that you are past hurdle one. If you can't get past hurdle one, don't bother with the rest because you won't fool anyone.
Hurdle two is the weld at the front. A butt weld can be made to join the muffler inlet stub pipe to the rear pipe and finished in such a way that it is undetectable. I have done it and seen it done by others on this board, but it takes a good welder with the desire to make it perfect.
Hurdle three is to remove the extra bracket from the rear of the muffler and make the place where the bracket was like there never was a bracket there. Not so hard given the muffler was blacked out, but it does take some careful work.
Hurdle four is to apply the blackout like the factory did.

If you can't do all four of these don't expect a no deduct judging. None of us can tell you how many points you will lose until you tell us how your mufflers look. Oh and don't forget that stop-sign shaped tab. I know the NOS mufflers will not have it because only the PRODUCTION systems had it. You will have to add it -- assUming your tips have the cut out for it. If they don't have that cut-out you will have another deduction.

ED: I tried to indicate in my first post (perhaps too subtle) that not all NOS mufflers are the same. Some had only the W, and some had the W and a part number, and some yet had the part number and some other raised lettering including a date. The answer to Jim's original question depends on just how much the muffler and the joint to the pipes vary from the factory installation. Obviously knowing which stamps, if any, are on his mufflers will go a long way toward getting him that answer.

It kind of sounds like his weld is not quite what the factory would have done. The extra bracket is easily removed, and the stop sign tab easily added -- if he knows someone with access to a spot welder, or can make a tab with a hole in the middle and do a plug weld. In judging that tab is largly a "by feel" assesment so it can be a little crude.

The days of buying a correct part off the shelf are gone. Everything will have to be modified to duplicate original. Of course one has to know what the original PRODUCTION system looked like. We better get used to that situation as we will be doing more and more modification to make the part look original. Craftsmen will be successful -- Bubba will lose points.

[Joe L.]

Re: 1972 BB exhaust system - judging deduction

After reading other postings regarding point deductions of Gardner, Allen and CC exhaust systems, it prompted me to ask:

How much point deduction should I anticipate to receive on a complete NOS exhaust system (pipes and Walker mufflers) for my 1972 (with 454)? I've welded the mufflers to the rear pipes and I'm using NOS muffler hangers, brackets, u-bolts, heat riser, etc.


Jim

Jim-----


For standard exhaust, there was NEVER a system available from GM in SERVICE that was the same as PRODUCTION. PRODUCTION systems used a longer rear pipe that was welded to the muffler at the muffler. SERVICE systems used a shorter rear pipe and a muffler with a forward extension and bell joint. As Terry mentioned, this can be "reconfigured" to simulate original configuration but it's difficult to do.

For 1968-72 2" systems there were once available mufflers with only the C3 rear muffler bracket. However, for 1968-72 2-1/2" systems, there were NEVER available SERVICE mufflers with only the C3 rear bracket (except for the 1968-only off road muffler/pipe assemblies). Except for the parenthetically referenced application, all 1968-72 SERVICE mufflers for 2-1/2" systems had dual brackets (for use on both C2 and C3 2-1/2" applications). Once-upon-a-time there did exist C2 2-1/2" mufflers with only the C2 rear brackets but they were discontinued in favor of the "dual bracketed" mufflers.

If you could find a set of NOS 1968-only off-road mufflers, they would be in configuration almost exactly what you would be looking for. Except for the somewhat louder exhaust note produced by these mufflers, this set-up would appear virtually identical to what was used for any 1968-72 2-1/2" application. Your chances of finding such a set of muffler/pipe assemblies? Virtually ZERO and undoubtedly mind-bogglingly expensive if you did.

You could also use a set of NOS 1964-67 off road muffler/pipe assemblies by removing the 64-67 rear hanger bracket and welding on the 68-72 bracket. You'd still be faced with the louder-than-original exhaust note but the configuration would be near identical to the original. However, these are extremely difficult to find, too, and very expensive if you do.

For the points involved, I think a person's best bet is to do the best you can with currently available "reproduction" parts.

[Terry M.]

Re: 1972 BB exhaust system - judging deduction

You could also use a set of NOS 1964-67 off road muffler/pipe assemblies by removing the 64-67 rear hanger bracket and welding on the 68-72 bracket. You'd still be faced with the louder-than-original exhaust note but the configuration would be near identical to the original. However, these are extremely difficult to find, too, and very expensive if you do.

For the points involved, I think a person's best bet is to do the best you can with currently available "reproduction" parts.

The 1964-67 off road pipes are available, I have seen them at swap meets so they must be on the net. Of course some people who do not sell pars have hem, but that doesn't count toward the available supply.

Your last sentence sums up the situation perfectly, Joe. But of course you knew that.

[Don L.]

Re: 1972 BB exhaust system - judging deduction

Great thread!

Does anyone have a picture of the stop sign-shaped piece Terry describes? I am aware of it and do have the cutout in my exhaust tips but need a model for creating the positioning key.

The AIM drawing looks like more of an arrowhead but is of poor quality. I've never seen one and am very interested.

Thanks.

[James B.]

Re: 1972 BB exhaust system - judging deduction

Terry and Joe,

Thanks for the detailed explanation regarding configuration and my options. Based on this, I'm going to try to utilize my NOS exhaust system (as I already have it and I also want to preserve the original exhaust sound). Yes, the mufflers have the "W" stamping (but no part number or date). As for the muffler inlet pipe extentions and welds to the pipes, I'm going to stay with that configuration for the time-being (realizing that I'm going to receive a deduct for that). The (circa early 80's) NOS exhaust tips do have the cut-out (but they also have the part number stamped in them, which I realize would be another deduct). BTW: I did have the exhaust tips welded at the seams years ago and the tips rechromed (another possible deduct?). As recommended, I will carefully cut-off the extra muffler brackets. To mirror Don's request, I would appreciate some more direction on the duplication of the exhaust tips stop tabs. Once the modifications are complete, I will attempt to duplicate the factory blackout. If anyone has comments on how much of the muffler (bracket end - including the bracket and hanger) gets blacked out, that would also be helpful. Perhaps even with this explanation, it would be difficult to determine the likely total point deduction. If so, I understand.

Jim

[William C.]

Re: 1972 BB exhaust system - judging deduction

The '64-67 "off Road" pieces are also configured differently from the ones used on the "68-up cars, most obviously at the area where the piped go under the bracket that hinges the lower adjusting arms. The '68 up systems are much more compressed in that area, due in no doubt to the reduction in the tire diameter starting in '68.

[Bill C.]

Re: 1972 BB exhaust system - judging deduction

Jim,

I went the same route you are.

I had the car judged twice at regionals. The most I lost in points was around 8 total. I was dinged for the weld, I did not butt weld the assemblies, just welded around where the muffler lipped over the mid pipe.
It was noted on the sheets about the stops missing, I am pretty sure it was included in the total deduct.

I replicated the blackout pretty well. I slopped the stuff on with the pipe assemblies off the car (do it upside down), used a brush of sorts, and let in run around the side of the muffler.

The fun part was removing the extra bracket - it took some care and time, but it can't be detected. There is some blackout spray over it and it covers any imperfections well.

If you want a nice replica set of tips, contact Richard Fortier. His are REAL nice, look exact to assembly line tips. I think they run around $400 shipped - NCRS discount. I got a set for mine, VERY happy!!

[Terry M.]

Re: 1972 BB exhaust system - judging deduction

I replicated the blackout pretty well. I slopped the stuff on with the pipe assemblies off the car (do it upside down), used a brush of sorts, and let in run around the side of the muffler.

The fun part was removing the extra bracket - it took some care and time, but it can't be detected. There is some blackout spray over it and it covers any imperfections well.

If you want a nice replica set of tips, contact Richard Fortier. His are REAL nice, look exact to assembly line tips. I think they run around $400 shipped - NCRS discount. I got a set for mine, VERY happy!!

Excellent advice on Bill's part -- especially the black out paint. I think the frame coating that is used on mid-years would probably work well as the muffler black out. I know the original stuff is very soluble in gasoline -- as is the mid-year frame paint, but of course that doesn't make them the same but it is a start. Most folks use BBQ Black and that is only a fair facsimile of the original coating. I personally think the BBQ Black paint sucks, but that is just my deuce centavos.

I'll have to see if I can get a pix of the hex shaped tab. I may have to lower one of the exhausts on the car and that is tough with it on the ground where it is parked. On the other hand I am getting revved up to drag it to Michigan for the National. It has been in hibernation for too long. No promises though.

[Patrick H.]

Re: 1972 BB exhaust system - judging deduction

On the other hand I am getting revved up to drag it to Michigan for the National. It has been in hibernation for too long. No promises though.

If you bring yours, I'll bring mine.



Then we'll see if our old cars drive on Milford as well as the new ones did.

[Terry M.]

Re: 1972 BB exhaust system - judging deduction

If you bring yours, I'll bring mine.



Then we'll see if our old cars drive on Milford as well as the new ones did.

OH NO. If we get to do Milford again I will be in the 2008. I know the limits of those 40 year old tires on the 1970. We had way too much fun last time.

Edit add: By the 2011 Nationals those tires will be 50. They are strictly display only.

[Alan S.]

Re: 1972 BB exhaust system - judging deduction

Hi Don,
It looks to me like at least 1/2 of the tab's shape and size is determined by the size and shape of the slot in the tip itself. The cut in the tip is rather carefully drawn compared to some details in the AIM. That info could well help you know what PART of the tab needs to look like.
Can you post a picture of the cut in your (Richard's) tips? Is it more than just a slot? It looks like it's more refined than just a slot in the AIM.
Regards,
Alan