Unusual Question on '67 Factory Sidepipe car...

[Richard M.]

Is there a simple yet effective way to reduce the sidepipe output decibel level on a set of originals without destroying the physical appearance? This is the 427/435 convertible you guys helped me with a few months ago.

The owner in Norway is getting hassled by the Motor Vehicle division inspectors. They won't pass his inspection because they say it's too LOUD. He explained it's totally stock but they won't budge. He needs to make them happy so he can use his car.

Rich

[Larry M.]

Re: Unusual Question on '67 Factory Sidepipe car...

Is there a simple yet effective way to reduce the sidepipe output decibel level on a set of originals without destroying the physical appearance? This is the 427/435 convertible you guys helped me with a few months ago.

The owner in Norway is getting hassled by the Motor Vehicle division inspectors. They won't pass his inspection because they say it's too LOUD. He explained it's totally stock but they won't budge. He needs to make them happy so he can use his car.

Rich

Rich:

There is a Moderator on the C2 Section of the OTHER CORVETTE FORUM that has done this. His screen name is "MasterDave". Search for his posts on this subject over the past year.

Larry

[Richard M.]

Re: Unusual Question on '67 Factory Sidepipe car...

Thanks for the info Larry. I just spent time reading his threads and saw that he did some pretty serious mods. He wanted them quiet.....but permanently.

I'm thinking of a temporary solution for now. I'm wondering what he could put in the pipes at the manifolds to quiet it down without loosing excessive performance and to not create major back pressure.

Rich

[Joel F.]

Re: Unusual Question on '67 Factory Sidepipe car...

He could stuff a bunch (whole bunch) of steel wool up there. Most of it would get blown out of the exhaust with the first spirited drive.

[Steven B.]

Re: Unusual Question on '67 Factory Sidepipe car...

I did what Joe recommends many years ago on some off road mufflers. First time I made the mistake of using 0000 steel wool. It ignites easily. Use the course stuff.

Steve

[Richard M.]

Re: Unusual Question on '67 Factory Sidepipe car...

Are you gents suggesting it goes in the ends of the exhaust tips, or near the exhaust manifolds?

[Dennis S.]

Re: Unusual Question on '67 Factory Sidepipe car...

Richard
I went with 2-1/2" Allen's reproduction pipes on my '69 BB and remember the orange warning sticker on their cardboard box stating "THESE PIPES ARE LOUD" and guess what...they really are...probably louder than a '67 BB system. Mine would undoubtedly drive those Norskis nuts.

When I bought aftermarket pipes for my Harley, I also installed some aftermarket "power cones" where the exhaust pipes bolted to the heads. They also had removable (somewhat pressed-in) internal baffles before the slash cut outlets...which I modified with a hack saw and re-installed...I wanted louder/less restriction, but did not want all the reverberation. Perhaps some similar type of baffle with a flared lip could be inserted where the exhaust tubes attach to the manifold and heat riser. They could then be removed after dealing with the authorities.

[Wayne M.]

Re: Unusual Question on '67 Factory Sidepipe car...

.....is getting hassled by the Motor Vehicle division inspectors. They won't pass his inspection because they say it's too LOUD. He explained it's totally stock but they won't budge. He needs to make them happy so he can use his car. ...

Chevrolet had the same problem back in 1969 with Chevelles and Camaros; also with the chambered (underneath) factory optional exhaust. Solution was to get rid of it ... obviously not a feasible option for your friend .

[Richard M.]

Re: Unusual Question on '67 Factory Sidepipe car...

We've been pulling our hair out on this one. Well the hair we have left that is....

I just had a crazy idea to run by you......

Several feet of #6 solid copper wire, with some 1" fender washers brazed to the wire every 6". The copper will bend into the muffler from the end. Feed it in and bend a circle/spring at the end to hold it in place.

[Jim T.]

Re: Unusual Question on '67 Factory Sidepipe car...

My experience with using the the 69 factory style side exhaust on my 1970 for many years (1974-1985) was how quiet new exhaust pipes were compared to a set that had been on the car for years. When replacement time came the mufflers were just shells since the insides had left. A new set of pipes did give a very noticable difference.

In the latest issue of NCRS Driveline on page 46 there is an add for 65-67 side exhaust from Sweet-Thunder. Perhaps a new set of their exhaust pipes would be quiet enough to get through the inspection. The side pipes are easy enough to install and replace one could put the old ones back on after the inspection and save the new ones for the next inspection.

Where I live I really don't think the police really care about the loudness of cars and trucks. There is no vehicle inspection here. Some motorcylces not all, mainly Harley's run straight pipes.

[Richard M.]

Re: Unusual Question on '67 Factory Sidepipe car...

Hi Jim, I went to their website the other day. Yes looks like it might be a option. However the caveat is what if the inspector thinks that even those are too loud? It appears that the owner is at the mercy of just one person during the inspection process.

Rich

[Steven B.]

Re: Unusual Question on '67 Factory Sidepipe car...

Are you gents suggesting it goes in the ends of the exhaust tips, or near the exhaust manifolds?

Richard, I put mine on the exhaust manifold/engine end. If you use this method be careful not to put too much in and block the pipe or muffler.

Steve

[Joel F.]

Re: Unusual Question on '67 Factory Sidepipe car...

If you are going to go thru the expense of installing the Sweet Thunder pipes temporarily then you might as well just fabricate the cheapest undercar exhaust you can to get it thru the inspection and then re-install the side pipes.

[Richard M.]

Re: Unusual Question on '67 Factory Sidepipe car...

Joel, the owner and I talked about that. Put something under, exit just behind the rear wheels(to keep the rear fascia with no holes), etc. He said they record the configuration of items like the exhaust, so if he got inspection with under-car, under-car it has to stay.

Rich

[Jack C.]

Re: Unusual Question on '67 Factory Sidepipe car...

Pull a few plug wires off.