7T1, no doubt the work done today in most shops isn't up to what it used to be. The Goodyear shop I've used for decades generally does good work. Same people have owned it all those years and they protect their reputation. Most of the mechanics have never seen carburetor, but then that's the norm nowadays.Maybe they have an off day.

DC, always good to hear from you. I am finding the same thing with the Cobras - singing on concrete. Good thing the country is going to hell and most states won't spend the extra bucks for new concrete on roads. Singing aside, since pumping up the tires to 32 psi before taking it out for a 20 mile shakedown on Sunday and then another 50 miles or so on Tuesday, I found only one tire under 32 psi last night, i.e. Wednesday. It was at 31. So, maybe they like to run around a little to keep the bead limbered up.

I assume the 4L60e continues to do well for you. Mine seems to be settling in though I likely have no more than 300 miles on it so far. I do still get a small whiff of tranny fluid, usually when starting out from from sitting at a light after it's warmed up. Did you notice any fluid smell after your install? I am pretty sure I have the level right. Pressures and temps look good - gotta love the Compushift TCU sending all those good readings out to the iPAD. And nothing is leaking.

In any case, I'm getting braver taking it out. And it's always an event for some of the older guys when I drive it to work since it is the car I was driving regularly on my first day there, July 16th, 1984. Being an engineer, I was wearing a blue sport coat, grey pants, tie, and short sleeve dress shirt. Of the 50 or so people at the location when I started there, only 4 of us are still there. And there are a few more who date back to within a couple years after that. A lot has changed in the lab since then, I usually wear jeans now for one thing. But the white '80 L82 showing up occasionally in the lot is kind of a ghost from the past for those who are still there from that decade.

 

Yes the new transmission is doing great. One of the best mods I've done. I haven't noticed any tranny fluid smell of late. I had a fitting fail early on and sprayed the underside of the car pretty good with fluid so that was the dominant smell for quite awhile. I've been daily driving my '73 unless the weather doesn't cooperate. The fuel injected 383 is doing good too. I gained over 100 HP and still managed to gain over 5 MPG on the highway at 80 MPH. Having overdrive certainly helped with that improvement. My car is really fun to drive.

I only have one issue to sort out and one more improvement to make. I still have an annoying exhaust drone between 1500 and 2000 RPMs. Different engine, different headers, different exhaust, different transmission, and different mufflers and the exhaust drone remained the same as the previous setup. Don't get it. I'm exploring J-pipes and Helmholtz resonators at the moment but don't know if I have room under the car.

The improvement I want to make is adding cruise control. This car is way too easy to drive at 90+ MPH on the highway. I need to figure out if I have room to mount an aftermarket cruise unit and I need to figure out how to connect it to the front throttle body on the XT intake. That may be my winter project.

DC

 

DC, good to hear things are running well other than the drone. I'll be curious how the cruise control works out for you. Mine had it originally but I ruined it when I put a speedo reduction gear between the tranny and the speedo cable. The reducer was one of those things that dropped the turns 40% on the 85 mph speedo so the kph scale would actually show mph . The gear didn't fit well and kinked the cable a little which put a load on cruise control transducer and caused it to fail. I ditched the gear after that and got a used transducer, but it was never stable. But now it may be time to get it back in the game.

 

The problem with the drone is because YOUR CAR resonates at 1500. GM had a similar issue with the B-body caprices and impalas back in the 90's. They solved it by adding secondary mufflers tuned specifically to that frequency. You can't get that far in the dirt, of course, but you might consider a set of small secondary bullet mufflers. Burns Stainless does a lot of custom stuff - they might be able to suggest something.

 

Thanks for the input. Borla has a set of resonators that match the mufflers I got from them. They believe the resonators will stop the drone but I'm not convinced because they are the same people who told me their crate mufflers wouldn't drone in the first place. They also recommended I install an x-pipe crossover to further lessen the possibility of drone. I did this with the new exhaust but the drone ended up slightly worse. Strike two Borla.

Borla's resonators will lower the sound level by 2 to 3 dB. But I like the sound of the mufflers the way they are and don't really want to reduce their sound level. It may come to that if I can't solve the drone other ways. It would irritate me if I reduced the sound volume of the mufflers but the drone remained.

I've tentatively calculated that a j-pipe resonator roughly 29" long will eliminate drone at 1750 RPMs which is the middle of my problem range. But, I used a frequency meter Android app to determine the resonant frequency and can't be sure of the accuracy. I really need a decent quality combination sound level / frequency meter to get it dialed in and I still need to take some measurements to see if I could even fit two j-pipes under the car.

DC

 

Funny you mention Borla. Their Impala SS system worked really well, and came with a set of mufflers and secondary resonators. The resonators worked great - very little drone. But I ended up taking mine off because I liked the tone of the mufflers without the resonators. I just put up with the drone.

One other thing - are you sure it's the exhaust causing the drone? Could be that the headers or the exhaust pipe or maybe the transmission or something is touching the frame and transmitting the drone that way. A long shot I know, but might be worth a shot.

 

It's a good thought but I've checked all those things a couple of times. The exhaust shop that installed my new system knew of my drone issues and they also checked to make sure it wasn't anything like that. An old timer told me that the shorter the pipe behind the muffler, the more likely an exhaust would drone. I'll try to find the time to start a new thread about drone so we don't further derail Vince's tire thread.

DC

 

X wont stop the drone...drive around that rpm range. ie dont use OD unless youre on the hwy or at least those types of speeds
Your 3-4 clutch will last lots longer to boot. My mpg was exactly the same at 60+in D as OD thats in a 5500 lb truck

 

Ive put 10,000 miles on my set of coopers the last year and half. I have 2 tires now that lose air. One had a nail that I put a patch in, 1 has no visible leaks. The patched tire drops about 5 psi a month, the ‘good’ tire loses about 3 psi a month. Annoying, but not the end of the world.

 

The car will sit for a least several days now. I'll keep tabs on the leaks and post an update. As Cmurray said, not the end of the world.

 

Have had 245/60R15 Cooper Cobra's on15 x 8 Steel Rally wheels on my 72 for five years. They hold air as well as the prior BFG Comp T/A's, GoodYear Eagle ST's & WingFoot's etc.

Aired all four wheels up in August by November each tire was down 4 to 5 pounds.

 

I installed new Cooper Tires on my C3 16 months ago and they leaked down "regularly". The rims were brand New but had some very minor corrosion on the sealing edge which kept them from sealing.

The leakage was from Bad Rim "preparation" on my part. Had I cleaned it off with a sheet of sandpaper before painting the rims there would have likely been no problems later on.

You need to have a clean smooth sealing surface on the rim or it won't seal at all.

BF Goodrich Tires are now coming with the raised white letters that turn Brown very quickly and a lot of people are angry about it. The Cooper tires have good ratings and were inexpensive as well. We are loosing our choices in the 15" rim size as few cars use them for performance applications.