I am not sure of whether God loves, tolerates or dislikes drone.

Ooommm.....

God gave us free choice, of course he dislikes drones

For God so loved the world he gave Mopars their beloved exhaust tone, that whoever doesn't have drone, shall not perish, but have eternal smiles.

Should take about an hour at most to drop a driver's side TTI header, at least it would in an ebody[?]. Drop it, press/bang it and go back together. The engine will move quite a bit on those mounts, you need sufficient clearance in a static and dynamic running state....FWIW i have a chromoly torque strap on my engine [which doesn't help NVH], the same transmission and zero drone. It's not much of a mystery, keep it from rubbing and put some decent mufflers on it.

IMO, if you aren't already, I suggest you take just a couple of trusted Moparts opinions and use them as your guidance. You can go round-and-round chasing rabbits within a large thread like this....

Things are pretty tight in an A-body. Even with a small block. But based of all of the information from this thread, I think this will be my plan of attack for my break.

1) Attempt to remove header and dimple.
2) If 1) fails, shim engine.
3) If 2) fails add resonators out back.

Taking a look at the engine bay, I feel more confident now.

Quick question. Is it worth it to replace my biscuits? The passenger side looks smooshed, kinda? If I do, should I go rubber, solid steel, or poly locks?

Someone else may need to confirm, but both mounts look out of alignment? They look to be rotated around a couple degrees????

my old eyeballs aren't very good any more, but those rubber mounts are not installed as they should be. they are to be in line with the block mounts, not having part of them angled off the K member pads. are they upside down perhaps ? there should be a "bump" of sorts that will locate the isolator in the block mount properly. am i seeing this correctly ? is this even the correct K member ? when i perform a transplant and don't have the correct K, i bolt engine and transmission together, locating the assembly with the transmission mount. then fabricate "towers" that will position the engine where it wants/needs to be on the K, after removing the original "towers" from the K before lowering the engine/transmission assembly into place.

This comes down to three common problems which require very simple basic fixes.

First, dimple the headers so there is ample clearance between the headers and the chassis.

Second, re-adjust the rest of the exhaust so nothing touches the chassis.

Third, add resonators near where the exhaust exits the car (parallel to the gas tank is the preferred location).

These three fixes will take care of your drone problem, period.

I had a drone on my 6.1 Hemi '69 Cuda with full 2.5" TTI H Pipe exhaust and Dynomax Super Turbo mufflers. Plus the exhaust was quite loud when cruising.
I installed a set of Flowmaster Resonators 15150S. Drone completely gone and exhaust much quieter. Very happy.
These resonators are a straight through 2.5" design with a closed tube alongside. Photos in this FABO thread http://www.forabodiesonly.com/mopar/threads/srt8cuda-build.218445/page-27
Jim

Cheeper way to go....

https://www.ruggedradios.com/index.php?main_page=product_info&cPath=111_22&products_id=17

The way your tailpipes snake around the spring and gas tank makes me think your best resonator location is in front of the gas tank. Looks like only a total of 120 degrees of bend added to each pipe.

Running pipes out the side in front of rear tires is much noisier than running out past the bumper.
R.

That's what I was thinking as they looked funky. Since I have to fiddle with them anyway, shouldn't I just replace them? Which motor mount biscuits should I use? Rubber ones are $5-15, steel is about $50 (but I feel it will cause too much vibration), and the poly-locs are about $200. Are the poly-locs worth it?



I can't. The mufflers are there and the X-pipe before that, and the trans cross-member gets in the way before that. I was planning on routing my "side exit" (angle exit?) exhaust behind the rear tires as that's the only room I have, if I go that route.

Motor mounts - I'd replace them if they look bad, but other than that I'd just get them lined back up. I have a set of small block mounts and they have a little bump on the mount that rides in a hole drilled into the motor mount brackets to keep everything pointed in the right direction. You may have the same thing as I do only yours got tightened down with the nubs out of the holes which is how yours went sideways.

Your car has a manual transmission so you'll want a torque strap or something to help secure the drive's side as that's where the action is. You can buy one, make, one, or overhaul your rubber driver's side mount and convert it to a solid mount with some steel and welding.

I would get the mounts straightened out one side at a time and work with shims and see what happens there first before messing with denting the header right away. If you do have to dimple the header tube you'll want to dust some silver header paint over the spot to keep it from rusting. In my mind having a header tube just barely touching the steering box is not the source of your drone sound. I think that is coming from the mufflers on back and is magnified by having an empty trunk compartment.

If you want to switch to side exit exhaust then look at the Dr Gas NASCAR style mufflers/exhaust tips. I think they would be fairly loud compared to rear exiting, but they may not drone. They are pricey, but offer the best look for that type of exhaust setup. Having a round pipe sticking out in front of the rear tire doesn't look very cool in my book.

https://www.youtube.com/watch?v=jucWtepx6PU

Alright, I can deal with that. So, as far as the mounts go, look for cracking in the rubber?

Thank you for the tips on repositioning the engine and possibly denting the headers.

I wasn't planning on doing a side exit exhaust in front of the rear tires. If moving the engine away from the PS box does not help, the plan was going to add resonators to the tailpipes. My problem is that I only have 11" between the exhaust hangers and the bumpers while the smallest resonators I could find are 14" long (10" long case). There are smaller "race" mufflers I can add that are 12" long (8" long case), but that's going to cost me a lot more per muffler than the resonators were. So, I was thinking about cutting the tailpipes off after the exhaust hanger, band clamping some 60 degree tubing, then adding (band clamps again) resonators so I'll have enough room to fit it all under the back of the car. The exhaust will still exit the rear at the bumper, but at a 60 degree angle pointing out. Or, I could do the same with 90 degree tubing and end at the back of the quarter panel. It may look a little funny though, but it will be different.

Next time you drive it you should fill the trunk with some blankets and sleeping bags and maybe a spare tire if you don't have one in there. I'd just be curious to see if the sound was reduced any amount by having stuff back there vs empty. Also there is a seat divider panel that goes between the rear seat and the cross bracing under the package tray in case you don't have one.

I have a suitcase with tools in the spare tire well right now, and I didn't really pay attention to see if it was better or worse.

I already have a divider. It's made out of the speaker box foam board stuff and I already put some dynamat on the back as I thought it was acting like a drum.

Very good practical idea to fill up the trunk volume. Ideal fill would be foam pillows from furniture, sleeping bad pads, folded beach towells, etc.

A quick test of whether metal to metal contact of the exhaust pipes is influencing the drone noise would be to buy some inexpensive high temperature rated, but flexible Silicone cookware pans, cut it up into small spacer pads, insert these pads into tight areas, and hold in place with those stainless steel cable ties.

A quick cheap test to see if a bit longer muffler would reduce the drone would be to insert a socket into the end of the exhaust pipe and temporarily hold it in place with a vice grip. This creates some additional back pressure that can be adjusted by changing socket size.

So, I untightened the bolt under the driver's side biscuit on the K-frame and put a jack under the engine and lifted it a bit. I found some scrap metal that was about 0.150" thick and cut out two 0.25"x0.25" squares with a 9/16" hole in the middle. I then used my angle grinder and slotted them. I threw one in and that was enough to move the headers away from the gearbox. I'm debating about throwing in the second for extra room (possibly between the exhaust and the T-bar on the driver side), but part of me wants to paint them before completely installing them.

Good that you were able to get clearance without denting the header tube.

Paint your shim tonight and install tomorrow? As long as you have clearance you may not need to do any more. Just keep an eye on it and if it sags back down add another shim if need be.

I painted them already, they're pretty dry. I may just throw them in tonight and tomorrow morning I'll go for a test drive to see if there is less vibration or drone.