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I had a professionally built 390 with a mild cam installed into my 1966 F100 LWB 2WD. Had Sanderson shorty headers installed. Dual exhaust with Thrush Turbo mufflers. Exhaust exits to the sides behind the rear wheels. When I picked it up from the shop, I left my window down so that I could hear how it sounded. Sounds great. A little loud for a long trip. After 5-10 minutes I decided to roll up the window to shut out some of the sound and the noise sounded the same. Loudness of engine and road sound the same whether I have the window up or down. My question is, is it worth installing insulation in the cab to shut out the noise? It would not be too hard to do the floor and the ceiling. But the firewall has so many holes for wires and cables to pass, I think most of the noise is coming from there. I still have the original firewall pad installed. Does insulation make much of difference or should I just embrace that my old truck is noisy and that is part of its character?
I had a professionally built 390 with a mild cam installed into my 1966 F100 LWB 2WD. Had Sanderson shorty headers installed. Dual exhaust with Thrush Turbo mufflers. Exhaust exits to the sides behind the rear wheels. When I picked it up from the shop, I left my window down so that I could hear how it sounded. Sounds great. A little loud for a long trip. After 5-10 minutes I decided to roll up the window to shut out some of the sound and the noise sounded the same. Loudness of engine and road sound the same whether I have the window up or down. My question is, is it worth installing insulation in the cab to shut out the noise? It would not be too hard to do the floor and the ceiling. But the firewall has so many holes for wires and cables to pass, I think most of the noise is coming from there. I still have the original firewall pad installed. Does insulation make much of difference or should I just embrace that my old truck is noisy and that is part of its character?
Thanks for any advice,
Rick
Quite a few members have been happy after insulating roof, floor, and doors. Not sure about the firewall. Dynamat is a popular - and expensive - choice. Not sure of the brand name(s) but there are much less expensive options that do as good a job. Others will chime in.
I have similar engine with headers and flowmaster single chambers going out behind the wheel. Should be louder than your turbos. Only insulation I've got is padding and carpet. Actually pretty quiet in the cab (aside from wind noise) One thing I did that inadvertently quieted things down quite a bit was installed a flex fan. Can actually hear the exhaust and not the engine. I'd say start with the floor and see what difference it makes before decide to do roof, etc. You've got nothing to lose and can always do more.
I did the 390 install with headers on mine and I took the layered sound and heat insulation approach. Not crazy expensive or hard, just a bit time consuming. On the floor and firewall area I installed a dynamat like material. I also used some inside the doors to mitigate any rattles and road noise. On top of the dynamat material I installed a jute padding on the floor and up the firewall just a bit. I then Installed a firewall pad and carpet. Finally I installed the dynamat material and insulation in the headliner. Truck is now well insulated and very quiet. In my opinion it’s well worth it!
I've done a fair bit to quiet the cab, and like the results - really makes highway driving nicer. Prior to doing the work, a reasonable conversation while driving on the highway was not an option.
I did use Dynamat and Dynapad all-around. Pieced it up in the firewall, on the floor, behind the tank, on the ceiling, in the doors. Makes a huge difference. Another big item is carpet under the seats, on the floor and up the firewall. I had a vinyl floor - turns out that everything echoes around inside the cab. The carpet really killed that. Next highly noticeable step was carpet over the tank.
I have a fair bit of road an engine noise w/ off road tires, 460 that runs 3000 rpm on the highway, F250 4wd suspension and drivetrain. My most annoying rattle turned out to be the transfer case shift linkage rod- nothing killed that noise except to fix the rattle at the source.
The dyna-stuff is expensive, and the dynamat is adhered with some type of bomb-proof mastic that will be hell to remove. We all have are spot with how we want to experience an old truck - I do like mine being quieter than how I found it.
I used a sound underlayment, then jute, then the vinyl floor. It is better than it was. I was worried about the dynamat being very difficult to remove if I even wanted to.
Here's some pics
The 'Dynamat' is the foil backed sound deadener - kinda like applying lead to the sheetmetal. The 'Dynapad' is a heavy foam product that comes in different thicknesses
If you're going to do the Dynamat, I highly suggest a good roller, with a radiused edge - like in the pic below.
The pictures are helpful. Doing the firewall looks tedious. I like the Dynapad on the firewall minus Dynapad written all over it. I see on Amazon where the Dynamat is bundled with a roller and tape. The roller does not look as good as the one in your picture. Is the tape necessary?
I remember reading reviews that that roller kinda sucks, which is why I went looking for something better. I liked the cantilevered roller with the edge radius.
I don't remember the tape being available when I did my project. I just read now that it's good for some edging and detail work. All mine is covered by something else, so not sure I would have much use for it.
The stuff sticks like crazy - you don't need to tape the edges, that's for sure. But the butyl 'mastic' does find it's way around a bit - for instance, perforating it with a screw gets the screw covered with the stuff. It's not runny or drippy at all, just very pliable.
You cant see that high under the firewall from any normal position - the pics are from a low angle. If you get carpet up to any normal level, you won't see the dynapad behind and above it
The firewall was a bit tedious, but honestly the entire project was, so working up the firewall doesn't add too much, if you're already committed and removing stuff (seat, tank, heater, shifters, etc.) for access anyway.
I put it on every flat surface I could get to. Makes a big difference. It really deadens the sheet metal “ringing”. My exhaust would resonate in the cab sheet metal till I deadened it with the insulation. Killmat.
Can’t add much to what’s already been said, but engine heat was an issue too. As far as applying Dynamat, I anticipated that the transmission cover would need removal at a later date.
I applied it to the cover separately and on both sides. Probably over-kill but it was a good place to install scraps and cutoffs. I also applied the dynamat right up to the transmission opening and secured the cover on top of it as a make-do seal.
Same for the floor mounted battery cover on the 65 4x4.
Two things I would add:
1. It's not necessary to cover every square inch to deaden a panel. I only covered about half of the floor, doors and ceiling. The tar based sound barriers work great, regardless of what brand you choose.
2. You also need to install new door gaskets. They make a huge difference in eliminating wind noise.
I don't have headers but I have a 3" exhaust that the head pipes merge into and that makes a rather loud drone. There is a huge difference in the sound outside my truck versus inside.
Thanks for the input. I think I am going to start with the floor when I install the carpet and the ceiling because I have a new headliner. And look at the door gaskets. I will let you know how it goes.
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