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Posted by: flipb Sep 21 2009, 08:21 PM

Tried searching but couldn't find a definitive answer:

The original rubber insulation on the engine side of the firewall... is that just soundproofing? Or does it serve as a fire barrier as well, as you find lining the hood of many modern cars?

On my '74, it's torn and falling off. I'm going to tear it out but just curious whether I should think of it as a piece of safety equipment, or just something to make my wife complain less about the noise... the glorious noise.

Posted by: ClayPerrine Sep 21 2009, 08:52 PM

Please... for the long term sake of your car, remove it and don't put it back. The insulation was rubber backed, shredded asbestos. It retains water, and makes the firewall rust. So put something like dynamat extreme on the inside behind the back pad. Your car will thank you in the long run.

Posted by: McMark Sep 22 2009, 12:03 AM

It's a great fire retardant when it's completely saturated with water.

Posted by: Rod Sep 22 2009, 03:39 AM

Use dynamat (or Damplifier,) then second skin spectrum, this can then be sprayed over to match bodycolour. Looks pretty factory too (in a dimpled way )

Posted by: charliew Sep 22 2009, 08:28 AM

I like Rods idea, now if I can just remember it.

Posted by: veltror Sep 25 2009, 10:28 AM

Can you be a bit more specific dyanmat I have heard of but what the hell is second skin spectrum... etc?

Posted by: mtndawg Sep 25 2009, 06:40 PM

I took mine out and I'm replacing with Fat Mat. That looks like a good one too.

Posted by: rhodyguy Sep 25 2009, 08:16 PM

the acid vapors are retained nicely along with the water. you may find a surprise in the lower right side corner upon removal. i hope not.

cleaning the firewall and painting to match the car is a popular option. it looks really clean. you can dynamat the interior side at a later date if you find engine noise is a problem.

k

Posted by: type47 Sep 26 2009, 07:04 AM

I'd like more information on updating the engine compartment back pad to something more efficient/modern. Sources? Pics? I have a car that could use an update.

Posted by: Jacob Sep 26 2009, 08:20 AM

I did a search for Auto sound deadening products and came up with a lot of responses.

Sound deadening mats:

Dynamat.
They seem to be the yardstick everybody else uses to rate their product.
http://www.dynamat.com/


Second Skin.
http://www.secondskinaudio.com/products/Sound-Deadening-Materials.php?gclid=COOb5disj50CFeRL5Qod4Vck2A

Fat Mat.
http://www.fatmat.com/

B-Quiet.
http://www.b-quiet.com/?ovrtr

A generic Soundproofing site
http://www.soundprooffoam.com/soundproofing.html?adsrc=2&camp=barrier&grp=deadening&OVRAW=Auto%20Sound%20Deadening&OVKEY=sound%20deadener&OVMTC=advanced&OVADID=4716788522&OVKWID=41147297022



Sound deadening paints:

(also see Second Skin)

Lizard skin available at Eastwood and Jeg's
Article about installing http://kitcar.automotive.com/81031/0803kc-applying-lizard-skin-ffr-roadster/index.html


There seem to be two main types of products. sound deadeners that cut the vibration of metal panels and sound absorbers that cut down airborne sounds. I have not used nor do I endorse any of these products. Maybe some people who have used any of these can add their comments.

Posted by: Gint Sep 26 2009, 08:22 AM

The last thread recently listed another product also. Raamat or some such thing.

Here's a link: http://www.914world.com/bbs2/index.php?showtopic=86906&

Posted by: jim912928 Sep 26 2009, 09:45 AM

I've purchased interior stuff from this guy...door panels etc. I noticed on ebay he sells replacement firewall pads for 911's, 914's etc. Stuff I have gotten from him in the past has been a perfect fit everytime. I haven't gotten this item yet but was contemplating it before I put my engine back in. He goes by appbiz.

http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&item=290351968068&viewitem=&sspagename=STRK%3AMEWAX%3AIT

Has anybody tried this item yet?

Posted by: Rod Sep 26 2009, 11:29 AM

No problem.

Ok, damplifier is a soundeadening mat, which is very similar to dynamat. it is metal backed and should really be rollered into place. this matting is great, but does not look very '914' So the next trick is to add 'spectrum' on top...It is a thin paste which can be sprayed, rollered or painted onto any metal surface.It was designed as a vibration/panel damper, but it also contains anti rusting compounds, so is ideal for painting on inner surfaces.

It can be painted straight over the matting, and ideally in a 2-3mm layer.. A thickening agent can be added to it to really thicken it up into a goo - but this is best left to the car audio guys..

Here is an image of damplifier covered in a layer of raw Spectrum. in this image it has dried to a grey, later (current) batches have a black dye in, which imo looks better. It can be sprayed or painted easily in a colour of your choice.



So there you go, I have used this in the past to great effect, and when I rip out my 1.7 and replace with a 2270, thats what i'll be doing to my engine bay