Couldn't find much searching under this subject. I don't even know if Datsun did this type insulating from the factory. Love to hear from someone that has insulated under the hood for noise and what their results are.

I would think a barrier between the hood and the valve cover would suppress a lot of mechanical noise and make for a quieter engine. Don't get me wrong, I like hearing my engine, but would prefer to get rid of any metallic sounds and here a more subdued power-if that makes sense.

I know some folks are worried about adding weight, but I'm not concerned. Maybe I need to step up the firewall insulation with some dynomat or something.

Most drown it out with ITB's or Webbers/Mikunis/Solex

You could always look into the under hood insulation that's on modern cars... Sure, that's all fitted to the make/model, but if you could find it in a bulk/moldable form...

An added benefit of using the modern stuff is that, in addition to deadening engine noise, it's also a fire retardant/suppressant.

There are many aftermarket sound suppression / heat shields available. I've never been a fan because I want the heat out from under the hood and feel like anything applied to the hood would serve to contain it.

The dynomat on the fire wall plus the tranny hump should quiet it down some ,I have that on mine and it is a very comfy cabin

Edited June 15, 201212 yr by 72 OJ

Two problems come to mind. First is that there isn't a lot of room between the engine and hood. Second is that the engine compartment gets rather hot even as it is, especially in the pre-'77 unvented hoods. Insulation would make the problem worse.

Most drown it out with ITB's or Webbers/Mikunis/Solex

Agreed! Triples are a must - with beer and carbs!! Triple Karmeliet and Mikuni's are my pick!

I used aluminum foil bubble wrap to insulate a Subaru hood. I was trying to keep heat IN, in the winter the thing took forever to warm up.

I used hot melt glue to attach the bubble wrap, now and then I'd have to go touch up the glue.

Cheap, worked well, and easy to remove if you decide you don't like it.

For any winter car, you can block off the front of the rad and get a higher temp. thermostat to help stay warmer and faster. A block heater can help too.

Other than firewall sound deadening, the one item that made a remarkable difference to engine noise for me, was the addition (replacement actually) of the weatherstrip across the lip where the hood latch is located. After applying this strip along with an overall WS replacement binge some years ago, I remember getting in my triple powered z for a drive, pulling away, and thinking "oh oh somethings wrong! The motor sounds wrong and gutless!" Nope, the noise coming back to me through the hood/cowl gap was sealed by that strip!

If you put on anything to keep the noise in, the heat will stay in too, so you'd need to get the air flowing through there, which means the splash guard and a fan shroud is in order.

Other than firewall sound deadening, the one item that made a remarkable difference to engine noise for me, was the addition (replacement actually) of the weatherstrip across the lip where the hood latch is located. After applying this strip along with an overall WS replacement binge some years ago, I remember getting in my triple powered z for a drive, pulling away, and thinking "oh oh somethings wrong! The motor sounds wrong and gutless!" Nope, the noise coming back to me through the hood/cowl gap was sealed by that strip!

That's funny you mentioned that, because that's the only weather strip I didn't install. Now I will install it and see if it makes a difference.