Heat Shield ‘70 300

[Samplingman]

So I was cleaning up a bit after running the motor for the first time and I noticed this funky discoloration where the rear seat would be, just over the muffler. That must have been a lot of heat, I’m wondering if there is supposed to be a heat shield over the muffler at that point to prevent my passengers from being uncomfortably cooked. I don’t see anything online or in the parts book for a heat shield, could I just fashion something out of sheet steel, or has anyone retro fitted from a later model?

 

[Big_John]

Never saw anything like that. I'll bet the muffler was against the floor at some point in its life.

Put something like this down and kill two birds...

FatMat Rattletrap 80 mil Self-Adhesive Sound Deadener 50 Sq Ft With Tools | eBay

Both Will and I have used this in our verts.

 

[MrMoparCHP]

Is there anything different than factory with the placement of the muffler?


Alan

 

[Samplingman]

Never saw anything like that. I'll bet the muffler was against the floor at some point in its life.

Put something like this down and kill two birds...

FatMat Rattletrap 80 mil Self-Adhesive Sound Deadener 50 Sq Ft With Tools | eBay

Both Will and I have used this in our verts.

So that is odd to see! Actually, that's a whole new exhaust from front to back, and the floor has been coated with silver por15 for the past few years, that's why it was so noticeable. I will be using the FatMat anyway, but I think I need another barrier underneath.

Is there anything different than factory with the placement of the muffler?


Alan

I'll have to get under there again and check clearances, but I know it's not right up against the floor. The fitment of the whole exhaust seemed to be spot on with factory specs. The break-in rpm was up around 3,000 for 25 minutes, but that's no different than highway speed.

 

[CBODY67]

When you did that break-in time, the exhaust system can get pretty hot, especially IF there is no airflow under the car to remove the heat. Seems like the exhaut pipe under the front floor is pretty much level with the bottom of the rocker panels, but about 1/2" above the lowest part of the rocker panel? The muffler should be level, too, with those pipes, in the same plane of things.

NO heat shielding on pre-catalytic converter cars, I know there was none of any of my Chryslers ('66 and '72) and "70 Monaco 383N. No closeness to the underbody, either.

Just some thoughts,
CBODY67

 

[HWYCRZR]

So that is odd to see! Actually, that's a whole new exhaust from front to back, and the floor has been coated with silver por15 for the past few years, that's why it was so noticeable. I will be using the FatMat anyway, but I think I need another barrier underneath.



I'll have to get under there again and check clearances, but I know it's not right up against the floor. The fitment of the whole exhaust seemed to be spot on with factory specs. The break-in rpm was up around 3,000 for 25 minutes, but that's no different than highway speed.

Air wash at highway speed does a lot to keep things cool. Sitting still at Hwy RPM’s the heat will go straight up instead of dissipating out the rear of the car.

 

[Samplingman]

When you did that break-in time, the exhaust system can get pretty hot, especially IF there is no airflow under the car to remove the heat. Seems like the exhaut pipe under the front floor is pretty much level with the bottom of the rocker panels, but about 1/2" above the lowest part of the rocker panel? The muffler should be level, too, with those pipes, in the same plane of things.

NO heat shielding on pre-catalytic converter cars, I know there was none of any of my Chryslers ('66 and '72) and "70 Monaco 383N. No closeness to the underbody, either.

Just some thoughts,
CBODY67

Thanks, without the airflow this is all making sense now. You can see from this pic that the fit of the exhaust wouldn’t allow for much more clearance from the floors. I’m guessing with the addition of the FatMat I won’t be burning anyone up under normal driving conditions. Thanks all!

 

[Ross Wooldridge]

I had a muffler that had an upwards pointing perforation (due to a backfire) that made a mark like that and ultimately set my carpet on fire...

Possible cause for that mark - exhaust leak.

 

[Samplingman]

I had a muffler that had an upwards pointing perforation (due to a backfire) that made a mark like that and ultimately set my carpet on fire...

Possible cause for that mark - exhaust leak.

Interesting. Of course it backfired several times during the initial start up....