<VV> CO Question

[Bill H.]

                                        B"H

Hi everyone.  I'm wondering if any folks have done some research on CO levels inside their cars during the winter season when the heater is on and the windows are up.

I have a 69 Monza, 59K miles, rust-free car, 110 motor with PG, single exhaust, and in excellent condition, mechanically and appearance-wise.  Recently, I removed the lower shrouds, cleaned them and sealed them with Permatex Ultra Copper.  I paid special attention to the gap where the exhaust pipes pass through the shrouds.

The car has a catalytic converter fitted where the tailpipe goes, and the pipe sticks out the rear of the car, instead of the stock location (under the rear fender passenger side).  Originally it got rid of the nasty exhaust smell that bothered my family (it's the old non-catalyst exhaust smell that was normal before 1975, perfect normal, but annoying, considering that the car lives in the garage that's built under the house).

As a result of the sealing, my car warms up faster and the heater seems to push more air.

Here's the issue:  I have a battery-powered digital CO dectector which sits on the floor between the front seats.

When I start the engine, the CO reads 0 ppm.  It's a typical New York winter morning, windows closed, temp around 30 degrees F.  I let her warm up a bit (she's in a heated garage overnight) then it's off to work.  After a minute or two, CO levels read around 40-50 ppm, and can go up to around 70.  So, I roll down my window, let the interior air out, and after a couple of minutes, we're at 0 ppm.  Window rolled up, heater goes on.  CO levels stay at 0 until we get downtown, where there's more idling in traffic than forward movement.  At that time, the CO levels can go back up to around 50-80 ppm.  If I run the heater, it seems to help to bring the CO levels back down.  That is, of course, a good thing; it seems to indicate that my heater is sealed properly and there are no exhaust fumes getting into the cabin via the heater.

However, I'm wondering where the CO is coming from.  BTW, 50 ppm or less are usually considered acceptable for humans to breathe without being a hazard, but of course 0 is even better.

Could it be the fact that the tailpipe sticks out the rear of the car, instead out the side?  Maybe I should replace the stock tailpipe?

I haven't had the opportunity to check CO levels in our Honda Odyssey, but I expect that car won't have any CO even with the windows rolled up.

Anyone have any experience in this area?

Thanks and regards to my fellow Corvairers...Bill Hershkowitz  Brookly NY