Rust blowing out from R/H side pipe

[welsh c2]

I started my '67 327[65 motor] in the garage for the first time in nearly three months today. A near handful of rust particles was blown out of the R/H side pipe while it was warming up, but nothing from the drivers side.
Could this be something to do with the heat riser or choke tube ?

 

[JohnZ]

I started my '67 327[65 motor] in the garage for the first time in nearly three months today. A near handful of rust particles was blown out of the R/H side pipe while it was warming up, but nothing from the drivers side.
Could this be something to do with the heat riser or choke tube ?

Sounds normal - the innards of the right side muffler rust out much faster than the left side due to the action of the heat riser valve, which allows more condensation to gather in the exhaust on that side and not get fully burned off. Right side muffler replacement outpaced the other side by about 4:1.

 

[welsh c2]

Thanks John for clearing that up
I've just checked a parts catalogue and see a spacer is available that can replace the heat riser valve. I think that I might substitute this as the car only gets used in warmer weather.
Richard.

 

[Tom Bryant]

This is also why you shouldn't short trip your car. I never start the Corvette unless I'm going to drive it far enough to completely dry out the exhaust system. The '81 still has it's original exhaust system in excellent condition.

Tom

 

[welsh c2]

Thanks also Tom!
I've always been careful to warm things up fully when using it. I guess it must be cooling off quicker than I thought between returning home and garaging it, as the heat riser valve must be near closed on tick over.

 

[Hib Halverson]

A byproduct of combustion is water and water vapor. The inside of exhaust manifolds and pipes rust. Rust particles, blown off the ID of the pipes, is what you are seeing. As to why you're seeing it out of one pipe after start up? If the engine has the stock heat riser functioning, until the heat riser valve opens, the majority of the exhaust flow at idle after a cold start is out one, rather than both, pipe.

 

[welsh c2]

Thanks Hib for the technical info.