The same potential for material getting back into a cylinder exists with the engine running as the chips can still get past the exhaust valves and into a cylinder during the camshaft overlap cycle.  The overlap cycle is where both the intake and exhaust valves are open simultaneously and it’s during this cycle where the exhaust is momentarily pulled backed into the engine.  As the lobe centerline on a camshaft is reduced, then the overlap cycle increases which in turn increases the amount of exhaust that returns to the cylinder during low rpm operation.

Lorena, Texas (South of Waco)

Here is a crazy thought- how about drilling it out while the engine is running, forcing any debris out the exhaust.

Ol'ford nutCentral Iowa

56 Vic w/292 & 4 spd.

Thanks, Ted... the possibility was on my mind, but I wasnt familiar with the anatomy of that portion/feature of the manifold thinking it was a "closed" system simply capturing/conducting heat... so I guess I'll take another tact.

Cheers... Brian

Cylinder Index = 84

Current Experiment = `57 Tbird, Grand Rapids, Michigan

The potential for drill shavings making their way to the top of an exhaust valve and then into the cylinder is high if working on the heat chamber of the intake manifold while it’s on the engine.  The intake really should be removed from the engine if doing any serious drilling on any of the internal passageways.

Lorena, Texas (South of Waco)

I want to change the heat chamber port fitting on my "B" intake manifold but it's shaped such that I would have to remove the manifold to clear the cylinder head...

So I'm thinking of drilling and taping the port fitting to my needs (it's brass and should be easy to do) but would no doubt get some filings down the through fitting and into the chamber (even with a shop vac on duty)... Am I correct that the chamber is a separate/closed system from the intake system, such that any filings would be contained?

Thanks... Brian

Cylinder Index = 84

Current Experiment = `57 Tbird, Grand Rapids, Michigan