Manifold heater valve

[GlennW]

Ran into a situation a while back where the car started & ran fine, then maybe 3-4 miles of city driving later it died and wouldn't restart as I coasted to the curb. Would restart after several aggressive floor stabs of the gas pedal prior to turning the key, but would only stay running with decent throttle. No backfiring or any signs of it being ign. related and the dist. isn't sloppy. Now of course, it won't do it. I can start it cold (leaving it parked) and it'll idle at high with the choke plate having set itself correctly with the usual pedal depress, and kick down easily with a quick throttle blip after I've let it idle a minute or so (it's 90° ambient right now). I mention all this only as background-while looking into things for anything obvious I noticed the #5316171 manifold heater appears to be immovable. The workshop manual shows the counterweight "lobe" at the 12 o clock position and mine's stuck at 9 oclock. Anyone recall what the hot & cold positions are? If 9 o clock is the "hot engine" position I'll leave it alone for now as it's a fair weather car anyway and I don't care if it's a little cold-blooded later. The coiled spring is secured to the outer weight, the weight just can't be moved by hand or by tapping on it with a 2' socket extension when at 180° operating temp. The white on the spring is just a paint pen mark I put on it cold. When at 180°F the outer coil of the spring had rotated counterclockwise maybe 1/16"~1/8", but the balance weight hadn't budged. Anyone remember if this at hot or cold? Thanks!

http://woodysfairings.com/images/5316171Manif%20A.jpg

http://woodysfairings.com/images/5316171Manif%20B.jpg

Edited September 4, 2015 by GlennW

[Rob Dudley]

I just removed mine because it was stuck in the same position when I got the car. I removed it completely since I had opened the exhaust to check.

Rob

[mfg]

The 9 o'clock position SHOULD be wide open, but this can fool you if the counterweight has come loose from the shaft.......The internal plate may still be closed or almost closed.

If you drive your Avanti in mainly warm temperatures, I'd remove the heat riser completely like Rob Dudley did.

You may need to make up a spacer plate the thickness of the discarded heat riser though, or the front exhaust pipe will probably rub on the frame.

[GlennW]

The 9 o'clock position SHOULD be wide open, but this can fool you if the counterweight has come loose from the shaft.......The internal plate may still be closed or almost closed.

If you drive your Avanti in mainly warm temperatures, I'd remove the heat riser completely like Rob Dudley did.

You may need to make up a spacer plate the thickness of the discarded heat riser though, or the front exhaust pipe will probably rub on the frame.

Thanks, most exploded drawings show movable objects in the "off" or "rest" state, so I was guessing 12:00 was cold but we all know guessing is seldom a good plan. The outer coil trying to rotate CCW backed that up, but not if the normal state was 9:00 and hot was 6:00, I've seen many a an drawing done by folks who weren't familiar with the whole assembly or late updates. We're 24 hours into a Sili-Kroil spray tube soaking, and I can move the weight back and forth a few degrees with great effort. The weight and shaft end sticking out of it are still bound as one so I'm going to leave it alone for now and give it a spray now & then. For sure, I'll make a spacer if I actually remove it, as I don't like changing any dimensions or flexing things that have been in one position for 50+ years ☺

I'm not really convinced it had anything to do with the stall out problem, but since it won't do that at the moment I have no problem to look for. Nothing ever fixes itself...

Edited September 4, 2015 by GlennW