TR FD question

I'm not sure I'm following what this gap you are looking for is all about?

The sensor plate should have 2 positions, rest engine off, set with the plate hieght adjust stop pin (set with hammer as Henry notes)and idle position, engine running, set with 3mm idle mixture screw. This second position can only be determined engine running and fuel system pressurized.

When the system is pressurized the center piston will move to it's farthest position and is moved to the position that creates proper idle flow of fuel by the 3mm setting screw, which acts against the Fuel Pressure to manuely move the piston.

What am I missing?

JRV: This is the gap between the plunger and the "push arm" of the air flow meter, with the engine off. With no fuel pressure, it is a spring, above the plunger, that keeps it down so that it seats.....thus preventing fuel from entering the air flow meter.

The first position is where the sensor plate rests, in relation to the air tunnel wall, with the engine off.

The second position is where the plate rests, just as the plunger is being touched by the push arm, again, with the engine off.

These are positions pre-set by the factory when they built the FDs......without running the engine.

The first position is changed by "hit the pin with a hammer" technique. The second is changed by adjusting the "stop screw" that holds the plunger in the FD, and adjusts it's height.

Fine tuning of the second position is done by the air/fuel mixture screw, while the engine is idling.

Jeff: Do you have your FD seperated from the air flow meter?

If so, I would like to know the measurement (exact) between the rim of the barrel (where the plunger inserts), and the surface of the slotted nut that screws the plunger in place.

If anyone else has this measurement, I would appreciate it. If so, I would also need to know what year TR it is, and whether it is US or Euro version......mine is an 88.5 US version. There could be a difference due to models, etc.

I would keep these measurements for future use by other members.

Thanks.

Jeff: If I understand you correctly, the top of the sensor plate (furthest from the FD) and at rest, lies ABOVE the "ring"? The ring would refer to that narrowest portion of the air flow chamber. And, when you push on the plate, to touch the plunger, the top of the sensor plate lies EVEN with the ring. And, the distance from rest to the plunger is about 3/16 inch. Is this correct?

Yes Henry...that is how I see it. The air flow sensor plate is even with the narrowest "lip" just below the air flow entrance rim. I think I would place more emphasis on getting the contact to the plunger at the same instant as the sensor plate is aligned with the narrow lip, and consider the 3/16 gap as a secondary measurement.

Jeff: I would tend to agree. At "zero" position, my plate lies ABOVE the ring line. The point where contact is made with the plunger, is called the "basic" position.

However, the WSM states that, at the zero position, "The upper edge of the sensor plate should be flush with the beginning of the cone at the point shown in fig. 28". The figure shows the top of the plate EVEN with the ring!!!!!

Also, the Probst Bosch service manual states: "....zero position of the plate should be even with the top of the vertical face - or cylinder - of the air-flow sensor that is furthest away from the FD." When touching the plunger, "...the plate should be at the bottom of the vertical face of the tunnel so you can see all of the cylinder, but none of the tunnel below." It also states that free travel from zero down to basic (where plunger contact is felt), must be 1-2 mm.

Can Ferrari and Bosch BOTH be wrong?????? Go figure.

This is the reason for my thread on air flow meter measurements.

>>the Probst Bosch service manual states: <<

You just answered the question I was going to ask, if you had the Bosch books. They are far more detailed and accurate imo. Here's my problem with understanding &amp; answering most of these questions so far..."I LOANED OUT MY BOOKS" {}

I'll see if I can get my Bosch books back later this week and study up on the relivant chapters. There are certian complicated procedures that I would always consult the books on to insure things are properly set up.

Regards, JRV