Jet-A-Vator carb grid.

[Isaac Zackary]

Any thoughts as to whether this device will actually increase fuel mileage? It's basically just a grid that sits under the carburetor.

[oil pan 4]

Yes it will increase mileage.
Its a restrictor plate, disguised to not be a restrictor plate...

[markweatherill]

Originally Posted by Isaac Zackary

Any thoughts as to whether this device will actually increase fuel mileage?

If you magnetise it, definitely.

[mcrews]

Here we go... Get some popcorn and pull up a chair!��

[user removed]

Nissan had an electrified (heated) screen in the last versions of their carbureted NAP-Z 4 cylinder engines.

This ain't one of those. I doubt it would even help with mileage unless you did some serious tuning on the host carb, including a major reduction in accelerator pump volume.

regards
mech

[Frank Lee]

Carb'd Tempos had that heated screen too. I never checked to see if it worked.

[Isaac Zackary]

Well, this thing is advertised as a fuel saver and a restrictor plate. It comes in three sizes, 20%, 30% and 40% reduction. That's % of the venturi, which is 26mm diameter or 531 mm^2 (not including the emmultion tube). So the 20%, 30% and 40% have 425, 372 and 319 mm^2 areas respectively. I wonder which one I should get. Apparently all three can handle 65mph just fine. I do live in a mountainous area so perhaps too much restriction would be counterproductive.

The site does mention the need to readjust the carburetor, especially the main jet. This 34 PICT-4 Solex carburetor that I have has a pilot jet, an auxiliary jet, a main jet, an air correction jet, two high speed enrichment jets and a thermostatic two speed accelerator pump that doubles as a third high speed enrichment jet. Not to mention the idle mixture adjustment screws. I have an oxygens sensor connected to an air/fuel ratio gauge in the cab. I also have a fully adjustable digital distributor. I plan on doing a lot of tuning obviously, perhaps with and without this device.

Those that I know that have tried it haven't always seen fuel mileage increases but they all have seen better cold starts, better pedal response and just smoother running over all. That seems to me to indicate that it must be helping with atomizing the fuel.

I'm familiar with those heated grids. I think they're called EFE's (early fuel evaporators). Apparently they aid cold starts and help reduce or eliminate the need for a choke. This Jet-A-Vator device is not heated, although during operation it probably will receive heat from the intake manifold and I do believe it's made of aluminum so it should conduct heat well. I was thinking of putting a small heating pad on it over night to see if it can eliminate or reduce the need for a choke. Mind you we get extremely cold winters here, as much as -40*.

[Isaac Zackary]

UPDATE: According to others it seems this device can have an adverse effect on fuel mileage when used with a stock distributor. The distributor normally recieves it's vacuum signal from below the throttle plate, which creates a restriction at part throttle, which creates a vacuum, which pulls on the vacuum advance diaphragm. But with the Jet-A-Vator it creates a restriction below the vacuum advance port. This causes less advance at the same load. Not good.

In my case I'll be using a digital ignition with a spark table and draw manifold pressure from below the JAV.

[MobilOne]

How about Carb icing?

[Isaac Zackary]

Originally Posted by MobilOne

How about Carb icing?

I haven't heard that the Jet-A-Vator affects carburetor icing. Why do you ask?