Ironcross

Would anyone know what is the optimum air meter and if they are interchangeable....and differences 57-65 if any

jim lockwood

There are numerous design differences in the air meters, generally trending towards better vacuum signal derivation as one moves from the early air meters to the later air meters. '63 and later air meters are shorter than '62 and earlier air meters.

Not sure what you mean by "optimum", but the '63 - '65 air meters will flow more air than the '61 and older. '62 air meters flow more than '61 and older but less than '63 and later. If you have an engine which can take advantage of the better air flow of the later air meters, it will produce more power with one.

A creative person could probably overcome the physical differences of the various air meters and adapt any air meter to any FI unit. A requirement of such an adaptation would be to have the equipment and skill to re-calibrate the air/fuel mixture under all driving conditions. Depending on the assembled combination of parts, it might be necessary to make internal fuel meter modifications to achieve proper calibration.

Why do you ask?

Jim

DZAUTO

Good info above from Jim.
Also, I'm curious, why do you ask? Are you building an FI unit from scratch or from misc parts?

From my experience, without question, the 63-65 air meters were the best in the Rochester FI development.
I personally have not done it, but in my opinion, using a 63-65 air meter on an early unit would provide the best results. And this would also require a compatible fuel meter, such as 62-65 fuel meters.
The next best air meter would be a 62 AM combined with a 62 fuel meter. The FI unit on my engine (SB400) incorporates a very early finned top plenum (chosen strictly for the appearance of the early FI units), 62 air meter and 62 fuel meter. I have incorporated some misc modifications to the unit in an effort to achieve the appearance of a 57 unit, but with the dependability and performance of a 65 unit.

Now, if a 64-65 (7380) unit is to be used, there is basically NOTHING (within being practical) that can be done to SIGNIFICANTLY improve the unit. Don't mess with it!!!!!
If an earlier unit is to be used, and increased performance is a prime objective, then without question there are several things that can be done. But the simplest, easiest thing that can be done is to upgrade it with a 62 air and fuel meter.
Generally speaking, if a person is not INTIMATELY knowledgeable with all the differences and changes from the first 4360 (1957) to the 7320 (1961) units, it is most probable that it will be messed up and be a great disappointment. Just leave it alone and return it to its as designed and as built configuration.

jim lockwood

I had a similar idea.

To preserve a somewhat original appearance, though, while still boosting air flow, I stuck a '63 - '65 venturi cone in Mongrel, my hodge-podge, assembled-from-pieces-and-parts FI unit:





On a flow bench, that air meter flowed 699 cfm (I typically round up and call it an even 700 cfm.... sounds better).

In a manner similar to what I was suggesting earlier, I had to modify the fuel meter and make a minor tweak to the idle boost circuit in the air meter. But, armed with a wide band air/fuel gauge, the process of getting this dialed in was straight forward.

Jim

Ironcross

I have a spare 62 unit {air meter}..its complete including correct springs, choke, ect. . 4 nuts and its installed. it was to be used if mine ever came up missing......and I was of the opinion the 62 stuff was the better unit...forgot why exactly..... and you gentlemen, ...answered my question....I guess I could sell it before that too comes up missing as the same fate as my other spare FI parts ..

I sold the Parts store and all the inventory...Most of my spare Vette stuff I had left got sold off the shelving....Never have an auction...,

Thanks to each of you however, for the information

Wally Knoch.....