Buy flow tested carburetor jets?

[RENNERS CORNER]

Originally Posted by katy

I bought "off the shelf" jets from Brattons a couple of years ago, I checked the sizes before I installed them and they were bang on.
The literature I have says: Idle jet: .021", Comp jet: .037", Main jet: .037", Cap jet: .039".

Flow rates are what matter, not the hole size.... not all holes are created equal

[ModelA29]

Originally Posted by DRG-ler

Here in Berlin, the price of gasoline is currently the equivalent of $8.29/gal... You'd want to save gas where you can.

I had a cheap engineer boss that was a mpg nut. He bought a new Toyota for almost 30 grand because it got excellent mileage. I pointed out his old 20 mpg car could go about 170,000 miles on $3.50 a gallon gas for what he just spent.

[Jim/GA]

The original Ford blueprints actually quote the water flow rate range that they want through each jet under specific conditions. It is very cool.

Of course, in order to give the machinists a number to drill the tip of the jet to, they specify both a drill number and a hole size range, but that was not the spec.

Example below for the Model A Zenith Main Jet. Note the 90 degree conical finish of the tip. BTW, compare to the hole size quoted for the Main Jet in the earlier post.

[Pete]

What ever happened to final testing with an AFR gauge?
I have seen cases where the final size was 2 notches from recommended.

[David R.]

I rigged up a simple test rig with pvc pipe fittings and flow tested new jets from a kit and originals. I think only two were within acceptable tolerances. I soldered the rest and resized with proper wire gauge drill and re-tested.

[Mike Peters]

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I bought a new set of Zenith jets from Brattons a week ago. Upon arrival, I flow tested them with my homemade flow rig and got the following results:
Cap jet- 170 ml./min.
Main jet- 160 ml./min.
Idle jet- 57 ml./min.
Compensator jet- 150 ml./min.

Cap, main, and compensator jets are all "in the ball park". The idle jet is a bit high, according to flow literature I have.

Next, I installed them as is in a Zenith and tried it on a car. Good idle, good throttle response, easy starting, etc. Very happy with these jets.

I also flow tested some old repro jets and they were all over the board. Some high, some low. These would need to be redrilled, soldered before installing in a carburetor. My experience.