Interesting Weber jetting

[Eljaro]

Hi Bernie,

before massaging the emulsion tube I would try a smaller air corrector jet. The smallest is a 0.80mm size. You should try that first.
You can also try a slightly larger main jet if that is not enough.

Modifying the F14 emulsion would imply drilling the inside well of the tube with a 3mm drill to a depth of 30mm and drilling 1mm lateral holes at about 28mm from the top. It would be a matter of drilling first one, then two and up to four holes and testing each time. The center hole can be plugged with a 3mm brass plug any time again and the tube would be back to original again.


I am glad to hear that my personal feeling about the good response of the F14 tubes has been confirmed on a dyno.
I am still putting my new engine together and have 8 42mm Venturis waiting to be installed. Will see how they work.

[BERNIE]

Originally Posted by Eljaro

Hi Bernie,

before massaging the emulsion tube I would try a smaller air corrector jet. The smallest is a 0.80mm size. You should try that first.
You can also try a slightly larger main jet if that is not enough.

Modifying the F14 emulsion would imply drilling the inside well of the tube with a 3mm drill to a depth of 30mm and drilling 1mm lateral holes at about 28mm from the top. It would be a matter of drilling first one, then two and up to four holes and testing each time. The center hole can be plugged with a 3mm brass plug any time again and the tube would be back to original again.


I am glad to hear that my personal feeling about the good response of the F14 tubes has been confirmed on a dyno.
I am still putting my new engine together and have 8 42mm Venturis waiting to be installed. Will see how they work.

Thank you,how do you expect to improve richness with one mm hole from 100 jet (difficult to get 080 air jet!!!).another question have tested F2,F5,F7,F9,F11,F14,F16 on dyno seems F2 not too bad,F14 really much better but too much leaner at the top,but not yet F15 what do tou think about?,

Regards,

Bernie

[Eljaro]

if you can not get .80 air jets you can take some of the larger air jets you have laying around, drill them larger on a lathe, make yourself brass plugs, plug them up and drill them new with a .80mm drill.You can also plug them with tin solder and drill them again to .80mm.
Do you have the dyno sheet on how the curve looks like with the F14 tube?
I do not know what the F15 will do. But from what you say right now the F14 is the best combination with only the lean top end to be taken care of. The only way to correct that now is with the air jet.Try the smaller air jet before doing anything else.
If you can get a smaller drill than .80, say 0.50 I would try that too. You can always keep enlarging the hole if you overshoot on top end richness.

[BERNIE]

Originally Posted by Eljaro

if you can not get .80 air jets you can take some of the larger air jets you have laying around, drill them larger on a lathe, make yourself brass plugs, plug them up and drill them new with a .80mm drill.You can also plug them with tin solder and drill them again to .80mm.
Do you have the dyno sheet on how the curve looks like with the F14 tube?
I do not know what the F15 will do. But from what you say right now the F14 is the best combination with only the lean top end to be taken care of. The only way to correct that now is with the air jet.Try the smaller air jet before doing anything else.
If you can get a smaller drill than .80, say 0.50 I would try that too. You can always keep enlarging the hole if you overshoot on top end richness.

Will try first with modify air jet and start at 0.50 and up and up to get perfect air/fuel ratio around 12/8,13.2.all around.
Dyno sheet shows around 15/20 more HP between 3200/4600 ,during dyno session between F14 and F16 ,(engine is a full race 289 for historic racing)

[Snakebit]

Bernie, are you running 40mm chokes on the 289? I have a 331 small block with 185 AFR heads 60 idle jets, 1.10 holders, f5 emulsion tubes, 155 mains and 190 airs. Running 37mm chokes. Plugs are black and is running rich. just ordered a set of 40mm chokes from VEE DUB parts.

[BERNIE]

Originally Posted by Snakebit

Bernie, are you running 40mm chokes on the 289? I have a 331 small block with 185 AFR heads 60 idle jets, 1.10 holders, f5 emulsion tubes, 155 mains and 190 airs. Running 37mm chokes. Plugs are black and is running rich. just ordered a set of 40mm chokes from VEE DUB parts.

42 choke,190 air is too lean try 155/ 160 air and 120 holder,probably better with 40mm choke

[Eljaro]

Finally I got my engine back together again, this time it's a KC 482 Pond Alum.block with hydraulic roller lifters. Well, the engine does run very well and does not leak (yet).
My old weber setup was now no good any more, and my self made emulsion tubes ran horrible.
So I got back to tuning.
First thing I noticed, now that the engine runns hotter because it is so new, is that the pump jet dumps gasoline into the the carb when the hot engine is turned off. All my efforts to keep the carbs cool have not brought any improvement.
I noticed that the gasoline in the accel.pump circuit starts to boil and spills out of the only orifice it has , which is the pump jet. This happens only with the 0 pump spill. I used th 0.50 pump spill, which got away with that, because the gasoline can flow back into the bowl when expanding.
Since the 0.50 pump spill produces a slight flat spot, I have ordered 0.35 pump spill valves which I hope will work better and get away with the slight hesitation on acceleration and prevent fuel spilling into the carbs when engine is off.
I used the newly ordered F14 tubes, which seem to work fine, but the top end is lean now with 120 air correction jet. I tried 100 air correctors and that is now much better, but I have ordered 0.85 air correction jets because that is what I think will work best.Main jet is 140 now, and idle jet is 70 with a 100 holder.
Next weekend I will get back to tuning with the new parts ordered. Will se how it works out.