Weber IDF Main jet help Options

[tornik550]

I am in the process of tuning my car after a rebuild. I have dual weber 40's. My engine is a 2.27L. Everything is going pretty well. I am slowly getting the jetting closer and closer. I was driving around at about 60mph yesterday. The head were hotter than I like (325 degrees). I checked the spark plugs and they were bone white. The main jets were at 160. I increased them to 170 (above 160 I only have increments of 10). With the increase to 170, the car is running very well and the temp at around 60mph cruising is around 275. I sped home, tuned off the car and took out the plugs- bone white. I was quite surprised.

The main jet size sounds high too me. Does it sound high to everyone else? Is it possible that I am needing a high main jet size because of the float level? I have my floats set at 10.5 with the gasket.

Any opinions would be greatly appreciated

[jmill]

Murray is correct in that changing multiple things at once isn't the correct way to troubleshoot. You have no idea what had the most profound effect.

Increase fuel pressure = rich
Increase float height = rich
Decrease AC jet size = rich

I suggest you set a new base line with the below info and make changes from there one at a time. Note what each change does from here on out and then adjust accordingly.

#1 - Change AC jets to 2.00 - Assuming you have the F11, you never said what ET you have. 2.00 is base AC jet for the F11. Above 2.00 you lean the mixture at high velocity, below you enrichen.

#2 - Float height = 10mm w/ gasket 11mm w/out. I suspect this was the main reason you were lean with the huge main jets. At 11mm with the gasket your main fuel wells were a low.

#3 - That bogging at 2000 RPM is because your pig rich. Reduce your main jet size. I'd suggest 160's and go from there.

#4 - That new sound your hearing is a result of the larger vents. I personally love the sound.

[tornik550]

Murray is correct in that changing multiple things at once isn't the correct way to troubleshoot. You have no idea what had the most profound effect.

Increase fuel pressure = rich
Increase float height = rich
Decrease AC jet size = rich

I suggest you set a new base line with the below info and make changes from there one at a time. Note what each change does from here on out and then adjust accordingly.

#1 - Change AC jets to 2.00 - Assuming you have the F11, you never said what ET you have. 2.00 is base AC jet for the F11. Above 2.00 you lean the mixture at high velocity, below you enrichen.

#2 - Float height = 10mm w/ gasket 11mm w/out. I suspect this was the main reason you were lean with the huge main jets. At 11mm with the gasket your main fuel wells were a low.

#3 - That bogging at 2000 RPM is because your pig rich. Reduce your main jet size. I'd suggest 160's and go from there.

#4 - That new sound your hearing is a result of the larger vents. I personally love the sound.

#1 I have F11 ET tubes. I also have a set of f7 that I could use. I changed the AC to 2.00. Things ran better but still rich. I did not notice any bogging.
#2 Thank you.
#3 I went down to 170 so far and things feel pretty good however I have not had a chance to check the plugs.