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

[tornik550]

I am new to carbs. I am a human mechanic and not a car mechanic. I am trying to learn and I appreciate everyones help.

Last night I only made three changes. The changes were that I increased the venturi size which should have leaned the mixture. I slightly increased the fuel pressure and I raised the float level from 11mm with the gasket to 10mm with the gasket. I then had a super rich mixture.

Today, I drove around quite a bit and played with the mains. I had AC jets of 190 the entire time. I tried 180, 170 and 160 and all were rich however 160 didn't seem too bad. I didn't have a 155 with me so I tried 150 and Now the mixture is lean. I am trying to find my 155's and i think that I should be dead on.

[ME733]

I am new to carbs. I am a human mechanic and not a car mechanic. I am trying to learn and I appreciate everyones help.

Last night I only made three changes. The changes were that I increased the venturi size which should have leaned the mixture. I slightly increased the fuel pressure and I raised the float level from 11mm with the gasket to 10mm with the gasket. I then had a super rich mixture.

Today, I drove around quite a bit and played with the mains. I had AC jets of 190 the entire time. I tried 180, 170 and 160 and all were rich however 160 didn't seem too bad. I didn't have a 155 with me so I tried 150 and Now the mixture is lean. I am trying to find my 155's and i think that I should be dead on.

...................terriffic......your jetting is in the range I suspected it might need to be in...., continue to keep an eye on the OIL temperature and Cylinder Head Temperature. Try a little longer trip after you get the 155,s in and see how it goes....Murray.

[jeffdon]

This is some of the most insightful carb tuning talk i have seen. And I am just getting started on optimizing my set-up, so its damn timely info.

Keep it coming.