jetting questions

[1972fritz]

got a 38-38 weber the main jets are 45s i haave been having problems with it running when oyu tip the throttle in while crusing i put larger mains in 55s and it seemed to like the extra fuel be it was way to rich kept fouling the plugs and hard to start. timing is great ball is steady.

[Guest Anonymous]

got a 38-38 weber the main jets are 45s i haave been having problems with it running when oyu tip the throttle in while crusing i put larger mains in 55s and it seemed to like the extra fuel be it was way to rich kept fouling the plugs and hard to start. timing is great ball is steady.

Are you confusing idle jets (on the side of the carburetor) with main jets (located inside the fuel bowl)? Idle jets have numbers like 45 and 55. Main jets have numbers like 145 and 155. There are also air correction jets and emulsion tubes that affect engine performance.

Grammar, punctuation and spelling might make your post more easily understood.

[1972fritz]

my bad. yes the idle jets not main jets.

[Guest Anonymous]

my bad. yes the idle jets not main jets.

Your post is unclear. If you read through the many other posts on the subject in the archives, idle jets influence part throttle operation. They work in conjunction with the other jets and may ameliorate, if not cure, progression issues (which may be what you are experiencing). If you are fouling plugs with the increased idle jet size, it would be helpful to know your baseline jetting. Tinkering with the M10 engine is very forgiving yet setting up the 38/38 to run well can involve much more than swapping idle jets and ignition timing.

[72Fjord02]

Hello 1972Fritz,

I think from other posts I have gathered you are in the Minneapolis MN area, which is where I am at as well.

I have a bunch of main, idle and air jets for the Weber 38 if you want to play with some.

I spent the summer messing with the jets on my 38 and this is the set up that seems to give me the best performance. It is not perfect, but as good as I can get it until I get an AFR next spring.

Idle:60

Main:135

Air:190

coil: Bosch Black

Plugs: NGK BP5ES

My car was happier running bigger Idles with smaller mains and slightly bigger air than the stock set up.

I don't have any problems with running rich/fouling plugs.

Let me know if you need any jets,

Kurt

[1972fritz]

i am now in madison wi and would love some hepl with jets could you email me with your contact info?

[TobyB]

55 'idle/transition' jets are still pretty small-

I think you need to look at your mains.

I seem to remember that a 135 main was on the small side of the range...

and that mine liked 140 or 145's...

t