[Hurst65]

I finished installing the wideband gauge this morning and started to do a little tuning.

The idle was pig rich! Jon, you were right! The gauge was reading between 12.12 & 12.5:1 at idle. So, I turned the mixture screws in all the way and then back out 1 turn. That proved way too lean-- the car wouldn't idle well and the gauge was pegged out. I then went another turn out, for a total of two turns. That was a close but, a little too rich. Right now, I'm at 1.75 turns on the mixture screws and the gauge is reading about 14.5:1.
I never knew that the mixture screws were that sensitive. The slightest little turn makes a big difference!

I think I'm okay with the idle. It idles real nice at a steady 900 RPM, w/15 degrees of timing, pulling 11" of vacuum, and the wideband gauge reading 14.5:1. The idle is really smooth-- almost stockish.

Ok.... so, then I went for a short drive. The mains are pig rich too! The gauge was reading about 11:1 to 11.5:1, in any gear, at 2500 RPM. How much of a jet change do you guys think I need to make?

Thanks!

[Schurkey]

Originally Posted by Hurst65

I finished installing the wideband gauge this morning and started to do a little tuning.

The idle was pig rich! Jon, you were right! The gauge was reading between 12.12 & 12.5:1 at idle. So, I turned the mixture screws in all the way and then back out 1 turn. That proved way too lean-- the car wouldn't idle well and the gauge was pegged out. I then went another turn out, for a total of two turns. That was a close but, a little too rich. Right now, I'm at 1.75 turns on the mixture screws and the gauge is reading about 14.5:1.
I never knew that the mixture screws were that sensitive. The slightest little turn makes a big difference!

I think I'm okay with the idle. It idles real nice at a steady 900 RPM, w/15 degrees of timing, pulling 11" of vacuum, and the wideband gauge reading 14.5:1. The idle is really smooth-- almost stockish.

Ok.... so, then I went for a short drive. The mains are pig rich too! The gauge was reading about 11:1 to 11.5:1, in any gear, at 2500 RPM. How much of a jet change do you guys think I need to make?

Thanks!

What happens if the idle speed is more reasonable? 900 is kinda high.

Is that 11" of vacuum at idle the most the engine will make at that throttle position? Does changing the idle mixture screws increase the vacuum from there?

[Hurst65]

Originally Posted by Schurkey

What happens if the idle speed is more reasonable? 900 is kinda high.

Is that 11" of vacuum at idle the most the engine will make at that throttle position? Does changing the idle mixture screws increase the vacuum from there?

Great question. Okay, so I wanted to see the same thing. Here's what I found out--
1.) I can go down to 750 RPM but, the engine doesn't seem to like it. It kinda starts to lug and it's just not very smooth. I brought it up to 800 RPM and that seems like a good compromise.

2.) I was able to eek out about 12" of vacuum after some further tinkering. Not a big change in vac. readings.... maybe + or - 1" of vacuum either way with the screws. But a tiny turn of the screws, one way or the other, really makes a big difference on the wideband gauge.

I opened up all 3 carbs this afternoon to verify my baseline.

Center carb - Idle tubes are at .0355", .066 Jets (waaaayy toooo fat!)
End carbs - .072 Jets

I switched the end carb jets to .070 while I had them open.
I was going to put smaller jets in the center but, I don't have any. I'll have to order some. I'm not sure where to start, thou. I'm thinking .063's. ??

Overall, I think I'm going in the right direction. I just need to get some smaller jets for the center carb and go from there.

[carbking]

Originally Posted by Hurst65

I finished installing the wideband gauge this morning and started to do a little tuning.

The idle was pig rich! Jon, you were right! The gauge was reading between 12.12 & 12.5:1 at idle. So, I turned the mixture screws in all the way and then back out 1 turn. That proved way too lean-- the car wouldn't idle well and the gauge was pegged out. I then went another turn out, for a total of two turns. That was a close but, a little too rich. Right now, I'm at 1.75 turns on the mixture screws and the gauge is reading about 14.5:1.
I never knew that the mixture screws were that sensitive. The slightest little turn makes a big difference!

I think I'm okay with the idle. It idles real nice at a steady 900 RPM, w/15 degrees of timing, pulling 11" of vacuum, and the wideband gauge reading 14.5:1. The idle is really smooth-- almost stockish.

Ok.... so, then I went for a short drive. The mains are pig rich too! The gauge was reading about 11:1 to 11.5:1, in any gear, at 2500 RPM. How much of a jet change do you guys think I need to make?

Thanks!

Have you changed the spark plugs yet?

Running as rich as the engine has been will foul the plugs to the point the wide-band will not be as accurate as possible; as the fuel-fouled plugs will not produce the same spark as they would when new, thereby sending a false reading to the wide-band.

Once you get close on both idle and main...............CHANGE THE PLUGS! You will probably find you need to adjust a wee bit more (leaner) on fresh plugs.

And yes, if you need the spring kit, we still have them.

Jon.