Weber tuning with Lambda sensor - Page 13 - Alfa Romeo Bulletin Board & Forums
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post #181 of 188 (permalink) Old 09-10-2019, 09:48 AM
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Ed - thanks for the reply. If I take the ZT2 ground back to the battery, is that considered a good ground (from an electronics perspective)? i.e. is this likely to eliminate potential ground loops? regards
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post #182 of 188 (permalink) Old 09-10-2019, 09:56 AM
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The signal from coil -ve is with reference to the engine because the distributor body is the ground. So in theory a connection to the block or front cover is best.

Ed Prytherch
79 Spider
76 Suzuki GT500
2011 Jaguar XKR

A little government and a little luck are necessary in life, but only a fool trusts either of them. - P.J. O'Rourke
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post #183 of 188 (permalink) Old 09-10-2019, 10:02 AM
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Mike,
I looked at the Weber drawings for emulsion tubes and F16 and F11 are almost identical except that F11 has 4 extra high holes which I think are intended to lean the mixture a little at high rpm.
John Passini wrote that nearly all Ford engines with DCOE's use either F16 or F11. F16 being the choice for full blown race engines and F11 for "less hairy" motors.
In my case it is mid range richness that I would like to lessen when the top end is tuned for 12.8 to 13.2

Ed Prytherch
79 Spider
76 Suzuki GT500
2011 Jaguar XKR

A little government and a little luck are necessary in life, but only a fool trusts either of them. - P.J. O'Rourke
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post #184 of 188 (permalink) Old 09-10-2019, 05:16 PM
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Ed, I have a set of F9s. If I remember correctly I had them in but changed to the F11s because a sputter or bumble at steady rpms without any load. It was so long ago before I had the wide band. It's a totally different motor now and since I have the wide band it can't hurt to drop some F9s in to see what happens.
When I pulled the plugs to do the compression check the insulators were white white but with no deposits and the outer base was black. I'd like to see a light chocolate brown on the insulators and base.

The passenger seat is 15 miles an hour faster than the drivers seat.

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post #185 of 188 (permalink) Old 09-10-2019, 06:08 PM
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F9's did not work well for me either. The top went lean and I could not get it back with smaller air correctors and I had to go up on main jets which made it too rich in the mid range and at part throttle.

Ed Prytherch
79 Spider
76 Suzuki GT500
2011 Jaguar XKR

A little government and a little luck are necessary in life, but only a fool trusts either of them. - P.J. O'Rourke
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post #186 of 188 (permalink) Old 09-11-2019, 01:31 PM
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Interface circuit

I built another of the little interface circuits today and played around with it on the bench. The capacitor should be 10 nF and the resistors should be 22K for best results. I hooked it up to the coil -ve and I got a pretty clean rpm trace up to 7000 rpm.

Ed Prytherch
79 Spider
76 Suzuki GT500
2011 Jaguar XKR

A little government and a little luck are necessary in life, but only a fool trusts either of them. - P.J. O'Rourke
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post #187 of 188 (permalink) Old 09-11-2019, 03:54 PM
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Ed, did the new interface clean up the tach signal compared to what you had? We can still swap ZT-2s sometime.

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post #188 of 188 (permalink) Old 09-11-2019, 05:42 PM
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Yes, it cleaned it up and therefore I should not need to swap ZT2's.

Not sure what did the trick, changing component values or running a good ground from the bar on the rear of the cam cover to the ground point for the ZT2, or a bit of both.

Ed Prytherch
79 Spider
76 Suzuki GT500
2011 Jaguar XKR

A little government and a little luck are necessary in life, but only a fool trusts either of them. - P.J. O'Rourke
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