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What is your idle speed, what is the manifold vacuum at idle? If you’re between 18-22 you’re fine. Yes re-jetting is mandatory on the 38/38 IMHO. Running the f-66 emulsion tubes with a slightly higher float level on mine. Jet from there and record all changes. Here’s my current set up:

European 2.0 bored from my 1.9L. OGTS pistons and valves, cam 405/256 regrind.
3/14/21
70° ambient
Idle 47’s Mains 145’s Air’s 185’s
F-66 emulsion tubes
Pump jet 60
Brass Float 39/49mm (with gasket)
Idle 14.4:1 turns: ⅝ inner screw ¾ outer screw, ¾ turns in on speed screw

Cruise 50 mph steady/tip in 14’s:
part throttle decel 13:1-13.5:1
Cruise highway 14’s & 15’s mostly 15.5:1
part throttle highway decel 13-14.5:1
Light acceleration 14-16.5:1
Aggressive acceleration 12.6:1- 13.5:1
Hard decel part throttle closed 13.5 to over l8:1
WOT 12.2-13:1

Rarely ever in the 16’s except for the occasional phantom lean spot off closed throttle while cruising (wouldn’t even notice it without the afr gauge). Good power on the mains.

No flat spots at all with the exception of the occasional low rpm off idle stumble getting better with screw setting adjustments from often to occasional but can’t seem to get it to disappear completely.

33-34 mpg highway

25 mpg city

28 mpg combined
 

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Discussion Starter · #62 ·
idle is 750rpm . vacuum fluctuates between 22-24 (needle is vibrating) around 1000rpm needle stands still @ 23. rising rpm al little more it goes to 25 and stays there. all measures while car not moving
 

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Those fluctuations on the needle symptoms indicated a vacuum leak on the intake manifold #3 cylinder, in my case it cleared right up once I replaced the gasket.
Measured all exhaust and intake flanges to be sure that they were 12mm anything less caused a vacuum leak.
In this case it was a rapid fluctuation and yes it did disappear when I bumped the throttle open a little. The needle is smooth now at 18 HTH
 
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