More advise - Weber Jets.

jeffdon · 03-08-2004, 08:47 AM

First of all, thanks for all the advice here. Saved me alot of time in the thinking chair in my garage.

I am running a stock 2.0. Have moved over the 40 IDFs from a 1.8 that had been barreled and slightly cammed, and where they ran great.

Have fiddled with tuning and have it about as close as i can get it, now i think i need to address the jetting. Jets read as follows:

Idle 65
Main 120 (at least the have a 20 on them)
Emulsion tube F7

As you can tell, i am looking at the easy to get to parts.

From what i am reading, the Idles are too big, and the Mains might need to be bumped up. Any thoughts? I have yet to pull my venturis.

The car was not happy accelerating even at rest, and would not rev past about 3000. Fiddling with mixtures has improved it, as has just starting the thing up every day and letting it run.

Any thoughts?

SGB · SGB's Garage

I run 55 idle and 120 main. I think the E tube is F-7. I think you are too rich. Try 55 or 60 idles and make sure the "mixture volume screw" is turned about 2.5 to 3 turns out on each barrel. That should give a leaner operation of the main jets, but rich enough for good idle.

jeffdon · 03-08-2004, 09:05 AM

Oh, and i do get some popping when holding it at higher RPMS (sitting still again, in the garage).

Do you think maybe, the mains should be increased?

Jake Raby · 03-08-2004, 09:09 AM

what size Venturi is in the carb/?? This is very important in jet sizing..

what is your altitude??

jeffdon · 03-08-2004, 10:08 AM

Have not pulled the venturis to check, but will bite the bullet to do so. And i am in the bay area, so pretty much at sea level.

jeffdon · 03-08-2004, 01:39 PM

I pulled on, and I have 30mm venturis.

SteveStromberg · 03-08-2004, 05:37 PM

Where elevation are you at?Steve

lapuwali · 03-08-2004, 07:25 PM

I'm running a stock 1.7 with 40 IDFs, using 28mm venturis, 55 idles, 120 mains, 170 air correction, F11 emulsion tubes. I'm also in the Bay Area, so we're pretty much at the same elevation.

65 idles are too rich, and will cause some drivability problems at lower revs. I found 50s were too lean, causing mild hesitation at slow speeds. 55s were just right.

Your 120 mains may be fine, but what air corrector jets are you running? The 120/170 combo I'm using now runs smoothly, though perhaps a bit rich up top.

In addition to jetting, you want to make sure the carbs are properly synchronized, the throttles are closing completely, and you have no air leaks anywhere below the throttles (at the carb to manifold junction or the head to manifold junction). When I first fit the carbs, I had quite a bit of popping until I got the carbs reasonably in sync.

Generally speaking, you'll find smaller venturis will make the car less sensitive to jetting, with better drivability. You'll lose some top end.

Dave at Pelican Parts · Dave at Pelican Parts's Garage

Quote:

Originally posted by SteveStromberg
Where elevation are you at?Steve

Read the note immediately above yours, Steve...

--DD

jeffdon · 03-09-2004, 10:45 AM

In the bay area, and at sea level.

jeffdon · 03-09-2004, 03:19 PM

My air corrector jets are 160's

lapuwali · 03-09-2004, 05:12 PM

160s are quite rich, which probably explains why it won't run well above 3000rpm. Sounds like you're rich everywhere.

On a stock-ish engine, the usual recommendations for a starting point are 55 idle/115 main/200 air correction.

Where are you in the Bay Area? I have a set of 50 idles, 115 mains, and 200 air correctors on hand. We can swap them out and see if that helps. If so, you can buy yourself a set. If not, no harm done.

jeffdon · 03-09-2004, 11:16 PM

just ordered up some 55 and 60 idle jets, but if you want to sell the jets you have, i would be intrested in trying them

I am over in oakland.

Jake Raby · 03-10-2004, 07:17 AM

125 mains with the 30mm Vent @ sea level.... May run a tad rich in the winter and need a 122.5 but for summmer back to a 125

Dave at Pelican Parts · Dave at Pelican Parts's Garage

Winter?? What's that?

Oh, you mean the four months out of the year that we actually see rain!!

It is very rare for overnight lows in the Bay Area to get into the mid-30s. Ever. "Winter" high temps usually are in the mid-50s, often up to 60. I don't think that really qualifies as winter to a Georgian.

I would bet that the "summer" setting would be pretty good here all year 'round.

--DD