1975 2F Piggy with Weber 38 carb and DUI dizzy...need some insight please:) (1 Viewer)

[jdog35]

Well we are still progressing here, but at least rsb and I identified one issue.

My idle jets were 45s. From your Weber thread Johnny, sea-level size should be 60s. So I am picking those up in the next hour.

The main jets were 150s (close enough we figured), and the air correction jets were 180s.

To all the experts out there, would these improper idle jet sizes be the issue you think? rsb can chime in here too to legitimate my claims We are pretty sure the idle mix is right (maybe a touch rich), and the timing is on. Thoughts?

I will post again once I have installed the 60s. rsb also thought maybe my float was a little off too, but I am going to tackle one variable at a time to eliminate any and all possibilities.

Thanks guys!

 

[rsbcruiser]

Found the float level numbers, jd. They are 40mm min. and 50mm max with a setting of 44.5mm max for offfroad apps.

 

[jdog35]

Okay here are the new jet settings:

Main Jets 38/38:
Elevation:
155

Air Correction 38/38:
185 (didn't have 180s in the kit

Idle jets 38/38:
60

 

[JohnnyC]

the higher numbers for the air correction leans it a bit...however its slite...i would say your numbers look good....did you throw them in yet?

most 38's i have talked to people with all had 60's in them....a much lower idle jet leans it out alot....the idle jet works full time on a weber and is an intrigal part of the mid range settings...

hows it run now?

 

[jdog35]

Well I think it is running even better at idle than before. I put the #60 idle jets in and it sure sounded better to me.

I then pulled the carb apart to put the #155 main jets in (it had the 150s before I think). The air correction jets were #185.

I didn't put the entire carb back together yet with the minor main jet adjustments because I was going to check with you guys on the float level first. I'm not entirely sure where/how to measure the distances, but this is what I think I have.

From the bottom of the carb to the float when it is at 'neutral' (for lack of a better term) it is 33-35mm away from the plate (couldn't quite tell a 1-2mm difference with my metric ruler). At the 'dropped' position (for lack of a better term), the float was at 45-47mm away from the plate. Does that nomenclature make sense? Sorry. I should have taken photos.

I know the recommendation is 'between 40-50mm', but that leaves a lot of wiggle room. Irregardless, would those minor adjustments account for the problems I've been having?

Depending on your responses, I will either adjust the float tomorrow and then re-test, or I will leave it and reassemble. I guess the next stage if all this checks out and it still dies is hooking up the Fluke and testing the voltage under load correct?

Thanks again Johnny, rsb, and dog. You guys are a god-send with this piggy-project!

 

[jdog35]

This is the image I went off of for my measurements by the way.

 

[JohnnyC]

33-35 at 'rest' for the float is ok....but set at 39-40 for best

set the 'drop' (valve full open) to 44.5...measure from bottom of carb base to end of float...it doesnt matter if you have plastic or brass float...the drop is best for off-road/on-road at 44.5

i normally set the carb base up on 2 tall glasses to check float setting...both hands are free then

use a piece of stiff paper with drawn..... the 40 and 44.5 lines to check....then you know its on.

 

[JohnnyC]

from previous post....if the float setting and rejetting doesnt work out....
are you confident its not in 180* out?

you may want to bring #1cyl up to compression and check that timing is on and that the firing order is correct (1 5 3 6 2 4)

did you check to see your getting a full 12v to the dizzy key on?

 

[jdog35]

At this point I'm not confident in anything I've done anymore. I'm happy to re-start/re-check everything from the ground up with the dizzy. I have not yet stuck the Fluke on the dizzy to see what it says. Which points should I be checking on it?

On the float adjustment I just need to let the float hang in between the glasses I'm assuming? It seems so odd to justs BEND a piece to adjust it Old school right?

 

[JohnnyC]

yes old school

the glasses just hold up the carb....the float drops inbetween them ....so you can adjust it

on the dizzy....its the power-in wire (key on wire)

 

[JohnnyC]

i made a 38dgas float spec diagram

we were needing pics...i like pics

 

[jdog35]

I like pics too. And as soon as I get done with all this I'll be going nuts with my 7D.

So I literally have to bend that little piece of metal in there to adjust the float? That just seems so...rudimentary. Am I missing something or is it really that basic? Hope I don't break it!

Tackling this float-issue tomorrow. Today was full of Christmas trees and youth basketball. Tis the season!

Thanks Johnny!

 

[JohnnyC]

alil bend ....thats it .....bends easy...dought you'll break it

 

[rsbcruiser]

Take care not to drive the needle down into the seat when you go to adjust the the float tab it is attached to.

 

[jdog35]

Hey guys. So the float is adjusted. I'm right at 40-45mm between the two points.

I can definitely get a little more rpm out of it before it dies now. But it will still chuga-chuga-chuga and then die (with a light grey puff of exhaust/smoke coming out of the carb barrells).

 

[JohnnyC]

from previous post....if the float setting and rejetting doesnt work out....
are you confident its not in 180* out?

you may want to bring #1cyl up to compression and check that timing is on and that the firing order is correct (1 5 3 6 2 4)

did you check to see your getting a full 12v to the dizzy key on?

did you check these?

pic of dizzy side of engine?

 

[jdog35]

I checked the voltage to the dizzy by placing the negative lead of the FLUKE on the negative battery terminal, and the positive lead on the port that says "BATT" on the distributor. Is that correct? If so, it read pretty solid 11.8-12.0 volts.

 

[jdog35]

On a whim I just checked the voltage to the plug going into the distributor (I believe it's the electric choke). That is running 12-volts beautifully. However, this plug circled is pulling nothing. That can't be good can it?

 

[Pighead]

However, this plug circled is pulling nothing. That can't be good can it?

The circled plug is a water temp sender...

 

[jdog35]

So that's probably not mission critical then huh? Hmmm...