1980 B200 Sport, freshly rebuilt engine, runs/drives great. I've been driving this truck for 10 years with a Weber. Runs like a CHAMP on gas.

Nothing out of stock except EGR removed and PCV is routed to carbon can with crankcase vent routed to air filter. Basically I altered the basic emission system to keep only parts of it.

I have switched to E85 and this is my first time changing anything other than the primary idle jet.

I went from 55 to 75!
Bumped mains from 140/140 to 150/155.

I bought a mess of jets and air correctors.
I will be taking another crack at jetting tomorrow.

My main problem is start up and warm up. It falls pretty dang flat when coming off idle, struggles to idle with choke on.

Thoughts? Suggestions?


I need advice and all my car friends run Fuel injection.....

 

I got some vids on tuning on my yt channel I'm getting ready to put another couple of vids I just gotta wait for a go pro my phone starting to look janky but anyhow I got some vids on tuning to explain the jetting check it out and support the scene.
https://www.youtube.com/channel/UC_8...13flA067hr7xkA
my experience with falling on face is usually it's the main jet the air correcter is supposed to be 60 sizes bigger than main jet size.

This guide will be in future vid but it gives an idea of what the relationship between jets is.

 

Thanks for the reply!

where did you hear the airjet to main jet +60? is that for gas? I am running e85 so that very well could change things a lot...

I've determined its running LEAN.
Got an AFR gauge installed today. very helpful!!!!

note on my A/F data: my setup is calibrated for gas so 14.7:1 on my gauge is actually around 9.0:1 with E85.

I'm idling a little rich 12.8ish.
cruising around town its about 15-16 (lean).

current jetting is:
primary
90 idle, 165 main, 160 air, f50 tube
secondary
60 idle, 160 main, 160 air, f50 tube

I am waiting on more, bigger main jets and an f6 tube.

I have not really messed with the secondary at all, im trying to get the primary dialed in first. plus its set up with the biggest jets I have at the moment.

I will be putting in 175/180/185 mains then go from there.

 

In some weber books. I like the one by pat braden weber carburetors
on pg 37 il snap a pic for ya.also I found this pdf ya might enjoy.
https://usermanual.wiki/Document/Web...746466219/view

Here's a part in pat braden's book pg37.

Heres a section from another book I it's called weber technical introduction

I think you'll need to change the emulsion tubes for best performance. I'm not sure but I'd bet its gotta be richer.
I bet you can upside your needle and seat size also.im driving on the baseline tune that it describes it seems to run good I know my truck no longer stumbles in 4th and 5th gear at 3.5-4 rpms I'm gonna be making a video going through the tuning techniques soon also showing the baseline tune.then some test runs but for now it runs great. I've noticed the carb temp plays a role in the stoich so I gotta temp sensor to wire up soon also.

 

Also when my float level was not set right my truck would barely idle with choke on. Maybe it's your float level. I got a vid on how to set it.
there's a diagram at the end of the vid.

 

I bumped up my sec idle to a 90, still have the 165/160 mains but my bigger ones arrive today.

lowered my air jets to 165/160 or vice versa I can't remember. helped a lot staying on the idle jet and not getting leaned out by the 165 main.

set as it is, with idle screw 2 1/8 turns out with the 90 idle jet I hover around a stoich.

IT PASSED THE OREGON DEQ EMMISSION TEST YESTERDAY!!!!!

I am still fighting with it to start, I think my fast idle is set too high, engaging my undersized main jet and throwing the mix off. when, eventually, it does start with the choke its running LEAN.
NOT SUPPOSED TO WORK LIKE THAT! no wonder it struggles....

will post an update.