77 Bus - 36 IDF Carbs Are Flooding! FIXED!

[Mark]

I had a similar issue, and it was brought to my attention of a potential problem with IDFs and the fuel enrichment circuits. The washers, springs & keepers for the brass plungers can come loose, allowing fuel to leak past.

I tapped the bores out, and used some 3/8" set screws to keep the plungers seated. Easy.


In 1000 words or so...





Disregard the dirt on the carbs, they received a full cleaning before reinstall. :P

[Sluggo]

I had a similar issue, and it was brought to my attention of a potential problem with IDFs and the fuel enrichment circuits. The washers, springs & keepers for the brass plungers can come loose, allowing fuel to leak past.

I tapped the bores out, and used some 3/8" set screws to keep the plungers seated. Easy.

You may have just nailed it. I've noticed a small amount of fuel coming from the plate that covers that chamber below those set screws in your pic. I'll pull the tops tomorrow & see.

[chitwnvw]

As an IDF owner, very interesting. Keep posting, please and thank you.

[Amskeptic]

As an IDF owner, very interesting. Keep posting, please and thank you.

And thank you for the photographs. Oh, by the way the carb appears to have some dirt on it, I'd clean them before re- installing on the engine.

[Sluggo]

It's not the enrichment circuits. They are nice & tight. Noticed fuel in the 1/2 bowl was quite high. Covered most of the float & the float was heavy (but still half functioning). So I need to replace the other float but I don't think that's my entire problem.

Needles & seats seemed to block air flow (blowing through seat with needle in place) but the needles have rings around the mating surfaces. So I'm trying to order those too. All I can find are 200 & up. I need 175. Aircooled.net has them but 50% of the time I've ordered from them I end up canceling the order because it has taken so damn long.

I need a needle tutorial. I know that they operate kind of like a toilet valve where the float rises and pushes the needle into the seat to block the flow of fuel. My question is what does the ball & spring do? My best guess is that it's a little shock absorber for the needle so the float doesn't press it into the seat too hard.

[Sluggo]

Getting much worse. Tried to go to the store and could barely get the Bus to idle. Once I got it to idle it started popping with the slightest throttle. Actually shot a little flame out of the tailpipe! Flooding out like mad.

New floats, needles & seats. Same jetting as when running good. Fuel pressure is now down to 1.5 in an attempt to stop the flooding. It's not flooding while the engine is off. Fuel is not filling the crank case. All this started when I changed the carb top gaskets!

[BellePlaine]

Getting much worse. Tried to go to the store and could barely get the Bus to idle. Once I got it to idle it started popping with the slightest throttle. Actually shot a little flame out of the tailpipe! Flooding out like mad.

New floats, needles & seats. Same jetting as when running good. Fuel pressure is now down to 1.5 in an attempt to stop the flooding. It's not flooding while the engine is off. Fuel is not filling the crank case. All this started when I changed the carb top gaskets!

I don't know if this will help or not, but you mentioned having to trim the top gasket to fit the idle jet. I wonder if it's possible that your problem might have to do with that. For instance, after I "refreshed" my aftermarket carbs, I mistakenly over tightened the idle jet. It ran like crap. I don't know, just a thought.

[Sluggo]

FIXED!

The rich running and bad MPG was being caused by 2 things.

1. Floats were set at 11 which is for 40-48 IDFs. 36 IDFs should be set at 9.2.
2. The new gaskets didn't have holes for the two tiny ports right next to the idle jets (which they also did not have holes for). Punched the holes & reset my floats & I'm golden.

I emailed the guy who built them for me in Italy and he knew exactly what was happening.

The problem with not idling and the backfires were caused by one of the new seats coming loose and severely flooding the 3-4 carb.