idle drifts down

4 of 50 Commited Dubber

71 posts · joined Sep 2003 · 7 Jun 2004, 6:45 pm

#183566

Will anynoe help with the cause of the following?

After a few gentle dabs at the accelerator I leave the throttle completely off. The engine idles OK for about 3 seconds and then the rpm drops. This is OK when the engine is hot but not so good when it is cold.

Thanks

'77 2L bus with twin solex carbs. Recently changed main jet from 130 to 145 and air jet from 175 to 155.

Peter Leonard Moderator Volatile

1,456 posts · joined Apr 2003 · 7 Jun 2004, 6:54 pm

#183570

because it's cold....:alien

let sleeping dubs lie

Bizarre Moderator The artist formerly known as blue74l

12,789 posts · joined Aug 2002 · 7 Jun 2004, 7:09 pm

#183573

Why did you change the jets????

Futue te ipsum!!!

4 of 50 Commited Dubber

71 posts · joined Sep 2003 · 8 Jun 2004, 3:37 pm

#184123

Thanks Peter but the same thing happens when she is hot, only when hot she wont stall.

Why did I change the jets?

I wanted to do a carby overhaul because there was a lot of black smoke and poor fuel economy

Once in side i found that someone had been using the left carby as a hash pipe. The air correction jet was virtually closed over

I was advised by a good mechanic to change the jets to a calibre more suited to an older engine

The bus runs like a dream now and has much improved fuel economy but this idle thing is a bit wierd

[Edited on 8-6-2004 by 4 of 50]

Bizarre Moderator The artist formerly known as blue74l

12,789 posts · joined Aug 2002 · 8 Jun 2004, 4:14 pm

#184146

4 of 50 wrote:Recently changed main jet from 130 to 145 and air jet from 175 to 155.

sorry but still a bit confused.

"Why did I change the jets?

I wanted to do a carby overhaul because there was a lot of black smoke and poor fuel economy "

It was running rich and you have richened the system up by increaseing your jetting.

Ok ok - its running better?? just confused that you have said it was running rich and its now richer????

Futue te ipsum!!!

kombikim disfunctionally capable

1,521 posts · joined Dec 2002 · 8 Jun 2004, 4:27 pm

#184154

the jet choice you have made is very good, this has nothing however to do with idle, it really only affects over about 1800 revs or so, if you have a '77 , then you may have a "dashpot" on the throttle cross shaft, (it looks a bit like the vacuum advance, without a tube off it) it is designed to delay the throttle going back to low idle for a few seconds.
the other thing is that the idle mixture could be a bit rich so that the plugs gradually load up with unburnt fuel residue, becuase they can't burn it all off, this reduces the idle speed through lack of efficiency when hot & can Vrtually flood the plugs when cold, causing engine to stall

Please, I need drivers side window regulator (winder mechanism) for my '54