Wandering idle

matara Custom Title Time!

1,342 posts · joined Aug 2002 · 9 Feb 2009, 1:30 pm

#694234

I just rebuilt my Brosol H30/31 carb on my 1600SP in my splitty, and all went well no problems. I've put the carb back on the bus, and however I adjust it, the engine won't hold a steady idle. Its will idle, but it seems like every 3 or 4 seconds it misses, nearly dies and then springs back to life again.

I've checked the ignition and the points, as I put a SVDA dizzy on it about 3 months ago, but until I rebuilt the carb it was running fine. I was careful to make sure all the drillings were nice and clear, and I've checked for manifold leaks etc.

I was careful not to alter anything before and after I replace the carb.

Just wondering if anyone has any tips before I pull it all down again to check everything

Thanks

Steve

Bizarre Moderator The artist formerly known as blue74l

12,789 posts · joined Aug 2002 · 9 Feb 2009, 3:25 pm

#694249

matara wrote:I and I've checked for manifold leaks etc.

What about checking the carb for leaks??

Sounds like a air leak

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greedy53 Bishop of Volkswagenism

3,062 posts · joined Mar 2006 · 9 Feb 2009, 4:19 pm

#694261

i would be prepaired to venture an opinion that there is some crap in te carbys inner calleries take it off remove all jets and anything that can be removed than stick a good compressor and blow all the gallies out
been there done that
good luck

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RISKYBUG Seriously Crusin Dubber

187 posts · joined Mar 2008 · 9 Feb 2009, 5:09 pm

#694270

and what about the electric cut off
make sure it's working

1916baja Custom Title Time!

1,990 posts · joined Sep 2007 · 9 Feb 2009, 7:11 pm

#694288

It probably wont be this but my baja was doing he same thing and when i replaced the coil it fixed it. The spark seemed fine to look at but it obviously wasn't. Just a thought although probably very unlikely...

jedidan Officially Full-On Dubber

304 posts · joined Oct 2006 · 10 Feb 2009, 9:39 am

#694380

may not be the culprit, but check to make sure you got the little spring at the distributor locating gear - sometimes this can cause the idle
to be erratic.

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matara Custom Title Time!

1,342 posts · joined Aug 2002 · 16 Feb 2009, 8:49 am

#695498

Ok I worked it out this weekend. I bought a new H30/31 carby from George at Classic Veedub after my engine developed a knock last Friday. I feared the worst since the knock, sounded like a ticking sound, and I thought one of the small end bushes on the number 3 rod had flogged out!

Before I decided to pull the engine, I just wanted to check to see if there was a recessed valve, so I pulled off the rocker gear to check that all 4 valve stems were at the same height. Whilst doing this I noticed the rocker gear stud next to cylinder 3 was loose, adn the thread had stripped (just the nut not the stud itself. Put a new nut on it, and torqued the stud down, and changed the oil to check for any debris which ended up being clean.

Started the engine, and it purred, no more knocking and a consistent idle.

so now I have a spare 30 PICT, but at least it wasn't a rod!!

Thanks for your suggestions

Steve

geodon Wolfsburg Wizard

478 posts · joined Aug 2002 · 16 Feb 2009, 3:40 pm

#695540

Steve, I know hindsight is 20-20 but I usually pin down these one pot misfires by increasing the idle speed temporarily then disconnecting or shorting out each spark plug in turn. If you short out a healthy pot, the idle speed drops. I f you short out a crook one, the idle speed doesn't change.
Cheers.