Crikey! Dropped Idle

[ruckman101]

So tuned up Bertha Bus yesterday, prepping for our Maupin/Eureka run. Changed oil and such. The timing had crept forward, back to zero, valves good, two slightly tight exhaust, but that was it.

Still getting a slight scrape of drum on brake backing plate, despite new drum, despite washer spacer that Colin customized for it two, threes ago? The castellated nut kept loosening as the washer compressed. Found a thicker one, and thought I would back the back end of the bus into the bay where Gretchen Ghia was, and now some crusty tractor is there on blocks, enough space to get a jack under Bertha, but after backing her in a bit too far and knocking the tractor off of it's blocks, I realized there wasn't really enough room, so pulled out and set up in the gravel, as there were no bays open. Got the tractor back on it's blocks, customized the newer washer, loaded up Bertha and headed to Vancouver to run my daughter in law to the airport.

No worries, but then, after dropping Jen off at the airport, heading back, leave the freeway, and Blammo! Oil light on, generator, too, at idle. Lights go out at higher rpms.

Assessing, it would seem my idle has dropped so friggin' low that the pressure isn't maintained. Nothing overly hot, no puddles, no drips, all the new oil is still there. Parked it, did the shopping, started fine, no light, until it warmed up, then, exceedingly low idle. WTF?


Anyway, too late tonight, in the morn, we will give it some more attention.
sheesh,
neal

[Hippie]

O Mighty King of Bwana, is this a carbureted early bus? I forget.
Cause when the wire fell off my idle shutoff solenoid, it acted like that.

[Amskeptic]

leave the freeway, then, exceedingly low idle. WTF?

VW used "hot idle compensators" on the dual carb buses. This tells us that hot conditions deteriorate the idle.
My 1970 bus has a 30Pict3 carb with a vacuum only distributor timed at 0* static. I have retarded the timing a tad to allow me to crank open the air bypass screw on the carb as much as possible. This keeps my idle speed at a rock solid 1,000 rpm coming off a hot freeway run.
1971 issue dual port engine originally came with a vacuum retard distributor that teamed with a 34Pict3 carburetor with a good sized idle air bypass. Of course, people sometimes decide that they ain't payin' for some stupid dual vacuum unit, and they crank the idle air screw shut to get the idle speed down after the retard unit fails. Then you get stalling after hot freeway runs and hesitation under acceleration.

I have found that keeping your engine factory stock down to the last detail gives you pretty good behavior.
Colin

[ruckman101]

Or a sloppy loose electromagnetic cutoff valve giving me a major vacuum leak? Pretty sure I'm not supposed to be able to snug that up by hand. Was sure backfiring on decel, too.

Bertha Bus is sporting a 1600 sp these days. 30/31 carb. Stock. She was running a tad hot, but not burning up the oil or drastic, which I attributed to our fully loaded set up for camping heavy. Vacuum only distributor at 0 degrees with a timing light at idle.


neal

[Hippie]

Ouch, hot valves!
So it's fixed then? Cool.
I got a vacuum only set up and adjust it to 10º BTDC statically. Colin and me figured that was running right that way somehow a few years ago on a test drive, but I'm not sure it is supposed to be the best or recommended setting.

[hambone]

Richen up the mixture 1/4 turn, see if that helps the hot.

[ruckman101]

Did the quarter richer at Grants Pass. Better idle, still backfired on decel. Left the quarter turn richer, ramped out the bypass even more to get an idle, timing advanced, got back to zero at idle, ramped the bypass out a bit more for a healthy 900 rpm idle. Tomorrow a drive, but encouraged. Don't think anything cooked excessively.



neal

[Hippie]

No, I don't think anything cooked in that amount of time either.