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rustbus Samba Member
Joined: June 18, 2009 Posts: 2078 Location: alberta
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Posted: Sat Apr 23, 2011 8:51 am Post subject: 1 cold intake on dual PDSIT's ? need help |
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guys,
My bus has been freed from the shackles of the shop and out into the sun - did a dual carb tune up on it per Amskeptic, and drove it all around yesterday.
before i took it out i checked the oil level, and its seemed high...i was super frustrated as i'm paranoid about the gas getting through these old carbs and into the crankshaft...
i started it anyhow, then shutdown and waited for awhile. checked the oil again, and it was much lower (had been sitting for weeks prior) so i said "screw it" and took it out, tuned it, (valves are set, plugs gapped, timing @ about 26/27 @ 3200-3400rpm and dwell always on with magnetic points) i have no idea what gas in oil smells like, i know this oil smells different than unused oil, but this oil has about 10 km on it.
after the tune it ran well. booted around town, very little hesitation, etc. but I'm not confident it is running its best... and when i grabbed the intake manifolds under the carbs, the left side was cool and right side hot. so after about 10minutes of cool down i cam back to it with my lazer thermometer, and found the hot side at about 80-90C and the left side at about 50-60C...this shouldn't be?! what causes this?
after all the effort i've put into the bus over this winter, i must figure out these carbs or im gonna freak!
any advice? why is this happening? anything i can check? i'm gonna go out and tinker now... _________________ May of '72 Deluxe. 2.0L L-Jet CS & 091 trans conversion
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Amskeptic Samba Member
Joined: October 18, 2002 Posts: 8568 Location: All Across The Country
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Posted: Sat Apr 23, 2011 2:47 pm Post subject: Re: 1 cold intake on dual PDSIT's ? need help |
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rustbus wrote: |
left side was cool and right side hot.
after all the effort i've put into the bus over this winter, i must figure out these carbs or im gonna freak!
any advice? |
Chill pill.
With engine off, loosen each spark plug wire at the distributor cap.
Start engine. Pull each wire off one at a time, and see which cylinders make the rpm drop *less*.
Check plug color for differentials.
If the weak cylinders are biased to one side of the engine, adjust that side of the engine at the mixture screw for a little more fuel if the plugs were not already sooty. If the hot side of the engine has whitish plugs, you have a vacuum leak nearby like a brake booster elbow causing lean heat.
Check for an intermittant cut-off solenoid (ignition on see if solenoid chatters when you wiggle its wire) or a choke heater failure (carefully touch each choke cover after five minutes of running, they should have equal and noticeable heat).
Colin _________________ www.itinerant-air-cooled.com |
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rustbus Samba Member
Joined: June 18, 2009 Posts: 2078 Location: alberta
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Posted: Sat Apr 23, 2011 2:55 pm Post subject: |
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thanks Colin,
I pulled plugs earlier - not in an organized fashion as you've mentioned, but noticed obviously that the left/colder side made almost no difference in RPM. specifically #4, thats left rear i believe. left front made a touch of difference, but a near stall when pulling the right side plugs.
so i'll go out and test it like you've said. I'll double check for vacuum leaks, but my booster elbow on the left sure seemed fine. Also, I have no chokes, they are completely disabled (and I don't feel i suffer much for lack of them)
thanks! _________________ May of '72 Deluxe. 2.0L L-Jet CS & 091 trans conversion
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rustbus Samba Member
Joined: June 18, 2009 Posts: 2078 Location: alberta
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Posted: Sat Apr 23, 2011 8:49 pm Post subject: |
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ok, heres some info i found today
the cold side is all sooted up ...checked compression while i was there.
when i pulled the plugs at the distributor cap, 3/4 made almost no change, maybe 50rpm. pulling 1/2 brought it down by 200rpm
i checked the solenoids, they click well, and noticed no loose connections on any wires. they are screwed in in tight.
double checked both booster elbows, they look and feel good. found a extra little vacuum nipple on the right side carb, capped that, no real change. i did not double check the manifold bolts but i'm certain they are tight (but will check) UNLESS - i have the booster elbow that has the small nipple to the air horn - could that be faulty and leaking O2 in?
not sure what to do? cant make the left side any more rich right? i just rebuilt these carbs and paid extra special close attention to detail. could a loose part be causing this? like a main jet loose or anything?
stumped? any help appreciated... maybe i need to run the tuneup procedure again? i set my throttle plates back when i rebuilt them, so i didnt second guess them this time... i figured i set them best in my hands when they were all clean...
also noticed that the right carb mixture screws spins kinds easy....maybe too easy? or not related...
anyhow! tomorrows another day. _________________ May of '72 Deluxe. 2.0L L-Jet CS & 091 trans conversion
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