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Poorer cold performance

(I am using "cold" in a very relative sense -- think 70F/20C)

A few weeks ago I had the Wonderbus running really well, with its newish dual Kadrons and new SVDA dizzie. A touch on the pedal and it scooted along right well. Even cold, it idled well and didn't require much, if any, feathering of the throttle to get rolling. It has no chokes.

But all that has changed and I am scratching my tiny brain trying to figure out what might want looking after.

I pulled the engine three weeks ago to correct some undertorqued head bolts (a lack of understanding about the use of anti-seize compound). The cheap-o carb linkage got tweaked in the process. I re-installed the engine, sync'd the carbs, adjusted the linkage accordingly, checked the timing and advance and everything seems to be copacetic.

However, when the engine is "cold" (see above definition), it runs poorly. The idle is rough and I have to keep feathering the pedal to keep it from dying. It seems to have little power: a LOT of feathering is needed to get the bus rolling away. This eases after a minute or so.

But here's my favorite: roll up to a stop sign, feets on clutch and brake. Stop. Shift into first, press on gas a bit to bring rpms up a smidge -- not heavily, and no engaging of clutch yet . . . and the engine dies. Tach drops from 1000 rpm to zero like a paralyzed falcon. I didn't even bring the clutch out enough to start to engage.

Quite unnerving, really, to roll through a left turn with foot on clutch, downshift to 2nd gear, start to release the clutch and press on the gas to match the engine to the trans and have the engine want to die. (I've driven manuals for 37 years and know what I'm doing.)

But not always -- it's unpredictable whether pressing on the pedal will cause the engine to die or speed up. Probably 20/80, if I had to make a guess. And maybe it only happens when I am pointed downhill. Maybe, no sure.

Once the engine is warm, 10 minutes or so, then the rpms go where I expect them to and the engine does not hesitate or want to die.

Reply to
Mike Rocket J. Squirrel Elliot
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The kadrons are quite "primitive" with little or no cold enrichment(choke function), the transition circuits are not the best either... It will be hard/impossible to find a jetting that works for both ends of the temperature scale.

Has humidity/temp changed since your first experience with the carbs?

J.

Reply to
P.J.Berg

Hah. This is Southern California, where we have the "Lite Jazz" of weather. No, very little change of climate.

Reply to
Mike Rocket J. Squirrel Elliot

IMHO, that's the nature of the beast in cold weather. My 1776 with dual Kadrons behaves the same way and it's in top shape.

Reply to
jjs

"Mike Rocket J. Squirrel Elliott" wrote

You just said the word "cold". What does cold mean in Southern California? I'm speaking of 47 degrees F as cold. Anything much colder and I just don't drive the Kadron car.

Reply to
jjs

First line of my original post: "(I am using "cold" in a very relative sense -- think 70F/20C)"

Reply to
Mike Rocket J. Squirrel Elliot

But the point is that prior to my last engine pull, they worked peachy when "cold" (65F) and now the engine is piggish when "cold."

Reply to
Mike Rocket J. Squirrel Elliot

It hates you.

Reply to
jjs

LOL! Finally an explanation that makes sense.

Reply to
Mike Rocket J. Squirrel Elliot

you might have had the idle mixture a bit richer before....

Reply to
Eduardo Kaftanski

wrote:

Possibility! Maybe one of the mixture screws got tweaked when the carb was removed for engine removal/moval.

Reply to
Mike Rocket J. Squirrel Elliot

wrote:

My 1776 with dual

worked peachy

"cold."

before....

when the carb

Reply to
Busahaulic

I've heard rumors of spraying various highly-flammable aerosols and liquids on or around the carbs and various bits that they connect to.

Sounds mad. I'll post the question.

Reply to
Mike Rocket J. Squirrel Elliot

"Paint" all connections with fuel and a small brush, gives you the same effect but under more controlled circumstanses. It is also the method listed in the workshop manual for my Benz...

J.

Reply to
P.J.Berg

Last saturday I drove 80 miles to where my brother lived to tow back his yellow bug (my ex bug) and ended up driving it back...

Most of the problem ended up being a vacumm leak on the right side of the engine. How I discovered it? I realized that side had both cilinders weak and was pulling the spark plugs with the engine running to see if I could make one fire when I saw a speck of dust getting sucked into the engine :)

Reply to
Eduardo Kaftanski

How did you know that the side had both cylinders weak?

You saw a speck of dust getting sucked into the engine -- into the open spark plug hole?

Reply to
Mike Rocket J. Squirrel Elliot

engine was running very poorly and that side was colder...

into the intake manifold to cilinder head joint....

Reply to
Eduardo Kaftanski

On the subject of vacuum leaks. In my case, I dismounted both intake manifolds in order to pull the breastplates and access the upper head bolts. Before re-mounting the manifolds I coated the mounting surfaces liberally with Chap-Stik (a waxy lip balm sold in the U.S. -- this a suggestion from John at Aircooled.net. He recommended lemon flavor for junker cars, and I suppose that cherry could be used for trailer queens) as a gasket-sealing compound.

The left manifold I mounted back on the engine prior to installing it. But the right needed to be installed after the 2 o' clock engine-transmission nut was affixed. There is not a lot of room for re-mounting a manifold in the bus and I had to do it without being able to see the mounting surface on top of the head. So there might have been some mess-up there, though other than a twig lying across the mounting surface I can't quite imagine what could prevent a good seal.

But since the carbs were never removed from the manifolds nor disassembled, this is the only connection that might have a leak that I can think of. The gaskets on top of the heads are a rubbery compound. I might just first tighten the bolts a bit more and see if that makes a difference.

Thanks for the suggestions, folks.

Reply to
Mike Rocket J. Squirrel Elliot

wrote:

Makes sense.

Thanks.

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Reply to
Mike Rocket J. Squirrel Elliot

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