SPITTING CARB - 914-6 all stock, Need assistance - please see latest post to this thread Options

[ctc911ctc]

1970 - 914-6 All stock

Got the car off the rack after a 1 year clean up documented here:

http://www.914world.com/bbs2/index.php?sho...3371&st=100

- tightened the lugs, check one more time for leaks.......

Car started first try, backed out of the driveway and went around the block

Drive strong.....very strong......

#2 cyl-carb is still 'spitting' definitely not backfiring. Chasing this through my trusty guide:

https://www.performanceoriented.com/special-procedures-1

See "notes" section

Seems that when I performed the Lean Best Idle procedure #2 failed during the procedure......the diagnosis within the document states that either the path in that carb #2 is blocked or the jet is the wrong size - my bet is a clog......though the carbs were very clean when I got the car.

There is a little noise from the right side, that in a 914-2L 4Cyl would be considered quiet, my hope is that it is not valve noise and may be exhaust leaking......did I tighten the heater manifold small nuts????? dry.gif

Carb advice sought from those that have chased a SPITTING Carb

[Ninja]

Not hard to flush the circuits but if the critter will idle after warm-up you shouldn't have plugged circuits.

If the idle circuits have any spots that could leak air into the circuit you might have too much "air correction" until the carbs heat up enough to close/minimize the leak.

So, all of those plugs referred to in the previous post might be a problem.

It might be possible to blow air into circuits while spraying plugs with soapy water to check for leakage.

I use an ultrasonic detector a bunch, but I don't think it would work very well on a running 6 as they are noisy.

Some carbs have an O-ring on the idle jet carrier, and I've seen many of those screw up and cause problems. However, the problems do not magically go away when warm.

Another thought is the base idle settings are on the lean end of things when warm and it just won't provide enough fuel for cold operation.

This might be exaggerated by stock carbs with stock jets running a physically larger engine or higher performance parameters.

If you cannot diagnose it, I might try 1 or 2 steps larger idle jets.

[ctc911ctc]

Great notes Ninja, comments added within

Not hard to flush the circuits but if the critter will idle after warm-up you shouldn't have plugged circuits.


Got it - makes sense

If the idle circuits have any spots that could leak air into the circuit you might have too much "air correction" until the carbs heat up enough to close/minimize the leak.

So, all of those plugs referred to in the previous post might be a problem.


Understood


It might be possible to blow air into circuits while spraying plugs with soapy water to check for leakage.


Interesting - I did perform a smoke test - nothing leaked out of the control parts of the carbs nor from the manifold.



I use an ultrasonic detector a bunch, but I don't think it would work very well on a running 6 as they are noisy.


Out of my league - interesting!


Some carbs have an O-ring on the idle jet carrier, and I've seen many of those screw up and cause problems. However, the problems do not magically go away when warm.

Another thought is the base idle settings are on the lean end of things when warm and it just won't provide enough fuel for cold operation.


Larger idle jets?


This might be exaggerated by stock carbs with stock jets running a physically larger engine or higher performance parameters.

If you cannot diagnose it, I might try 1 or 2 steps larger idle jets.

THANK YOU NINJA!