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PostPosted: Fri Jun 16, 2017 4:38 pm 
4 BBL ''Hyper-Pak''

Joined: Mon Mar 10, 2014 9:00 am
Posts: 44
Location: Brisbane, Australia
Car Model:
Hi SL6 Forum,

Thought this might be useful as I haven't found any info on the site regarding this specific issue.

I've had an issue with my 1965 AP6 Valiant slant 6 not starting easily in the morning (or if it has sit idle for half a day). Once it got going it was fine. It did have a pretty pronounced hesitation at times on acceleration from slow speed (~20 km/h) depending on how you used your right foot...

Things started getting out of hand (getting really hard to start) to the point where I 'd have to sort it out.

A check of the usual suspects quickly turned up that I was not getting a pump shot with the motor off. The car had the accelerator pump plunger replaced a year or so ago as part of a general service and brake work being undertaken (by my mechanic as I just didn't have the time) and ever since has not really been "quite right".

I rebuilt the carby around 6 years ago.

So for the last couple weeks, I'd squirt 20-30 mls of fuel down the carby and even on the coldest morning (10 deg C or 50 deg F) it would start first go.

On Thursday, I had a couple hours spare with the car, so I decided to try sort it out. Armed with a service manual and rebuild kit, i pulled the carby off and stripped it down. What I found was that the check balls, pump discharge check ball (small) and pump intake check ball (large) were swapped around. Also the float levels looked a little low by 2-3 mm. The gaskets still looked sound and there were no leaks.

So I just quickly cleaned the stripped carby's individual pieces with carby cleaner and compressed air, reassembled it, swapping the check balls and readjusting the floats and reinstalled the carby. I didn't touch any other settings (idle mixture, etc.).

Result - problem solved! I have a strong accelerator pump shot, the car starts first time, and the hesitation has been significantly reduced. You gotta love a happy ending!

Has anyone else experienced BBD carby issues related to having the check balls the wrong way around. If so are these symptoms that I experienced consistent with that?


Bare Metal Maz

Love cruising in a bare metal Val!

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