Tuning the 009 Distributor/34 PICT Carburetor Combination
This problem is discussed in depth in the Hesitation article on our main Web page.
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Someone wrote -
I am having all sorts of problems with the 34 PICT/3 carburetor on my 1600 twin-port engine (new manifold boots and gaskets, new plugs and leads, 009 centrifugal advance distributor). I have read lots on the common flat spot problem and have tried the adjustments, but I still have the flat spot.
I have opened up carburetor and checked the float, needle valve and seat -- all okay. I also cleaned and blew out all visible rubbish. The motor seems to idle okay, but it spits and coughs when accelerating.
If I up the size of the main jet and idle jet by one size or two will this help?
Rob responded -
Carburetor troubles can be related to all sorts of things -- fouled plugs, bad plugs, bad or weak coils, blocked fuel filters, etc., etc.
A significant source of "flat spot" trouble stems from the combination of the 34 PICT/3 carburetor and the 009 centrifugal advance distributor. We discuss this problem in depth in our article on Hesitation. Also in that article is reference to John Connolly's (Aircooled.Net) excellent article on Choosing the Right Distributor. John recommends the single-vacuum dual-advance (SVDA) distributor for use with the 34 PICT/3 carburetor.
Someone from the RAMVA Newsgroup suggested -
Take off the accelerator pump cover and check the diaphragm -- it may be torn or old and stiff. I bet there is heaps of crud in there too. Clean it out, replace the diaphragm, and see how that goes.
Someone else suggested -
The answer to your problem is simple. If you don’t care about fuel consumption too much, run a 1/16th drill bit through the main jet. Try it as it works, and easy to get another jet if you don’t like the fuel consumption. And as for your 009, if you see a 050 for sale BUY it.
Rob responded to the jet drilling suggestion -
I hope that "1/16th drill" wasn't serious???
That's 158.75 in Solex jet size equivalent!!! The normal jet size for a 34PICT/3 with vacuum distributor is 127.5 and with a 009 is 130 or 132.5. With a 158.75 you'd have about 24% increase in fuel consumption!
The guy responded (paraphrased) -
Yes, my suggestion to drill the main jet with a 1/16" drill was serious. As I said, if you don’t care for the fuel consumption you will find that it works. Try it -- its only a jet.
Rob responded -
I wonder if you realise just how BIG 1/16th is (hence the Solex size equivalent I noted.) If drilled to 1/16th" the jet will supply so much excess fuel that you'll have...
About 24% increase in fuel consumption -- worse than the average Holden V8.
Serious plug fouling.
Serious wash-down of the oil film on the cylinder walls, resulting in massively increased wear.
Oil dilution and contamination (see 3. above re increased wear).
Disclaimer stuff: Rob and Dave have prepared this information from their own experiences. We have not assumed any specialised mechanical knowledge, but we DO assume that anyone using this information has at least some basic mechanical ability.
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