34 pict 3 POS help!

[joshbuchan]

Just about ready to launch this little carb! built a manx with a 1776 and cant get the thing to run right........I have lots of experience with dual IDA and IDF's but nothing with stock singles
motor has stock cam and DP heads everything is fresh, DVDA dist. with points, dwell set to 48, timing at 5 deg BTDC and around 30 at 3000 rpm.
I have done hours of reading on the 34pict and have had no luck yet.....

thing is running stupidly rich and wont idle....when I look down the throat of carb fuel is drooling out of the cast tube in the middle of bore (I believe this is the main circuit.....comes up from main jet and though air corrector into tube)
has a stock idle and air corrector and I reamed the main out to a 135.
the only thing I haven't checked is the fuel pressure as I don't have a tee but I would think if it was high the float level would be high which it doesnt seem to be?

Any stock carb gurus have any insight on this for me? have had carb off way too many times to count and it's getting a little old

cheers Josh

[aryue]

Your dealing with either a bad float valve, which screws into the top half of the carburetor - or - the float itself needs replacing.

Last but not least - measure your fuel pressure from the pump. It's supposed to be 2 PSI.

- Andrew in Austin, TX -
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[joshbuchan]

Thanks for the reply Andrew! Didn't mention I just rebuilt the carb and kit had replacement inlet valve with new .020" copper gasket under it. Carb body was run through an ultrasonic cleaner and all blown out and throttle shaft seems pretty snug.....

If float or needle valve were pooched wouldn't the bowl be overfilled? When I remove top while carb still on motor level is about 9-10mm from gasket surface (didn't actually measure it and it has been a hot day here and sitting all day bowl has half evaporated)

[baked beetle]

make sure the discharge tube isn't ready to fall out and get eaten by your engine. It's probably leaking cause it's loose.
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[joshbuchan]

[uglyduck]

What is your compression ratio? Too high and could possibly be sucking fuel from the venturi @ Idle.

[clonebug]

It's got to be a float problem.

I think spec is 11 mm down from carb top if I remember correctly.

the rebuild kit should have two different thickness washers...try the thicker one, it should be around .032 in thick.
That might take care of it. It is a cheap test otherwise.

I would guess your float valve isn't holding and you need a better quality one.

That is also a cheap test to see if it is. You should verify your fuel pressure first though.
I run 3.5-4.0 lbs of pressure on my turbo buggy and I have no trouble with fuel pressure.
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[joshbuchan]

Compression ended up just below 8:1 so not outragous are these solexes that sensitive?

I'll pick up a tee tomorrow and check pressure

[Alstrup]

Float height is too high. i bet you used the thin copper washer that was in the rebuild kit. - That was not a good choice. But how could you know if you´ve never worked with these. The washer needs to be 1,3 - 1,5 mm thick. By then you will most liely need at least a larger main jet, and possibly a ,57-,60 idle.

Ignition is not right. With a DVDA dizzy the timing at idle should be 5 degrees AFTER TDC with both hoses on. Max advance with hoses on, about 38-40 degrees. Max advance w. hoses off 29-30 degrees.

T

[Greezy Joe]

Too high of an idle stop screw adjustment can cause this problem. Idle stop adjustment should be about the same as doing idle on Webers or any other carb, back out until the screw doesn't touch and screw it in until it touches and screw it in a 1/2 to 1 turn and start adjusting things from there.
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[joshbuchan]

Update..... Fuel pressure is 2.8 psi checked with a $10,000 calibrator

Changed copper washer under needle valve to thicker one, re-set fast idle arm to touch and then half turn in and got it running.
Starts nice and got the small screw to react now but I think the right side of the throttle shaft Has a little vac leak.....fiber bushing has a bit of play, not much but it wiggles. Spray it with carb cleaner and wants to die.
One other thing I checked was the dual vac can on distributor.... Retard side holds a vac but advance doesnt?
Lastly trying to adjust the acc squirter and having a hard time getting it to hit the edge of the butterfly. Is it the rear side you aim it at? I can hit it when car isn't running but when it's running as soon as the stream of gas leaves the nozzle it gets sucked into the center of Venturi..... What am I doing wrong?

[aryue]

Ah, the joys of a worn carburetor bushing and a leaky vacuum advance diaphragm.

[Alstrup]

The idea with the spray giong to the edge of the butterfly is correct according to the maintenance books. BUT, it is actually better to aim it at the aux supply , so that the squirt hits the edge of the aux supply. It will then create a range that gets mixed better into the air, hence better atomisation and less risk of stumble due to the fuel going back to droplets.

T

[joshbuchan]

sooooo lots of fidling and it's better but not great

made some brass bushings and then for extra insurance also o-ringed the throttle shaft. opened up a 26mm venturi up to 28mm and re jetted to 140 main and a 60 idle.

couldn't find a replacement vac can so I threw in a german 009 for now

starts and idles great, better power but seems to "load up" whenever I am either cruizing and put my foot back in it, try and lug it off the line or come to a stop and don't blip the throttle before taking off first............ any ideas? is this the dreaded off idle hesitation that you read so much about with the ol 009? to me it feels like there is an excess of fuel hanging out waiting for the throttle to be cracked and it clears once reved up??? Acc pump squirter is set as reccomended above and adjustment is halfway between middle and + side, so 3/4 of a maximum shot. Was going to try and back off on this a bit??

one thing I did when I had the carb apart was put the butterfly out of a parts 34pict meant to run on a SVDA (has a smaller bypass air hole than DVDA model) in antisipation of running the 009..........read loads on this where guys put a rivet in the bigger hole and push out the center pin..... suppose to help with the 009 stumble?

[Alstrup]

Idle jet is most likely too large. Go ,55 - maybe ,57

Did you make the acc pump squirt direction as I wrote previusly ? If so, there should not be the need of more than average pump amount.

Main jet may still be too small. Try the 0,55 idle and 145 main solution and see where that gets you.
T

[joshbuchan]

Yes pump squirts as suggested, I'll try and dial that back first then source some more jets

[joshbuchan]

What is the small jet beside the idle jet? The one that is behind a little brass plug

[aryue]

[aryue]

[joshbuchan]

Cam is stock 1600

Elevation is between 0-200 ft.......I live on an island

SVDA Would be ideal i know but......This is a major budget build, thing is for sale to fund my 55 rag so trying not to spend anouther $150