pict 34 3 and other vw questions in one thread

[the13bats]

Warning im ADD OCD and have nervious issues this will be long winded.

I will assume there are at least a few cats here tech savvy on the pict 34 3 and vw engines,

Ive been a gear head close to 40 years wrenching on all kinds of junk including other trikes and vw vehicles but this time im not finding the solution,

One problem is it doesnt always do it,

Basics 1600 dual port pict 34 3 vac dizzy,

To the best of my testing no vac leaks and valves are set.

The carb is adjusted as per rob and daves online papers which with the exception of fast idle adjustments most agree on turning the pict 34 3.

Its not epic.

But here is my issue, take off run thru the gears, it doesnt like 4th before 40mph then up to 45 to 50 now get off it, downshift to 3th and about 8 out of 10 times it bucks and stumbles wants to die takes careful finesse of throttle to keep it going then smooths out runs great, within a minute,

Did it go lean or rich?

Another symptom, running about 35 to 40 in 3rd floor it, sometimes it takes off smooth and hard, well as hard as a 1600 takes off other times it has a stumbling flat spot that then after it clears it doesnt do it again during that outing

Has anyone has had these type issues.

Now related unrelated,

Pict 34 3 adjustments,

For the accelerator squirter, how do we know if it needs more or less?

Since a trike is lighter could it might be happier with less squirt?

Any great way to know the squirter is set correctly?

I have seen at least 4 different ways to set the so called fast idle screw on the choke stepped cam,

Most want a little more that the screw just touching the cam .25 turn past just touching,

That really drives my OCD nuts anyone got a more exacting way of setting it?

Just how critical or forgiving is it?

Many thanks

cheers

b

 

[DeathBySnuSnu]

Well......I know very little about stock parts. I can throw out there a few very general thought, but not very specific and lots of it is second hand info.

Vacuum leaks. Intakes, joint boots, carb base, rotted out intake manifold at heat riser port. Loose butterfly shaft in the carb base.

Diaphragm on the distributor, advancing, sticking, worn out bushings, vac hose plugged to correct carb port.

But...it sounds more like you are choking on fuel.

Carb, float, needle and seat.

I hear of this more and more......fuel pump. I see others with crazy pressure issues. The stock type replacement pumps just are not right. The flex of the diaphragm and/or the tension of the spring is not right over pressuring the carb. You only need 2 to 3 lbs at the max or it will be running over inside.

 

[the13bats]

Like i tried to point out the silly stuff i have eliminated, but i felt like this IS an issue i know just slipping my mind posted here to butt kick it into gear now the fuel pressure theory, i need to look at that,

A side note on stock vw and solex especially pict 34 3 and other models with bypass and mixture screws,

Any vaccum leak even small will make it basically impossible to adjust, the bypass screw will do little to nothing and the mixture screw will do nothing but perhaps kill the engine if screwed too far.

Both these screws have an initial setting of 2.5 turns out from soft bottom out, screw them in too hard something can get ruined.

When adjusting them keep in mind 2-3 total turns on either is all it should take to find that sweet spot,

You really can hear that slight drop turning the mixture screw in, most times sweet spot is with .25 a turn from that 2.5 initial setting.

Many times when a person cant get the responses they desire or the bypass screw just wont set a nice idle they make the mistake of turning the fast idle screw, this is a nono on pict 34 3 and any pict with both mixture and bypass adjustments.

To set the fast idle screw it should just drag or touch the very bottom of the stepped choke cam then .25 in,

I have seen cases that needed perhaps a hair more than .25 but i do mean a hair.

It drives my OCD nuts.

At first one might say well if fuel pressure is too high there would be issues at idle, maybe but just arm chair diagnostics, if im going 45 50 mph in 4th then i am thinking the float is down and allowing steady flow from pump,

When i abruptly slow down there could be a surge so to speak and the carb gets overfilled for a moment,

Im thinking if the float is down needle open then its easy for the fuel pressure to keep the needle open a few moments but it doesnt at idle because the pressure isnt really great enough to push the needle open but rather just flow too much when it is open,

Havent felt goid enough yet to go do some simple tests for this theory but i do know 2.5 to 3 lbs is all a solex can stand, thats fairly low and 4 to 5lbs might be enough to cause this and even in this odd intermittent way.

Looking forward to checking it out.

Will update

 

[grandpanystrom61]

wow, not my carb set up, but when I read about this happeing on my set up, well it was more about not getting enough air at the time, to much fuel to air ratio. For me to correct the issue I need to up grade air flow in the carb. Of course I live at 4500 feet altitude and most are set factory for much lower elevation.. Wish I could help other than this.

samba is the VW place, many know alot about stock carb.'s and their issues. I learned alot about the VW from just reading the threads and what others had to say.

Hope you resolve this issue you are having.

oh and I did over adjust the carb.'s to compensate for excessive fuel pressure, once corrected the pressure issue, well I had to reset the carb.'s again, but it does run nice now.

 

[the13bats]

I used to like thesamba but like with many forums it offers little to me now, too many overbearing cats who think they know it all and dont know enough.

Its no help and i cant learn if a walking pile of fertilizer wants to force on me my problem is something already ruled out.

I did post a version of this there and my favorite reply was a guy saying my carb is too big for a light weight trike, whew, you can lead a horse to knowledge but cant make him think, guess he would really balk that my last trike ran dual 48 webers.

C'est la vie.

In the case of the pict 34 3 im running there is no way to turn it for too much fuel pressure just add a regulator and since about 3lbs is a nice place for a solex on a stock rig i look into one of those low pressure 1-6 lbs that mr gasket and others sell with the dial you turn but like with many things guys on hamb report they are dangerous junk they will spray fuel all over,

So the low pressure holley is my answer but i have to mail order it not one store here carries them,

Holley was having a great sale with free shipping,

I would bet a big gulp fuel pressure is hurting me, but to prove it i need to install that regulator, waiting on snail mail,

Until then ill just putz with other stuff.

 

[rodekyll]

I have a difficult time following you. If you are still using the solex, the "squirter" is properly adjusted when the squirt hits the gap between the bore and the just-opening butterfly. It should give a solid stream immediately as the throttle opens and no drips before or after. The nozzle can be gently twisted and bent to aim it. Also, iirc, there is a check ball in the circuit, under the nozzle on the 34. It's a common mistake to leave it out.

You're bound to get better and answers if you don't call the people trying to help you "walking piles of fertilizer" for suggesting that you overlooked something. Who would volunteer to step into that? If you did properly cover all the bases you wouldn't be having the problem. So if anyone is shoveling fertilizer, it's not them.

Just my opinion.

 

[the13bats]

You managed to twist what i said all around,

 

[Gorilla]

time to get back to the issues

 

[DeathBySnuSnu]

Just a thought. I saw (internet) where someone made up an orifice bypass to bleed off some pressure back to the suction side. Then claimed it also stopped residual line pressure and percolating carb. Cleaner starts and less gas smell with still enough line pressure for stock carb.

No real experience myself. But it was an interesting read. Sorta made sense.

 

[the13bats]

I hope everyone had great holidays and a great new year,

Sorry for my update delay but the holidays and other things pushed trike on back burner.

The quick answer is the regulator was the fix,

I ran the holley low pressure reg rather than that dial type as too much bad feedback of the dial type leaking or rather pouring fuel.

My speculations were confirmed both by my testing and talking to a few old timer acvw gurus,

I assumed my problem started with the electric fuel pump but i was informed that the stock mech fuel pump can and do have too much pressure and it seems the newer ones are really bad,

Their fix were spacer shims some people just stacked gaskets or the real techie gear heads machine down the push rod.

The trike is a new creature now, i want to fine tune again on a day in the 80s but i was just amazed at the difference just the regulator made, really purrs.

The trike up and running means i soon as i hook up sink and tub in upstairs br i can get my car running which i do look forward to.

Have a great year year,

Cheerz

b

 

[DeathBySnuSnu]

Good news then.

And a happy holidays to you also.

Things are also slow with me and any personal projects......just not into anything right now.

I do not like the idea of shimming the pump or shortening the rod. I would think either would also reduce output volume....and I dont think that would be good to do. But then I have zero actual experience with that situation.

I do think a decent regulator is the correct way to go. Maybe one day you will have to go flat out up a massive long uphill mountain pass kicking the rpm up there in third gear sucking up the fuel.

 

[the13bats]

I am very ADD OCD and have nervious issues like ptsd,

I have a lot of hobby interest and after about sept between hoildays and shows ( i was in nightclub music, biz and still do guest shows ) i get swamped exhausted, but now after all that is behind me i get to putz with projects.

In my other car hobby ( c3 corvettes ) there is an odd mindset with some if its posted on that one forum doesnt matter who posted it or why it still must be gospel,

That doesnt float for me and my OCD no matter what im messing with i do research from many sources i come to my own conclusions and theories based on what i then believe.

I like many acvw owners are running an electric fuel pump, so the only reason i mentioned mech pumps was because the problem exists for both camps,

I hear you, the excessive fuel pressure fix for acvws of adding gaskets or cutting pushrods sounded down right hack job to me normally ( im my gearhead world ) stock mech fuel pumps are self regulating.

So sure saying add gaskets or shorten the pushrod to lower pressure sounds odd at the very least,

To add to that i even read that when installing a stock mech pump if the push rod measures too short mill off a little from the base of the pump.

There are at least two stock fuel pumps, short for alternator engines long for generator engines and it would appear variants to them so some would like to blame too much fuel pressure 100% on mixed up pushrods,

Not so fast, when we toss aftermarket into the mix, both pumps or rebuild kits, i see some getting pressure reading way high over 20psi in some cases, and no, gasket or pushrod mods wont fix that,

The problem there is the aftermarket springs have too much tention, clever guys go back and try their orginal springs and all is well.

The ones fixing the pressure problem adding gaskets or modding the pushrods are getting to the desired 2.8psi by adding say one ir two gaskets or cutting one mm from rod, this is not going to be a fix for a stock aftermarket pump with way too high spring tention, but rather how vw fine tuned it.

http://1967beetle.com/fuel-pressure/

Thats a link to a guy who words it far better than i can.

For me its moot, i seldom run mech fuel pumps this was a case where i was not seeing the forrest for the trees, i have a pump that puts out 7 to 10 psi to a carb that gets upset at anything over about 3.5psi

i can see this being a real pita for a guy who replaces his old mech pump with a new mech pump and now his vehicle wont run or run correctly.

Not too many great hills in florida but i can assure you that 2.8psi will never starve my stock 50hp vw engine

Now my punched out 454 with silly cam, yeah, its rather thirsty.

Sorry that is such a long post i was in a hurry and couldnt make it any shorter.

 

[LarryA]

could this be as simple as... carb kit maker just increases needle/seat inlet diameter/area, without giving the float more area to counteract increased forces on the needle? Maybe aftermarket floats are undersized or made of less bouyant material. just a thought...

 

[the13bats]

Larry,

Since its a fact in my mind aftermarket stock replacement mech fuel pumps and rebuild kits do sometimes have too much spring tention and too high of pressure aftermarket carb kits might be junk ( imho ) too, i wouldnt be shocked the acvw aftermarket is overflowing with garbage.

I will only run real solex carbs and parts, no bocar or empi clones, they lack quality control, very hit or miss, one guy might love his empi the next 5 never could make them idle correctly.

Be all that as it may, the german manual says "about" 2.8psi is right, so too much pressure has to be corrected.

 

[DeathBySnuSnu]

I would think a lot of it has to do with the physical size of the float.

Small float is small seating pressure.

Large float being able to put more pressure on the seat and close off more psi.

Well.....all that said.....I run 47psi......and nothing remotely stock.

So bottom line is you gotta check these details and do the research on the equipment you want to use.