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Go Art go!!!

We are heading north today for a bar-b-que and are dressing for the rain, snorkles and all. I think it is supposed to get better. Still watching your progress.

Lee

Update,

Mileage, 60608
Idle jet confirmed 55
Main jet Confirmed 180
Emulsion tube, 60z lowest 2 holes soldered shut.
power jet 0.65 mm
float .032 washer
No choke plate
Boost 10.738 lbs.

Well, I haven't done an update since I received an order of new emulsion tubes and an adjustable main jet that was made by Bugpack for the Formula Vee cars according to the instructions that came with them.

I checked out the adjustable main jet which came in the original packaging...



....and after hunting for a correct sized o-ring at the local True Value store I got it installed. The funny thing about this adjustable main jet is that it would not work on a Solex 34 pict but it worked fine on the Bocar 34 due to the different way that the main jet sits in the bottoms of each individual carb.

Here is the Jet installed in the Bocar.





I was soooo excited to get what I had thought was the jet to end all jets that I never bothered to check it's size. I installed it and set it to 2 full turns out thinking it would get me close enough to run. I also grabbed the 60z emulsion tube and promptly soldered the two bottom holes shut and stuck it in. I also pulled the power jet and drilled it from a 0.50 mm to 0.65 mm figuring that would get me the rich upper end I needed so bad.

Got it fired up and warmed up and took her out to go fast!!!
Well, As soon as i took off on the main road I saw it go full lean and thought WTH!!!! hmmmmm the main needs to turn out a bit. I pulled off the road and since it was dark I had to hold the flash light and try to get my fingers in there....Oh yeah... and a wrench .... and try to loosen the lock nut and then turn the jet out another two turns.
Here is a pic that doesn't show the difficulty real well but you get the idea. The idle cut-off solenoid really makes it tough to get in there.



I kept getting interrupted by good neighbors and strangers asking if everything was o.k. since I had all the lights off when the key is off and I was working in the dark.

I tried it again and it was still lean!!!! Stopped the buggy, got out and gave it two more turns which put it at a full six turn out now. Tried it once more and it was still lean.

I headed back home and pulled the 50 idle and tried the 55 idle to see if that made a difference. It helped a bit but it was still lean like the main jet was too small. I couldn't even rev it high enough to see if the power jet came in at 4000 rpm and helped the top end.

Time to go back and think about it. The adjustable main seemed to drip fuel a bit so I didn't want to leave it in there. I pulled the carb and put in the 170 main jet with the 60z air jet and went and tried that.
Pig rich 9.5 to 1 at 2500 rpm to high cruise. It would lean out to 14.5 to 15 to 1 at over half throttle with load in third gear. Full throttle would go full lean at 17 to one at anything over a few lbs. of boost.

Obviously my thinking was going in the wrong direction. Everything I do will not richen up the high load high boost areas. The emulsion tube just makes the mid range pig rich so that is not going to help.
I got the best mid range and high boost with the 170 main and the 75z air jet/emulsion tube.

I decided to leave the 170 in and the 60z in and drive it to work for a few days.
The weather has been getting considerably cooler in the last few weeks so the drive to work in the early mornings have been quite brisk due to the temps being in the low 40's and the last couple days down to freezing. Needless to say I am wide awake by the time I get the 11 miles to work. This is with a light pair of gloves on and my normal work attire which consists of a t-shirt, light flannel shirt, carhartt jeans (sometimes insulated) and my high visibility vest. Since I have a lot of hair I don't ever wear a hat.(makes my head itch )

The last few days have been raining so I had some time to think everything over and come up wit ha new plan.

I pulled the 170 main out and decided just for the heck of it to check it and a few other jets I have with my new set of wire gauge drills. It turns out that my 170 main was not a 170 main after all ... it was marked 170 ... but the drill showed it to be a 180.
Before a week or so ago I had no way of checking the sizes so I guess I can't be too hard on myself. I also check the adjustable main and what do you know!!!!!! ..the max size the hole was ended up being a 165 main.
No wonder it was running lean at 6 turns out. I also checked the needle and when it is six turns out it is completely past the inlet holes and is just another 165 main jet.

So, I have a couple thing to try after this frustration.

I need to figure out how to get the upper end richer without making the mid range pig rich. I think what I should try next is a bigger main like a 190 or a 195 and then put a bigger air jet in it. That would lean out the rich main at mid range which is where the emulsion tube comes on and if I solder the lower holes shut it should go full rich at full throttle.

It is worth a try.

I have dropped my boost down to 10.5 lbs. to try to get enough fuel at top end but that seemed to make little difference at this time.

I have the carb off and I am going to install a 195 main and a 125z air/emulsion tube with the lower two holes soldered shut and see what happens. I am also going to reinstall my carb top with the choke plate since it needs more fuel when it is this cold out. That should ease my warm up times a bit.

If the weather holds for tomorrow I should be able to test it after work.
I have managed to catch my wife's cold now and feel a bit under the weather, if it doesn't improve I will have to wait a day or two.

Stay tuned

Clonebug

Update,

Mileage, 60625
Idle jet confirmed 55
Main jet Confirmed 190
Emulsion tube, 125z lowest 2 holes soldered shut.
power jet 0.65 mm
float .032 washer
No choke plate
Boost 10.738 lbs.


Did a main jet change and an air jet change to test my theory. Put in the 125z air corrector to lean out the 190 main that I had. Soldered the two bottom holes shut.
My theory was correct. The big air corrector made the 190 main almost perfect in mid range cruise at 13.5 to 15 to 1 but as soon as I go full throttle in third it went full lean at 18 to 1. Grrrr.
I went right back to the garage and pulled the carb again.

This time I took a spare 75z and drilled it to 95z. Soldered the two lower holes shut and tried it again. Put the choke plate back in to see if it wanted fuel at cold startup.
It does not need all that fuel with the choke on since it blubbers and farts at 9.5 to 1 or richer.
Took it out for a test after warmup and it is still lean at full throttle. I can only accelerate at very light throttle. Any push past 1/3 to 1/2 and it falls on its face. Can only get to 3 lbs boost before max lean.
It is the worst leanness I have had. It will not even pull at half throttle like it used to. Vacuum is down to 5 inches at cruise. This is definitely not the jetting it wants.
Back to the drawing board.

So far... my best running is the 180 that I thought was a 170 main and the 75z air correction with 2 holes soldered shut. That is the richest I can get it at full load in third at 14.5 to 1.

I am going to drill the power jet to an unbelievable size to see if I can watch it come in on the O2 sensor when I go to full throttle high rpm.

I am running out of ideas.........

Clonebug

Maybe you could try some kind of "modulator ring" or ristrictor above the venturi like we run with dual Dells or Webers to try and bumb up the amount of air pressure acting on the float bowl? It's a big part of what it takes to keep the AFR increasingly rich as flow and boost pressure increases (more important with higher boost levels usually, from what I understand of it). IIRC the bowl vents right into the center of the venturi on the 34pict, so a mod ring might not be the way to go...unless you can make one below the level of the vent or extend it up above the mod ring somehow.

I've seen where, instead of mod rings, the float bowl vent can be tapped and plumbed to a higher source of boost pressure. Mod rings just restrict the amount of potential air flowing down the vent(s), so not very helpful for max output, etc. Your problem with this kind of mod is finding a source of higher boost pressure. If you were running a charge cooler, you could plumb both your fuel pump boost signal and your float bowl vent to a fitting before the cooler, so the bowls "see" more pressure than the venturi and the fuel can still keep up with it. If you had a larger plenum above the carb you could hard-line your float bowl vent up into the boost pipe leading into the carb top and potentially feed the bowl with a slightly higher pressure than the venturi gets, but your pressure ducting doesn't really have a large expansion chamber above the carb like duals have, so that might not be effective either.

Either way, I'd get your jetting back to where it worked best for you and then try modifying the bowl vent pressure signal to richen it up under boost.

Update,

Mileage, 60657

Karl's comment above made me do a little thinking since the weather has been quite crappy for buggy driving.
I looked at the carb and there was no way to add a modulator ring above the vent or main jet nozzle so I decided I would try a modification that I read about on Flat4ever in France.

Basically he made an auxiliary venturi out of a piece of copper tubing and it seemed that it would be an easy enough mod for me to try.

I had a couple of spare junk Pict 34 carbs laying around that was given to me by Bashr. One was in fairly decent shape but did have some screws missing and a few other parts missing but all in all was good enough for a test carb to see if the French Mod was worthy of trying.

Here is the web page I used. I did not think of this mod but I am not above trying someones ideas.

http://www.flat4ever.com/34-pict-3-mod- ... ht=carbman

It was interesting to say the least. If it will richen up my top end I will be pumped!!!

Here is how I did it.

Took the throttle plate out by filing the screw threads, then turning them out using a quality screw driver blade.

Removed the throttle shaft to clear the way for the venturi.



Took a small drill bit and drilled the two punched areas that hold the plug in which locks the 26 mm venturi in the carb throat.
The plug is out already but here you can see the two shiny areas where I drilled a bit of metal out to remove the plug.



After checking to make sure I drilled deep enough to get rid of most of the overlapped metal I took a punch from the inside and tapped the plug out.

This allowed me to use a punch to push the original venturi out through the bottom of the carb. It is in there fairly tight so you have to be a bit careful to not scratch the crap out of everything.



Next I had to get rid of a little casting bump that would be in the way of holding the new venturi so I took a grinder and ground it as far as I could then took a file and filed the rest off to get the area flat.
Next I found a nut and used that to gauge my spot for the hole to hold the new venturi in place. I needed enough room for the nut to lay flat and a socket to fit on it so that is how I decided where the hole should be.

Drilled the hole out for the holder.



Cut a piece of 1/2 inch copper pipe at 7/8 inch long as a guess for the length to clear the throttle plate.



Went to "Ace is the Place" and picked up a couple #10 x 1 inch fine thread screws and headed home.

Got my neighbor the braze the screw to the copper pipe and then massaged it to fit everything. I had to do a bit of filing to make everything fit and ended up with the copper being 3/4 inch long. It could have been a 1/16 inch longer but I cut a bit too much off after the third trial fit.



Here it is installed. It fits pretty nice!!







I then drilled the throttle shaft area for o-rings to seal it and tested the fitment.





Used a couple #011 o-rings and put the throttle shaft back together.

As soon as my new carb top gasket arrives I can finish putting the carb back together and give it a try.

I don't know if French fuel is that much different than ours but They ran a 190 main jet and a 80z air correction jet which I have in stock.

I will probably try them first to see what happens and tune from there.
All I will need then is some good weather to get out and test drive it.


Clonebug

That's an interesting "auxiliary venturi" idea. Does it completely do away with the stock venturi? Or does it still sit in there somehow?

What's the most boost you've seen/hear/read about someone running through one of these carbs? Could you be at it's limit already? I'd hate to see you hurt your engine by continuing to run it lean under boost while pushing the limits. It's pretty awesome to see how much fun can be had with a stock engine though .

turbobaja wrote:That's an interesting "auxiliary venturi" idea. Does it completely do away with the stock venturi? Or does it still sit in there somehow?

What's the most boost you've seen/hear/read about someone running through one of these carbs? Could you be at it's limit already? I'd hate to see you hurt your engine by continuing to run it lean under boost while pushing the limits. It's pretty awesome to see how much fun can be had with a stock engine though .

The stock 26 mm venturi has been removed.

The most boost I've seen is the 13.0 lbs that I have been putting through it. I have not read of anything higher.
I have not been able to get mine to run rich enough yet.

Kubelguy got a little taste of what this buggy would do when it was running pretty decent this summer and I have to say that it was a hard pulling SOB!!!

I am down to 10.5 lbs. boost now and still having trouble getting enough fuel.

Two others have run the 34 pict that I know of.

1. Jweirs has done it and I think he was at 10 lbs boost. I have not seen him on in a while though.
2. Mike Thompson also ran the 34 pict and seemed to have the best results. It seems he was also working on the enrichment issues. Mike has not posted in quite a long time... seems he has found new interests. Last I read with him he was at 10 lbs and did a 9.7 second 1/8 mile at around 75 mph.
3. Flat4ever did the mod that I have just done and got great hp but no vid of a run or anything.

I have tested the new mod I just did but was pretty disappointed with the result so I haven't posted on it yet. I decided to take a couple days to think on my work.
I got a severe leanness as soon as I gave it anything over 1/3 to 1/2 throttle. Goes right to 18 to 1 or leaner.
It was really not drivable that way whereas the mods I have done on the E-tube gave me much better results.
At least there I was pig rich at low rpm.
Now I am good at low throttle but crap lean at any heavy throttle.

The weather has really sucked here for any serious testing so I have been laying a bit low.

I have to figure out how to get more fuel.
I am in essence now running a bigger carb due to the 34 mm venturi instead of the 26 mm stock. It is now getting more air but has less draw if the aux venturi is not working like it should.
It is built as close to the Flat4ever photos as I can get.

I don't see how I could go differently due to the fact that there is only so much room for length before the venturi hits the throttle plate. I have it tight up against the main jet feed too and that is what their pic seems to show.

I have a known 190 main in it and I put my 80z air/emulsion tube in. I did solder the two lower holes shut trying to get more fuel at higher rpms.

Didn't seem to help.
I also have my power jet drilled out to a 0.50 which should help after 4000 rpm except that I can't rev it that high right now.

I am going to pull that carb out and go back to my Bocar 34 with 180 main and 75z e-tube that gave me my best driving and see if I can duplicate my former happiness.
Once I have that baseline back I will go from there.

Since I now have two carbs to mess with I can change one while driving on the other.

Stay tuned

Clonebug

turbobaja wrote:Maybe you could try some kind of "modulator ring" or ristrictor above the venturi like we run with dual Dells or Webers to try and bumb up the amount of air pressure acting on the float bowl? It's a big part of what it takes to keep the AFR increasingly rich as flow and boost pressure increases (more important with higher boost levels usually, from what I understand of it). IIRC the bowl vents right into the center of the venturi on the 34pict, so a mod ring might not be the way to go...unless you can make one below the level of the vent or extend it up above the mod ring somehow.

I've seen where, instead of mod rings, the float bowl vent can be tapped and plumbed to a higher source of boost pressure. Mod rings just restrict the amount of potential air flowing down the vent(s), so not very helpful for max output, etc. Your problem with this kind of mod is finding a source of higher boost pressure. If you were running a charge cooler, you could plumb both your fuel pump boost signal and your float bowl vent to a fitting before the cooler, so the bowls "see" more pressure than the venturi and the fuel can still keep up with it. If you had a larger plenum above the carb you could hard-line your float bowl vent up into the boost pipe leading into the carb top and potentially feed the bowl with a slightly higher pressure than the venturi gets, but your pressure ducting doesn't really have a large expansion chamber above the carb like duals have, so that might not be effective either.

Either way, I'd get your jetting back to where it worked best for you and then try modifying the bowl vent pressure signal to richen it up under boost.

I need to give a big thanks to TurboBaja for bringing up this point.

I have spent a fair amount of time with the auxillary vent mod on the 34 Pict carb mention in an above post and it has not impressed me much.
I did everything according to what the Flat4ever guys had done but My results were not anything like their's.

I was all the way up to a 190 main and a 60z air and it was worse than the Bocar 34.

I decided to go back to my Bocar 34 with a 180 main and the 80z air jet and just test around that since that was the best performance I had.

After driving it with a couple changes today I went and did a web search on 34 pict Emulsion tubes and came up with a few interesting hits.
One of which was a guy that was running a 2110 on a Bocar 34 with venturi removed!!!
Hmmmm very interesting. He even had a video up on youtube.

That brings me back to thanking TurboBaja. I owe you a bottle of my Apple Pie hooch for this tip!!!

PM me your address and I will send you a bottle.

You had mentioned referencing the float bowl with higher pressure. I thought about it but tried the auxiliary venturi idea first. I also thought that since the vent tube was dead center in the carb that it should be getting good pressure reference the way it was being that it was at least one inch above the stock Venturi.

Well, turns out Turbo was right and here is the mod I did. Now I need a new friggin clutch!!!!
Here is what the vent tube looks like stock.



Two inches of fuel hose with a clamp to keep it from coming off.



Since my intake pipe is such a cluster I couldn't make it any longer.



I put it all back together after trimming the hose to fit and took it for a drive.

Just going out of the development it was running very rich at 1500 to 2000 rpm so I knew something was up.
Got on the road and gave it the goose and it went to full rich instantly and just squatted down at pulled!!!

It went as rich as 9.5 to 1 at full throttle all the way through third gear!!!
I turned right around and went back to the garage.

Pulled the 180 main and installed a 160 main. Left the 80z with 2 holes soldered shut and took it out again. Pounded the throttle down on the straight and it just hauled ass!!! I was spinning in first and started spinning hard in second. Hit the red line and banged third and it just started pulling like never before!!!
The little I could glance at the AFR meter showed at 11.5 to 1 most of the way. When I let off and slowed to a stop it wanted to go lean for a bit for some reason.
I got out and gave my MBC a 3/4 turn tighter to bump up the boost again and jumped back in the drivers seat. Turned around and headed back. First gear spinning, second gear fishtailing and third gear the clutch started slipping but I wasn't going to let off!
Sheesh...... this is how it was supposed to run!!! I never even had a chance to see how much boost I was pushing!!!

Now i have to go back to the drawing board and figure out my jetting all over again. I also have to refigure on the pict 34 whether it might perform better with the removed venturi and give me even more power!!!!!

Stay tuned

Clonebug

P.S. Anyone want to recommend a clutch and PP that can handle the power from my engine and won't blow the crap out of my tranny??

Alright CB!!

I'm glad to see something so simple work out. Can't wait to see what you come up with on boost. Way to stay with it!

Nice work!!...sorry about the clutch .

Mmmmm apple pie hooch sounds yummy . Food for thought wins desert beverage .

Glad I could help.

Turbobaja wrote: "... Mmmmm apple pie hooch sounds yummy. Food for thought wins desert beverage ..."

CB gave the wife and I some and the wifie-poo loved it. Due one of the meds I take I can't have alcohol but I did sneak a small sip and it was taaaaasty. Turbo, you are going to be soooo lucky!

Lee

Well,

Somewhat of an update......

Mileage 60684
idle g55
main 145 power 0.75
Air/emulsion 80z 2 bottom holes soldered
Float 0.022 in washer
Choke installed
Boost 13.35 max

I did a little change this evening to test my hunch.
Last night I went from a 180 main down to a 160 main and got great response and a lot of power out of it but it was still pretty rich at cruise and on boost.
So tonight I pulled the 160 main and installed a 145 main. Now I am getting back closer to the stock 127.5 or 130 main that most 1600 engines run stock.
I was still a bit rich at 11.5 to 1 at cruise but that is better than 10 to 1 or richer.

I hooked up the laptop and decided to run a log to see what was up.
I pulled out of the developmant and went easy up in gears to see how the engine ran and it was going nice. When I traveled a bit in third and saw it was running nice I put a bit of load on the engine to see how it went. It was pulling nice but all of a sudden the clutch started slipping so I let off. I think I had a bit of foot pressure on it when I loaded it so that is why it was slipping.
I glanced over to my Tuner Dash and noticed that max boost on the gauge showed almost 16 lbs!!!!! (Turns out the data log only shows 13.35 lbs. boost max. I wonder why it is showing a 3 lb difference from the gauge to the datalog????)

I jumped out and turned the MBC out a quarter turn and tried it again. This time I made sure I was not resting my foot on the clutch.

Went easy in first and hit hard in second, got a little fishtale and went to third, it started pulling real hard and then I heard a slight ping so I immediately let off. Intake temps were a max of 166 degrees at 13.35 lbs. of boost according to the data log.

When I slowed down to a stop it went to full lean and started missing at idle..... I thought oooooohhh ooooooh.....
Now, it has been going a bit lean after going through the gears whether it is on boost or easy. It would lean out and then come back to 12.6 to 1 where it seems to be best lean idle.
I got out of the buggy and went in back to see what was up but since it was dark I couldn't see anything but I could hear a vacuum leak somewhere. After almost getting my finger caught in the alternator belt I thought I had better get home and see what i could find.
It would miss until I got to 2500 rpm then it would run decent so I nursed it home into the garage to see what the damage was.
I idled it in the garage and I ended up finding the left side red silicon intake coupler had split open.
Apparently 13 plus lbs is the limit for those couplers.
I now have to pull the whole buggy apart to get those boots out. I can not remove the intakes without lifting the shroud and the shroud can not go up without the body being lifted.
I need to find some better couplers. Any one have any suggestions???
I will not be able to see if there is other damage until I get the vacuum leaks fixed and see if that takes care of the miss.

Bummer. It sure pulls hard on boost!!!

Clonebug

Hey Clonebug.

Sounds like an awesome time modifying your carb!

I can't wait to ride again, but I think Ill be scared this time

Hey Kubel!!!

I am still working on the tune and going way down on the main but it pulls like never before. Now third gear pulls hard all the way through instead of lagging like it did when you rode in it....
Hopefully I didn't hurt anything on the last test. It will be a few days before I get to it and also need to find some better intake boosts.


Clonebug