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Do you have a way to monitor your fuel pressure while the engine is making boost? It sounds like you're leaning out (and I'd be freaking out @ 15:1 full load ) when the fuel demands really go up. It would be pretty simple to T in a vac/pres gauge in your fuel line to the carb so you could temporarily test if your fuel press is keeping up with boost. How is your float bowl being pressurized (air)? Do you have an external port you're feeding boost pressure to, or is it simply through the throat of the carb? I don't know if something like a modulator ring would work on your carb, but ideally you should be increasing the amount of pressure acting on the float bowl above the pressure being fed down the throat of the carb as boost rises to keep enough fuel flowing.

Most importantly, it's great to see you're having fun with this machine! Nice work getting it to where it is already

turbobaja wrote:Do you have a way to monitor your fuel pressure while the engine is making boost? It sounds like you're leaning out (and I'd be freaking out @ 15:1 full load ) when the fuel demands really go up. It would be pretty simple to T in a vac/pres gauge in your fuel line to the carb so you could temporarily test if your fuel press is keeping up with boost. How is your float bowl being pressurized (air)? Do you have an external port you're feeding boost pressure to, or is it simply through the throat of the carb? I don't know if something like a modulator ring would work on your carb, but ideally you should be increasing the amount of pressure acting on the float bowl above the pressure being fed down the throat of the carb as boost rises to keep enough fuel flowing.

Most importantly, it's great to see you're having fun with this machine! Nice work getting it to where it is already

Thanks TurboBaja!!

I have had a Vac/Pressure gauge on the fuel line when I first started this project and I am certain that the stock fuel pump works well being boost referenced.
I watched it when I first got it running with the turbo and my pressure was consistently at 4 lbs. initial and always stayed at that pressure above the boost all the way to 10 lbs. boost.


Clonebug

Update,

Mileage, 60343
Idle jet 50
Main jet 170
Emulsion tube, 75z lowest 5 holes soldered shut.
power jet 47.5
float .020 washer
No choke plate
Boost 12.915

I took the buggy out for a test drive and I am happy to say that I can see a definite difference in AFR with the smaller air correction (emulsion tube) jet.
It lowered the AFR by 2 full points so I am now at 13.5 to 1 by 5000 rpm.
I had to drop the boost down to 12 lbs. to get rid of the detonation. I am having a tough time keeping it from rattling at the top of third gear. It only seems to happen when I role the throttle on in third gear from low rpm. If I bang through the gears it will not detonate as easily.
My MAT is at a max of 182 degrees so I do get a little advance retard from the IAT ignition tab. Advance is down to 17.8 degrees at 12 lbs. and 182 degrees IAT at 5053 rpm.

I wish I could find a 70z or 65z air correction jet..... I would be in fat city. In fact I bet I could decrease my main jet a bit by doing that.
I might be able to find one in time..... we will see.

Clonebug

CB, do you think you have maxed out or close to maxing out the carb yet?

Since my only foray with Pict 34s a bust (new carb went south in less than a half hour) so the question is if there any more adjustment left on the accelerator pump/shaft (if there is one anyway).

Lee

Ol'fogasaurus wrote:CB, do you think you have maxed out or close to maxing out the carb yet?

Since my only foray with Pict 34s a bust (new carb went south in less than a half hour) so the question is if there any more adjustment left on the accelerator pump/shaft (if there is one anyway).

Lee

I don't think I have maxed out the carb yet....The problem is that the jets I need to adjust are not available and if I try to drill them myself I would have to fill them in first then redrill smaller. The emulsion tube is an air jet and I think the power jet is too. Both of those jets work in the rpm range I need to richen up.
The holes are very very very small the way they are now.

If I would settle for 10 lbs. boost I would probably be able to jet it with what I have but then that wouldn't be any fun......would it???

Clonebug

I went looking for the pin vice and (small) numbered drills I told you I have. I haven't found them yet but I have found a lot of stuff I had forgotten about; there are still two places I haven't looked at. Heading to the dunes this week (another work project, no help this time) and I will look down there. I was going to do some jet work down there and may have forgotten them there; I will try to remember to do the search as I know where the box is.

http://en.wikipedia.org/wiki/Drill_bit_sizes

http://www.custompartnet.com/drill-size-chart

http://www.zaviation.ca/reference/ref-drillsizes.htm

Lee

Edited to add the drill bit sizes

Ordered up a set of metric drill bits online today.
From 0.30 mm to 2.00 mm with a pin vice shipped to my door priority for $15.00.

I am going to increase the size of the power jet which as near as I can figure is a 0.475 mm hole right now. I want to increase it to 0.50 and try it to see if I can get rid of the full throttle lean area I have right now.

Going up on the main makes mid range too rich. I am going to pull the Emulsion tube out and unsolder all but the two bottom holes to see if I can get the mid range leaner and full throttle richer.

I would like to get the main back down to a 155 main jet which is where the engine seemed to run the best in cruise.

All this is dependent on the rain stopping

Clonebug

Update,

Mileage, 60412
Idle jet 45
Main jet 170
Emulsion tube, 75z lowest 2 holes soldered shut.
power jet 47.5
float .032 washer
No choke plate
Boost 12.334

I had a few days to think everything over and decided to do a little test. Found a idle jet marked g45 and decided to see if I could get any leaner afr readings at low cruise rpms.
I found that I had to turn the volume screw out almost 2 full turns in order to get it rich enough to idle without popping. when I tested mid range throttle I found that the AFR would run form 15 to 1 to 12.5 to 1 in cruise. I got a bit of tip in leaness and it would go 18.5 to 1 lean at tip in after a fairly hard run.
Power seemed to be no different and it ran pretty nice except for the lean off throttle area, Specifically when letting off to go around a corner then when accelerating it would falter to 18.5 to 1 for just a bit.

I seemed to have a bit of float trouble too because I noticed after heavy throttle I would get a really rich condition like the float bowl was flooding.
I decided to pull the carb again and do some internal changes.
1. Pulled the top off and replaced the newer float valve with an older one thinking the new one was a POS.
2. Took out the 0.22 washer and installed a 0.33 washer to get the float level down just a bit to keep the fuel form overflowing after heavy boost. Also pulled out the Mexican plastic float and installed the Solex gray float.
3. Pulled the Emulsion tube out again and unsoldered all the holes, cleaned it up and then resoldered the two bottom holes. I figured that I had too many holes soldered shut and that was causing some of the richness at mid range rpm.
I had studied a bit more on emulsion tube theory and came up with the idea that I was causing the rich condition by having the upper holes soldered shut. All I should need is the lowest holes shut since they would be exposed at high rpm which is where I am lean. The upper holes would be exposed at a mid rpm setting which at the time was running too rich.

I took it out for a test even though it was a little wet out.

I have to say that when I hit second gear on boost, it becomes quite a hand full to keep straight!!!!
It was shaking its tail all over the place!!!

It seemed that it has never pulled that hard in second, it really squats down and just takes off like a rocket.. I have no time to look anywhere except the road.....Third gear has very little lag anymore and the afr is running about 14.5. It is still too lean under third gear full boost but I think tomorrow I will be able to fix that if my wire gauge drills show up.
I think I can get the fuel if I drill out the power jet a couple thousandths of a millimeter. Stock is 0.475 mm and I am going to drill it around a 0.50 mm to try first. The power jet is supposed to work at the 4000 rpm to 5000rpm area.
We will see tomorrow.........stay tuned.

Clonebug

You also have to take in the outside air temps into consideration too. When it's cold and moist out that dense air just loves to give our turbo's cars more power!

MarioVelotta wrote:You also have to take in the outside air temps into consideration too. When it's cold and moist out that dense air just loves to give our turbo's cars more power!

OH BOY!!!

Some of it also might be that I haven't driven it in a couple days due to the wonderful weather....

Clonebug

Update,

Mileage, 60453
Idle jet confirmed 50
Main jet 170
Emulsion tube, 75z lowest 2 holes soldered shut.
power jet 47.5
float .032 washer
No choke plate
Boost 12.334

My drill set showed up the other day and I can not believe how small they are and how they can get the precision in those drill bits!!!



They are so small my camera can't even focus on them.!!!



Here is the jet that I will be working on.



This is the power jet which is supposed to come in at 4000 to 5000 rpm. It is drilled at 0.475 mm and is TINY!!!

It is under a little brass plug and is inside about a half inch so you need an itty bitty screw driver to get it out.



Here is the plug on the left and the power jet on the right.



I took an 0.50 drill bit and carefully drilled it through the jet.

That is only .025 mm larger than what it was stock!!!
I figure if it is that small it won't take much to get more fuel to the engine.



Later today I will pull the carb and put this jet in and give it a try.

I also found a supply for emulsion tubes and ended up buying a 60z and a 70z air correction/emulsion tube.

He also had a really cool item that I couldn't pass up so I had him toss that in too. It is an adjustable main jet.

This is going to be fun!!!!

All this should get me right where I want to be.... I hope to decrease the main jet and with the adjustable main it should be easy to get my mid range cruise back where I want it.

Stay tuned.

Clonebug

Off to the garage!!!

Clonebug

Update,

Mileage, 60465
Idle jet confirmed 50
Main jet 170
Emulsion tube, 75z lowest 2 holes soldered shut.
power jet 0.50 mm
float .032 washer
No choke plate
Boost 12.334

I pulled the carb off yesterday afternoon and was going to put the power jet I drilled from the spare Solex carb I had into my Bocar.
But of course I missed just a slight detail when I had those jets out.
I found that the Solex carb jet has a larger thread size than the Bocar carb does so now the two spares I have are not going to work.

I had to drill the original jet out to 0.50 mm to make it work.

I reinstalled the carb, hooked up the computer and went out for a test drive.
I checked the logs and at the 4400 rpm range found that i had dropped the AFR from 15.017 to 1 down to 14.41 to 1 AFR.
So, It seems it did do a little bit of good but I am running just too rich in the mid range cruise with the 170 main.

I am going to wait for the new air correction jets to get here and my new cool adjustable jet and see if I can get the mid range down before messing any more with the full power boost.

Hopefully I am on the right path and get somewhere before the weather goes down hill.

Clonebug

Update,

Mileage, 60527
Idle jet confirmed 50
Main jet 170
Emulsion tube, 75z lowest 2 holes soldered shut.
power jet 0.50 mm
float .032 washer
No choke plate
Boost 12.334

My new jets and air correction/Emulsion tubes haven't arrived yet so I got a little bored this afternoon and decided to do a little electrical work.

My brother had given me a new tach that he bought quite a few years ago. He had planned on putting it in his LS-6 1970 Chevelle but ended up selling the car for big bucks therefore relegating the tach to a spot on his shelf.

Here is the tack....It is a Mac tools 3.5 inch tach with internal shift light.



Here is the old 2 1/16 inch Sun tach that I picked up at a swap meet for $5.00. It has served me well for 7 years but it is time to retire it to the shelf as a backup.



Here is the new tach mounted and half wired.... I ran out of 18 gauge solderless connectors to finish up the wiring. I will get it in the morning if I have a rain day...If it rains as hard as it is supposed to for the next few days I doubt that I will be able to test it.



Clonebug

Tach is now installed and fully wired.

I just checked my email for delivery confirmation of my package of jets and this is what is says.....Your item is out for delivery at 9:15 am on October 22, 2011 in LYNDEN, WA 98264.

I should get my mail around 1:00 or 2:00 pm today and I will be working on the carb again.

Hopefully the rain will stop for a while so I can test it........

Stay tuned.

Clonebug