Hi,

After watching Just SU DVD so many, I decided to rebuild my '72 3 screws SU carb.

It took me 3 hours to clean up 1st carb to remove 40 years gank, but 2nd one took me just 1 hours.

Following DatsunZgarage instruction and use clear tube to adjust float level for both SU carb.

http://datsunzgarage.com/engine/index.htm

http://forums.ctzcc.com/viewtopic.php?t=4181&sid=b15c6070a9563fa4173bb07bbd52d213

It took me so many times to adjust float setting matching to 23mm line for both carb.

Them, put back everything, spray Engine Start Spray, it start a bit and stole.

Adjusting choke level, nothing is improving. No matter what I did, when I spray, it runs a bit and stole.

Before, rebuild carb, engine could've run above 3000RPM.

I got new spark plug, new spark plug wire, new MSD blaster coil install.

Can some one give me an advice?

Thanks,

tamo3

Have you checked to make sure you are actually getting fuel from the tank? If your carbs were that gunked up, what does your tank look like?

Do you have fresh fuel?

Remove the fuel lines and crank the motor and see how much is coming out.

You also cleaned the inlet fuel screens in the carbs?

Make sure you have no vacuum leaks.

Steve,

Thanks for the advice. Gunk was no outside of carb, not inside.

Fuel is comming from the tank since I check with clear tube for float level, I could've seen the fuel is coming when mechanical fuel pump clank.

I replace to new gasket, insulator too.

Where should I check vacuum leak?

Thanks,

tamo3

Normal stuff like the pcv line and any other vacuum lines, brake booster.

Then you can double check your ignition wires for firing order, points, ect...

Go back over the basics to make sure you didn't miss something simple.

I am assuming you checked the SU pistons for the drop test.

Is the choke actually moving the nozzle?

By all means make sure you are GETTING FUEL TO THE CARBS. Electrical is okay because it's trying to light off with starting fluid or what ever that was. The worse job of float adjustment should at least get things to fire if gas is getting into the float bowl. It's all gravity from there into the fuel nozzles.

Thanks Madkaw, Bruce.

I replace to new fuel filter, new battery, new fuel tube, check vacuum leak, but still does not help.

After testing, changing fuel jet adjustment, I finally figure out that front carb has too rich fuel comes in. It gets spits out fuel before engine stole everytime.

I tight up fuel jet adjustment nut and finally, engine runs continuously!

When I use clear tube to check float level for both front and rear carb, both are almost exactly on 23mm line, but it seems like front carb gets higher fuel pressure than rear and gets more fuel comes in.

Use Synchronizer to adjust air flow level for both same level now.

I can get great power after 3,000RPM. However, around 1,500 ~ 2,500 RPM, I loose power extremely. It almost stole engine while I'm driving low gear.

Does it something to do with SU carb setting?

Thanks,

tamo3

Have you visually checked to make sure the jet NOZZLE is seated up against the body of the carb. There should be no brass tube showing with the choke off. If that nozzle hangs down it will cause a very rich mixture.

When you put the needles back into the piston of the carb- did you fit them flush or how?

Now you have it running- what do the front plugs look like?

Did you check the syncro balance at 3000 rpm?( air flow)

Do you have a picture of your current set-up so we can see

Hi Steve,

Thanks for your advice.

Finally, I got time to try again for trouble shooting.

I found out one big mistake. I rebuild distributor and I did not aware of the timing. After turn distributor position, engine get much stable and have enough power in low RPM now!

Damn, your timing must have been way off. Glad you figured it out

Thanks Steve!