Johnny wick

Ill have to leave it fouling again as i cleaned it with a brass brush

Both valve seals in that cylinder were replaced last year.

The only way to check and replace those seals is opening the engine. We are still guessing here.

Ill run a compression test first to determine the psi in each cylinder. I was also considering on closing the fuel mixture knob at least 1/2 turn and let the car idle for 15 to 20 mins, pull out the rear carb plugs (4, 5 and 6) to determine any fouling

Ill have to do a compression test again. That was way back in 2018. I did replaced both valve seals in that cylinder and the problem was never fixed

9 years struggling with this crap and wasting money in inexperienced mechanics

I know the firing order. The picture is taken 6 5 4 3 2 1. Number 4 the problem child.

Thanks for your honest advice. I think its about time to take this engine out of the car. Im running BP5ES plugs in all 6 cylinders and the order of the plugs is 6-5-4-3-2-1. If i close the fuel mixture nut half turn in at the rear carburetor i loose power.

Problem came back. 3 to 4 minutes idling in stop and go traffic. Engine started misfiring, pulled the spark plugs and there you have the result.

Come on guys. Get serious! Im taking the car for a spin and leaving it on idle for 20 mins so you can judge those plugs for yourself. What else do you need to know from this car? Is dual electric fan and new bigger radiator the solution?

That was already done. I guess i will need to check the float levels on each carb again and try.

Engine had good compression on all the 6 cylinder. Asides from that, we even replaced the intake and exhaust valve seals from that cylinder last year. Do you want me to tear the whole engine down?

This is what i have inside the engine. The only thing changed is the camshaft. Now a Schneider 274F. Ill take the car for a spin today and will pull out all the plugs again. Maybe there is a better solution than throwing money on unnecesary fans and radiator

I guess the variables must be really examined. The engine was sent by PO to California Datsun and was bored from 2.4L to 2.6L. It also had a Far 311 race cam which i replaced with a Schneider 274F cam for daily driver. Nevertheless, an experienced mechanic told me that if remove the fan clutch and install a dual electric fan and bigger radiator the issue could be solved during traffic jams. Do you agree?

My car has a schneider 274f cam installed

Thats correct. So how do i tackle this?

you close the jet all the way up and then you turn 2.5 turns from the base line. Lean is when the jet is flush with the bridge of the carb. The nozzle drops when turning it.

Let me explain this better: I adjusted the floats during the pandemic in 2020 when i had some spare time. I did this using a float sync device built and sold by one of the members here. If i close the fuel adjustment to 2.5 turns clockwise car has no power when accelerating. it even pops at the exhaust when releasing the gas pedal.

2 turns does not give enough power to drive the car. Mine are set to 3.5 and 4 turns rear.

72 240z with stock su 3 screws carbs reman by z therapy

The carbs were remanufactured by z therapy in 2014. I invested in this.

So you are of the opinion that those plugs should not foul black as shown even if the car is sitting in traffic for 20 to 45 mins?

He even sold me the valve seals and told me that wasnt necessary. Car has good compression. I guess there is a piece of the puzzle we are missing.

I called him and he said the engine was reconstucted perfectly.

How come after 8 years im still pulling plugs after they get fouled from 30 mins at idle either on traffic or at the shop? Been struggling with this and nothing.