I am getting popping in #5 and #6 only. I have balanced the carbs left/right and I have checked the timing and adjusted the valves. I have tried adjusting what I think is the only adjustment of the fuel/air mixture. (The one just below left of the yellow nipple) I have taken the adjustment screw all the way in and it has no effect on the carb. Not sure what the problem is? Nothing I do gets rid of the popping.

These are Solex (Zenith) Carbs, I am wondering if there is another adjustment screw here that I do not see. I do not know alot about these.

I was hoping someone could identify the adjustment screw(s) and provide a possible solution/advice. BTW I know the picture of from the other side not 5/6.

Click to view attachment

Did you adjust the valves?

I adjusted the valves and set the timing. This made it better, I was getting popping in 1/2/5/6, now only 5/6. Nothing else I have done seems to change that.

When you balance take one linkage arm off, when done replace arm so that it doesn't move the carb arm even a hair. Bend the crossbar mounts if you have to.

Also check for exhaust leaks

Thanks for the suggestion, I took one side of the linkage off when I balanced them and rechecked them when I but it back and there was no change.

I installed a new exhaust, I checked again this morning for leaks and could not find any. I am stumped

...POPPING....please explain this a little more....1. is the popping occuring upon deceleration throttle/gas pedal completely ...A.off........B. partly off?....2. Or is popping during acceleration, or , while at a stable, continious rpm.?...In other words, explain the circumstances in which the "popping occurs".........

Are there any leaks between the carbs to intake or intake to head? (squirt some propane down by the gaskets and listen for the engine speed to pick up - that will indicate an air leak).

Are there air correction screws that can be closed to richen up the air fuel mix just a little more?

Are the jets right?

Zach

I am not sure if there is an air correction screw, I have no idea what the other screws do? I have not been able to find out any technical information on these carbs. I was hoping someone would be able to look at the photo and tell me what screws do what.

I will check for leaks at the intake, thanks for the suggestion Zach

It pops on accel and decel and at higher revs if it is held there steady. The only time it does not pop is at idle.

Popping on decel is often an exhaust leak.

Popping on accel, but not idle, is a linkage issue, opening at different rates.

I have a synchrometer, Weber Synchrometer and it shows all 6 cylinders are almost identical at idle and at power. How close do they need to be?

I will check again for an exhaust leak.

Thanks

Start the engine and back out the idle jet carriers just a little (like 1/2 a turn) on the cylinders that are giving you problems. If the idle stumbles a little when you back it out, then that jet is working, if nothing happens that jet or the passage to that jet is clogged. Don't back out the jet carrier too far or it will start leaking fuel.

Ok, In the photo, which one is the idle jet?

...Popping ..at acceleration, and decelateration...and at a steady state rpm..... suggests that.... your VALVE LASH is too tight, ....and ...probably time for you to take your car to an EXPERT for a major tune up before you have cataclismetic damage to your engine. If you are JUST LEARING ABOUT IT NOW ..I don't think ANYONE is going to be able to walk you through every possable problem you could have. such as ...1. low fuel pressure (many reasons )...2.basic carb adjustments, v/s clogged jets, "dropped Floats", (many reasons)...3. Ignition timing (many reasons)...4. valve lash/ or broken valve spring(s) Engine overreved , bent valves, (other reasons)...5. Air leaks into engine ...(many reasons). 6. Get a generious old expert to go thru a major tune up, assessment ,and ask HIM to explain what the hell went wrong. bet if you ask he will explain in detail. Then you will know. and you will know who is going to maintain your car. Maintaining porsches, as incredable as this sounds is not an osmosis kind of thing. Just because you own one ...doesn;t mean you can maintain it, with out traveling down a long, long road, of experiences, costs (tools), and effort.....too consider.