'73 240z needs engine and su help

[chicago240z]

Hello everyone i just got my 240z flew to denver to pick it up was told it was running rich played with carbs got it reasonable running clutch goes out on way home fun limping it up hills through neb and iowa having to stop every half hour to let plates cool. So change plugs, cap, rotor runs better no more really bad fumes plus added auto trans fluid to carbs was told good weight for them i think i put to much in but later for that, so i get it back from shop with new clutch let it warm up and go on a little cruiserunnning ok then starts to bog in high end in 1st and second clears up then 15 minutes later i cant get it past 35- 40 miles per hourin 3rd 4th just bogs around 3000 put in clutch and it revs right up put back in gear and boggy my question is is it that i need timing ,vaccum leak, su adjussted(have carb adjusting sync tool tinker with them tomm ) i am baffled i made it back from denver with burnt matchstick like plugs i did put oil in after i got back what level should they be at really bummed out in chicago thanks for any help

[beandip]

First off ATF is 5wt oil. What is recommended by Nissan is 20w , I use this and find that it works the vary best in my Z. What are the ''plates'' that need cooling?? Sounds like you have a serious vacuum leak if the plugs are burned bad in that short of a run. Use NGK bpr6es plugs. I have no idea about the timing . What is it set at? Are you running a stock dist with points? Or electronic ? Makes a difference. The dampeners in the carbs only hold about 3cc of oil. You cannot over fill them because any excess will be burned by the engine with no harm done. If you have 10w30 you can get by with that . 20w can be found at a cycle shop , ask for fork oil. Stock 240 dist set the timing at 10*btdc . ZX dist can be set at 15*btdc The reason for the engine going flat at 3K and above could be clogged fuel filters. If this is a '73240 there is a in line filter between the electric fuel pump and the gas tank as well as the one on the inner fender in the engine bay. I would change them both in any event. Gary

[gogriz91]

try searching, there's a ton of stuff here, on zcar.com and at hybridz.org on how to "tune su"s. Another option might be to change your fuel filter, maybe something n the lines or the tank is gunking things up?

[beandip]

You just need to check for vacuum leaks , check the vacuum advance to see if it is working properly. Change the filters before you start messing with the SUs. Especially if you are not knowledgeable with their adjustment. They are not hard to adjust, it is that you can easily have them so out of whack you wont know if the problem is ignition , vacuum leak or carbs. Eliminate one possibility at a time , not all three at the same time. Gary:rambo:

[WarrenZ]

This sounds all very familiar, take a look at another current thread that might give you some clues

http://www.classiczcars.com/forums/showthread.php?threadid=28875

Warren

[Pop's Z]

Don't forget there is a fuel filter INSIDE the electric fuel pump, also. Take the pump off and twist the bottom off. New filters are available at any auto parts store or mail order...ie: Rockauto, MSA, Black Dragon, etc. Remember, it's usually never just one thing that causes your problem. Use the "search" feature and you will become enlightened. Be happy in your work....Cheers, Mike

[kenz240z]

Yep, as has been mentioned the '73 has TWO fuel filters. One on the passenger side inner fender, and the other INSIDE the electric fuel pump mounted back by the tank (also on the passenger side.

I had a similar problem with my '73. I replaced the fuel filter on the inner fender when I bought the car, along with new distributor cap, rotor, points and plugs. Still had problems.

Then I "discovered" the filter in the electric fuel pump and replaced it. The old filter was thoroughly caked with silt and sediment from the tank (the car had been sitting for 7 years, go figure!!!). I also noticed that the fuel hose from the tank to the electric pump had a split. So I replaced ALL the sections of fuel hose in the fuel line: to the carbs, to/from the mechanical fuel pump, etc... At this point the car ran great for a while, but then started having problems again. On a whim, I replaced the filter on the inner fender again. Problem solved. Apparently, this filter got plugged up from the sediment, too. It just took a little longer for it to become a problem.

Focus on the simple things first. Then fine tune everything. Start by adjusting the valves, as this affects the vacuum signal, which in turn affects the timing and the carburetors. Then replace the dizzy cap, rotor, points, plugs and plug wires. Take care to gap the plugs properly and adjust the point gap. Next set the timing. Finally, adjust the carbies.

[chicago240z]

Thanks guys for all the ideas car in shop now ill know wednesday the final outcome the only thing that keeps me going is knowing i have a mint 240z with no rust i saw it up on lift and it looks better than a new car underneath plus alll the great comments on car