needs choke to run right

[Guest skidpan]

So i was trying to figure out what the hell was wrong with the Z I recently bought for my wife. I found out that 2 of the spark plug wires were crossed, and it had several vacume leaks. I got thoes taken care of, and it runs a little better, but still has a bit of a miss/ hesitation at about 1500 rpm under load to about 2200 rms then runs like a bat out of hell after that. That is unless the choke is just below half way. it the choke is on a little it runs absolutly great. it idles a little high, but runs alot better. so are my carbs running too rich, too lean? whats the deal? It is a l26 block with a 240 head, and the flat top (yeah yeah) carbs. what could i do to get this thing running right?

[Pop N Wood]

Sounds to me like you still have a vacuum leak or a misadjusted mixture. You must be running lean, so putting on the choke dumps more gas into the carb letting it run better.

 

If the car has been sitting then I guess you can't overlook the possiblity the carb is gunked up causing it to run lean. Maybe some dirt blocking a fuel orifice.

 

Get some starter fluid or propane and continue to look for vacuum leaks. pay special attention to the throttle shaft bushings since those are what caused me to replace my early carbs. Of course replace or tighten all the vaccum hoses and check the brake booster for leaks.

 

If all of that works, pull the carbs and rebuild them.

 

Reading back through this I realize that maybe the carbs are just out of adjustement. But I don't know anything about adjusting the flat top carbs.

 

I have a set of dual downdraft webers I could make you a deal on.....

[ktm]

It sounds like the previous owner did not take good care of the car. This would lead me to believe that it may need a good tune up. Your problem can be caused by a number of things such as fuel starvation, weak spark, bad distributor, etc. I would suggest a few things:

 

1) Replace the distributor cap and rotor unless you know when it was replaced. You could be getting a intermittent spark or a weak spark.

2) Check your plugs and replace if necessary. I suggest NGK plugs.

3) While the engine is running, pull a spark plug wire off a plug and listen for a change in tone. If there is a change, that cylinder is firing. If not, you know that one cylinder is not firing. This is just a trouble-shooting technique. If the plug looks fine was replaced and the distributor cap/rotor were replaced, you may be looking at new plug wires.

4) Check your valve lash and set accordingly if necessary.

5) Check your timing as well and set accordingly if necessary.

6) Your carbs have a mixture adjustment nut on the bottom. Screw them all the way up and then back them out 2-1/2 turns. This will get you close to the mixture, assuming your carbs are synched.

7) Check and replace your fuel filter unless you already have.

8) Have you checked the float bowels to make sure that the banjor fitting, screen, needle valve and float are working correctly?

9) What does your gas look like? Is it clear or colored?

10) Have you checked to make sure your carbs are functioning properly? Do the dampers have oil? Do they have the right kind of oil? Are you able to lift the piston on the bottom of the carb? Does it return with a clunk (it should)?

 

Finally, I see that you are in So. Cal. Pop N Wood has a pair of downdraft Webers and I have a pair of round-top SUs I could make you a deal on (I live in Irvine).

[Guest skidpan]

yeah i have done the propane trick, Ive changed the wires, cap, and rotor. All of the spark plugs look good. the fuel filter my have something to do with it. KTM what do you want for the round tops?