SU Carb question.

[Pleadingbark]

I have a 71 240z I just picked up, I was going through the carbs and I noticed that the front is a 3 bolt and the rear is a 4 bolt. I also noticed that the choke on the back one doesnt pull down. Is having the different carbs going to affect anything on the way the car runs?

[Walter Moore]

The carbs need to "match" in terms of how the pistons are timed. (At least that was what it said in the Z Therapy video.) But the 3 screw vs 4 screw just relates to the cover design I believe.

When you say the choke doesn't pull down, do you mean the linkage is stuck or the jet will not move in the body.

It sounds like the PO scrounged up whatever parts he could to keep it running. There is normally a banner add about Z Therapy on the site. You really should check with them. I love the rebuilt SUs that I bought from them.

[Gary in NJ]

I also noticed that the choke on the back one doesnt pull down.

You're going to have to explain this one a bit more. The SU's don't have a traditional choke plate. It's actually an enrichment circuit where the fuel nozzle is lowered, allowing for extra fuel to be present at the venturi.

If the nozzle is frozen, hit it with some WD-40 ( from the top side) and then you should be able to get it free. After it is free you'll want to polish the nozzle and the chamber. When it is reinstalled apply white grease to the nozzle before it is reinserted into the carb body.

[Pleadingbark]

You're going to have to explain this one a bit more. The SU's don't have a traditional choke plate. It's actually an enrichment circuit where the fuel nozzle is lowered, allowing for extra fuel to be present at the venturi.

If the nozzle is frozen, hit it with some WD-40 ( from the top side) and then you should be able to get it free. After it is free you'll want to polish the nozzle and the chamber. When it is reinstalled apply white grease to the nozzle before it is reinserted into the carb body.

There is a little thumb screw under the carb body where the fuel feeds in, I noticed on the first car that whole fuel needle thing can move down, but it doesnt on the second 4 bolt carb.

[Gary in NJ]

Right, If you remove the screw from the bottom of the nozzle and move the arm out of the way, you should be able to remove the nozzle (give it a twist). From there you can clean and lube it.

[Pleadingbark]

I tried, it was a no-go. Even let it soak in a thing of carb cleaner for about 20 minutes and nothing. Ill try shooting some wd40 down there tonight when I get home.

[SteveJ]

You might try going over to Eddie's shop and seeing if you can buy a carb from him to get you running.

[Pleadingbark]

You might try going over to Eddie's shop and seeing if you can buy a carb from him to get you running.

Good thinking!

Ill call him now.

[SteveJ]

If his phone isn't working, send me a PM with your phone number, and I'll get him the info.

[Pleadingbark]

Called and spoke with his wife never heard back from them regarding an extra carb. Oh well. Hopefully it starts.

[SteveJ]

Sometimes you just have to drop by his shop. If you can't make it on a weekday, sometimes someone is working at the shop on a Saturday. If that's the case, try early afternoon.