I have a 72 240z with round top SUs and no air pump. It drives ok, but has a 1-2 second lag when starting from a stand still. It is there, but not as noticable when shifting into later gears. I thought it might be a problem with the vacuum lines, but I can't find a diagram or picture that shows my setup. Are there any other likely possibilities? Either way, a diagram, book or picture would be very helpful to get the lines set up properly.

What do you mean exactly by lag? Describe the problem more

I will engage the clutch, it will move, but just barely for a second or 2, and then accelerate as it normally should. It happens bad on the first gear, and a lot less each subsequent gears.

Is the clutch slipping?

When you are saying lag . Is it the engine stumbles or hesitates?

Sounds like not enough timing or a carb problem.

Sloppy throttle linkage?

You probably mean/ should have said hesitation.

"Lag" is what you experience during online game play when someone has a bad connection or is resetting their #$*@ing modem. There is also "turbo lag" which is a genuine form of engine lag.

It might be best to give the car a "full" tune up. Before balancing the carbs be sure that you have adjusted the valves. Get a dwell meter to set your points. You can get by with feeler guages but it's better to use the meter. Make sure the rpm is right when setting dwell/gap.

Check for free movement of pistons in the carbs. Do they stick? Check by hand as outlined in many manuals. Tear down and clean with brake parts cleaner or laquer thinner.

Ignition can also cause some poor performance of this nature. Check the condition of plugs and clean/replace if necessary. Points in poor adjustment or condition can cause hesitation as well. A distributor with sloppy bearings can wreak havoc on points ignition settings.

In synopsis...

Get a Haynes manual.

Adjust tappets

Check/replace spark plugs

Clean and adjust carbs

Service the ignition...

Points, condenser, clean terminals in or replace dizzy cap

(Best to replace points condeser, rotor and cap)

There are a few things outside the tune up which could cause "lag". Do the tune up first and check back.

2c

Hope this helps.

Jim