Z therapy SU carbs not running right.

[azriel_strife]

You should check your timing at all rpms up to max advance to understand what it is doing and when. Try with and without the vac advance to see what is going on.

The neat thing with the distributor is that it is independent of load. It only depends on rpm.

I'll have a look when I get some extra time here soon. I would think that i can only have one or the other if the advance range doesnt meet my engine needs, correct? so if i have to choose, i should tune for operation RPM, not idle?

Guess I sounded snarky there - sorry.

Maybe not the best dizzy and they are all different as far as mechanical advance.

How much timing all in?

Might consider a ZX dizzy or electronic ignition .

I am sitting at 32 degrees total advance @ 3000rpm without advance plugged in.

[madkaw]

So you are advanced now already?

What dizzy model are you running and what's your static timing

[azriel_strife]

I don't know how to tell, i'm assuming it's a stock 240z dizzy, it's a points unit. I read that 32 degrees was a good place to be with locked timing. just trying things at this point because I don;t have any information pertinent to my particular setup.

[240260280z]

Try taking measurements and filling in the list below to help us help you

Advance measured with VAC connected:

Idle:____________ (degrees)

1000:___________ (degrees)

2000:___________ (degrees)

3000:___________ (degrees)

Idle RPM:______________

Max Advance RPM:_______

Advance measured with VAC disconnected:

Idle:____________ (degrees)

1000:___________ (degrees)

2000:___________ (degrees)

3000:___________ (degrees)

Idle RPM:______________

Max Advance RPM:_______

[azriel_strife]

Try taking measurements and filling in the list below to help us help you

Advance measured with VAC connected:

Idle:____________ (degrees)

1000:___________ (degrees)

2000:___________ (degrees)

3000:___________ (degrees)

Idle RPM:______________

Max Advance RPM:_______

Advance measured with VAC disconnected:

Idle:____________ (degrees)

1000:___________ (degrees)

2000:___________ (degrees)

3000:___________ (degrees)

Idle RPM:______________

Max Advance RPM:_______

Idle: 10-11 degrees (mark jumps around)

1000: 15 degrees

2000: 25ish degrees

3000: 30ish degrees

The vac hose being connected didn't make any difference to the readings, so all of this is with vac disconnected.

Max advance is right around 2800rpm, I cant see any difference after that no matter how high i rev.

My good timing light kicked the bucket, so my replacement doesn't do offset.. I can't see beyond 15 degrees on the indicator for the pulley. so anything beyond 15 degrees is a best guess based on distance.

If I advance any farther i get knock at low RPM high load. it;s likely my increased compression ratio from the F54 with flat top pistons and the N42 head.

The amount of advance i am getting is quite high, wich leads me to believe i have a crappy emissions distributor, maybe I should consider getting a 280zx distributor instead.

If anyone has an e12 80 ZX distributor available for purchase I will buy it right away.

Edited June 25, 2014 by azriel_strife

[azriel_strife]

So i was looking and I didn't see it before, the flywheel and block have been painted so the markings for timing on the flywheel and block were almost invisible.

To my surprise each tooth on the block for timing is 2 degrees, what i thought was 10 degrees initial timing at idle was actually 20. it seems that my timing is way too far advanced. it also seems that the spot i thought was zero on the toothed indicator on the block is not zero at all. i need to go have a look again.

[azriel_strife]

ok, so i have set my total timing to 34 degrees at 3000rpm, and the car seems to hesitate under light throttle (vacuum) at 3000+rpm. Seems like it's getting too much vac advance. Other than that it is running and idling happily.

If I unhook vac advance, it doesn't seem to do it anymore, but I lose a noticeable amount of torque on initial pedal press.

I may have to check and make sure my balancer hasn't spun on the rubber. is there a good method of doing this?

[240260280z]

Great stuff.

You may be able to remove the vac advance but give it more initial advance to compensate.... say ~ 17 to 19 at idle. This should help the mid RPM problem (from too much vacuum advance). However the small print side effects of no vac advance are: It may be more difficult to start and, you will loose fuel efficiency at cruise.

The vacuum advance canisters are adjustable but you need to chip off the epoxy blob to access the limit screw.

Edited June 28, 2014 by Blue

[240260280z]

http://www.classiczcars.com/forums/electrical-s30/34559-adjusting-vacuum-advance-zx-distributor.html

[azriel_strife]

Great stuff.

You may be able to remove the vac advance but give it more initial advance to compensate.... say ~ 17 to 19 at idle. This should help the mid RPM problem (from too much vacuum advance). However the small print side effects of no vac advance are: It may be more difficult to start and, you will loose fuel efficiency at cruise.

The vacuum advance canisters are adjustable but you need to chip off the epoxy blob to access the limit screw.

It does run better without the vac advance plugged in, but it seems like it's still lacking timing under light load with no vac advance. If i advance the timing up to 38-40 degrees total advance it seems happy. This is what makes me think my balancer may have spun on the crank.

Should i use the old screwdriver in the #1 cylinder to find tdc trick and compare it to the marks on the balancer?

My distributor is an old points unit, so i'm not sure if i can adjust the vac advance on it.

[240260280z]

A non-points distributor is a great upgrade....especially at high rpms'

yes get the piston at TDC then check the marks

[azriel_strife]

I ordered a hot spark electronic conversion kit for my distributor today. my car doesn't have the ballast resistor either, so it should be an easy swap over.