One last thing,

Don't forget to plug the vac lines that go to the choke pots.

Unless the carbs have been O/Hauled before then I would think that the float level would be pretty right, but once you remove them it's better to double check now.

Buy a machinists steel rule, not as handy as a dial caliper but cheaper.

Yes, I do need to get a machinists rule. Maybe Sears or the local auto parts might have them. Thanks, Victor.

I totally disagree with any effort to remove or disable the pollution control devices. This type of action is what gets the legislature in various states chasing after us old cars, with this and that law, to put us off the streets.

The flat tops have a bad reputation because in 1974 no manufacture had the ability or skill to make an engine run well and meet the polution rules. These carb were their feable but best effort to meet the restrictions.

If you rebuild a carb and make some necessary adjustments, then they will run rich enough to solve the TOO lean problem that plagued them when new.

1974-76 was a dark time in automobile history with terrible running vehicles. Small changes to the system can cure this problem, and removing all the controls or disabling them is not only illegal but poor citizenship. We should all strive to have strong running cars that pollute as little as possible. Work the system. People change to round tops because these are more flexable and adjustable carbs at face value. The problem you have is finding the people who can do the key adjustment during rebuild that will make the flat top do the job.

Not that I'm trying to jump up on anybodies soap-box here, but I kind of have to agree with tanny here on this one.

I don't understand your statement, Lowell.

These carb were their feable but best effort to meet the restrictions. If you rebuild a carb and make some necessary adjustments, then they will run rich enough to solve the TOO lean problem that plagued them when new.

So they were too lean to meet emission standards. If you richen them up so they run right, then they are polluters! Take one stand or the other, Lowell. Make up your mind.

Also, your tag says you're an original owner of a '72. Ever have to work on a set of flat tops and make them run? Trust me, it can be done, but it's not easy.

Taking my step down....

I totally disagree with any effort to remove or disable the pollution control devices.

Lowell, Does this mean you still have your air pump connected? I think the vanes last only 2 years.

My air pump is connected and works. I have replaced two of the valves in the air injection system,some hoses, and replaced the airpump as the old one rusted up due to my extended storage of car. My car runs as clean and strong as new. Over all the 31 years of ownership I new saw someone beat me in an autocross because they took of some part of their polution system. There were other reasons.

Given all that, the car still is dirty enough to kill you in a garage. My new SVT Focus, and other modern cars, burn so clean you can't event use them for the final solution in a closed garage.

Those who like and respect older cars should respect that to make them "better" doesn't mean pollute more.

My SVT Focus will run rings around my Z, and do it almost pollution free. And now I read on the web young guys yanging off the catalyst, for what purpose?

I can debate this issue, but if you are of a mind to call names, if that is your best effort at rational thought, then I would not be spending my time with any expectation of communication would I.

Yes the richness does create more pollution, but the other controls mitigate that to a great extent. Given that the pollution would probably not be any more than a round top, the point is mute.

A previous writer clearly has stated and has experience in rebuild of flat top that are set to produce good results.

Yes I do recycle, maintain my car, don't dump trash, litter, etc. And I can have some sense that those who do are poor citizens who abuse the opportunity to reside in a free society. Go visit Singapoor, have a good time.

You can't compare 70's carburator technology with todays electronics.

Nor can anyone say for certain that an early de-smogged car in a perfect state of tune will pollute anymore than a smog equipped car in a sad state of tune without putting them on a machine and comparing the levels.

You cannot even compare the 74 cars with the flat tops to the 75's with FI as they are two entirely different systems. The early FI systems are now where near as good as todays, as todays systems are reactive and update their own paramaters during driving.

In the early cars, smog equipment was an after-thought brought on by very demanding legislative ruling. Because of this, it created quite a significant burden on the system causing loss in power and efficiency.

IMHO, they were still 'learning' about how to create a good system all the way through the mid-80's.

I've had the opportunity to run a couple different Z's with the emission-control equipment both on and off the car. The difference is quite noticable.

There are two sides to this coin. Emissions and fuel consumption. These two sides can be (and have been) argued until we're all blue in the face.

Originally posted by Lowell Marx

Well get back, I only stated " I strongly disagree with any effort to remove or disable the pollution control devices"

None of you have made any effort to state why doing so is good for the vehicle, society, you, me etc.

I came across this today (see link below). It's a timeline since the birth of the Z.

http://www.zonc.org/TechnicalInformation/Timeline.html

The problem with the pollution control devices is that it decreases horsepower. You can see a few complaints in the timeline about the decrease in horsepower over the years. This is why Nissan created the L28 and the EFI system.

So, it appears that Nissan did NOT understand the impact of this system on the engine until the car was on the market. And, it wasn't until the mid-70's that they tried to overcome and design for it.

In conclusion, the decision to remove this system from a Z is merely to obtain additional horsepower. I also think that not everybody needs additional horsepower, so, leaving the emission control equipment in place is just fine.

Sometimes the common goal of maximizing horsepower is a little too generalized. When people remove the emission control equipment, do they really know why they are doing such things?

...Just a bunch of name calling and verbal arrows.

I read back through this post and I don't think it's in the best interest for this group to see this again. These are called flame wars and they can get to be out of control. Hence, the need for moderators.

Anyway, I hope you got some of your questions answered.

Mike,

In the interests of making the thread readable, is it possible to remove those threads and replies which diverted the attention of the intended thread?

If you feel that this is not possible or would rather not, could you please copy the salient details relating to flat tops into a new thread.

The info in the thread must be regarded as interesting to people who[m] for whatever reason do not want to change to pre-emission SU's

Originally posted by Zedrally

In the interests of making the thread readable, is it possible to remove those threads and replies which diverted the attention of the intended thread?

Yea, good idea. Done.