We're bringin' back the Flat Tops!

[motorman7]

Continued the part removal process.  Removed the Transmission and drive shaft.  Also started removing door hardware and windows.  I may be able to get this off to the paint shop by next week.  That would be nice since the paint job is the long pole in the process.  Paint will take about 4-5 months.   Will work on motor re-furb, and undercarriage parts while body is at the body/paint shop.

[Gav240z]

Good to see flat tops being utilised, I've heard they are actually superior to the early round top SUs as the idle circuit can be set independently of the rest of the throttle range. I think the flat tops suffered from the old grape vine, in that a lot of folks never actually took the time to understand them, restore or fix them so they work properly and just ditched them based on what "other people said". But many of these people would not have verified the facts for themselves.

I would be very interested in the opinions of those who have had experience with them and got them running right!

The only downside I see with them is that they make the engine bay look a lot more complex than the earlier simpler carbs. 

[Captain Obvious]

There are several technological advances built into the flat tops, but as always... With more technology, comes more complexity. And attention to detail is paramount.

I'll never expect a huge groundswell of flat top love and people ditching their round tops to replace them with flat tops, but I do believe that if they are working properly, the flat tops are better carbs. However, because of the additional complexity, you must be willing to put in the time and effort to set them up right and keep them that way.

[Gav240z]

Makes sense to me, which is why it sort of upsets me that so many were likely thrown out over the years. What a waste.

Interestingly this 260z 2+2 came onto the market in Australia a while ago and 1 of the things that appealed most to me about it, was the fact it still had the original flat tops and steel wheels and caps!

https://photos.app.goo.gl/CWdhoXxY9WjdXoKE2

All the emissions gear was there and in place too. Beautiful.

[Captain Obvious]

Agreed. And the damage to the reputation is already done, and (I believe) is irreversible.

So, that 2+2 you posted about... I don't know anything about cars that were stock gear in other countries, but that 2+2 would not have had all the pollution equipment in the US. If it were here, it would have had EGR, and throttle opener, just at quick glance. And air injection with the pump.  So if you think flat tops were complicated in your part of the world, you aint seen nothing! 

So how long did the flat tops run in Australia? I assume they started in 73 just like they did in the US, but here they stopped in 74. In Australia (and elsewhere in the world), they ran the flat tops for a number of years beyond 74, didn't they?

[Diseazd]

Sorry, but I think the fact that so many tossed the 73 flat tops in the 70’s speaks for itself.....flat tops just were a major step down from the earlier carbs.....glad you folks are going for originality, but I wouldn’t even think about trying to make them work. I just picked up a 73 for one of my friends who bought an original 73......had to use starter fluid to get it started.  No thanks.....and good luck to you for trying!

[Patcon]

34 minutes ago, Diseazd said:

Sorry, but I think the fact that so many tossed the 73 flat tops in the 70’s speaks for itself.....flat tops just were a major step down from the earlier carbs.....glad you folks are going for originality, but I wouldn’t even think about trying to make them work. I just picked up a 73 for one of my friends who bought an original 73......had to use starter fluid to get it started.  No thanks.....and good luck to you for trying!

Maybe @Zup will take you for a ride in his 73 in Oct. He is running flat tops from Paltech and I don't think he has any issues with them

[zKars]

Flat tops got to the place and reputation for three reasons.  IMHO

1. Complexity. When they wear out, and they all do, rebuilding them was difficult. Kinda the same, keeping them in tune was also tricky.

2. Availability of the earlier simpler round tops. Why bother when something simpler and better is available, barring some polution law in your kneck of the kwoods that made you do it.

3. Rebuild kits were NLA for a long time. MSA has them again, I bought a set. 

I have a bushel of flat top cores if someone is wanting some....  Crickets......

I have previously expressed my admiration for the design of the flattops.  While I threatened to build a set and show the na sayers some time slips, well, you know what happened. Too complex, time consuming and there are these fantastic folks at ztherapy....

[motorman7]

20 hours ago, Gav240z said:

I would be very interested in the opinions of those who have had experience with them and got them running right!

My only experience with the flat tops is that I had a '73 with them on and they ran great, even in bad traffic on the 5 Freeway.  Hard for me to complain when I have only had a good experience with them.

[Captain Obvious]

3 hours ago, Diseazd said:

flat tops just were a major step down from the earlier carbs....

LOL.  And it's exactly this kind of claim that I'm talking about when I said the damage to the reputation is already done, and (I believe) is irreversible.

[jayhawk]

20 hours ago, Diseazd said:

Sorry, but I think the fact that so many tossed the 73 flat tops in the 70’s speaks for itself.....flat tops just were a major step down from the earlier carbs.....glad you folks are going for originality, but I wouldn’t even think about trying to make them work. I just picked up a 73 for one of my friends who bought an original 73......had to use starter fluid to get it started.  No thanks.....and good luck to you for trying!

So you had a hard time starting a 45 year old car, and from that you concluded the flat tops were a "major step down"? Hmm.  My flat tops ran just fine during the 70s while commuting and making sales calls all over southern California, but like many of us, I was convinced by a 1980 mechanic's presentation at the Orange County Z club meeting that the round tops were so superior, and paid him over $500 to replace my carbs.  Funny thing, he (and zTherapy) made a lot of money, but I had NO performance or drive-ability improvements. 

One can only speculate why mechanics (and zTherapy) love to disparage the flattops...

 

 

 

[240260280]

I thought it was the extra pollution stuff on the 73 manifold that caused the complexity and problems which painted the flat tops with the same brush.