Flattop to Roundtop carb conversion. Help with hoses, intake manifold, etc please!

[Bruce Palmer]

Needle nosed Vice Grips in that un threaded section in the middle works fine.

Edited February 7, 2012 by Bruce Palmer

[yoshi_w]

My car is a 1973, and I haven't checked the float levels yet, but I'll be sure to do that. I appreciate all the help you guys have provided! And as for starting the car, are you saying I give the carb fuel, then hook up the fuel lines? And also, do I need those emissions devices? because Im trying to keep everything as simple as possible, thanks!

[Bonzi Lon]

To prime my fuel system when fully dry from tank to carbs, was to remove the valve cover and manually work the fuel pump arm until the bowls filled. This way you can see if the fuel pump works without starter / engine noise, you can see the fuel go into the fuel filter and it will help spot any small leaks in the system before firing up.

Bonzi Lon

[Captain Obvious]

Yes, I'm saying that you use a short piece of tubing to connect a small funnel directly to the input nipple on the carb float bowl, and then slowly pour gas into the funnel until the carb won't take any more. Then after the bowl is as full as it's gonna get, do the same thing to the other carb.

After you're done with both, set the funnel and short tube aside and connect up the fuel lines from the fuel rail and then try to start the car. If everything is working properly, the fuel in the carbs bowls should be enough to run the engine for at least thirty seconds or more before they need more fuel, and by that time, hopefully the fuel pump is on-line and pumping it's little heart out.

Your question about "do I need those emissions devices?" is a little tougher to answer. It all comes down to what you mean by "need".

All of the emissions devices on your car were put there for a reason. That reason is to make the world a cleaner, greener, better place for all those who walk this earth after you. Your car would probably run smoother and perform stronger without any of them in place, so if you look at it that way, you don't really need any of them. However, if you care about doing your own little part to preserve what's left of the environment, then you should try your best to comply.

Some systems on the car do not cost anything in the way of performance yet do have environmental benefits:

The PCV system

The evaporative emissions system

The throttle opener system

And then there are some systems that do potentially cost performance:

The EGR system

The AIR (Air Injection Reaction) system (the air pump)

All depends on where you stand and that part is up to you...

[LeonV]

My car is a 1973, and I haven't checked the float levels yet, but I'll be sure to do that. I appreciate all the help you guys have provided! And as for starting the car, are you saying I give the carb fuel, then hook up the fuel lines? And also, do I need those emissions devices? because Im trying to keep everything as simple as possible, thanks!

Yoshi, this is Leon, the guy that sold you the carbs. I ran these on my first 240Z with the emissions stuff plugged off. The emissions hoses were cracked and old, and there was no AIR pump to be found on that car, so I decided to plug them off as to alleviate some vacuum leaks.

The PCV valve should still be in the balance tube, all you have to do is connect your block breather tube, located underneath the distributor to the PCV valve. The flow guide valve hoses should be easy to hook up as well, reference the manual. [EDIT: I think one hose goes to the block breather and the other to the air cleaner, but I'm not 100% on that.] The throttle opener is currently not hooked up, but you could if you wanted to. I rarely drove the car and didn't see a need to make it work, but you could if you wanted to, again the manual will show how it goes (remember to reference '72 and older manuals). If you don't have an AIR pump, and your AIR gallery is not functional or present, then you obviously will not be using the AIR system. There are no provisions for EGR with these carbs, although I suppose you can make that work if you wanted to by using the flat-top balance tube.

Good luck and let me know if you run into any problems!

Edited February 9, 2012 by LeonV

[yoshi_w]

Alright, I shall try this on the next sunny day! Thanks all for the help, can't wait to get the z running again finally, and yup leon, I shall definitely ask you for help, took me way too long to finally muster up the courage to change the carbs hahah. Hopefully all these suggestions work out, otherwise I'll be back on here . Thanks again everyone!

[LeonV]

Alright, I shall try this on the next sunny day! Thanks all for the help, can't wait to get the z running again finally, and yup leon, I shall definitely ask you for help, took me way too long to finally muster up the courage to change the carbs hahah. Hopefully all these suggestions work out, otherwise I'll be back on here . Thanks again everyone!

Not a problem. I'm pretty busy these days, but I could probably manage to stop by sometime if you're having trouble. Feel free to PM me, or give me a call if you still have my number.

[yoshi_w]

So I am in a bit of a trouble spot. I am getting kicked out of the garage I have been working in by March 31st, but the car is not running, I need to look for another garage, but I need to find one that lets me work on the car as I'll probably have to bring over on a tow truck, otherwise I could just have a shop finish what I've started. It has been slow working on the carb swap due to missing some stuff and having midterms and lots of studying. I have the carbs and the linkages on but noticed in pictures that I need a spring hooked onto what looks like a heat shield? Is this vital, and Leon, do you possibly have this part? Or alternatively, where could I get this? Or is there anything I can salvage from the flattop carbs? Thanks for all the help!

[Bonzi Lon]

Yes, you need the springs for the throttle return. I've seen many different types of springs used on them, just enough strength to close sharply, but not too hard to push open. The heat shield is for that purpose, there are several variations, the one above has the cut out for a header tube. I have one with out the cut out.

One of the more interesting spring uses I've seen, was 2 screen door return springs cut down to attach to the front brake line. It worked!

Bonzi Lon

[Bruce Palmer]

We have heat shields and new return springs....

[LeonV]

So I am in a bit of a trouble spot. I am getting kicked out of the garage I have been working in by March 31st, but the car is not running, I need to look for another garage, but I need to find one that lets me work on the car as I'll probably have to bring over on a tow truck, otherwise I could just have a shop finish what I've started. It has been slow working on the carb swap due to missing some stuff and having midterms and lots of studying. I have the carbs and the linkages on but noticed in pictures that I need a spring hooked onto what looks like a heat shield? Is this vital, and Leon, do you possibly have this part? Or alternatively, where could I get this? Or is there anything I can salvage from the flattop carbs? Thanks for all the help!

Yoshi, I'll have to take a look and see if I can dig up a heat shield. I can't guarantee it though, my garage is a mess!

I can come by and have your car running the same day, we can improvise on a throttle return if you just need the car moving. I commute to Petaluma so I drive through SF everyday. I can stop by and give a few pointers or an extra hand sometime, just let me know if/when and we'll try to schedule it.

[yoshi_w]

Leon, that would be massively helpful! I'm on spring break this week, so if you are available any time this week I would greatly appreciate it!