couple of carb questions

[mperdue]

I searched the forums and couldn't find answers to these questions. Thanks for any help/info etc.

Ok what does the balance tube on the intake manifold do? Does it simply equalize the pressure between the 2 intakes? Is there some adjustability there? Anything else? Any idea what happens if you block it off?

Second thing, anyone know how intake gas temperature affects HP, fuel economy or any other engine "metrics"? If you're going for HP is cool gas better? I know later models piped heat into the intake radiated either from the exhaust or through the air filter. Was this just for emissions reasons?

Thanks again

michael

[Bambikiller240]

Does it simply equalize the pressure between the 2 intakes?

AFAIK, Yes, that's all it does (except to also provide a port for vacuum needed for your brake booster

Is there some adjustability there?

No.

Any idea what happens if you block it off?

Unbalanced breathing of cylinders?(front 3 cyls v.s. rear 3 cyls)

No port for vaccum to the brake booster.

Second thing, anyone know how intake gas temperature affects HP, fuel economy or any other engine "metrics"?

Cooler air/fuel mixture = more dense charge to cylinder, more air and fuel = more potential for power (if the charge gets fully burned)

If you're going for HP is cool gas better? I know later models piped heat into the intake radiated either from the exhaust or through the air filter. Was this just for emissions reasons?

The heat was/is only applied when the engine is cold. After about 80 degrees water temp (temp spec according to 2ManyZ's) the water flow is cut off by the valve at the back of the manifold. Heat applied to a fully warm engine would likely result in fuel vaporization in the carbs.

This feature is generally not needed unless you face ice and snow weather. It has been routinely eliminated by people seeking optimim performance since the mid 1970's. (original "How to Modify Dasun Engines and Chassis" published in 1973)

[240ZX]

What you said Carl......excellent answers!

[mperdue]

Carl,

It's good to know that that port is for the brake booster. I wasn't sure about that. What I'm asking all this for is I'm considering swapping my 210 carbs out for my 240Z SUs. I wasn't sure if I'd still need the balance tube but it sounds like I will. Also I was wondering if I need to pipe heat into the intake somehow but maybe they'll run fine without a heat pipe. Hmmm, this is goign to take a lot of work I can tell already. But before I do anything I need a better understanding of how all of this stuff works. Thanks for the info. I'll keep searching the forums for more tips.

Michael

[Bambikiller240]

Michael:

If you are thiking of using Z car SU's in the B210, you might find a lot of info on how/What to do from the DimeQuarterly (Datsun 510) email list folks. Doesn't it use the same 4 cyl engine? I don't have the info on how to hook up with them, but Victor Laury probably does.

[mperdue]

I think the 510's use L series engines whereas the 210's are A series. Smaller, not OHC, many other differences probably. You can find a manifold for this application in Oz but they're very rare. I've found one for sale actually but now I'm not even sure it works with the Z SU's. LIke I said, I've got a lot of research to do.

Michael

[Bambikiller240]

I think the 510's use L series engines whereas the 210's are A series.

Ah, I didn't know they used A series engines. Wonder why they switched to that engine?