vacuum port on left rear of head??

[ofg]

Trying to get my 79 210 back up and running. there is a plastic vacuum port thingy on the driver side rear of the a14 cyl head. Its white plastic, has 3 ports for vacuum lines. Was not connected when I got the car.

 

Sorry, no pics yet!

 

Anyway,, can I take it out and plug the hole? Whats it for? Doing complete emissions delete,, so..What is it?

[datzenmike]

Probably power brake booster. Another line would go to the air horn snorkel for the mixing of warmed air from the hot exhaust. Should leave that if you live and drive in areas that see temps drop below 40F. If you have an automatic there would be a vacuum line to the transmission and one to the anti backfire valve.

[Kramer1981]

My guess is emissions crap. Taken plenty of that out of V8's, still new to Datsuns though. I will look on my 75 tomorrow, but its probably a whole different animal.

[metalmonkey47]

Vacuum switch is what you're talking about *I think*.

 

Can you get pictures? Just kinda curious... Don't recall my A15 having vacuum port on the cyl head.

[ofg]

Part in question is the white plastic thing with 2 small ports sticking up. its just under the last manifold stud. Has a third port on the end broken off. I dont think its for brakes because the hose to the brake booster is the big one with a chipped end that winds up and right in the pic. It has a dedicated port on the intake manifold.

 

 

 

 

 

[Kramer1981]

My 75 doesnt have it....I think its a temperature switch, switching vacuum lines, probably some emissions or EGR crap, as I said I have taken many of them off V8s.

[ofg]

Your right, it is a temperature switch. I unscrewed it,, and coolant came pouring out. Its a temp controlled vacuum switch for the distributor advance. Apparently, it controls dist advance according to engine temp, to reduce emissions.

 

Heres the dilemma. Do I need it to get optimum performance from my system? Can I control distributor advance by connecting the vacuum lines differently?

 

I would like to see some vacuum diagrams from other a14 cars that do not have all the emissions crap.

 

Another problem..To get it loose, I had to break off the 2 remaining vacuum ports on it,, so I could get the closed end of a wrench on it. The open end wrench was just slipping. Sooo.... its broke. Do I screw it in tight and not worry,, or replace it and sort out the dist vacuum lines???

[ofg]

All righty then! Tech wicky at the datsun 1200 club provided some amazing info and even drawings! Looks like it is for egr and dist advance.

 

Ima mind to just leave it alone and find another source for dist advance. Yep,, back on track. Unless somebody here sais else wize,, but by then,, the manifolds will be in place,, and Im not gonna worry about it.

[datzenmike]

The way it works is there is a vacuum bleed through the thermal vacuum valve. When cold, vacuum to the dizzy or the EGR is leaked so there is no vacuum to the dizzy or EGR. When the coolant warms, this bleed is closed and vacuum is applied to the dizzy or the EGR. You have three hoses to it, one goes to the air filter to supply filtered air into the bleed. The other two go to the vacuum sources on the carb. If you know which is which just connect the carb directly to the dizzy.

[Kramer1981]

Just find your ported vacuum on your carb. should be drawn just above throttle blades. with the car running, it will have little to no vacuum signal at idle, then progressively increase with engine speed. That should go straight to your vacuum advance on your distributor...and go buy a new piece of vacuum hose, not some brittle piece of crud you found under a car at the boneyard.

 

you might not do tht sort of thing, but I have been known to, and it causes headaches