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Whats the name of this part?


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Was gonna just ask what the part is called that i was looking for but then realized this may be a good place to post the oddities. And hard to find part names and numbers.. Anyway im looking for this thing.. Its the white valve with two ports.. Not even sure where this pic came from but its got what i need in the right place .. Now just gotta see if i can load the picture.. Or maybe the url will work for now.. It seems that non of the auto stored arou d here have one.. Or may e weve just been searching in all the wrong places..hah thats why knowing the name of the part you bring in (broken in the palm of my hand) helps



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Have you tried this sight for reference pics?

Not sure what year or motor but this might help...



Also on posting pics....

People seem to like Imgur if on a computer. I use postimage from my phone. I find it easier.... says hot link for forum... copy and paste here....

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Used on all Z24 engines.


It's job is to leak air into the vacuum advance line to lower the vacuum advance signal going to the distributor when driving under load. It receives a vacuum signal from the carburetor venturi that varies with engine speed. When the vacuum exceeds a preset limit it opens and vacuum advance is reduced.


Unless you have smog testing you don't really need it. If removed or missing make sure you plug the short hose going to the TVV (thermal vacuum valve) right beside it. That's the thing with three hoses going to it and bolted into the base of the intake manifold. If it has to pass a visual inspection, a broken one is as good as a new one.

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The lower hose on the TVV???



top goes to air filter for filtered air.


middle goes to the EGR ported vacuum


bottom goes to the ported vacuum advance. The vacuum valve switch is also connected to it as described above.



The TVV is an open air bleed on the EGR and vacuum advance when the engine is cold. As the engine warms up the air bleed closes on the TVV and ported vacuum can now be allowed to the EGR valve and the distributor advance. Thus there can be no EGR or vacuum advance before the engine is fully warmed up.

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There should be three ported vacuum supplies on the carb base. The rear most one is for the VVT valve near the EGR valve to the rear of the intake. This ported vacuum should have a Tee with a hose going forward to the Vacuum control valve.

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Check out the link to the pic that works by the original poster....he posted a link for a reference pic.. so click on the article it gives a really good breakdown of all those vacuum lines.... might have what you want to see....


Yeah I found where the upper hose goes, but couldn't find where the lower hose goes.

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My rig came with a broken Thermal Vacuum Valve. I'm out of luck with the Vacuum Control Valve too. I just installed a Weber with only one port for throttle-dependent vacuum. So even if I do get a TVV and VCV from a source, I'll need the Hitachi's above, and below, throttle plate ports for distributor vacuum advance moderated by the Vacuum Control Valve. A straight connect from the Weber to the distributor makes the timing go beyond 20 degrees BTDC. Should I just stick with centrifuge advance by itself? What should the timing be on a manual transmission Z24 Hitachi with applied throttle in neutral? I'm thinking that having a properly configured VCV is more important, but I think that I saw a YouTube video with a Weber running vac advance.

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On the TVV if just the top of the three are broken off it will still work. The top hose fitting is only to supply filtered air from the air filter. Open into the engine compartment will work just as well, just not filtered.


Directly connecting the Weber ported vacuum advance to the distributor should work. There should be no ported vacuum at idle but only when revved. Then the throttle plate rises above the port and manifold vacuum is applied. Is this the case? If you have vacuum at idle perhaps the throttle plate is open too far. Or connected to the intake? or the wrong port?

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