What is this?

[Rat baby]

Been reading and looking quite a lot but can not find what this part is or a part number for it. It had a little red cap that fell off. It doesn’t seem to make any difference if it’s hooked up or not. Just can’t stand not knowing. Thanks! 

[datzenmike]

 That's the vacuum control valve. It's connected into the vacuum advance hose to the distributor. It's function is to limit excessive vacuum signal from the supply port on the carburetor. Probably on sudden high speed deceleration. It will run just as well without it. Yours is actually broken or at least... missing the top from it.

[paradime]

Nah, isn't that the fratostat recirculation filter to prevent pre-evaporated flush charge from reentering the choke advance clutch during warm starts? Pretty sure it is. 

 

 

Damn Mike, sometimes you scare me. 

 

 

[datzenmike]

I had a functional Z24 in my 620 and tried to get everything working on it. Most of the emissions stuff does nothing until the engine is warmed up, then it only does it between idle and full throttle so it really doesn't do much when driving it hard. There is an idle fuel shut off on deceleration that actually saves gas that would normally not get used. A couple of things affect tail pipe emissions but have zero effect on running. It's down side is complicated hoses and routing.

 

It now has an L head on it and I'm waiting for summer to try making more emissions in my 710.

[Rat baby]

17 hours ago, paradime said:

Nah, isn't that the fratostat recirculation filter to prevent pre-evaporated flush charge from reentering the choke advance clutch during warm starts? Pretty sure it is. 

 

 

Damn Mike, sometimes you scare me. 

 

 

 

Do you know where to get one for an 84 720??   🙂 

[Rat baby]

11 hours ago, datzenmike said:

I had a functional Z24 in my 620 and tried to get everything working on it. Most of the emissions stuff does nothing until the engine is warmed up, then it only does it between idle and full throttle so it really doesn't do much when driving it hard. There is an idle fuel shut off on deceleration that actually saves gas that would normally not get used. A couple of things affect tail pipe emissions but have zero effect on running. It's down side is complicated hoses and routing.

 

It now has an L head on it and I'm waiting for summer to try making more emissions in my 710.

 

Thank you! Very helpful. Loving all the knowledge you guys drop. So many improvements getting done, thanks Ratsun! 

Edited March 14, 2019 by Rat baby

[paradime]

 

 

3 minutes ago, Rat baby said:

 

Do you know where to get one for an 84 720??   🙂 

 

The vacuum control valve, or the fratostat recirculation filter?  For the latter, I have a connection with a dealer in Borneo. 

 

Good luck with that truck Bro, 🤘

[datzenmike]

1 hour ago, Rat baby said:

 

Do you know where to get one for an 84 720??   🙂 

 

Probably another 720, I doubt you can just go to NAPA and get one. Try a want ad in the classifieds... https://ratsun.net/classifieds/category/9-datsun-parts/  ... maybe someone has an old engine laying around. May have been used on other years.

[Crashtd420]

Probably gonna have to what Mike says.... unless you find an old stock....

Looks to be discontinued....

 

 

 

I think this is the nissan part number you want.... 

[datzenmike]

At the end of the day it will run without it. Excessive vacuum advance would only happen on deceleration at high engine RPMs.