vxturboxv

iTrader: (2)

Ok not technically retarded, but not advanced.

After doing the "rat nest removal" I realized I'm applying vac to the distrib all the time. (advancing timing) With the rat nest removal at idle there was no vac to the distrib.

I like the way the exhaust sounds with no vac. It's more of a deep pinging throaty note, but the idle seems less stable at low rpm like this. I could easily hook up a solenoid to return the car to the factory no vac idle setting. Just wondering why mazda decided this was beneficial?

Kentetsu

You have the vacuum advance line running to the wrong nipple on the carb base. Some of them always provide vacuum, and some only when on the throttle. I believe either of the two on the far right will get you where you need to be.

vxturboxv

iTrader: (2)

Good to know, but is there any benefit to doing this? Why not keep it advanced all the time? Is it just to prevent over heating at idle? I don't seem have any problems there.

Your saying not like this.....



But like this.....

Kentetsu

Right. You don't want the vac advance running at idle, because then you'll never get it to idle correctly. Also, if you set it up that way, you won't get proper advance when you do need it.

Just going by memory, I think there are five nipples on the base of the carb. Check each one for vacuum at idle, and use one that doesn't have any. I believe either of the two on the far right will work for this. I had this problem for a long time before I read this information and got it corrected. Setting idle speed and mixture is much easier once this is corrected. Idle should also be a lot smoother too. Good luck.

j9fd3s

iTrader: (3)

the timing is setup like it is, because they had to pass smog, and the distributor is a little limited. dizzy can adjust the timing like 20-25 degrees, the FC efi does 48 + whatever retards it needs

if you dont have emissions, the idle timing can just be set to where it idles the best

Ozmodiar-X

So the red one is correct and not the orginal? that could explain something then.

vipernicus42

iTrader: (4)

hmm... I've got mine connected on the second spot, like in the first diagram. How do you know which of those nipples gives vacuum when? I mean I guess a vacuum gauge could tell you vacuum at idle, but how do you get a vacuum reading under load?

Jon

Rogue_Wulff

The second from front *should* be a venturi vacuum. Venturi vacuum is drawn from above the throttle plates, only as they are opened, which is how the vac advance is designed to work.

Kentetsu

I'm only going by memory here, and I'll admit I'm getting a little old so I may be wrong. I hooked a vac line up to each nipple and felt for vacuum at idle. Once I found one that was static, I plugged my vacuum advance line up to that. I'm pretty sure it was one of the last ones to the right, but the alzheimer's could be kicking in again... Carl or Sterling should know for certain which one you (we) should be using...

rotaryboy23

iTrader: (1)

Not meaning to thread jack, but I just had a major concern,,, I have a Holley (non-RB) on a RB intake manifold with no emmission and thus, I have my vacuum advance hooked to a constant vacuum source on my Holley Carb... is this why I have to set my idle @ 1300 RPM to get the damn thing to idle? I thought it was vacuum leaks the whole time! What SHOULD I BE doing in this case? I assume the Holley would also have a venturi vacuum source... no?

1badFB

iTrader: (1)

I dunno bud, but when I had my vac advance hooked up wrong it didnt change much. Does run a bit smoother now tho...

Try pulling your vac advance tube and plugging it, and see if that helps your idle. If it does you gotta find yourself one of them fancy venturi vac ports if there even is such a thing on the holley. I am not sure if theyre are but its a start!

vxturboxv

iTrader: (2)

My car with the 2nd gen coils and intake mods I did will idle at 600 rpm with the advance hooked up. It actually won't idle as well with the advance not hooked up. (static) But it does sound cooler! I'll play with it and let you all know. As long as your not over heating I don't think it hurts a thing to have it constantly advanced.

I was more interested in the WHY not the HOW. But both are good to know!

thanks...

dbragg

iTrader: (7)

[QUOTE=vxturboxv]...intake mods...QUOTE]


elaborate please. i assume youre talking about the mods to the inside of the runners for better atomization, correct? if so, i was really wanting to do this but i have yet to have anyone answer me how these need to be. random design? duplicate spiral? ive read the whole other thread about it, but in there my questions were ignored. any info will help. thanks

pm me if youd like to not hi-jack this thread

vxturboxv

iTrader: (2)

[QUOTE=aws140]I did a little write up on it... The design isn't all that important. Read up here.

https://www.rx7club.com/1st-generation-specific-1979-1985-18/cutting-grooves-intake-manifold-555308/

dantheman

iTrader: (4)

I wanted to chime in here and say that I had mine set up wrong. I connected it up right and it runs quite a bit better now.

Thanks!