borrow some manifold vacuum

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like_A_pike

like_A_pike

that's not factory
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I need to run cooler when not moving. I understand that smoother idle can be obtained too (which i could use)from getting some neg. pressure from below the throttle plate. The only port in the manifold is connected to the carb however. Can I split that source between the carb and the distributor to achieve my objective?

thanks
 
Instead of running the vacuum advance from the port in the carb I want to run it directly from the intake manifold. Can I splice the hose that currently draws manifold vacuum for the carb to another hose routed to the vacuum advance can on the distributor? ....maybe a better way of saying it....
 
....photos..... I don't understand why any MANIFOLD port would be connected to the carb, unless I misunderstood how you described this.

But you can't tee two sources like that
 
It sorta looks like a closed crankcase vent on the carb, but it's not hooked to a PCV on a valve cover, its drawing right off the intake manifold??? I'll take pix after work. I can't find anything on why this is hooked up like this.
 
I think you're talking about using manifold vacuum to provide extra spark advance at idle. Correct?
It's not running hot because of a lack of advance. It's running hot because there's not enough air getting pulled accross your radiator's fins when the car's not moving. I'm assuming buzzing down the road is fine?
 
moper your absolutely right and I am also going to install a shroud and go back to a factory fan. However, since the point of ported vacuum is to actually make the motor run hotter on purpose, and I'm chasing a smoother idle anyway, I thought I'd give this a go too.

After 67Dart273 comment, I visited the holley site and that hose isn't in their manual. So I took it off, blocked both ends, and went for a ride. The motor seemed to run a little smoother. I think that manifold port just became available!
 
like_A_pike said:
moper your absolutely right and I am also going to install a shroud and go back to a factory fan. However, since the point of ported vacuum is to actually make the motor run hotter on purpose, and I'm chasing a smoother idle anyway, I thought I'd give this a go too.

After 67Dart273 comment, I visited the holley site and that hose isn't in their manual. So I took it off, blocked both ends, and went for a ride. The motor seemed to run a little smoother. I think that manifold port just became available!
Click to expand...


Sorry, but you're mistaken. Ported vacuum is to advance the timing in relation to engine load (throttle opening). It has nothing to do with temperature expectations. If a cooling system is properly functioning, a change of 20-30° in timing at idle will not raise the indicated temperature of the engine at any speed. Manufacturers have done both ported and manifold vacuum setups when carburetors were OEM. But that had noting to do with temperature. If removing the vacuum advance hose from the ported helped the idle quality and overall smoothness, install the fan and shroud, and try setting up the rest of the ignition curve properly. You don't use the vacuum advance at full throttle, but the best way for a street driven carbureted engine to run is with the vacuum advance connected and the timing curve properly set. That is until such a point where the engine is beyond the ability to run with one, which is fairly rare.
 
Moper that really could be! a newbie picks up alot of different things on the internet. so I'm kinda fishing in here and experimenting. Sounds like we agree that the cooling system is a priority though. I could hurt something if I keep running too hot while trying things.

Tell me, I'm pretty confident about my temp gauge readings, what is too hot? thermostat is 180* and it sits there even at a crawl, but if it sits it goes into the 220's in 5 minutes , i've never let it go to 230
 
Have you looked at your water pump? I had a pump only a year old go out. The pump blade seperated from the drive shaft. Went through the entire cooling system, engine timeing, everything not suspecting it to be my new pump that went out.
 
My Neon has had bad a bad fan control (part of the engine control module) for years. If I sit, it overheats in minutes. Once I'm moving, it's at normal temps. The radiator can't work without air going over the fins. If you have a small electric, it may not move enough. If you have a flex fan, it may not move enough (and it's dangerous). If you have no shroud, it's not enough. My point was while timing does have an effect on temps, if the system is working properly... Meaning the block's not full of casting sand, waterpump or Tstat full of silicone, or the radiator's not 1/2 plugged or pinched off... It can cope with it fine.
 
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