Just 2 quick questions about my carb/engine...

Have newly overhauled my carb...Have got the perfect dwell rating now and it is running perfect...But I am a little bit curious about the fast idle speed??
How high should that be??...It's an 87model E4ME....

My car is now running on about 1500-1600RPM in fast idle..I think it is a little bit to much....I don't have the label under my hood or anything that shows me what is standard...Could anyone please help me???

And the last question...When I mounted back all the parts on the carb I forgot just one part ...The Float Bowl Insert peace...This black peace of plastic that is around the float bowl....Would this have any effect on my carb??..Cause it was broken on one corner so i figured out I could just buy a new one...So that would take a little time...I was just curious if it has any effect on my car that i'm using as a daily driver now????

Hope it's understandable..
Thanks

 

I'll have to go look at my label, but that sounds about right. It's set with the engine warm, so it won't be as high when the engine is actually cold.

I never have heard a good explanation for what good that plastic piece does. As far as I know, it doesn't hurt anything to leave it out.

 

The explanation I've always heard is that it reduces the bowl volume so that there's less fuel to evaporate.

 

I don't know what factory spec is, but I know from EFI'd cars you don't want your cold curb idle higher than 1200 or so. 1500-1600 is too high, regardless.

 

That's because FI cars have a computer to vary the idle speed to keep it on target. Carbed cars don't, so the fast idle speed is set high enough that it'll start and keep running under all conditions. 1500-1600 isn't too much at all.

 

I heard that black plastic thing is to keep fuel from sloshing out. Now that I think about it, i'm not sure how....
But in a q-jet tweaking book they recommended cutting off some of the bottom, to increase fuel volume, but they sure didn't recommend leaving it out...?

1600RPM sounds bang on for a hot engine, flicked onto the max cold idle tang. When it's COLD that'll barely be over 1000RPM. As it starts to climb up you just blip the throttle and you're back down.

 

The lable on my 84 Z28 say's 2000 rpm for fast idle and you can set that when the engine is hot and then it will be just right for a cold engine. If you don't set the fast idle this fast your choke settings will probley have to be reset. I have tryed a bunch of fast idle setting and the factory setting works the best.

Auggie

 

I have an 87 w/ a 305 E4ME and under the hod it specifies 2200 rpm when setting the fast idle

 

You know I think that you are right!! I was going from memory and I knew that the fast idle was at least 2000 rpm.

Auggie

 

1400-1500 warm is usually good. Don't worry about what the factory setting was.

All you really need is for it to be running fast enough that it will start cold and run reasonably smooth without risk of stalling. I always set my carbs (Qjet and Holleys) to run around 1400-1500 rpm warm, which is usually around 1200 cold, and I never had a problem - whether it was when my 350 was basically stock, or after all the mods - it worked just fine like that.

Just my $.02

 

, gonna try lowering fast idle to ~1500 rpm & see if cold starts are better.

 

The float bowl "stuffer" is there to keep from flooding out the carb when you slam on the brakes- all the fuel sloshes forward, unloading the float and causing it to over-fill the float bowl causing a immediate stall when you come to a complete stop.

 

after 2 months cold starts especially during Nov were awful - annoying engine rev 700 - 1100 rpms & took long time for engine to warm up. So put back Fast Idle setting to somewhere close to specs, and cold starts have improved (less engine revs, now about 900 to 1100 and much faster engine warm up). will probably be leaving the Fast Idle at factory seettings year round now.

 

It's simply amazing how well the factory settings work on these carbs.

 

Okey, I see here is a lot of answers to my question...And I must say I am a little bit in shock when I hear people are talking about 12-1300rpm on hot engine??....

When my engine is hot it runs perferctly in 750RPM's...My only small problem is cold starts...The engine don't die or stalls but I have a RPM on about 12-1300 now so I was just curious if that is about it?...

But I really think I need to reset my choke since I have repaired the carb for some months ago...But I don't have any of the special gauges to do that

 

1200-1300 on a hot engine, that is sitting on the fast idle cam. They're not talking about the engine idling that high all the time, this is just for setting up the fast idle cam for when the engine is sitting on the choke and cold.

 

okay..then I'm with you again..I misunderstood some of the answers..sorry..