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Idle question on an idle day

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JPSmit

JPSmit

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I think i forgot to mention that Ms Triss is finally awake. Went to her first/ show swap meet today. No pics but the usual hive of 'B's etc. a few Loti a maxi amount of Mini's a couple of odd Austins etc. actually more cars and vendors than i have seen at this event. Anyways, here's the question. When i start the car it idles at about 800 rpm as it warms up idle increases till at all warm it is about 1400 rpm. Any thoughts? Vacuum is disconnected.
 
Sounds like it is running lean and the mixture is correct when it is warm. Do you have to use the choke when you start?
BillM
 
Billm said:
Sounds like it is running lean and the mixture is correct when it is warm. Do you have to use the choke when you start?
BillM
Click to expand...

Only initially - but it was cold today too. 40 deg F or so
 
OK, then not lean. Maybe your intake manifold has come a little loose and is opening up when it is warm?? or a vacuum hose has a crack in it that opens when it is warm? after that I don't have a clue.
BillM
 
what carb(s) do you have jp?


m
 
SilentUnicorn said:
what carb(s) do you have jp?


m
Click to expand...

Single HS4 - rebuilt (professionally) in 2010
 
Billm said:
OK, then not lean. Maybe your intake manifold has come a little loose and is opening up when it is warm??BillM
Click to expand...

X2, tighten your intake especially the rear lower nut.
 
kellysguy said:
Well, your nuts tight?
Click to expand...

sicko

rain snow mix called for on the weather - ain't going anywhere outside I don't need to.
 
<div class="ubbcode-block"><div class="ubbcode-header">Quote:]Only initially - but it was cold today too. 40 deg F or so[/QUOTE]

Soooo... I am sure someone will correct me if I am wrong on this... but as I understand it a "choke" on a ZS or SU carb is not strictly speaking a choke. It's more of a starting and warm up enrichment and idle control. The way it is intended to be used is you pull it out and leave it out until the car warms up... then you push it in. So it sounded like from your description, that you are pushing the choke in right after start up which is going to make your car run lean until it warms up, and then it will give you your "true" idle.
 
Morris said:
<div class="ubbcode-block"><div class="ubbcode-header">Quote:]Only initially - but it was cold today too. 40 deg F or so
Click to expand...

Soooo... I am sure someone will correct me if I am wrong on this... but as I understand it a "choke" on a ZS or SU carb is not strictly speaking a choke. It's more of a starting and warm up enrichment and idle control. The way it is intended to be used is you pull it out and leave it out until the car warms up... then you push it in. So it sounded like from your description, that you are pushing the choke in right after start up which is going to make your car run lean until it warms up, and then it will give you your "true" idle.

[/QUOTE]

I think you are right. Certainly I push it back in. But if my "true" idle is 12-1400 (which it certainly could be) I am stuck with the fact that it would die when cold if I turn it back to 800 when hot - does that make sense?
 
Again... I am on thin ice here because my experience with HS4s is limited, but I think you can set fast idle separately from regular idle. So the procedure is you pull the choke, start it up cold, set the fast idle, let it warm up, push in the choke, then set the slow idle.

Nevertheless, if your slow idle was 800 last year and 1400 now, a good ol' fashion vacuum leak hunt is in order. You also may want to check your dashpot oil if you haven't already.
 
Twin hs4's on a 1500 here.

I set my idle hot. Not warmed in in the driveway hot, but road hot.
Make sure the jets are on the adjustment stop. They must operate and return equally when the lets are lowered by the choke knob. I use a little dab of grease to help. Tweaking the linkages us usually needed to accomplish this. Make sure the high idle is disengaged. When the choke knob is used i try to get it to kick up the idle at about half travel. My car will not idle cold with out the high idle engaged. Takes about minute and half to be able to set the idle using the choke. As warm up occurs my idle speed increases till i push the choke all the way in.

Hope this helps JP.

m
 
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