Z24 idle/temperature question

[KrazzyKevin]

Hey guys, I've got two quick questions I thought I'd throw together in one thread. Basically I don't have any real problems with the Z24 engine in my 720, but I'm curious about a few things. Firstly, my temperature gauge NEVER comes even half way up to warm. I made a short video to show this. The video was filmed after about half an hour of fairly hard driving (including stomping all over this silly girl in an accord :fu: ) That's about as warm as the gauge ever says my engine gets. Does that indicate that I need a new thermostat? Or is the gauge itself broken somehow?

 

My other question is that my motor idles at roughly 1100-1200 RPM. My factory service manual shows that it should be idling lower than that. If I rev it pretty good, like up over 3000 RPM or so like I did, it idles down to about 1000 for a bit, then comes back up. I assume the carb just needs some adjustment? Its the stock carb.

 

Here's the video:

 

 

Oh, and ignore the 'Boop-beep' half way through the video. That's my phone getting a text. haha :D

[datzenmike]

First I would run a ground wire to the yellow/black stripe? temp sender wire. If everything is working properly, the gauge should go to FULL HOT with key on. If it only goes to where it is now, the gauge is stuck.

 

It's very very slightly low. There are no numbers so it's just a warning when something does go wrong and changes it's 'normal' position.

 

It's probably got the original thermostat in it and it may be stuck slightly open. This will slow the warm up and give poorer economy because the motor never warms to operating temp.

 

I would get a good $12 thermostat and gasket about 185 to 195 range. If the gauge still reads the same I'd live with it.

[KrazzyKevin]

Thanks Mike. Got a new thermostat, just put it in. I'll report back when I start it up and see what the gauge does.

 

Edit:

 

Started her up, let her idle for 10 minutes maybe then drove around the block, the gauge works now!

 

 

Thanks again mike.

[datzenmike]

You may notice it runs better, easier to drive.

[Spades]

are you still having the high idle issues? did you try turning the screw that controls the idle down slightly? After turning the idle screw down, turn your headlights on(with highbeams on) to get the alternator regulator to kick in. With the alternator on and the vehicle fully warmed up, you want the idle closer to 700 rpm.

 

If it idles rough after dropping the idle speed, turn the mixture screw. What I normally do on carb'd cars is tune by ear, we have a sniffer at our shop so I can see if the car is running rich or lean, but most of the time by ear I can dial them in spot on. Turn the idle screw out till the car almost dies or wants to die. if it stalls, turn the screw back in a hair and restart the motor. then, counting how many full rotations you do, turn the idle mixture screw in until the car almost bogs out again. Say you had two full turns, then when you have the idle screw in so far its about ready to die, back it out a turn.

 

That process will put you in the halfway point, and you can make minor adjustments with the idle fuel mixture screw until it sounds like it is running the best.

 

Once the car is tuned, I normally have to re-tune it only for summer and winter...provided its not a finicky carb that falls out of tune easily.

[KrazzyKevin]

You may notice it runs better, easier to drive.

 

 

I'm actually noticing some hesitation on acceleration now. I don't know if that's related to the thermostat or not. In second or third gear if I step on it, it sort of.. hiccups. I don't really know a better way to describe it than that. It like, bounces ever so slightly and doesn't accelerate. if I let off the gas for a second then immediately step on it again the problem goes away and everything is fine.

 

Basically I'm getting pretty annoyed with my stock carb. I've got a webber on the way. Hopefully that solves my high idle and this problem.

[ggzilla]

Small vaccuum leaks cause those symptoms. Not usually the carburetor. Replacing the carb you will probably eliminate some hoses, problem goes away...