360 tuning issues - cold weather driving

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superdart

superdart

Shade Tree Tinker Gnome.....
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Here is my issue, all feedback is welcome:

Warm weather: Car runs and drives fine. Have been driving for a few years with no issue.

Cold weather: Car is gutless, like the parking brake is still slightly applied. It misses at lower rpms while accelerating, then once it gets up to 1800 - 2000 rpms it's fine. WOT runs great. I never really drove it in the cold weather before, so this is a "new" issue to me. I am assuming it is running lean with the extra dense cold air.

I had a friend over to help me tune it since I have no experience at this. We tweaked it a bit and it's better, but still missing.

360 9:1 CR
625 Carter AFB - Electric Choke (new type)
FBO Ignition
Cam: Herbert E3N 455/475

Warm idle: 940 rpms (800 in gear)
Timing @ idle: 22 degrees
Gauge shows good vacum at idle in neutral and in gear.

Since it seems to be an off-idle issue, is it possible I need to change my meter rods?

If you need more info let me know.....
 
I would also guess it is a lean condition. Before you try a metering rod change, adjust the pumpshot for the intial off the line move.

Then try a twist of the idle screws.

Since the car actually runs on the idle circuit for a litle bit, this could possibley resolved with the above idle screw twist.

IF not, then a metering rod change may very well be in order.
 
I'm curious with all that timing why you would need an idle that high. What is your total timing and at what rpm? The combo seems rather mild to need anything crazy. What I would suggest is to start by re-setting the initial timing to 15° and set the idle speed to 750, then re-set the mixture screws. If it wont idle there, take some cylinder pressure readings because there's something amiss. You are right, it sounds lean, but fromt he idle and timing, it sounds lean to begin with.
 
OK, now you guys are talking Greek to me. Adjust the pumpshot? Remember this is the first time I have ever done this. I have the SA Carter book, but I'm still reading it..:read2:


Actually I had the timing at 18 degrees, but my buddy bumped it up. It's too high for my taste...when I bought the ignition setup from FBO, he told me to set it for 19 degrees at idle, and it would hit 34 at 3400 RPMs...that is based on my final setup...which is still lacking the correct gears (2.45s, but putting in 3.55s soon).

That is just where we set the idle...I'm sure we can bring it down more. I will try pulling down the idle and resetting the timing at least to where Don specified and see how it does.

Any other ideas?
 
The 625 Carter is an electric choke carb.

It does it if I start driving right away..but again, only in cold weather. Dallas is looking to be in the 75-85 degree range next weekend, so the car will most likely run fine.
 
I always disliked high idle speeds. In fact, I find better response by setting the thing low, and then simply increase the speed with the screw once the best vacuum reading is gotten. Adjusting the accelerator pump shot on a carter involves first switching the hole the rod is in... closer to the pivot point means a longer duration, further away is less shot. You can also bend the link rod if you really want to fine tune it.
 
You keep on reading that book and also go to Edelbrock.com and look up the instructions for the carbs. It's detailed and not hard to read and understand. It'll show you how to tune it and all the parts of the carb including the pump shot and how to work on it.

Take your time. Carbs need to be worked on and that takes a little time to iron everything out.
 
my car has the same problems in coldweather,i mess with the timing but all in all i just wait for the weather to warm up shes a cold blooded beast
 
Well boys its likly his heat cross crossover is plug or has none.when this happens the intake cant warm up fast enough.Remember back in the day when there was a tube coming from the right side exhaust to the breather that help warm the air coming into the carb.
 
Umm...the intake is an Edelbrock Airgap.

I have tinkered with it some more and this is what we have:

Neutral Idle: 780rpms
Idle in Gear: 690rpms

Vacum: 15 inches <- This is the best I can get out of it, but reading up on the web says that's normal with bigger cams and more overlap.

I adjusted the carb per the manual...I think it's reasonably close.
Fully warmed up I am reading 240-260 degrees at all of the header primary tubes (ceramic coated).

The car still missed just a little today...and it was 78 degrees. Apparently it's not a "cold weather" issue as much as a "cold engine" issue. Here is a video of what it sounds like when it misses.

I drove it for 15 minutes at both city and highway speeds, and this was the only time it did it, 3 minutes out of the garage.

http://s289.photobucket.com/albums/ll236/cowtownmopars/Personal/?action=view&current=Dartmiss.flv
 
Try this, When the engine is cold take off the air filter, start the engine and see how far the choke is open. There should be at least an 1/8" gap between the choke flap and the air horn. If not, you will need to loosen up the choke housing and rotate it slightly till you get the gap.
Worth looking at, and would explain your condition untll engine warms up.
 
Don't feel bad, I have the same problem with my 360 in cold weather. I have the Airgap intake with a Eddy 600 on it. I just figured it is a cold natured engine.
 
I'd say I have about 1/8 gap with the choke engaged.

Here is the other thing I forgot to mention. With the adjustments on my previous post, it heat sinks BAD.

I let it idle until it hits 200 degrees (point at which fans kick in), then I shut it down. After letting it sit for 20 minutes I try to start it back up, but it just sits there are cranks.

Do you think maybe there is still too much timing? Right now it's set to about 17 degrees @ idle. I've never had this issue before, but I've never had the idle speed set this low either.
 
The plug color is not really generated by the idle mixture. If the plugs show rich, try sticking in a fresh plug on each side after the engine is warmed up (whatever ones are easiest to reach) and drive the car a while. Then check those two.
 
Something to consider......

I had the car out today for a 50 mile run (Mopar show at our sponsoring dealer).

The car ran good the whole way in both the highway and the city. I think the last piece of this puzzle is making sure my A/F mix is correct and I should be good to go.

One thing I DO need to fix is my temp gauge. It's an electronic VDO gauge that I bought new, but for some reason it reads almost 20 degrees high. The gauge will read 210, and an IR temp gauge on the sensor will read 190. I might have a bad wire or solder joint....I am assuming that increased resistance=higher temp..but for now at least I know how much it is off.
 
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