Running really poor when cold LONG SORRY

[Anonymous]

Tim hit the nail on the head...

the engine really idles around 1000
800 is only when the engine is nice and warm... this morning idle was surging between 900 and 1000 which is normal for the cold weather.

Problem is, when I would drop the idle down to 700 which is where my cam manufacturer recommends their 270 cam it gets really really rough and will not maintain any idle, it usually stalls after a few moments of idle at that speed... bring it up to where it smooths out and it idles better.

I had a really low vacume reading (ony about 10-12 inches) and probably an intake leak, hopefully now I have that fixed, I will not know until this weekend, I am going to try to drop the rpms again and tune from there...
the idle has smoothed out a lot since I changed the manifold gasket, but I have not had a chance to tweak the engine yet.
:roll:

J.

 

[Anonymous]

The surging you mention is what I was talking about the unstable idle due to the throttle plates being openned too much. Advanced ignition timing from the vacuum can will smooth out the idle and also raise the idle speed. But then you can back off the idle speed adjustment and close the plates up, and it should idle smoother at the lower rpm.

 

[BIGREDRASA]

There are anumber of choke adjustments that you'll just have to wing, because there is no "book" on your setup.
First, the choke is supposed to close only to a point, a measurement done by placing the proper drill bit between the horn and choke blade. Next, the "pull-down" measurement is when the linkage forces the choke blade to open farther as the pedal is depressed. Next, the high speed idle is set by placing the adjustment screw on the proper step of the fast idle cam (usually has an arrow or other mark), and setting the high speed idle speed to specs (around 1500-1800). This is not the regular idle or mixture adjustment.
The bottom line is that when the choke is set, all these things have to be within limits. All these linkages must be able to move freely. With no book, you may need to find somebody who really knows carbs.

 

[ricksmol]

Jimbo:

My car has always idled at 950-1000 RPM. It seems to really like it at that range. Whenever I tried to lower the idle speed things roughened up. So what is wrong with that idle speed? You have a 5 speed manual trans like I do so the idle speed will not cause the car to lurch forward or have to have the brakes on tightly in a stop, as you would with an automatic.

I'd much rather have a nice smooth idle at a higher RPM anyday. I really do noth think that it makes that much difference in the mileage you'll get either, unless you spend the whole day idling.

As far as hot water going thru the intake..yes..yes! definitely do it. It helps a lot in cold weather.

Rick

 

[Anonymous]

Red,

that has been a problem for me from the start with this 2300 carb...

1. with the choke pulled all the way closed the plate is closed completely. Which is no good as the engine will not run.
2. with the plate closed to where it leaves the proper gap for the engine (i.e. drill bit measurement) the fast idle tang barely engages the throttle.

The wired thing is there seems to be no way to adjust the position of the choke plate? On my carter there was a clip in the rod that connected to the idle lever and you could bend the lever or move the pin location on the lever.

What I did to overcome this was I put the choke plate at the proper opening for the engine (which is about 1/3 of the way closed) then I cranked the fast idle screw up so that when the choke is set at this 1/3 position the engine is running at 1600 rpms. Then I adjusted the manual choke cable inside the car so that when I pull the choke closed it only goes to the 1/3 mark and stops there...

This was not the best method, but the only way I could find to get the choke to work for me? And it does work when it is cold out. But when the rain is in the air, even warm rain things will not run right at all? The moisture is getting me more than the temps.

I know I need to adjust the carb idle and I will play with that in the morning... not sure about the carb?



I am also going to revert back to something that was told to me a while back about the Aussie 2v and the Holley 2300 350 cfm.... I was told the venturi on the 350 was not big enough to let in adequate air at idle and that down under they had problems with this carb and rough idle... the best method of overcoming this was to go to the larger 500 2300... or drill the throttle plates on the 2300 or use the base of a 500 and the top of a 350.... the 350 has better atomization of fuel than the 500 but the larger venturi idles better... just wanted to mention it FYI?


Thanks


Rick, I have no real problems with the idle at 900? none.
but if that is an indication of a larger problem I am trying to sort that out.

For me my problems right now are the poor starts when wet, the idle is still rough at 900 sometimes, and the engine seems to crap out at 3000 rpms no more power over that? Temps are uncertain, and I am getting a lot of deiseling at that rpm when I shut her off.

 

[MustangSix]

I know it's an emission strategy, but my Jag idles at 750 rpm. The crossflow idles at 850-900 mostly because of cam timing. It's not an unreasonable speed.

 

[Anonymous]

I don't think 800 rpm is all that excessive with a cammed engine. I know timing may not be the answer to all of your problems, but I went through these same symptoms last year on a Pontiac that was a Heinz 57 of parts. Engine dieseling is a sympton of the throttle plates not being closed fully at idle. Retarded timing at idle will cause higher cylinder head temps that also contribute to dieseling when the idle screw is used to smooth out the idle. Insufficient advance at higher rpm's is also gonna make the throttle response flat and doggy.

 

[Anonymous]

my head is spinning....

i dunt understand all this....

 

[Anonymous]

Well fortunately I do...
most of it anyway...

I am going over everything tomorrow with a fine eye and see what I can figure out.. this is my last shot, then I am taking it to a mechanic this week.

I am going to get vacume readings.
check the plugs and wires.
Install a mechanical temp gauge.
install an in car vacume gauge.
Check the timing at 500 degree increments.
Drop the idle to at least close the throttle plates.
And spray for leaks, check the headers again.

I know I have too much all-in advance. The engine is timed at 10 degrees on the nose. I cannot go further without going really high on the total advance...

I need to re-curve this distributor, and I think I should make sure I have not blown another vacume canister... I have gone through a few. I also need to measure the vacume this carb is drawing from it's ported outlet.

I am betting I find lots of these things are off... it may be that I am simply in need of a serious tune-up, I have 2500 miles on the engine now.

I will post my findings and hopeful improvements over the weekend.


One more thought, could the problems I am having be from the engine runnning too cold? Even the oil buildup on my valves? if you saw my other post.
I am wondering if my gauge is really off

 

[Lazy JW]

As they say in Australia, "You have carburetor icing, mate!" Also, poor voltage control in your spark plug wires. Just for grins, try REDUCING the gap at your spark plugs. Way down, like .025". That will help in the wet weather. Also, try using manifold vacuum instead of ported vacuum for your ignition advance, this will speed the idle way up, and you will be able to close the throttle to where the idle circuit might work better. And yes, I think it is running too cold. Put a hotter thermostat in it, and hang a feed sack in front of the radiator like we do here in Idaho
Joe