Re: [Chrysler300] Idle speed adjustment question

On Apr 20, 2014, at 6:38 AM, mgoodknight@xxxxxxxx wrote:

Hi Mike,

In my opinion it is not very likely that your idle stalling problem is the result of a loose and slipped timing chain. It is certainly a possibility for such an occurrence as I have experienced it personally. In my case (LA block 360 engine) the chain became worn enough to sag quite a bit at the crankshaft sprocket when the engine was not running. As long as the engine was operating the chain remained well engaged to the sprocket teeth, but when shut off the crankshaft would come to a stop and then bounce back just a little against good compression. It was at that moment or on attempted restart when slippage occurred. The chain sag and change of crankshaft direction can completely disengage the chain from the crankshaft sprocket and allow a slip, usually for only one tooth at a time. Mine did it twice, but I was able to rotate the distributor re-advancing the spark enough (barely) to drive it home even with the valve timing badly upset.

I do think it's likely that you have a timing problem or an air leak. As you know your engine will slow considerably at idle speed when you retard the spark and it will speed again as you advance it again. Something that hasn't yet been mentioned to you is the possibility of a problem with the mechanical advance system in your distributor. What I think is happening is that you are losing spark advance when you put your transmission into D thus making it slow more than it should by just adding the torque converter drag. This can be caused by a centrifugal advance mechanism that is allowing advance to occur at too slow a speed maybe because of a broken spring or worn weight.

Another possibility is in the vacuum advance system. I'm uncertain how your vacuum advance system is designed as I've not studied a ram induction car. There are 3 basic kinds of systems-- -referencing the vacuum source for the distributor. One is "manifold vacuum" where the advance diaphragm is connected directly to the intake manifold so that spark advance occurs even at idle. Another is "ported vacuum" where the diaphragm is connected to the carburetor at a location that does not get vacuum thus no spark advance when the throttle plate is at idle, but a port is revealed to vacuum with only a slight off-idle opening. The third system is ported in the carburetor to a location where "venturi vacuum" is sensed and this also gives no spark advance at idle. If your car has manifold vacuum connection you might be experiencing a low vacuum condition (air leak, valve trouble, etc,) that is causing a greater than normal loss of vacuum and loss of spark advance as the engine slows when the transmission is engaged.

I will do a little research now to determine how the vacuum is sourced on the ram induction engines . I'm curious. I have an uninstalled ram setup with 2903 carburetors that I will look at as well as a '64 service manual.

Hope this is helpful information.

Happy Easter,

Marshall Goodknight c300

---------- Original Message ----------
From: Michael Moore <mmoore8425@xxxxxxx>
To: "kmaniak@xxxxxxx" <kmaniak@xxxxxxx>
Cc: Chrysler300@xxxxxxxxxxxxxxx
Subject: Re: [Chrysler300] Idle speed adjustment question
Date: Sat, 19 Apr 2014 18:41:57 -0700

Chris, how did you find it had actually skipped a tooth?

If I time my engine "by ear", i.e., advance until I get max rpm, then back off slightly, then when I drive up the hill to my house and the pistons start trying to change cylinders I back off some, if I time it that way it is with the timi ng mark apparently way more advanced than 10 degrees, A few years ago when I noticed that I decided the outer part of the damper was slipping so I bought a new damper-same thing.

I have never seen an engine which actually skipped a timing tooth. I can more easily imagine engines where the timing sprockets weren't correctly aligned.

I also may be running into problems from the rebuild in 1984 where the builder, a top race engine builder in Illinois, did me some favors because he knew the car was going to California, and he knew the days of tetraethyl lead were growing short. So he had a custom designed camshaft made by Barnes. Its purpose was to lower compression ratio by adjusting the timing of when valves opened and closed. I never liked the way the engine ran since then. I recently found what is probably a 300H camshaft which I plan on installing.

Gasoline quality is another issue I suppose.

Best, Mike Moor e

300H

On Apr 19, 2014, at 4:05 PM, kmaniak@xxxxxxxx Moore

300Hcom wrote:

Mike:

I know this may sound like a silly question, but...

Did you check the timing first to verify that it hasn't retarded since the last time you checked it? The last time one of my K's refused to idle at a stoplight and I had to employ the "one foot on the gas and one foot on the brake" procedure, I discovered the timing chain had skipped a tooth.

Chris the K MANIAC

-----Original Message-----
From: Michael Moore <mmoore8425@xxxxxxx>
To: Listserver Chrysler Club <Chrysler300@xxxxxxxxxxxxxxx>
Sent: Sat, Apr 19, 2014 3:43 pm
Subject: [Chrysler300] Idle speed adjustment question

I just spent an exasperating half an hour adjusting, (or trying to adjust,) the idle speed on my carbs.

The problem I am trying to eliminate is the engine dying at stop lights unless I keep a foot on the gas and one on the brakes.

Out of gear, the idle speed fine except the transition form hs idle to curb idle is pretty raggedy.

I have been following the factory service manual procedure which calls for initial one turn open on idle bypass screws and one to two turns open on the idle mixture screws . I can get the engine idling at 650 and each idle mixture screw seems to be at max rpm. But when the car goes into gear, it dies. I've been increasing idle speed up to 800, but it still struggles in gear at a stop.

Is it too lean?

I am guessing unscrewing the mixture screws ought to richen it up.

Should the bypass screws be so open as to have audible hissing from the intakes?

Thanks,

Mike Moore

300H

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