Rodchester Carb experts?


Old 08-20-04, 02:38 PM
Trying2Help's Avatar
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Join Date: May 2001
Location: USA
Posts: 715
Question Rodchester Carb experts?

Is there anyone out there that could give me some information in this carb? Rodchester Quad #17088152 off of a 1988 Chevy Caprice with a 305, automatic trans, A/C.
I overhauled and cured one problem, but created a couple of others...

Now the car will diesel when you shut it off.
I have the idle set at 600, according to my tach, but it sounds higher to me, I will get another tach to double check this. If I turn it down to where it "sounds" right the engine will sometimes die at a stop sign.

Timing is good.

How do you adjust the idle metering jets? Since the rebuild I can get to the adjustment, however now of the books I have cover the "on vehicle" adjustments and I haven't been able to find anything on the web.

Could the float being to high/low cause this? Other than these two thing the car runs great.

I would appreciate it if you could point me in the right direction.
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Old 08-20-04, 05:45 PM
Join Date: Dec 2001
Posts: 2,538
im going to assume that it is still on a 88 caprice and all electrical components such as mc solenoid and tps are ok.
the mixture is posed to be adjusted with a dwell meter or scanner to where your mc dwell on a fully warmed up car is 35 to 40 degrees at idle there is a green connector near the carb that is used for checking dwell, you can get somewhat close by just finding highest rpm and leaning it out 100 rpm but it may cause check engine light to come on if it is not correctly set. and you may which to see a shop for adjustment of the tps and idle mixture along with many other adjustments that likely may be off during carb rebuild.
if you do try to adjust just by rpm make sure your rpm never goes over 900 while adjusting the idle mixture if it does you will need to lower the base idle before continuing as you will be getting out of the idle circuit above 900 rpm.
600 in park with all accesories off is to low and it will die 750 to 800 rpm is where it should be set but your fuel mixture is likely way off causing you to open the throttle plates up more and causing dieseling.
Old 08-23-04, 08:05 AM
Trying2Help's Avatar
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Join Date: May 2001
Location: USA
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Thanks Bejay,
Yes, it is still on the 88 Caprice. The data sheet on the grill sames to adjust it to 600 RPM for idle.
Where do you connect the dwell meter for the mc solenoid? Do you just back probe the connector? or is there a better way?
The big thing now is the dieseling, I would like to get that problem taken care of as it is a bit embarassing to shut the car off and have it sit there and try to run. I didn't get a chance to work on it this weekend so haven't got much more to add to this. When I get a chance, I will be out there checking the this thing out.
Thanks again for your help.
Old 08-23-04, 08:16 AM
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Join Date: Nov 2003
Location: Shenandoah Valley
Posts: 1,147
dieseling is...

almost always caused by idle speed set too high. it could also bee from a small amount of fuel leaking internally in the carb. having said that, carefully look down the throat of the carb while it's idling and see if you see any fuel dripping onto the throttle plates...if you do, you need to correct that.

these things are rule of really need the correct service info and procedures to adjust the rich/lean stops, tp sensor, idle air bleed and idle mixture. carbs when rebuilt often need to be tweeked a bunch before you find their sweet spot. remember that as you change timing and/or idle mixture, you will change idle speed and so therefore will have to go back and readjust it.

as for using the dwell connect it directly to the lime green connector (powder blue wire) that hangs out of the harness near the carb. you set the dwellmeter on the 6 cylinder scale (it doesn't matter how many cylinders the engine has).

a new O2 sensor is money well spent when a doing a feed back carb too...

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