truck running rich


marinetanker18
01-22-2011, 08:51 PM
Well, I have a 1983 dodge D-150 pickup, it has the 225 1-bbl with an auto tranny. When i bought the truck it had a holly 1945 model 1-bbl carb and still had the lean burn computer, well most of it anyways, but the truck was running rich then. Since then I have replaced the carb with a holly 1920 model, replaced the lean burn with mopar electronic and replaced the intake/exhaust gasket, the plugs, the cap and rotor button. I cannot get the truck to lean out at all, when I try to adjust the mixture screw it has no effect on the engine, but off idle its awsome. Somebody help me out, I am at a total loss here.:runaround:

mikefaster
01-22-2011, 10:45 PM
Try removing the adjustment screw (don't lose the spring), use the straw with carburetor cleaner and shoot it in the hole... When you see it stream on the inside of the carb, then put the screw back in and give it a try...

Other than that, those slant 6 engines are notorious for needing valve jobs; often mistaken for needing a carburetor... They almost never run "perfect"... You're also better off making sure that rockers tap... Trying to adjust the lash and NOT hearing a tap, WHILE trying to make it run perfect, is nearly impossible... If it taps a little, at least you know that the valves are seated... Basically, what I am saying is make sure that nobody tried to adjust the valve lash... When you get it running right, THEN you adjust the lash if need be...

Another test, is to put you hand over the carb, a little at a time and see if it stalls easily, or you gotta put both hands over it to stall it out...

Hope that helps...
Mike

mikefaster
01-22-2011, 10:49 PM
I'd like to add, that you should also make sure your timing is set right, because changing the carb, can change everything...

Also, everything runs good when it runs rich (well sort of)... It was a way to sell a car back in the days that would start to need a valve job; just make it run rich, and it ran "acceptable"...

marinetanker18
01-22-2011, 11:55 PM
well i cant adjust the valves, it has a hydrallic cam, i will try the carb cleaner tomarow. I have the initall timing set to 15 deg btdc. but im not sure as to why it would run so good of idle, but i will check that out tomarow and post back.

mikefaster
01-23-2011, 12:11 AM
They were mechanical tappets for a LOOOONG time...

I guess they changed it?

Like I said, everything runs "good" when rich...

Oh well, let me know how it works out...

marinetanker18
01-23-2011, 02:20 PM
ok, so i tryed the carb cleaner through the idle mixture screw, didnt help, double checked timing, set to 15 deg btdc. Found the wire to the automatic choke burnt up, so i replaced it and now the choke is working great. but it didnt have a big of an effect as i suspected. So i took the 1920 holley off, and put the 1945 model back on. Runs about the same. It seems to be doing better, but it is still smokeing really bad, not black or white smoke but more of a grey color, but only when parked, idle in gear or driving its not nearlly as bad. I am going to check the plugs when i get in to see the color.

mikefaster
01-23-2011, 02:50 PM
Another idea, is to check the vacuum and if all else fails, a leakdown test...

Did you try to make it stall out by putting your hand on the carb???

You said you changed the intake/exhaust gaskets, right? Try spraying carb cleaner over the gasket area (be careful of spraying a flammable liquid on a hot exhaust manifold) to see if the idle changes...

Seems like a valve job... Does your engine "tick" at all???

mikefaster
01-23-2011, 02:54 PM
Just asking about the "tick" to see what condition the camshaft is in... It should NOT tick then... Looks like they went to hydraulic cam in 1981... I did not know that...

marinetanker18
01-23-2011, 08:09 PM
well i checked the plugs out, black as night.did try the hand over carb trick, stalled instantly.hooked a vacum gage to it, its holding 24 lbs of vacum at idle,( thats how i normally tune my carbs) enywase i did do a compression check, all between 120 to about 131. and yes i have done the carb spray thing, used about 3 cans so far looking for leaks. I swear I still think it is the carb thats giving me a fit, and it is highly possable that i got a crap "new one" from the parts house. just becouse it is new, dosent mean it works.

mikefaster
01-23-2011, 08:29 PM
Rebuilding carbs is an ancient science...

My friend had GREAT results with a HOLLEY FACTORY rebuilt Quadrajet for his Chevy... When from running absolutely terrible, to absolutely perfect...

marinetanker18
01-24-2011, 10:43 AM
where would you suggest to purchase a carb from, I have been looking at national carburator, they seem like they know what they are doing.

mikefaster
01-24-2011, 04:06 PM
I haven't heard of them, but I haven't dealt with too many carbs recently...

Like I said, my friend bought a Quadrajet Carb off ebay from a Holley Factory authorized rebuilding facility...

It really ran flawless... And no core was needed...

If you can get a company that has a test engine that they can run the carb on, so you can see it run for yourself, is a good thing, but it would be hard to find it...

If you call Holley, they may be able to find a facility within driving distance as well...

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