need ideas on a rich running 360

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dart44072

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I have a 360 in my 64 valiant. It was rebuilt .30 over with a 274 XE Comp cam. No matter what I've tried I cant get this thing to run right! The plugs foul in minutes (heavy black carbon). I've rewired it,changed plugs,cap,rotor,dist,ecm,volt reg,coil,several carbs blah,blah,blah....I reset the manifold but it sounds and acts like a vacuum leak? I just came in from my latest attempt and the engine runs with the jets turned all the way in? It runs but sits there and shakes like it has broken motor mounts. If anyone has any suggestions I WILL listen and try just about anything at this point! Thanks,

Dave..........
 
Check the fiering order. You may have some wiers crossed. Allso could try spraying some WD-40 while the motor is running. That will help you find any vacume leaks. A change in idle will tell you that you have found it.
 
I agree with burntorange. Make sure #1 on the cap is really #1. #1 can be any of the 8 depending on how and who put the distributor in.
 
'serveral different carbs" tends to rule out fuel bleeding unless you are running an electric fuel pump. Those can override the needle and flood thee bowl on most any carb. Good luck
 
Electric fuel pump with no pressure regulator at the carb will do just what RedFish says. Did to mine anyway!
 
dart44072 said:
Mechanical pump with 6# of pressure.
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Have you verified that pressure with a gauge or going by a printed spec ?
The mechanical fuel pumps have a relief valve in them. If it fails the pressure could be way wrong.
If its not fuel delivery, my next best guess would be cam indexed wrong.
 
did you have the engine decked or the heads milled? if so did you check the intake for fittment? the intake could be leaking on the underside causing a vacuum leak and could pull oil in and foul the plugs.
 
RedFish said:
Have you verified that pressure with a gauge or going by a printed spec ?
The mechanical fuel pumps have a relief valve in them. If it fails the pressure could be way wrong.
If its not fuel delivery, my next best guess would be cam indexed wrong.
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Gauge verified. I haven't had any shaving/decking done to the heads. The fouling isn't oil its powdery soot/carbon. Not wet at all. Every plug is the same. Actually I had this problem with a older style 480 cam. I thought maybe i wiped a lobe so i changed the cam,(I thought it was to big anyway) so I replaced it. Nothing changed.
 
It will probably run best at around 16 to 18* with your total at 36. Disconnect the vacuum advance. Make sure the plug wires are in good shape. Then start tuning the carb.

Check the float level, power valves and make sure the carb body and base plate arent warped. I know you've tried other carbs, just trying to give you a path to check.

Alsi, check around the intake for a leak, Use some carb cleaner and sparya it around the intake and any fittings that are screwed in ti the plenum or runners.

If your running an intake that works with either spread bore or square bore carbs, like and M1 single plane or Performer make sure you run the adapter plate between the intake and carb.
 
dart44072 said:
Today I had it at 13degrees. But I've tried every number imaginable.
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Double check the firing order, it's easy to swap 5 & 7. Do all the normal stuff to get the distributor phased properly. Get #1 on compression and line it up with #1 on the cap.

Check the float level too..

Put more in it. It's going to want it. I bet it will get close to 20*

My 340 with a a tad more compression and smaller camshaft 214*/224* has 16 initial, IIRC.

If you have a vacuum gauge set it with that. Keep the idle constant and keep dialing in lead. You'll be shutting down the primary throttle plates as this occurs. That's the best way to get you the initial advance that the engine wants and not some random number pulled out of the air. Dial it up until the gauge stops increasing then back 1" out of it by retarding the timing. Lock it down and you should be done. Put as much initial in that the starter will tolerate.

Once you have the initial set up where the engine wants it, I bet your idle mixture screws will start to work.

You'll likely have to limit the mechanical advance in the distributor after you find your initial number.
 
Also if you exhaust pipe is too small it will be restrictive that will cause an ovewr rich mixture also to much jetting is bad blown power valve in a holley will do that idel to high not good week spark.Good luck
 
Snake said:
Also if you exhaust pipe is too small it will be restrictive that will cause an ovewr rich mixture also to much jetting is bad blown power valve in a holley will do that idel to high not good week spark.Good luck
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72 primarys,67 secondarys. 6.5 power valve. I actually had this carb built to the exact specs of my engine.
 
ok here is my 2 cents /first check or change the power valve if it is busted you will run rich/ next how much vacuum do you have at idle? also check the adjustment of the acclerator pump i believe it is supposed to be .015 or .020/ has the acclerator pump cams been changed/ does it have the stock pump or has it been changed ? go down on the main jet 2 numbers at a time until the plugs are tan in color /this will or at least get you going in the right direction
 
Thanks for all the input guys, i'll take notes and check all these suggestions in the morning. NOTHING you guys suggest will be tossed aside without trying it first! Thanks......

Dave..........
 
sixpakmopar said:
ok here is my 2 cents /first check or change the power valve if it is busted you will run rich/ next how much vacuum do you have at idle? also check the adjustment of the acclerator pump i believe it is supposed to be .015 or .020/ has the acclerator pump cams been changed/ does it have the stock pump or has it been changed ? go down on the main jet 2 numbers at a time until the plugs are tan in color /this will or at least get you going in the right direction
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According to the carb build sheet, the pump is 30. I'll check the vacuum in the morning.
 
Before you spend time dicking with the carb other than to check if the floats are adjusted correctly or anything else is busted (power valve), Get the initial timing squared away!

Timing almost ALWAYS effects carb adjustments, carb RARELY, IF EVER effects timing settings.

Timing first, then carb setting.

Just my 2 cents.

72 pri with a PV and 67 sec???? That's a head scratcher.
 
Random thought... does it have issues without the air cleaner on it i.e. while you are tuning it? I had similar issue where I could get my 360 to run decent without air cleaner while tuning, but on the road it was crap, stumbling, plugs fouled black dry sootty, etc...

I found that my air cleaner was too restrictive and starving the car for air (running rich) especially under a load. Made a test run without the breather and started running as I expected it too. If you rule out power valve, vaccum, and timing then might look at air flow.
 
crackedback said:
Before you spend time dicking with the carb other than to check if the floats are adjusted correctly or anything else is busted (power valve), Get the initial timing squared away
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I totally agree with this statement. Since I have tried 4 different carbs you would think one of them would let it idle smooth if nothing else was wrong.
 
dart44072 said:
Holley 3310 ,750 cfm.
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Make sure that the air bleeds aren't stopped up with dirt or trash. If they are the carb will run rich, or if the air bleeds are too small the carb will also run rich. This is a problem with the 3310 holley carbs. In the last week I had a carb off of a boat that a customer brought to me and the carb was painted all over. When they painted the carb they painted over the air bleeds and the carb wouldn't idle right or run as it should. The man that owned the carb called the manufacturer and they said everything else was wrong except the carb.

After a rebuild of the carb that was just rebuilt, and a good cleaning of the parts, and opening up of the air bleeds, the carb now runs great and the man is very happy with it and the boat now RPM's like it should.

If you checked everything else and it seems to be fine then give me a PM and I'll walk you through the process of the changes that need to be done.
 
I had a car do that once.. out of the blue. It was a spark issue, not fuel, and it was the distributor shaft got bent.. It threw off all the terminal alignment. So the spark was just enough to light once in a while. The fact that you chagned carbs and it made NO change leads me to think it might be something else. It should have gotten better or worse. Does it clean up when you rev it or bring the rpms up?
 
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