Engine lacks power

[The_Handier_Man1]

From: PureUnrootingMetal  (Original Message)
Sent: 4/25/2005 5:28 PM

I have a 77 chieftain (see new photos), it has a 440 with a 4 barrel thermo quad manual choke. It has as much power as a moped. It takes 10 to 15 min to get to 55 mph. I tried to adjust the choke but still the same thing. Can anybody help? thanks.



From: Boise_Chief1
Sent: 4/25/2005 9:22 PM

By No Power is it:
Motor sounds good but seems to rev and rev and you don't get up to speed or

Is your motor coughing and spitting and running poorly? Or, is it running fairly steadily and just doesn't accelerate?
Sean



From: denison
Sent: 4/25/2005 9:54 PM

I would suspect a couple of culprits:
If it is running smoothly, but just has no oomph, I would think the centrigufal advance mechanism inside the distributor might be stuck in the “idle” position. The upper part of the distributor shaft rotates on the lower part, and there are spring loaded weights that do this. As the weights swing out they rotate the top of the shaft counterclockwise; the rotor and the lobes for the reluctor, or ignition rotate with it. This is the centrigual advance scheme. There is a lube point on the top end of the dist. shaft, under the rotor. With a 440, where the dist. rotates counterclockwise, you should be able to twist the rotor about 7 degrees counter-clockwise, and it should spring back freely when you let go.
Another possibility is that the throttle butterfly for the secondary throats are not opening â€" and you are only running on the primaries. They could be stuck, or if operated by vacuum, you could have a bad diaphram in the vacuum chamber.
Lack of fuel being delivered to the carb fast enough will normally cause misfiring, and very uneven engine running. I think a lot of misfiring would be the case if one side of your carb had a clogged air or fuel passage; or if the venturi for the secondary throats wasn’t feeding fuel. It is possible for an observer to look down into the carb and watch for this as you drive along, with the engine cover and air cleaner off â€" BUT it can be hairy if it backfires.
A choke plate that is stuck shut could cause such a problem, but you would probably see black smoke from the tailpipe as a result. The same would be true if the air cleaner was clogged, or if a mouse nest was filling the carburetor inlet.
If the ignition overall timing was that far off, it probably would be hard to start, would barely idle.
If it idles well, I would discount a skipped timing chain.
A 77 would have an EGR valve, and I don’t know how they affect operation, if the thing were jammed all the way open. It would probably idle poorly then.
I did a compression check a couple of weeks ago, and carefully put the ignition wires back on. But it turned out I had #2 and #4 plug wires reversed. It ran smoothly enough â€" but had very little power.
Check that no part of your exhaust system is squashed nearly shut.
You should have at least a steady 12 inches of vacuum in the intake manifold at an idle, or else something is not right.



From: denison
Sent: 4/25/2005 9:55 PM

It could also be a combination of such things!



From: PureUnrootingMetal
Sent: 4/25/2005 11:05 PM

If you floor it, it just slowly picks up speed. It sounds great (with new muffler and tail pipe). But still you have to wait a long time before you get some speed. Forget about passing people. Just can't.



From: denison
Sent: 4/26/2005 6:46 AM

I would probably start with an ignition timing check, but instead of just checking it at an idle, rev it up and make sure the timing advances noticebly with rpm. This is difficult to do, because of the location of the timing marks. An alternative would be to take the distributor to a business that can run a timing curve check on its centrifigual and vacuum advances.
I set the timing mark at 7° BTDC with the engine stopped, then painted marks on the bottom of the vibrtion damper and the front of the oil pan - so I could connect up the timing light, and lie under the front of the RV to check the timing in comfort. You would need an assistant to open the throttle and speed up the motor, but at least you would be doing this inches from the fan blades.
Unfortunately checking whether the timing chain has slipped a tooth is not so easy to do. Its also very rare, unless the engine has way over 100k miles on it, maybe 150k or more.



From: denison
Sent: 4/26/2005 6:50 AM

If your brakes are dragging it could cause the symptom, but you would be able to notice the furnace-like heat from the brake drums in back or the rotors in front, if you got it up to 35 or 40, then let it coast to a stop, like on a slight upgrade. If it comes to a stop and you havent pushed on the brake pedal, the rotors should only be gently warm. While you are at it, you might check whether the center driveshaft support bearing or any of the universal joints or the differential are hot.
I think I am out of ideas.



From: DaveVa78Chieftain
Sent: 4/26/2005 9:51 AM

Do you really mean 10 to 15 minutes or is that frustration talking.  To help, we need real info to determine if it' even close to correct.  Is the engine runnig rough at idle or missing under load?  What is the idle vacuum reading (both in park and in gear)?  Runnig flat at a steady 55mph what is the vacuum reading?  Ever rebuilt the carburator?
I have a 78 Chieftain however, yours looks to be basically the same as mine.  Mine has a 77 M400 chassis, 440-3 w/Thermoquad, 26ft length.  GVW on these is 12,000lbs.  Not sure if it was 76 or 77 but Dodge dropped the compression ratio again along that timeframe which resulted in lower horsepower.   Just something to think about when trying to push a very heavy box up to speed.  For reference, it takes me close to 45 seconds to get mine from a dead stop up to 55mph.  If I floor it kicking in the 4-barrels, it does a bit better (lots of weight on these) but I rarely do that (being miserly).  Engine is sensitive to timing.  Timing needs to be within the 7 +/- 2.5 degree window.  My vacuum at park idle is about 16, 14 in gear.  Flat 55mph vacuum runs around 12-13.  EGR valve amplifier has been known to casue problems though I have never experienced it. 

Dave



From: Boise_Chief1
Sent: 4/26/2005 11:21 AM

I see in your future a Tune up.  I think dave is right.  You very likely have a problem with spark plugs in the wrong firing order.  But You should do a full tune up.  Plugs wires cap rotor condenser.  If you are not comfortable with reseting timing and adjusting your carb, Take it to a shop and have them do it.  You will save money if you change the plugs and wires.  They are a drag to do and a shop charges you for the inconvienance. 
I am not good with carbs, so I do everything else myself and pay to have the carb tuned.

You mentioned a new exhaust.  did it have this problem before the new exhaust was installed?  It is possible the new muffler is to restricted and the back pressure is choking out the motor but it's unlikely. 

One last highly unlikely idea.  My speedo is off by ten miles an hour.  Do you feel like you are going faster than 55 should feel?  I was having a problem getting up to 65 little did I know it was more than 75.  I timed myself between milemarkers and realized my problem.

I think your problem is either firing order , the carb all plugged up maybe plugged fuel filter.  If you are only getting limited fuel that could be the problem.  but even if you have no secondaries (stuck float) you would still get to 55 in under a minute.



From: Slantsixness
Sent: 4/26/2005 2:34 PM

timing, distributor, vacuum advance, bad fuel pump, clogged fuel filter, clogged air filter (varmint nest?), burned out spark plugs or bad wires, distributor cap and rotor, exhaust restiction, bad cam, low compression, low trans fluid or bad transmission front pump/torque converter?

give us a little more info on just how it's running. You said it "sounds" good. It could even be your parking brake stuck on?!

Tom



From: denison
Sent: 4/26/2005 4:50 PM

One more thought: with the air cleaner off, push the gas pedal to the floor and see if the primary throttles are going all the way open. Just before my thottle cable quit, the clamped on end was slipping. Gas pedal on the floor, but throttles only open half way.



From: Mex83winne2
Sent: 4/26/2005 5:12 PM

IF TIMING CHAIN JUMP A TOOTH ENGINE WOULD BACKFIRE ALLOT YOU WOULD SET DISTURBER AND WOLD RUN NORMAL FOR AWHILE THAN START BACK FIRING.



From: PureUnrootingMetal
Sent: 4/26/2005 7:14 PM

I have power to go about 30 mph around town but when i try to get on the hwy, it takes 10 min to 15 to get to 55 mph. I think its something to do with my secondaries. I just looked at it last night and when i took it in, they wired my manual choke to open my primary barrols. Had it running and found out that when i tried to unstick the secondary barrols, it has lots of power. I just have to find a way to get both to work.



From: daved27c
Sent: 4/26/2005 10:20 PM

Cam;

First of all Welcome back. I think you need to find someone who knows and understands carbs. Someone may have messed with you carb before, or it needs to be rebuilt now, or both.

Dave