Jump to content

806 L.P. Idling miss


Tonyinca
 Share

Recommended Posts

Fellas, My 806 L.P. Misses off and on at all RPM's of idling , Under pull seems to run fine. Running down the road, high speed intermitted missing. Miss seems more like a flutter then a dead miss.

Tractor is all rebuilt and restored. Originally set up with electronic ignition , tried every type plug , now back to  points and AB6 NKG plugs.

  I get little wet moisture on exhaust pipe , does not look or smell like anti freeze , no signs of water in oil .   Had regulator rebuilt by knowledgeable  L.P. firm of M.M. L.P. equipment have set carb and Reg. settings according to op. manual.

 I am at wits end ! Need expert advice .

  Thank you !

 Tony 

  • Sad 1
Link to comment
Share on other sites

49 minutes ago, Tonyinca said:

Fellas, My 806 L.P. Misses off and on at all RPM's of idling , Under pull seems to run fine. Running down the road, high speed intermitted missing. Miss seems more like a flutter then a dead miss.

Tractor is all rebuilt and restored. Originally set up with electronic ignition , tried every type plug , now back to  points and AB6 NKG plugs.

  I get little wet moisture on exhaust pipe , does not look or smell like anti freeze , no signs of water in oil .   Had regulator rebuilt by knowledgeable  L.P. firm of M.M. L.P. equipment have set carb and Reg. settings according to op. manual.

 I am at wits end ! Need expert advice .

  Thank you !

 Tony 

I would check the points over really well. Grease on the cam? Condensers can do weird  stuff but did it do it with the electronic ign? Otherwise it would be a intake leak or a valve sticking

  • Thanks 1
Link to comment
Share on other sites

Dirt Boyz Proving Grounds at your service ? I will get my bag packed Tony ? Do you have you got a distributor with points setup in it , try changing that out also do you have the metal wire spark plug wires ? Look inside the distributor cap and see if the rotor is riding to hard on the cap /coil contact area , I have seen the rotors don’t fit down on the distributor like they should . Start it up and run it and put your Fluke Meter on the wire feeding the distributor from the coil and see how much power you have . I know there is different setup with those electric ignition setups . Is the heat range on the auto lite plugs the same as a Champion D15 Y plug ? 

Danny

  • Thanks 1
Link to comment
Share on other sites

Oh no!  Not again.  How many hours are on that thing?  Is it possible, just wild guessing, it needs to be loaded up and gotten hot?  Like it never been "broke in".  Put on dyno and let her go.  I bet your so fit to be tied with this issue again.  The original miss when you did her was a valve issue wasnt it?  I am not much help friend.  Maybe points got some corrosion from sitting?  I know our 464 G is way more finiky about plug than it should be imho.  Dad swear modern ones are not as good, or over done...?  

  • Thanks 1
Link to comment
Share on other sites

My guess is you have an idle fuel mixture problem.  You’ve thrown everything but the kitchen sink at the ignition -- with no improvement.  And what is more telling to me is that it does not miss under load.  If there is something that is weak in the ignition system usually a miss will get worse under load -- throttle plate more open = more compression pressure = plug is harder to fire.

I would try tinkering with the fuel mixture at idle and see what happens.  It has been too long since I had my hands on an LP carb, but if it has a choke I would try using the choke incrementally and see what happens as the mixture richens.  If that makes things worse then see if closing off the fuel flow helps.  

  • Thanks 1
Link to comment
Share on other sites

l have no help to offer Tony but l can't help thinking that John A. could probably pinpoint the problem in a heartbeat. Just hold your phone next to it and he could've told you exactly what it is....even all the way back here in Texas.

  • Thanks 1
Link to comment
Share on other sites

This is ALMOST always a leak problem. Rangeing from carburetor or manifold gasket to intake valve. With throttle plate closed ( no load). Vacuum is high fuel flow is low. Leak makes big difference in fuel air mix. With plate open (under load). Vacuum is low fuel flow is high. Leak makes little difference to mix. Use some type of fuel to check for gasket leaks. Then cylinder leakage test for valves. If that don't reveal problem. Look for to loose or tight guides. Probably should have checked valve clearance before this.

  • Like 1
  • Thanks 1
Link to comment
Share on other sites

If you had the manifolds off the engine and reinstalled them, the first thing I would do is put a wrench to those fasteners. Manifold hardware has a way of coming loose after the first few heat cycles. 

Link to comment
Share on other sites

Tony first things first that NGK AB6 is 6 heat range and is too cold.  My 291 build with 9:1 compression on gasoline I am using a 5 heat range.  You can call NGK tech line to confirm, they recommended my plugs for me based on my application.

I run plug adapters from REAM Corp so I can use a 14 mm plug for more selections if you can't find a hotter plug in 18mm.  The advantage of a 14mm is they are a extended tip that allows the plug to extend further into the chamber increasing efficiency.  For reference mine are a NGK TR5 2238, see pics below as comparison.  Also don't be decived by the longer 14mm plug note the picture of it in in the cylinder head. This is the difference between a modern day plug and 20th century technology.

Also can't say I am a big fan of points.. as I have dyno result to prove electronic ignition will increase hp as well as the constancy for years to come.

Scott

Screenshot_20210501-080631_Chrome.jpg

Screenshot_20210501-080540_Chrome.jpg

HEAT RANGE CROSS REFERENCE_1.jpg

20200418_112811.jpg

  • Thanks 1
Link to comment
Share on other sites

So some of you might not realize Tony has had a ignition / fuel mix slight Miss on this tractor after a massive restoration and a second head tear down I'm also wondering if you figured anything out Tony I see you took it to a show

Link to comment
Share on other sites

20 hours ago, TroyDairy said:

So some of you might not realize Tony has had a ignition / fuel mix slight Miss on this tractor after a massive restoration and a second head tear down I'm also wondering if you figured anything out Tony I see you took it to a show

I cringed when I saw Tony was having more trouble with this engine ..... again :(

I am also thinking it's not an ignition issue giving consideration to what you have done so far

Link to comment
Share on other sites

I agree on the above on know this engine was a pain for Tony.  The more I think about the moisture in the exhaust the more concerned I get.  Unless he has some bad LP fuel you should not have any moisture in the exhaust especially LP.  It burns ? hotter then gasoline and dryer.

Link to comment
Share on other sites

21 minutes ago, 460 said:

It burns ? hotter then gasoline and dryer.

From a chemistry standpoint propane makes more water than gasoline when it is burned as propane has a higher proportion of hydrogen to carbon than gasoline.  Gasoline is usually simplified as C8H18 and propane is C3H8.  During combustion the C is oxidized into CO2 and the H is oxidized into H2O

  • Like 1
  • Thanks 1
Link to comment
Share on other sites

3 hours ago, Gearclash said:

From a chemistry standpoint propane makes more water than gasoline when it is burned as propane has a higher proportion of hydrogen to carbon than gasoline.  Gasoline is usually simplified as C8H18 and propane is C3H8.  During combustion the C is oxidized into CO2 and the H is oxidized into H2O

 

3 hours ago, 460 said:

I agree on the above on know this engine was a pain for Tony.  The more I think about the moisture in the exhaust the more concerned I get.  Unless he has some bad LP fuel you should not have any moisture in the exhaust especially LP.  It burns ? hotter then gasoline and dryer.

I am not smart enough to know why it does but similarly our propane forklift puts moisture out of the exhaust pipe

  • Like 1
Link to comment
Share on other sites

17 hours ago, bitty said:

 

I am not smart enough to know why it does but similarly our propane forklift puts moisture out of the exhaust pipe

I am not either but I don't recall the moisture out of the propane units I have been around.  In the late 90's to early 2000's I worked at a machine shop that did a lot of rebuilding of propane powered 4.3L chevy's.  They were hard on exhaust seats and valves!  Clean burning as compared to gasoline!

Scott

Link to comment
Share on other sites

18 hours ago, bitty said:

 

I am not smart enough to know why it does but similarly our propane forklift puts moisture out of the exhaust pipe

I've noticed that also on both of ours

Link to comment
Share on other sites

The presence or lack thereof of water in the exhaust system is going to depend on how cool the exhaust gases get before they exit the muffler/exhaust system.  The more cooling that occurs the more water will condense from vapor to liquid in the exhaust system.  A good example of how this works is a high efficiency gas or lp furnace.  They are able to pull about 98% of the heat out of the exhaust and the result is that there is a lot of liquid water (condensate is the official term) in the exhaust of those units that must be disposed of.  Most have a dedicated drain for the liquid water that forms in the exhaust tract.  I have a  90,000 Btu HE  LP furnace in a barn where there is no way to pipe the condensate away so I simply have a 5 gallon bucket under the condensate drain.  When the furnace is running hard in cold weather the bucket might need to be dumped twice a day.

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

 Share

×
×
  • Create New...