86' 312A Power loss under load and hills

[oe espo 32]

Just got my #26 Carburetor from a notable carburetor builder for my K301S.  Tractor still doing what it did before.  Major power loss under load and especially up hill.  at a loss here.  lots of hours on it.  I didn't check compression yet  Any suggestions appreciated.

[953 nut 51,532]

Being an"86 model you have a battery ignition system with points, condenser and a coil. Have you replaced the spark plug, condenser and points?

[oe espo 32]

Haven't done the points and condenser.  the plug has been changed.  I will look into both. Thanks.

[Ed Kennell 35,615]

Do you have a good fuel supply to the new carb?    Pull the line off the carb and secure it in a can to catch the fuel.   Then crank the engine and you should see a good strong spurting of fuel.

[oe espo 32]

Update:

Fuel looks like its pulsing good.  during pulse hose is full and strong. Started filling a coffee can pretty quick I think.  Compression, cold, 60psi.

Points look a little burnt picture attached

Plug pic attached

Well wont attach!

 

Suggestions?

[953 nut 51,532]

14 hours ago, 953 nut said:

Have you replaced the spark plug, condenser and points?

If they don't look good the chances are they are the culprit. 

[oe espo 32]

All back together.  better but just looses rpm up hill or under heavy load.  catches up after load reduces.  governor?

[oe espo 32]

Or hydrostatic problem

[scotty 252]

Are you running it wide open? The hood on my 416h says it should be ran full throttle for best performance.

[953 nut 51,532]

16 hours ago, oe espo said:

looses rpm up hill or under heavy load.  catches up after load reduces.

Are we talking a considerable loss of RPM, (from 3600 down to chugging), or loading down and recovering? The governor will respond to load changes, but if you are under a load that requires eight horsepower and the load doubles you can't expect a twelve horse motor to do sixteen horsepower wort of work.

16 hours ago, oe espo said:

back together.

I presume this means a new plug and new points and condenser. 

[oe espo 32]

Points and condenser are in. Just reset points with timing light to "S" mark. Full throttle 3300rpm with hydro pump disengaged.  Drops about 250 rpm when engaged.  Idles at 1650. Not against throttle screw?  drops to 2500 2600 up grade with pto on.  once on top.  if you stop on brake rpm will slowly climb back up. mowing level drops to 2800 rpm cutting 3/4" of grass off.  so 3400 I think is the the book governed speed and I'm getting 2800  this is a 312 a with converted Eton 700 to 1100 transmission from a 416 

Test

Edited July 26, 2016 by oe espo

[oe espo 32]

Ok now for the dumb question.  when taking out the plug. Is that the top of the piston that you see????  my screwdriver only move up and down less than an inch. How could it run if the rod is broke or what am I mising here?

:

Edited July 27, 2016 by oe espo

[oe espo 32]

OK. I'm a .  it's not an OHV V8.

So I took the shroud off.  Found the "T" mark.  Hooked up my leak down tester.  Got 78% out the exhaust.  Rotated 360 to mark and got 100% out the carb.  another 360 and 78%out the exhaust.  Burnt exhaust valve?  Any suggestions appreciated.  Thanks Rob

Edited July 26, 2016 by oe espo

[WHX?? 46,693]

It probaly wouldn't hurt to pull the head and check, specially if the tractor has a quite a few hours under the belt. clean the head check the cylinder walls valves & seats etc. while your at it. Does new oil seem to get dirty fast?

[TimH 105]

I have the same problem Mine was a burned ex valve Got a new one for 21.00 laped them in adjusted and all good to go. When you pull the head you will know right away/

[oe espo 32]

Just got done pulling the head.  pulled the valves.  Maybe you would call it a burnt valve.  it only has a couple of contact "shiny" spots. Looks like some carbon was keeping it stuck open.  The exhaust stem is also very loose in the guide compared to the intake. But probably gets more clearance anyway but still seems out of tolerance. Piston is marked STD. Although she got some miles on her, I can't do a bottom end right now.  can a guide be replaced on the tractor?

 

Whys the trick to uploading pics?  Do I have to delete pictures from old posts??  says 0.02 MB max total size.

[953 nut 51,532]

5 minutes ago, oe espo said:

Do I have to delete pictures from old posts

Becoming a supporter will solve that problem and is a great way to say  to the members who have been trying to help solve your engine problems. 

[oe espo 32]

You can see the burnt carbon. I scraped. Of but didn't touch the seat.  What do you guys think?

:

 

Cylinder walls look good.  carbon was pretty thick

[953 nut 51,532]

Looks like a new valve is in order.       

[woodchuckfarmer 333]

Id say do a valve job while its apart.

[WHX?? 46,693]

I'd say just clean it up and button it back up if this is your main worker but plan on a full go thru when you can. Valve job motor should be completely taken  down for other measurements and what not. When I do valve guides I do a little porting just because its cheap and it really brings out a few more ponys. Std pistons on an older motor might mean out of round so check that too.

 

Btw yer name looks cherry in RED!!...thanks. ...helps keep the coach from having to resort to ads to keep the lights on.

[oe espo 32]

Anyone else see what I'm seeing?

[oe espo 32]

The piston is starting to melt in the last picture right at the exhaust. 

UPDATE:

Intake valve truer up nice.  You can see the exhaust warped.  guide is bad, or feels bad to me.  Ordered new exhaust valve and guide.

 

How hard to put the guide in??? Suggestions?  thanks

:

 

[WHX?? 46,693]

Can't say on what it takes to do the valve guides as I have a professional do mine. I don't have the tools required to do it. New valve would have to be seated in I would think.  Now that you mention it the piston does look a little scorched near the exhaust but I would say that is fairly normal for a well worked horse. Any Idea how many hours are on this motor?

[oe espo 32]

1986 Tracor, so 30 years of service .  Non-working hour meter shows 1,488 hours.  The intake vs. exhuast clearance between guide and stem is way tigher than exhuast.  Not sure if that is normal or previous owner had it replaced?