Jump to content

Nominations for Tractor of the Month
Garden Tractors and Parts on eBay



Photo
- - - - -

Blow back through the carb on 314


  • Please log in to reply
82 replies to this topic

#31 WNYTractorTinkerer ONLINE  

WNYTractorTinkerer

    Tinker Master

  • Senior Member
  • -GTt Supporter-
  • Member No: 10789
  • 8,306 Thanks
  • 4,659 posts
  • Location: Avon, NY

Posted May 30, 2016 - 08:22 PM

If you clean the valves up and re-gap and it still dies it, The cam has ACR..  Sometimes the spring takes a hiatus and it won't stay in the correct position @ WOT..  It would definitely have the same symptoms as the ACR keeps the valves open a bit on the compression stroke releasing compression for cranking purposes,,  

 

Once the engine gets going weights on the cam extend and return the cam lobes to the full compression position..  Missing or busted springs are a cause of symptoms you are seeing.  LOOK at the cam in the picture to show what I'm talking about..

 

Ignition timing could also cause the issue due to firing too early..   The rotation of the ACR also affects that too since the whole cam lobe spins independently of the inner shaft..

 

Just saying..


  • Trav1s, jimmy G and shantzonpoint have said thanks

#32 shantzonpoint OFFLINE  

shantzonpoint
  • Member
  • Member No: 81961
  • 16 Thanks
  • 43 posts
  • Location: Michigan

Posted June 11, 2016 - 10:09 AM

Ok here's an update. I replaced the valves and set the gaps. I rebuilt the carb and put it all back together. It started fine and for the first 10 seconds it ran really good. I was really happy. .....then the spitting started to come back. After tweaking the carb, I turned the engine off and noticed it seemed abnormally hot for the short time it ran. It ran for about 1-2 minutes and i couldn't hold my finger on it for one second. Is this normal?

This morning I started fresh. I saw a few guys mention a sheared pin on the flywheel. So I tore into that and everything looks good.
0fb2216a508b5fd60a05517cbe59ed0b.jpg

One thing I found is the is the drive hub was broken. So I'm glad I tore it apart.
4f9548994b43ae09b005d05975306099.jpg

At this point, I'm thinking it's a timing issue. So I checked the gap on the points it was pretty much dead on. I couldn't get the plunger to go in while it was on the tractor. I'll look into that now that it's easier to get at. What other tests can I do to check timing? (or anything else I should look at while engine is out?) Again thanks for all the help.

Edited by shantzonpoint, June 11, 2016 - 10:13 AM.


#33 shantzonpoint OFFLINE  

shantzonpoint
  • Member
  • Member No: 81961
  • 16 Thanks
  • 43 posts
  • Location: Michigan

Posted June 11, 2016 - 11:23 AM

I put the flywheel back on and spun it just to see if something didn't seem right.  Not sure if this is normal or not.  You can hear air blowing out of the carb right before you hear the intake valve close  I can also hear air gurgle out of the breather at the same time.

 

.



#34 DH1 ONLINE  

DH1

    Electric Tractors

  • Senior Member
  • -GTt Supporter-
  • Contributor
  • Member No: 62
  • 4,587 Thanks
  • 5,295 posts
  • Location: Markham Ontario Canada

Posted June 11, 2016 - 01:52 PM

The intake valve closes  when the piston is on the way up in the compression stroke, It doesn't close right at the bottom.

The air you hear is most likely coming from the breather. 

 

A quick way to check the valve timing if you have the head off is in between the exhaust and intake stroke, when the piston is at the top, TDC, both valves will be open the tinniest amount. If one is open noticeably more that the other valve timing is off


  • Sawdust said thank you

#35 shantzonpoint OFFLINE  

shantzonpoint
  • Member
  • Member No: 81961
  • 16 Thanks
  • 43 posts
  • Location: Michigan

Posted June 11, 2016 - 02:13 PM



The air you hear is most likely coming from the breather.


I can actually feel the air coming out of the carb. :-/



Sent from my SCH-I545 using Tapatalk

#36 DH1 ONLINE  

DH1

    Electric Tractors

  • Senior Member
  • -GTt Supporter-
  • Contributor
  • Member No: 62
  • 4,587 Thanks
  • 5,295 posts
  • Location: Markham Ontario Canada

Posted June 11, 2016 - 02:30 PM

I can actually feel the air coming out of the carb. :-/



Sent from my SCH-I545 using Tapatalk

 

Since the valve closes when the piston is going up on the compression stroke air will come out the carb until it closes, when turning the engine by hand.

When the engine is running, turning faster this does not happen. There is a time delay in the movement of the air.

 

Are you sure the intake valve is sealing, not leaking under pressure?

Is the exhaust flow restricted more than it should be?



#37 shantzonpoint OFFLINE  

shantzonpoint
  • Member
  • Member No: 81961
  • 16 Thanks
  • 43 posts
  • Location: Michigan

Posted June 11, 2016 - 02:35 PM



Since the valve closes when the piston is going up on the compression stroke air will come out the carb until it closes, when turning the engine by hand.
When the engine is running, turning faster this does not happen. There is a time delay in the movement of the air.

Are you sure the intake valve is sealing, not leaking under pressure?
Is the exhaust flow restricted more than it should be?


Thank you for explaining that .

Is there to way to see if it's leaking by? When I lapped the new valves during installation, they made a nice tight fit (valve seat was even all the way around). It's hard to tell after installing the valve springs if they're actually seating though. I can easily tear the head back off of need be. I just need to know what to be looking for. ...lol.

Sent from my SCH-I545 using Tapatalk

#38 DH1 ONLINE  

DH1

    Electric Tractors

  • Senior Member
  • -GTt Supporter-
  • Contributor
  • Member No: 62
  • 4,587 Thanks
  • 5,295 posts
  • Location: Markham Ontario Canada

Posted June 11, 2016 - 02:38 PM

Thank you for explaining that .

Is there to way to see if it's leaking by? When I lapped the new valves during installation, they made a nice tight fit (valve seat was even all the way around). It's hard to tell after installing the valve springs if they're actually seating though. I can easily tear the head back off of need be. I just need to know what to be looking for. ...lol.

Sent from my SCH-I545 using Tapatalk

 

If you have the right valve gap set, as per manual, it should seal.  



#39 shantzonpoint OFFLINE  

shantzonpoint
  • Member
  • Member No: 81961
  • 16 Thanks
  • 43 posts
  • Location: Michigan

Posted June 11, 2016 - 02:40 PM

I'm positive i have that. I set them with the engine cold and piston top dead center.

#40 shantzonpoint OFFLINE  

shantzonpoint
  • Member
  • Member No: 81961
  • 16 Thanks
  • 43 posts
  • Location: Michigan

Posted June 11, 2016 - 02:42 PM

For reference, the original ones were set correctly as well. I checked before I tore them out.

Sent from my SCH-I545 using Tapatalk

#41 DH1 ONLINE  

DH1

    Electric Tractors

  • Senior Member
  • -GTt Supporter-
  • Contributor
  • Member No: 62
  • 4,587 Thanks
  • 5,295 posts
  • Location: Markham Ontario Canada

Posted June 11, 2016 - 02:51 PM

Ok here's an update. I replaced the valves and set the gaps. I rebuilt the carb and put it all back together. It started fine and for the first 10 seconds it ran really good. I was really happy. .....then the spitting started to come back. After tweaking the carb, I turned the engine off and noticed it seemed abnormally hot for the short time it ran. It ran for about 1-2 minutes and i couldn't hold my finger on it for one second. Is this normal?
 

 

Did you have all the engine shrouds on when you ran the engine?



#42 shantzonpoint OFFLINE  

shantzonpoint
  • Member
  • Member No: 81961
  • 16 Thanks
  • 43 posts
  • Location: Michigan

Posted June 11, 2016 - 02:56 PM

Did you have all the engine shrouds on when you ran the engine?

Not all of them. I had the top shroud off. I wanted to make sure the head gasket sealed.

Here is a video I took before I replaced the valves. You mentioned both valves should be open a smidge at TDC. You can see the exhaust opens but the intake doesn't budge. I'm guessing this hasn't changed.
https://youtu.be/Pt9j9vytQfY

Sent from my SCH-I545 using Tapatalk

#43 DH1 ONLINE  

DH1

    Electric Tractors

  • Senior Member
  • -GTt Supporter-
  • Contributor
  • Member No: 62
  • 4,587 Thanks
  • 5,295 posts
  • Location: Markham Ontario Canada

Posted June 11, 2016 - 03:05 PM

I see what you say, it might be not timed right, 1 tooth off.  ???

The only way to know for sure is remove the pan and check.



#44 Trav1s ONLINE  

Trav1s

    Got points?

  • Senior Member
  • Member No: 5472
  • 2,602 Thanks
  • 3,750 posts
  • Location: Cedar Rapids, IA

Posted June 11, 2016 - 04:02 PM

Is it too lean? 



#45 shantzonpoint OFFLINE  

shantzonpoint
  • Member
  • Member No: 81961
  • 16 Thanks
  • 43 posts
  • Location: Michigan

Posted June 11, 2016 - 05:09 PM

Is it too lean?

No I don't think it's too lean. There was excessive carbon build up on the intake valve that I replaced. I installed a nabs new plug when I put it back together. I looked at it after I yanked the motor abs it already had carbon build up on it after running for about 5 minutes.

I leaned it out as much as I could without the engine running really rough.

Sent from my SCH-I545 using Tapatalk
  • Trav1s said thank you




Top