Briggs 16hp 326437 Has me stumped

[GravelyBrad]

I would like to give a short introduction. My name is Brad and i "tinker" in almost everything. Generally anything i want i buy it broken and try to fix it for myself. This gravely is an exception to that as i bought it working and it stopped on my hands.

What happened. was mowing medium-tall grass and mower stalled, and wouldnt restart (crank but wouldnt turn over). It was low on fuel so i filled it up and it didnt help. Drifted it into the garage and tried starting again. After cranking for like a half min it will start, but wouldnt throttle up.

So keeping a long story short, engine is 326437 0247-01 8005121 16hp briggs single cyl. Currently it will only start on low throttle and if i try to throttle up it stutters terribly untill throttled back down.

Here is a list of what i have done so far.
-Drained tank and made sure in tank screen is free and clean.
-Ran all new fuel lines and new fuel filter.
-installed a new fuel pump (runs off a vacuum)
-Cleaned and rebuilt carb (i am not a pro at this)
-Bought and installed new carb just in case i didnt rebuild properally
-new park plug (periodically recleaning new plug to make sure its not getting fouled from carbon)
-made sure governor is adjusted properly.
Tested compression (3 results ~120)

Here is what i (think) i know
Spark seems to be strong
compression seems to be good at 120
not a fuel delivery issue as when i try throttling up and its stuttering a small spray of starter fluid does not help.
If i try to throttle up very very slowly it will sometimes throttle all the way up but as soon as there is any kind of load (moving/ turn mower on) it goes right back to stuttering and whatnot.


Please any help would be appreciated as this is the extent of my small engine knowledge which is get it air/fuel/and spark and it will run. (clearly im wrong) Since this engine is so very old i am finding very little information on it.

 

[John R]

Have you checked the fly wheel key?

 

[GravelyBrad]

Have you checked the fly wheel key?

I am assuming you mean check to make sure timing is correct?

I have not yet but i was told as long as its running at the low rpm's that the timing would have to be correct, is this bad information i got?

 

[reynoldston]

You have good compression at 120. If you have a tight valve you will have good compression till things heat up and you will now lose that good compression. It sounds more to me like a weak ignition. Bad plug wire, coil, etc. Are you getting a good strong 1/4 inch of spark?

 

[Midniteoyl]

Last time my 16hp Briggs did this it was the exhaust valve seat. Compression good when cold, but would run rough and completely die after putting any load on it. Wouldnt restart until cold.

 

[GravelyBrad]

You have good compression at 120. If you have a tight valve you will have good compression till things heat up and you will now lose that good compression. It sounds more to me like a weak ignition. Bad plug wire, coil, etc. Are you getting a good strong 1/4 inch of spark?

Dont know exactly what you mean 1/4 inch of spark but spark is blue color which i was told is good.

 

[GravelyBrad]

Last time my 16hp Briggs did this it was the exhaust valve seat. Compression good when cold, but would run rough and completely die after putting any load on it. Wouldnt restart until cold.

Well it runs the same now cold or warmed up. will start at low throttle but i cant throttle it up. when i try it spits and stutters.

 

[Midniteoyl]

Well it runs the same now cold or warmed up. will start at low throttle but i cant throttle it up. when i try it spits and stutters.

Doesnt take much to pull the head and look, though it might look ok while cold.. The valve seats in the 16hp Briggs are usually staked in and do loosen. Was a $25 job at my local place to have it replaced.

Of course, you might find another problem, like blown head gasket, warped head, etc..

 

[GravelyBrad]

Doesnt take much to pull the head and look, though it might look ok while cold.. The valve seats in the 16hp Briggs are usually staked in and do loosen. Was a $25 job at my local place to have it replaced.

Of course, you might find another problem, like blown head gasket, warped head, etc..

Yes i had the head off already so i can do that no problem. What am i looking for there exactly?

Would it be better to just buy a leakdown tester and do that?

 

[Midniteoyl]

Yes i had the head off already so i can do that no problem. What am i looking for there exactly?

Would it be better to just buy a leakdown tester and do that?

Well, first you probably need this: http://rich.homeunix.com/gravely/engines/briggs/16hp-single/01_270962SingleCylinderLHead.pdf (service manual)

If you pull the head, look for any burning/scorching around the valves, valve seats, head/cylinder mating surfaces/gasket, that the valves move properly, excessive valve/valve seat wear, etc..

Here's another manual that might interest you: http://rich.homeunix.com/gravely/engines/briggs/16hp-single/13_CE8069RepairmansHandbook19191981.pdf