Walt & Bill
Thanks for your quick responce.Walt I've looked all over the engine can't find any # except the one I gave.I did find the Model#13AN693G118 & serial#1C063B70109 these were under the seat but Idon't know if they have anything to do with the eng.#. Bill the eng. is over head valve 16.5Hp.B&S. After adjusting the valves eng. cranked and ran I let it run till it was warmed up then shut it off let it cool down and it would not restart same old problem.Sounds like too mutch compression.

Thanks again for all your help
Mike

one thing you said that caught my eye ... the piston really should not be at TDC when your doing your valve lash adjustments ...

it makes the difference...

ALSO - I recently worked on a large Briggs twin - that had a similar problem... It turned out it was the solenoid... it was 10 years old and just causing me nothing but trouble... I replaced it - and the owner is very pleased with the unit again.

that should be a Model 31Q777
.004" intake
.006" exhaust
+/- .001"

IF you haven't set them with the piston 1/4" past TDC, you sren't doing it right!

Look on the valve cover for the model number.

Walt Conner

Walt,
Thanks again for all your help. The model # is 31C707 I was looking for a metal tag or a sticker with the # on it.After your last post I took a wire brush & carb. cleaner to the valve cover knowing where to look is half of the battle.

Thanks again Mike

P.S. Sent you an E-Mail yesterday .I'm not very good with computers so I don't know if you got it

"Walt,
Thanks again for all your help."

You are certainly welcome and I did get your email of thanks but since you did not request Valve Adjusting Instructions, I did not send them.

Walt Conner

My B&S 17.5 hp has compression coming out the carb when I turn it over.
Has: New coil, plug, stator, oil change.

I removed the fly wheel to replace stator. Could that affect the timing?
Engine has spark, fuel, compression, battery. After 10-20 cranking revs., pressure coming from carb/intake and back fires thru carb somtimes.

I need help before I throw this B&S out the window.
Thanks,
Darryl B

I have the same problem with my 13 hp B&S lawn mower. When i remove the plud it spins good. Any luck with yours.

Hade same problem as listed above. Very hard to start. even after valve ajustment by the book .25 inch past TDC.

Then I found this video not by the book, but all is well now turns over easy

Here is a link that might be useful: valve Ajustment

Hi Guys,
I see this thread is quite old now, but I came across a solution with the help of a buddy whose a small engine mechanic. I teach small engines at a high school, and had the "too much compression" issue in some of our 5.5hp OHV briggs engines that the students tear down, measure and reassemble. I've attached a couple photos from the textbook I remembered I had once the local small engine guy tipped me off about the compression release.

Many Briggs and Strattons have a compression release system that relieves excess pressure during the compression stroke by releasing a small amount of compressed gas through either the intake valve or the exhaust.

There are two main ways that they accomplish this. The first is through what they call an "Easy Spin" compression release system. They use a second raised side on the cam lobe to raise the valve slightly off of the seat immedietly prior to maxumum compression pressure. Briggs admits that they'll have to do away with this in time due to stricter and stricter emmissions testing.

The second way, and more common way, is to use a mechanical release. The ones we have at school opperate simply by a weighted arm and a small spring. The issue we had with too much compression was due to the little spring coming unhooked. My small engine mechanic friend said he repaired one where there was actual pieces broke off, and picked up on it because there was a bit of damage to the cam from broken pieces that the customer claimed were never there in the first place. (The customer must have opened the crankcase, chucked the compression release mechanism, and claimed it never happened.)

If you're sure your timing is correct, as in you haven't had your camshaft out recently, or you're sure it's timed correctly, then follow the following procedure:

1. set valves correctly (make sure the piston is 1/4" down from TDC on power stroke, the reason it needs to be down 1/4" is to ensure that the compression release isn't interfering with your valve lifter).

2. check compression release

- Remove the spark plug
- Remove the valve cover, turn the engine flywheel clockwise while watching the valve action.
- When the Intake Valve closes, stop.
- Now focus very closely on the valve spring retainer of the Intake Valve, continue turning the flywheel clockwise. In about 1/4 turn, you should see the Intake Valve Retainer (and valve) make another little move towards fully closed.
- This indicates the Compression Release is working.
- IF you see no movement, try again.
- Still no movement, there is a problem in the Compression Release system. When the engine is cold, you can rest the side of your hand on the head and grasp the Intake Valve Spring Retainer between you thumb and index finger while turning as described and you should be able to feel the Retainer move.

I've done a bit of searching around on the internet and couldn't find this solution. Hopefully it solves everyone's problems, and that your engine is sitting in the corner of your shop or garage somewhere, and hasn't been sold for scrap metal! Again, ours was as easy to fix as reattaching a small spring that had become unhooked.

***"They use a second raised side on the CAM LOBE to raise the valve slightly off of the seat"***
With all due respect (you are a teacher after all), the second raised point is on the CAM BASE CIRCLE, not the actual "cam lobe".
The cam base circle is the low point on the cam, the cam lobe is the high point on the cam.
The camshaft is where all the individual cams are located.

is that camned or damned? Curious minds like to know... :) (I like the old petcocks, myself - they allus sounded so cool.)

Camn you rcbe! You and your camned questions!
:^)

Careful, Mownie!! You'll be in the discard pile with me! RJ

Ain't skeerd! :^)

Hi their i see this was a while ago but i have a 13hp ohv tecumseh engine and i have too much compression even with my valves adjusted correctly can n e one help

I have a Briggs & Stratton 16.5 numbers 31C707 0154E1 040522ZA.

Have adjusted valves 004 & 006 at 1/4 past TDC Checked spark, cleaned carb bowl & checked solenoid, will fire up once & run until turn it off then wont start again. any suggestions?

Why hasn't B&S fixed the cam compression issue?? No recalls?

I have the same problem with my 25 horsepower Briggs and Stratton twin engine overhead valveI have spark from both cOil wireswhat the spark plugs in trying to turn the flywheel by hand it gets to the point where you can't turn it take out the spark plugs at free spins easily when I'm crankingcan anybody help me out

Model445777. Type 0122.e1. Code000807yh

do a search this forum and possibly google for "briggs valve adjustment"... most of their later ohv small engines are finicky about needing incremental adjustment and sorry, I do not have procedure.

Mine had the original "plastic" cam. Junked it now since who can afford a new engine?? Makes me mad. I paid 1000.00 for that thing from my aunt. 2 yrs old.

i have a Briggs & Stratton 17.5 i adjusted the valves to .005 with motor 1/4 turn past TDC but it still acts like to much compression plz help

adjusted the valves to .005 with motor 1/4 turn past TDC "

This is NOT correct. IF you do not have proper instructions on adjusting the valves. I can send detailed Instructions which includes a test for compression release IF you like. Address below, put in proper format and remind me engine model number and what you want.

Walt Conner

wconner5 at frontier dot com

B&S 20 HP, model #331777 to much compression, I've been a 1\4 past TDC adjusted valves too .004 and .005 Ran good till it warmed up and started running rich, shut it down now acts like to much compression... any ideas??

This is a very old thread, posts above should help you including my offer of Instructions and Service Manual. Walt Conner

Have experienced these hard starting problems with several B & S engines. So many people in these forums try to blame battery, starter, cables, solenoid, etc. Test to eliminate these: loosen plugs and turn over. If it spins freely it is a valve clearance problem. On OHV= easy adjust valves according to specs. L-head (which I have) not so easy. Either a compression release device is not functioning or the lobes on the cam are worn to the point that the valve is not opening= compression lock. Mine will barely turn over. Then I loosen the left side plug a couple turns and this allows enough compression release for it to turn over fine and start. This seems to be very common. I will be disassembling to look at camshaft and compression release. Are there any experts out there that would like to weigh in and confirm or debunk. I have spent hours on this and believe I am correct.

I suggest you start a new thread then post your engine model number so people know WHAT engine you are talking about. That said, L head engines do not typically have valve adjustment problems and do not have automatic mechanical compression release mechanism. Have a passive system.

Walt Conner

Here is the problem and resolution: B & S has a pressure release gizmo on the cam shaft. It makes a small lobe that slightly opens one of the valves just before TDC. This allows the starter to turn the engine easier. This lobe is held out by a spring, but the spring is overcome by a weight as the engine spins faster. So this lobe goes down after the engine starts. The problem is the spring often either breaks or comes off. The only way to fix it is to take the engine apart and pull the cam. It is a one minute fix usually, but it takes hours to get to it.

Randy Snotins video will not help. The ONLY way to fix this problem is to pull the engine apart.

Randy Who ?

bring the piston to tdc then adjust rocker arm so it does not move up and down but easily side to side.

I have taken out the compression release on a motor before.

And much quieter too...

lmao .

i have a briggs 15.5 i/c platnum 28n707 that it will only sputter with the starter and i haven't touched the valves the compression release works and i got a new spark plug and coil and fuel but still wont run.

Might be time to touch the valves. Or at least pull the valve cover. Could be a loose rocker or a worn camshaft. To check for proper lift, crank the engine with the valve cover off and the valves should both push downward about the same distance.

Just an idea about your tractor, Keep an eye on the valves as you turn the engine by hand and see it the bump (decompression) is working like it should. I had one that blew the governor on the camshaft and did what you describe.

Bump , worn cam shaft same scenario !

Do you adjust valves

If it doesn't have valves to adjust how do you get the starter to turn the motor

This is a briggs and stratton motor on a craftsman lawnmower

Yes your valves are in need of adjustment. I could tell you how to do that but probably the best way is to watch a video on you tube. donyboy73 has a video on an overhead valve engine that will give the needed steps to be taken. Good Luck

Yeah sounds like improper valve lash setting . intake and exhaust specs .003 -.005 Cold . Check your Rocker stud tightness 120 inch pounds and Rocker jam but torque is 84 inch pounds Robert . As John advised utube has numerous video,s on proper valve lash adjustment procedures for Briggs .

I removed the camshaft and still found the engine (B&S), difficult to turn over.

Probably would be as the valves never open....

It's the compression release on the camshaft

It's the compression release mechanism. Mine failed and is less than two years old. It's still under warranty but the authorized dealer can't get the parts for two months, they're back ordered. These engines must be failing by the 1000's.

Common problem, cam relief not freeing timing and building up comp. Till it gets over kind of like v_tech on Honda it will run fine but it won't turn over until compression is dropped through case return most u this for oil pressure and fuel pump pressure

for most people its valve adjust but for a select few its the engine design itself. the piston gets lubed by the engine splashing oil. if you dont change the oil yearly and are not using the correct weight oil, the top side of the piston and occasionally the head also will create tollerances so tight even the compression release wont be enough for the starter to push thru. usually i sugesst pulling the engine apart and cleaning the piston, valves, rings, and valve head. get then super clean abd put it back together. keep up on the maintence and it should run fine. also check the seloniod, they do go bad and it takes all that CCA to get these engines spinning