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Hello All,

I am getting a little frustrated with a second hand engine I have bought.
15.5hp OHV single cylinder briggs.

Model :
285H77 0173 E1 101701ZA

It didnt want to turn over and didnt have a spark.

I have adjusted the Valve clearance and swapped out the Coil.

Engine Now turns over as it should Sparks as it should.

I have looked for the Compression release bump on the cam and can see it working. The valves move as it should and it ' feels ' like it has good compression. I have cleaned the carb out (for good measure) as it had been sitting for 12 months.
Currently the engine will just not fire up. I have tried the tea spoon of fuel in the cylinder trick.

My next step is pull the head and check the piston and valves.

Before I do I was hoping for some advice as No matter how much i search I want a definitive answer on something.

On the end of he Valve stems ( underneath the rocker arms ) there are no little caps.

In the parts diagram, I can only see 1 pictured. in the repair manual it states replace if fitted, but being a second hand engine I have no idea if they were fitted and lost, or never there to begin with.

I thought ( hoped ) I had a bent push rod, pulled them out but they are both straight, then I checked the length of them.

The Steel 1 ( exhaust ) is slightly longer than the aluminium.

Only information Ive read online is if there is 1 cap fitted it goes on the exhaust, If my exhaust push rod was smaller I would put 1 on it and the rods would end up the same length, and all would make sense, but being as its the alum 1 which is shorter. to my engineers mind it could mean the intake valve isnt opening fully ( ie the thickness of the cap ) not getting quiet enough fuel, but as I say Ive put cleam fuel direct into the spark plug hole.

I may be getting bogged down worrying over something which isnt an issue.
My real question is can any 1 tell me if this engine should have 1 / 2 caps and
If this engine was missing 1 / 2 caps would this prevent it from starting?

That engine does not use any valve caps, from what I can find. This manual may be of some help to you.

The valve stem cap is item 238 on this diagram. Should be one on each valve stem.

Thank you IL, I missed that one. Sorry Cheffy for the bad info. Guess I better get another cup of coffee before I post in the morning.

Rivets said:

Thank you IL, I missed that one. Sorry Cheffy for the bad info. Guess I better get another cup of coffee before I post in the morning.

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Rivets, don't feel bad about missing it. Sometimes the parts locations are not well defined on the schematics. I have had to call up my distributor a couple of times and say I am looking for this part, what diagram is it on.

ILENGINE said:

The valve stem cap is item 238 on this diagram. Should be one on each valve stem.

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Many thanks for clearing that up!
any thoughts on if it would prevent it from starting?

I don't see it having a big effect on starting. Could possibly effect valve timing slightly due to the rockers hitting the retainers before the valves. Have you checked the flywheel key to see if it is offset or sheared.

ILENGINE said:

I don't see it having a big effect on starting. Could possibly effect valve timing slightly due to the rockers hitting the retainers before the valves. Have you checked the flywheel key to see if it is offset or sheared.

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Ill put that top of my to do list ( before taking the head off )

Appreciate your support in this!!

Missing caps will have no affect, some were issued with none. Rocker Arm will hit the top of valve steam where the cap would be. Aluminum push rod if shorter will only be by thousandths of an inch and will NOT affect the amount opening, that will depend on the cam shaft lobe. Both valves should open nearly the same, if not, signifies bad cam lobe.
Walt Conner

They are several reasons they are used. Many of which are important such angle of contact which prevent excessive valve guide. Mushrooming of the stem end. As mention the contact of the spring retainer before the stem that could loosen the retainer clips causing them to wear to a point of failing to hold.

If they are indicated on the IPL I would use them. I wouldn't be questioning the reason of the engineers that design this stuff as they definitely have a lot more experience with the induced problems. As said not all engines have them and some only have them on one of the valves on each head.

On the heads I have had the rocker arm did not contact the retainers before contacting the valve stem end when they did not have caps. The part numbers of components in heads with and without caps are the same. I think the prime reason for adding caps was to reduce wear and increase time between needing adjustment. Affect angle of contact? How thick do you think these are?
Walt Conner

Not very thick but it is can enough to put a slight side load on the stems.

StarTech said:

Not very thick but it is can enough to put a slight side load on the stems.

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The problem with these engines has been valve guides slipping mostly due to disregard of the cooling system not due to wear. I have never replaced a valve guide due to wear on an Intek, Actually, valve guides are not a replacement part for these engines. Believe me, side thrust was not a consideration for adding valve caps.
Walt Conner

Walt then let me ask a question how would you ever replace a guide in the first place since Briggs don't even offer them as replacement parts? And yes I have seen a few with worn valve guides, just have to replace the head when I find them just like those that the guides slip out of place. Now of course knurling the old guides is an option but usually there is a chance the head is also warped.

StarTech said:

Walt then let me ask a question how would you ever replace a guide in the first place since Briggs don't even offer them as replacement parts? And yes I have seen a few with worn valve guides, just have to replace the head when I find them just like those that the guides slip out of place. Now of course knurling the old guides is an option but usually there is a chance the head is also warped.

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Well I think I said that guides were not replaceable and as I said, I have never seen a worn out guide in all the rebuilds I have done of B&S Intek OHV engines. I was being facetious when I remarked about replacing them.

Also, I have never replaced a head because of a slipped valve guide. I do have a permanent fix I developed as well as some other people submitted to me for resubmitting. Some run from nothing to less than $10 tops. Waste of a customers money replacing a head for slipped valve guide. I have sent the fix to probably well over 100 people on Internet forums over the last many years, probably over 200 with no reports of failure though there probably are some from failing to follow instructions.

By the way, one machinest did make his own replacement guide, another waste of time. Knurling also a waste of time.

Walt Conner

I tried ring center punching one but it still moved. Maybe a couple spot welds. As for knurling what was the waste of time didn't create enough fiction fit or was it just considered too time consuming.

Oh well I just keep replacing the heads then as the customers are not shy about charging me when I go to their shops.

StarTech said:

I tried ring center punching one but it still moved. Maybe a couple spot welds. As for knurling what was the waste of time didn't create enough fiction fit or was it just considered too time consuming.

Oh well I just keep replacing the heads then as the customers are not shy about charging me when I go to their shops.

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As I said, I share my repairs and one furnished to me is actually welding in the case of V twins, I guess it might work one singles as well, never tried it on any. IF Interested, Email below, put in proper format.

Walt Conner
wconner5@frontier.com