Compression release

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hrdman2luv

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• Jul 31, 2017 / Compression release

• #1

Does anyone know how long it takes to change out a cam in a Briggs 17.5hp OHV? I'm pretty sure my compression release mechanism is broke. Have adjusted the valves like 3 times, (4 & 6), but it won't turn over passed the compression stroke.

I have a blown 17.5 that I could rob the part from. But not sure if that's a good idea either. Considering the $80 for a new one.

 

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ILENGINE

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• Jul 31, 2017 / Compression release

• #2

1-2 hours depending how hard that sump gasket is to remove.

 

H

hrdman2luv

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• Jul 31, 2017 / Compression release

• #3

ILENGINE said:

1-2 hours depending how hard that sump gasket is to remove.

Click to expand...

Thanks. That's not too long. It'll probably take me twice that long. Considering I never get any deeper inside an engine that adjusting valves or changing push rods. But, this is a good mower. And I can sell it quick, when I get this fixed.

 

Boudreaux In Eunice La.

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• Aug 1, 2017 / Compression release

• #4

I go 5 and 5 on all my briggs that have overhead valves never had one come back for the same thing.....

 

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hrdman2luv

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• Aug 1, 2017 / Compression release

• #5

Boudreaux In Eunice La. said:

I go 5 and 5 on all my briggs that have overhead valves never had one come back for the same thing.....

Click to expand...

That's were I started. 5&5, 4 & 6, 5 &7. And it won't go passed the compression. New battery. Good started. Etc etc.

 

BlazNT

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• Aug 2, 2017 / Compression release

• #6

How are you setting your valves if you can not go past compression? Just wondering.

 

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hrdman2luv

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• Aug 3, 2017 / Compression release

• #7

BlazNT said:

How are you setting your valves if you can not go past compression? Just wondering.

Click to expand...

A couple of different ways. Either with both valves closed at the same time. Or sometimes I'll adjust them when just one is fully closed. I think I did it both ways with this one. Thinking I might not have gotten the TDC right.

When I do them with one open and one closed (adjusting the closed one), I'll turn the crank until the piston starts down, about 1/4". with out the valve moving. I've heard that's the most accurate.

 

cpurvis

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• Aug 3, 2017 / Compression release

• #8

The most accurate position to set valve clearance is when the lifter (or valve stem, for flathead engines) is directly opposite the peak of the cam lobe. It's easy to find this position without removing spark plugs, finding TDC, etc.

For the exhaust valve, that position can be found by rotating the engine in its normal direction until the intake valve just finishes closing. At the crank position where the intake valve has just finished closing, set the clearance on the exhaust valve.

For the intake valve, that position can be found by rotation the engine in its normal direction until the exhaust valve just starts to open. At the crank position where the exhaust valve is starting to open, set the clearance on the intake valve.

Do not mistake a slight opening of the exhaust valve as the actual opening of the exhaust valve. That is the compression release on some engines.

 

T

Tinkerer200

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• Aug 4, 2017 / Compression release

• #9

I can send you detailed instructions on how to set the valves which includes a way to check the compression release and a Service Manual IF you like. Unless you are a wizard of some sort, do the work the way the people who engineered and built the engine say to do it and that includes clearances.

Address below, put in proper format and remind me engine model number and what you want.

Walt Conner
wconner5 at frontier dot com

 

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hrdman2luv

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• Aug 4, 2017 / Compression release

• #10

Tinkerer200 said:

I can send you detailed instructions on how to set the valves which includes a way to check the compression release and a Service Manual IF you like. Unless you are a wizard of some sort, do the work the way the people who engineered and built the engine say to do it and that includes clearances.

Address below, put in proper format and remind me engine model number and what you want.

Walt Conner
wconner5 at frontier dot com

Click to expand...

Thanks man. Sounds great.