Rebuilt engine hard to turn over, but then loosens up?

[unioncreek]

Ring gap was within specs.

 

[shadetree#1]

What is the model, code and type info on the engine?

 

[unioncreek]

It's a B&S 22hp V Twin model 407777-0274-G5. I figured out what the problem is. The #1 connecting rod is too tight when torqued to 100 in-lbs, I can barely turn it when torqued to 50. It turns out the service manual I was given was the wrong one. So, I torqued the cap to 150 in-lbs. Is it possible to distort the cap and cause the problem.

Bob

 

[shadetree#1]

Is that a new rod or the old one.
Have you heard of using plastigauge? (to check clearances)You can review such on-line.
You will probably have to try another rod (new rod) and then use plastigauge to check the clearances since you now know it's the issue.
You can test another rod without it being connected to a piston at first.


See pg 2 section 13 of the CORRECT Briggs service manual.
See #4
Make sure the rod cap match marks are aligned. (rod cap not backwards)

 

[unioncreek]

What kind of marks are you talking about? I'll have to look at it. They only fit on one way. All my plasti gauge is old I'll have to buy some new. I found a new connecting rod for less than $20.

Bob

 

[unioncreek]

I actually found some plasti gauge. It shows clearance is less than 0.002". I measured the crank at 1.495" and the rod at 1.498". With a micrometer and snap gauge. Do you know what the clearance is supposed to be?

Bob

 

[Hammermechanicman]

.0025" is what i like to see.
Take the rod and torque the cap down not on the crank and measure top to bottom and side to side and see if the measurements are equal.

 

[unioncreek]

I'll try and do that tomorrow.

Bob

 

[shadetree#1]

Also mic the crank throw. If you cannot see out of round using your mic's
try to confirm that both are not out of round (egg shaped)

might even try confirming clearances up/down, side to side is not out of round using the plastigauge and do the same with your new rod.

You indicated that you over torqued the rod caps due to using the wrong specs.
Wondering how much torque you used?
Did you also over torque the other rod cap?

 

[StarTech]

I was taught to always mark the rods and caps as to both the cylinder number and orientation. This marking is what the service manual refers to. I don't see the service saying to mark these on this engine but it should be done whenever parts are being reused. This is old school techinque but it works. This why I have a number stamp set here. Even scribe marks are better than nothing at times.