mechanics help!!!

[greenthumb]

I had to replace the connecting rod on a 15+ year old briggs and stranton engine that is on a lawn tractor. before I get the crankcase back on how do I know if the timing will be right. I know I need to get the cam and everything so valve open right etc. are there any marking to look for I need help.

 

[slammer]

I need the HP, vertical or horizontal shaft, OHV or standard? Plastic cam timing gear or metal?

Slam

 

[greenthumb]

It is 11 horse it is on jd 111 lawn tractor. it has vertical shaft and standard valve and has metal cam

 

[slammer]

Turn the crankshaft so that the timing marks, a small dot on the metal gear on the crankshaft and a notch in the cam timing gear, line up. Without the engine in front of me this is the best I can do. I am at home so no book! /forums/images/graemlins/confused.gif Hope this helps.

Slam

 

[frank_f15]

slammer will help u thro it . he gave tons of help with the starter on my GT

 

[Molerj]

Just to add to Slammer's advice, once you get the dots lined up, rotate the crankshaft & watch the valves. Intake open then close, exhaust open then close. At one point at TDC you should see both the valves opening & closing, when you rock the crankshaft back & forth.

 

[slammer]

I should have mentioned this before and you may already know it. When you align the marks on the cam timing gear and the mark on the crank true timing occurs when the valves are closed. Sorry I forgot to tell you! /forums/images/graemlins/frown.gif

Slam

 

[greenthumb]

ok got it all back together after spending the last four days on the couch from throwing my back out. what a great way to spend vacation time. I lined the only marks I could find on this briggs and stranton where these little dots on the outside of the gear theeth. they look like drill marks. I lined these up like in the attachment the engine will not start. I get gas in the crankcase and some back fire. I am wondering if these are not the timing marks. I also wonder if the piston rings mights be cause to this. they looked ok so I did not change them. the engine was working fine until the rod broke. I hope I have not confused anyone. by the way the engine numbers are
Model- 253707
Type- 0155-01
Code 83073011

 

[slammer]

To consolidate the posts.

The cam timing gear has a mark on it. The crank has a mark on it. Cycle the crank around until both valves are closed and the two marks are aligned. That's it on a regular valve engine. The "F" model engines have OHV's so they are differant but no harder.

Slam

 

[Ricco]

</font><font color="blue" class="small">( Just to add to Slammer's advice, once you get the dots lined up, rotate the crankshaft & watch the valves. Intake open then close, exhaust open then close. At one point at TDC you should see both the valves opening & closing, when you rock the crankshaft back & forth. )</font>

Molerj is correct, this is called the valves overlapping. Great way to identify each cylinders TDC when adjusting valves.