Why is my engine difficult to turn over with the spark plug in?

Because with the spark plug in you have full compression. take it out and you have no compression :-)

Lazza
August 2008

check the exhaust and intake valve clearence should be about oo4 exhaust 006 intake

DON
May 2007

Valve clearance is critical in those engines.
Adjusting the valve clearances should resolve your problem.

You can find instructions on how to do that on Briggs web site at this link:

http://faqs.custhelp.com/cgi-bin/faqs.cfg/php/enduser/std_adp.php?p_faqid=3441&p_created=1101860144&p_sid=99hT3rmi&p_accessibility=0&p_lva=&p_sp=cF9zcmNoPTEmcF9zb3J0X2J5PSZwX2dyaWRzb3J0PSZwX3Jvd19jbnQ9MTAxJnBfcHJvZHM9JnBfY2F0cz0wJnBfcHY9JnBfY3Y9JnBfc2VhcmNoX3R5cGU9YW5zd2Vycy5zZWFyY2hfbmwmcF9wYWdlPTEmcF9zZWFyY2hfdGV4dD1WYWx2ZSBBZGp1c3RtZW50&p_li=&p_topview=1

Big link, copy and paste it into your address bar. Scroll down that page to find "Adjusting Overhead Valves"

Rick
November 2006