i was taking a compression test on my engine and all the cylinders came up with 220 and the #1 cylinder came up with 260. I found this unusual and tried it again and got the same results. Any ideas as to why this may be? thanks

 

What did the plug look like from that cylinder? The cause of higher compression is something in the cylinder and it's usually carbon build up. Could be a clogged injector causing the cylinder to not run or should I say not burn correctly. Could be a bad plug/ wire type problem but doubtful. You should still be able to see something on the plug no matter the problem.

 

Also check your rocker adjustment for that cylinder or check for collapsed lifter, cam choice effects cylinder as rocker adjustment, I don't think carbon build up causes it, carbon build up will cause more compression but not that much, cuz if you go from 10.4:1 to 11:1 you wouldn't really notice anything on the guage, but a cam change will.

 

How did you perform the compression check?

Did you warm up the engine first? Remove ALL spark plugs? Crank with throttle wide open? Record the third pulse for each cylinder?

If so, I would suspect carbon build-up and maybe a slight oil leak into that cylinder. A bit of oil around the rings will increase compression during the test.