Link in my sig, first post has links to the cam I chosen
268 degrees of duration is the biggest cam you can use with wet exhaust.
Before I spent any money, I would use a dial indicator and determine what you have. Your cam is probably fine
However, with vortec heads most cams hotter than...
Backup drive is now taken apart, flushed, the lower sanded down and primed.
The lower will be going back together this week, and if lucky, will get the upper on and that drive painted
If you are re-ringing, you need new pistons and a bore\hone.
Mercruiser bought the same pistons used in trucks, and every other marine motor
Your stock pistons are GM flat tops with 4 reliefs
starts the same regardless of temperature from 90 all the way down to 45. first start is always, one full prime, then part throttle and turn the key. with two 30cc squirters, it fires off about the 4th or 5th revolution when cold, and about the 2nd revolution when warm
welcome aboard.
remember, Mercruiser just buys a GM longblock.
talk to your machine shop. make sure to hone to +.001 of a standard truck hone. ring gap is dependent on your piston type. cast, hyper, forged, etc.
i use the Harbor Freight "purple" gun often. just used it moments ago with my drive. (rustoleum, hardener and acetone to thin)
turn your pressure up to 45psi. you need more air.
what type of compressor do you have?
could be coming from anywhere.
could be a bad transom, bad transom shield seal, bad bellows, bad exhaust y-pipe, leaking screw hole, leaking thru-hull fitting, etc.
dry the bilge, get a flashlight and look
the answer to nearly all Mercruiser questions are in the stickies at the tops of the forums.
https://forums.iboats.com/threads/must-have-technical-information-for-diyers-an-work-safe-search-version-of.335378/
and if you dont like reading, Achris posted these vids a while back...
do you have a cam card?
My 1988 motor got an upgraded flat-tappet cam and vortec heads
vortec heads only care if the cam lift is above .420. then the heads need some machine work.
OPIE and NMMA has been pushing to keep E15 out of equipment and motors for over 12 years now
Its not good in any non-multifuel system
Its not a performance thing, its a your motor will fail type of thing. Small engines for lawn and guarden and marine have had warning stickers for the past decade
