New here and first boat I HAVE owned. Have always had the philosophy the best boat is your buddys boat...lol. Well wife and kids ruined that this year....haha. I have the HP500 Carb serial number 0K000499. Identifies as a Gen6.


Anyways Ive read and read on this setup and am changing the valve springs as I dont know squat about the prior records on this boat. It only has 330 hrs but better safe than sorry is my moto... at least on my race car stuff. I have a few unanswered questions Id like some help on please.....

1) I have the Comp 26929 springs on hand ready to go. Id like to change over to 10* locks and retainers. I am local to Jegs retail store so I get most of my stuff there if I can. The locks p/n I have come up with is Comp 249-612-16. Is this correct?

2) The retainers I have come up with are 249-741-16. Is that correct?

3) Will these still be installed at 1.990" per Comp or try and shoot for the 1.900" that I saw someone post from the Merc Manual? Or just shoot for something within .015" of the two?

4) I have checked port side valve on head seat psi (With my LSM tool) and all are 145psi and up with only one being 145 while others are 150 or above slightly. Would this lead you to believe someone has changed these before?

5) On lifter preload I have some now that I can wiggle but still seem to have not much if any lash. When I set the lash as described in 0 lash and half a turn plus the locking down I wont feel any rocker wiggle will I? Maybe its just from normal use currently.

6) What is the proper p/n for the exhaust manifold gasket? I want to confirm its what my parts guy gives me locally.


Any help would be appreciated. Im very mechanically inclined and have built/worked on engines for a very long time albeit on the automotive side. This is just a new realm of that and am catching on fast. It just sucks Im scrabbling cause I bought the boat (1997 Checkmate 253) last week only to find out we have to go down to South Carolina for my wife's grandma (issues) and I want to take the boat for the intracoastal waterway fun. So not as much time as Id normally like to figure out all the facts before I start on this.

I’d recommend replacing the lifters too….I replaced the springs only in
a pair of those of that vintage and those hours and 1 of them broke a lifter shortly after that

If you are replacing the lifters please DO NOT use Com Cam's. I have 2 buddies that had catastrophic failures with them, less than 300 hrs and NOT a radical cam nor high spring pressure.
FWIW
Congrats on your new to you boat.

What lifters are yall going with?

Thay went with Johnson self oiling
The Comp's had lower roller bearing failure and roller pins dropping out of the lifters, NOT GOOD.

If you can't find any in stock anywhere contact Ron Sporl Performance here on OSO. He has them in stock and for the same price as anywhere else, also a great guy to do business with.
Good Luck