Hey Andy how are things going!!! I am running 77's front 90's rear with no PV in the secondarys. I am going to run them the way they are for right now to get a base line over last year. And adjust from there.

WAY TOOOO BIG 74 and 84's also too much air flow 850cfm. I will see if I can find a set of 780's with vaccum secondaries for you to try/borrow

That's a pretty mild cam, but it appears to be ground with the correct marine advance (+4 to +6). A Merc 420 specs a little hotter, but your custom lobes may be more aggressive. I'm guessing not.

That IS a lot of fuel (jetting), but depending on your setup it may actually be correct. My guess is that it is fat. When you do your plug chops, make sure you use fuel with no alcohol in it since you get weird plug readings with the crap that comes out of the pumps these days. 71/84 is closer to what I would expect with Merc exhaust manifolds. Headers will require you to fatten up a touch.

Andy they are accually 800's and if you check out the dyno sheet (don't forgrt to click on it it will get bigger easier to read) the A/F seems to be spot on

Peak HP is at 4800, with those heads,carbs and intake it should be closer to 5000-5100. Tomorrow I will check your cam specs with comp cam's tech's.

**** UPDATE***

i finally got her in the water on sunday! The motors ran flawless for the hour and half we were out. no leaks or drips just no speed again. After racking my brain all the way back to the ramp and then again back at the building i was looking at the drives and it looks to be they are set wrong. Thanks to BOATMAN302 and also talking to Archer marine the trim guages are all wrong and it looks as if i was not trimming where it needs to be. Going to reset it tomorrrow and try a set of bigger props to see what happens. Here is a pic of the drives at MAX trim. As i understand it the drives need to be parallel to the bottom of the boat at CRUISE setting. it seems to me to be to low.

before you look into new props, consider revising the gear set ( inexpensive strait cut gears?) to change your ratio +/- 20%

what rpm were you at
where do you want to be (5000?)
i test drove a 311 kamma adn the boat rally lightenes up when you trim it to throw the roost.
also did you notice how long it takes to coast down when you cut the throttles . shows how efficient (low drag) a surface drive is

great news !!

Ramb

RAMB i was turning the these motors 5000 as well i want to stay there maybe 1 or 200 below since my motors make the most hp there. The is a gent in Nunica that was very gracious to let me borrow a pair of 17x27 three blades and a pair of 17x25 4 blades this weekend. i have 161/2 x 24s now so i am going to see what these do

makes sence
if you find there is more speed, you might still be able to keep your props and regear, unless he wants to sell at a great price.

the boat i tested had rebuilt mags ( ~420hp ?), and ran approx 70-72mph for a reference
not sure on prop pitch
Ramb

Glad the engine dramas appear to be done. Good luck with the setup work!