niteridder64

I have a 1996 27 powerquest w/ a built 502. I was running 61 gps before the rust in the head opened up water into the cyl and needed a rebuild. I spent a lot of money and put awesome Merlin heads w/ big intake vlvs, eng bored .060 over, big cam ,cmi headers sniper throttle body inj.etc and only run 62 at 5100 rpms.I expected a 70mph boat. Since I had one guy make the heads, one guy do the machine work, another guy do the build up and I installed the eng and put on the sniper there is not one guy I can take it back to and say WTF it is no faster than my stock eng.

What I am looking for is a shop in Florida, preferably near Tampa that knows how to make these things sing and has a prop dyno or can water test and see if we can find the weak link that is keeping this thing down on power.

niteridder64

niteridder64

heads

SB

iTrader: (1)

Can’t help w a tuner down there but curious on a few things.

what is your fotal timing ? Not guessed nor assumed, but actual ?

What is your a/f ratio at max rpm ?

Does your fuel psi stay at proper spec all way to top rpm on the water (not trailer) ?

what specs does this big cam have ?

are your plugs gapped at typical .035 or so and not the dumb .055+ DUI suggests ?

niteridder64

1 I know I am a bit retarded not personally but I am at 29 deg. I was w/ a friend last week out to set it at 32 when I spun the hub in my propeller.
2 I can't remember what I saw on the screen that plugs into the sniper, it was 11.8 at max rpm, 13.5 cruise,14 idle
3 I have a fuel press gauge just before sniper and holds at 60 at all rpm
4 I know .055 was ridiculous, I think that # came from their marketing dept, I am at .045

articfriends

iTrader: (1)

What was done to the merlin heads that made them "awesome'/ Out of the box they are virtually identical to stock rect ports at just over 300 cfm intake flow at .600/ 200 cfm ex at .600, unported they offer no real performance gain. Ported, thats a different story. what was your previous cyl heads, intake etc compared to what you now have, what are your cam specs/
what octane is lowest you ever run? whats your CALCULATED /ACTUAL COMPRESSION? IF you dont no real compression (most guys think its higher than actually is), what kinda dome is on your pistons, how far are they in the block?
Stan Weiss' - Cylinder Head Flow Data at 28 Inches of Water -- DFW / FLW Flow Files for use with Engine Simulation Software

sutphen 30

I think the merlin heads are your problem,,they suck,even if work them over,thin casting around the exhaust port,,work them to much and a few years down the rode,they spring a leak.salt water makes it happen way faster.

sutphen 30

what cam are you running?

SB

iTrader: (1)

Forgot to add, the DUI internal cap coil HEI distributors need a better power source and thicker wire than the OE Merc purple wire. Do a search. Several peeps spell it out with 10-12 gauge wire and relay.

niteridder64