restarting my whole motor project! need some advice
 

ok so i had a quick question! motor is coming out to get a few things(oil pump/ bottom end check out)

but it will still only spin 4200rpm
so im making a to do list

first im sure the mechanical pump is small so i bought a holley blue.... (even though i just posted asking what people buy after i bought it )

bought a new oil pump high volume standard pressure (the old one was pushing like 80psi and 60 with no movement)

going to check that when i pull the throttle it actually comes all the way open,

then last but not least timing..... just to make sure i have it figured out after reading some things.....
1. it should already be set up at plus 10
2. to make sure the balancer is in the correct place im going to bring to tdc and mark it as 0 correct
3. start the motor with idle around 700rpm and the timing light at this point should show 10 advanced
4. bring the motor up to 3000rpm and it should be at 24 advanced according to the timing light...

also a old race car guy told me his trick was always to hold the throttle at 3000rpm turn the distributor left and right until the motor raises and lowers..... when you find the highest point it goes up to lock it down there and it is in the right sport for what the motor wants..... any thoughts?

Why only spin it to 4200rpms??? It is actually harder on the engine lugging it at lower rpms than letting it spin up faster. Even if its a 330hp, it would run better spinning it up to 4600rpms or so.

Setting the timing depends on what ignition module you have. If you have a V8-24, then set it to 10* at idle and check it at 3700rpms and it should be 34* or so. Stock merc is 8* base and 32* at full advance.

Agree, x2
OK, so Griff and I both read it wrong, still a good comment on the timing issue.

Griff, I THINK he is saying the it will only spin 4200 rpms and he is trying to correct it.

Can you give us a little more information? Weight of the boat, estimated HP and target RPM, drive ratio, prop type and pitch. This may help us point you in the right direction.

Don't use any shade tree mechanics tricks or your motor will be toast. Set it at 34 deg. advance at 3000 rpm and leave it there. Boats are always running under load so they will knock if the advance is turned up too high. Knock = death to your engine.

1995 mirage 217 intruder... gutted for fishing boat by last owner so about 3500lbs
its a marine power 502 and they estimate around 425-450 hp (probably more like 425)
mirage plus 25p prop that came on the boat and worked fine with the 502 mag im told

and yes i want to spin around 5k 4200 is hard on my motor and kind of depressing seeing that its only like 55-60mph and i bought the boat with a 502 to be closer to 70..... dreamometer at 75! lol

Yea, somthing is not right there. I would think you should be high 60's. Did the boat run faster with the old engine? I asume this is a new engine, did you get a build sheet with cam, head, carb specs.
If you have a 24deg advance on your distributor you would set it at idle to 10 deg and it should be 34 total at 3k rpm and above. Maybe try a 23p prop and see what that does.