duksrule

I have a 342 with 502s and my top speed with 6 people and full fuel is about 64-65 on GPS. I am spinning 26s at about 5K. My boat is pretty heavy with the generator, a/c etc. I was going to play with the props and other stuff but you know what, 65 is fast enough for me. I love the boat and normally cruise about 40 and 3-3500 rpms. It is amazing that at 3500 you get good fuel consumption. When I take the motors to the firewall you can almost watch the fuel gauge drop.

anotherdimension

c beastwood great pics yours looks in great shape,ive got the hard screen version,they are a great boat my main rattles are from the sink unit going to take it out this winter and refix it,i will try and post some pics later ill dig em out.
jonnyboatman ill check my ratio
duksrule, thats cool must admit we spend most of our time in the boat at 3500 rpm i found fuel consumption is best there,agree full throttle my gauge goes down ,interesting your getting only 65mph,mine as no genirator or air con, so is fairly light,tried mine with low fuel and just me only 3900 rpm and about 63 mph just want it to hit 70 every now and again
for the fun of it!!!!!!

Griff

A friend of mine has a 342 withthe same options and the same results as you. I also believe that he is spinning his 26" props in.

duksrule

3900 us way to low. You should be hitting 4800+ on those motors. Props are also a good place to start. You may want to get a scan tool and check to see if they are running OK. If they start to knock the computer should retard the timing and that may be what is keeping it down to 3900. By no means am I an expert though.

Fastes I have ever had mine was 68 GPS and that was with just me, 1/4 of fuel. I must be one of the few on here that isn't chasing that extra few miles per hour. I just love my boat and am perfectly happy with it the way it is. Here is a pic of mine.

anotherdimension

duksrule and anyone else,nice pic duksrule my camera is down at the moment and none stored on my pc will be back in 2 weeks with my pics,
just at my boat and checked ive messed up there 26inch bravos, so its not the props ,could it be the timing whats the scan tool?
cant believe ive mucked up and there 26s help please!!!!

Griff

That boat should run 65mph with 26" Bravo props at 4900-5000rpms.

From all you've posted, your top speed is 64mph. I'm guessing that your tachs are off. No way you are going 64mph at 3900rpms.

anotherdimension

griff to be honest my reading of the speed was from the boats speedo which i believe is none to accurate next run out im borrowing a gps, from past boats it does kind of feel low 60s others seem to think it should be top 60s with these motors,both rev gauges do hit the same rpm though one a fraction higher than the other , ive got two weeks of next week which im spending on the boat so i want to get it right myself,could it be the timing, how do you set it up on the 502, at idle?

anotherdimension

ok ive been boating!,redid the timing on both and while in the engine bay did a few checks and by chance took of the remote oil filler pipes instead of just checking the oil on the stick and removing the top cap and filling, and oh no mayonase everywhere oil mixed with water yuck what a mess and this is on my port side motor where ive had work done!so i strip the top out and find the problem to be corrosion on the inlet manifold on the blank of sections at the back end of the engine so i do a quick repair on it with epoxy instant metal file it all down clean and fit new gaskets , flush the engine through with diesel and oil ,change the oil 3 times to remove the mayonase,change the plugs and all sounds great take out for a run my good engine now pulls 4500 rpm and my repaired one does abot 4250rpm ,so the question is have i done permanant damage to the engine , is it worht a rebuild or a new motor?

BY U BOY

I AGREE CHECK THE TACHS NO WAY THAT YOU ARE GOING THAT FAST AT 3900RPM

anotherdimension

by u boy things have moved on read the above post