boatman747

I have just installed two new 540,s in a 31ft formula with Bravo drives. I have a 632 lift hydraulic roller with 246 - 256 duration. The rectangular port heads flow 322. I run 850 Holleys and an electric ful pump set at the factory setting of 7 psi. The boat idles at 1100 or so. When I put it in gear it drops way down to 300 or 400 . It is terrible around the docks. In and out of gear is hard . Any suggestions ? The boat has awsome power. I can turn 30 inch bravo 4 blades abt 5600 or so .

mopower

I had a very similar problem all last season . Checked manifold vacuum at idle and only had 3 inches. When put in gear and the engine slowed more it dropped to the point it wouldn't pull fuel . If I riched it up at idle it helped but in no wake zones at 1200 or 1300 rpms the vacuum increased to the point that I would foul plugs . I also set idle for 850 in gear , yeah great , but put it in neutral and it idled 1500/1600 rpms not good.
Last winter I swapped cams and I now have 13 inches of vacuum and can shift in and out of , forward or reverse with no problem.


BTW mine were 540's with 630something cams and rectangular port Merlin heads. Only difference were Dominators and Carter 140 gph mech pumps regulated for 7 psi

boatman747

How are your drives holding out . What size is your Formula and what kind os speeds have you seen ?

Griff

Whats the timing set at????

boatman747

timing is set at 34 degrees total

Mr Gadgets

Boatman,
It sounds like your intial timing is a bit low. Total is good, but if you have 8 or 10 degrees at idle it will not run worth a hoot. If you have the merc ignition, you need to find a way to put more initial timing in. One way to experiment would be to check it by cranking up your timing.. I mean just twist the dist so the idle goes up. Lock it down and drive it at idle to see if that helps. DON"T attempt to run the motor that way, you'll end up with 50* or so of timng. If it helps then you can figure out a way to change your advance curve to suit your needs. Big motors like lots of timing at idle. I use a MSD dist on my 565" motor and lock it in at 34*. So I idle at 34*, I can idle in gear at 500rpms and usually see about 800 or so out of gear. Now I have a bigger cam and that helps, but I dont have any problems running the locked in timing.

I hope this helps, if it doesnt make sense, I will try to explain again.. just a bit slow this morning.
Dick