cigrocket

iTrader: (3)

My buddy has a Formula F3 (23) It has the Merc Mag 260HP 350. It has thru Hull exhaust. He wants to increase his horsepower by about 50. I told him it would probably take exhaust, intake and carb to achieve this. Does anybody have a tried and true method to get those horses out?? He wants to go the cheaper route. He was looking at dennis moore exhaust manifolds. Any help would be greatly appreciated. He is just into the boating scene.

SB

iTrader: (1)

It prob won't happen without a camshaft + valvespring change.

Here's why:

Stock flat tappet cam:
.004 " 270, 284
.006" 258, 270
.050" 200, 212
.400", .410" with 1.5
110 LSA

===============
Stock hydr roller
GM#14097395/ Merc#431-811658
.004" 258, 272
.006" 249, 264
.050" 197, 207
.430", .450
109 LSA

IRONMAN

Upgrade to a 454 and sell the 350, you will be happier in the long run. That is a nice boat but I ran one with the 300 tempest and it was OK but I did not feel that was enough .Torque is king
http://www.offshoreonly.com/classifi...2&cat=5&page=3

Donzi502

BBC or hartbreak and a smacked up wallet!

cigrocket

iTrader: (3)

Thanks for the replies. The drawback to the BBC versus the SBC is that he has an alpha drive. I figured if he could get it to 300-310 he would still be ok. I know they mated the 310 454 with an alpha.

merlyn1965

I did this for a friend, I put in a comp cam kit CCA-K12-236-3 and a fresh engine. Works like a charm and nothing is giving it away. No need for anything else but to rejet the carb. Best buy for the money @ $309.00 at summit.
my $0.02

cigrocket

iTrader: (3)

Did you get 50 more horse after the upgrade??

merlyn1965

The 262H grind is bigger than the 300HP mercruiser cam. I don't have access to a dyno and in that range, we don't really need it. Sitting on the boat and doing sea trials, the feel on the throttle and watching the smile on my friend's face told me that he got what he wanted and then some.
Pretty straighforward to do even if you've never done it before. Complete instruction with the package and the only special tool you'll need is a valve spring compressor.

unbroken

I have a set of Vortec heads for sale that would get you pretty close to 40 HP. That and a cam would make it well over 300, probably 320ish. Or stroke it and make it a 377!