Hey guys, I just found this site, and it's great!!! I learned a lot already just browsing around. I do have a few questions about my 1986 Formula 242 LS. Sorry about the long post, I am pretty desperate for some help.

I bought this boat about a month ago, with a blown motor. It came with a crappy 260 horse 5.7 and an Alpha one. I took the motor out and completely re-finished the bildge and transom plate. I had the drive re-built as well (1.5 ratio Alpha). I decided to keep the small block for $$$ reasons (maybe a mistake), and I bought a "Stage II" 350 from Jasper Engines' "high performance marine division". The motor is supposed to make 325 horsepower at 5400 RPM, and 370 ft/lbs. of torque at 3700 RPM. This motor has 4 bolt mains, all forged internals, Dart heads with 1.94/ 1.50 valves, and a nice healthy cam. I installed the re-manufactured long block with an Edelbrock Performer intake manifold, a 750 Q-jet from a Merc big block, a Holley marine high volume mechanical fuel pump, and all new GLM manifolds, 4" magnum risers, and spacers. It has open through hull exhaust into 4" Eddie Marine tips. I am using the Thunderbolt ignition set-up with the total timing at 32 degrees. I broke the motor in properly, and it sounds great. It just has no power.

I have tried 5 different props and can not get the motor to pull over 4300 RPM's. The best performance I have seen is with a Mirage 19 pitch prop. At 4300 RPM's, it is at 43 MPH on GPS. Deffinately a dissapointment...lol. I have tried 3 different size metering rods in the secondary's on the Q-jet, with no big improvements. I even tried an Edelbrock 600 marine carb, and it ran even worse. My last resort is to try a Holley 750 carb, because I think it may want more fuel. Does anyone have any ideas or advice for better performance? I hope I am not expecting too much, but I did hope the boat would do a solid 50 MPH??? I know it's a big boat for a small block, but I figured with 325 horse and 370 ft/lbs, it would run ok.

Any ideas or advice are greatly appreciated. I spent a ton of money and time, and I am pretty upset. THANKS!!!

Here is a link to the spec sheet from my motor, if that helps....

http://www.jasperengines.com/pdf/Che...ine-325-05.pdf

I'm not sure but I think you have way too much Carb! I had a Chevy 600 with a 350. I used to be in the logging business. I built the motor for economical preformance. I used to gross 50,000 pounds or more with this truck after I beefed up the suspension and added a dead tandam axle. This truck was a runner! It would blow the doors off a VW empty with a tare weight of 12,000 pounds! I was running a holley 450! Last I heard...years ago the truck had over 200,000 miles on my motor!

I would also have to agree, you need about a 600 cfm carb.
Your total timing at 32 degrees is conservative in my mind. You might want to bump it up to 34 and see what happens. Did you check to make sure you are really getting 32 degrees?

Your small block if it is as powerful as claimed, should get you to 50 mph.. My old big block mag got me there..

However, I think a 650 Q jet will give you enough fuel, as that is what I had on my 454.... I just did a rebuild, and I tried the 650 Q jet on my new big block, and ran into a wall at 3500 rpm.. However, the new motor is a 500 HP/550TQ motor..

Q jets are good to 365/375 HP per the old GM specs...

Maybe you have some clogged passages in the carb, and it needs a good cleaning and or rebuild.. The 750 will work, if jetted properly..

On the other hand, it's a heavy boat, and needs a lot of power to wake it up.. Mine feels like another boat all together with the additional HP/TQ...

I would have just put in a warmed Big block instead of doing all that stuff to a small block... Hell, a stock 454 mag would have you at 50+ mph with a 23P mirage 3 blade on a 1.5 B1 drive... (That's what I had..)

On the T-Bolt, it throws in the timing very late, and I am taking mine out as we speak.. I will go to an HEI setup with a Mallory box to limit RPM and control start retard etc..

On my new motor, I'm running a 1050 dominator with small jets on a single plane TM-2... I have mechanical secondaries, but would reccommend vacum secondaries and an electric choke for a no hassle installation..

Hope it helps..

Just out of curiosity, is the boat bottom painted with anti fouling paint. I've seen that kill a boats top speed and rpm's.
If it is it might be part of the problem, but..

It might be the exhaust thats restricting it.

I have holley 750's on my smallblocks with Stainless Marine exhaust with full length tailpipes and turn 5000 rpms with TRS drives and 21 Mirage 3 blades. My motors are very mild and never had them on the dyno but I've always estimated them to be 300 or so horsepower.

Thanks for the replys guys...

I had the Q-jet rebuilt and then re-checked. I also tried 3 different sets of metering rods, with no real change. I took it for a ride and pulled the plugs, and they are really white. That's why I decided to try the Holley 750. I think the Holley is a bit much for this motor also, but the timing is dead-on at 32 degrees at 3500 RPM's (I have a killed Snap-On digital timing light), and the plugs are still white with the 750 Q-Jet. I tried an Edelbrock 600 last weekend, and it ran even worse! I will report back after trying the 750, hopefully it will solve the lean issue.

You want grey plugs not white... you're running real lean there and a lean mix raises chamber temps to ungodly levels(think melted pistons). If you run a closed cooling system with green antifreeze, a coolant leak into the chamber will also run white, but I'm betting on a lean mix

Take the carb you have and run a couple jet sizes larger. Hi po Qjet parts are sorta hard to find, ask around local race shops, not parts stores

You may want to check and verify yoiu are running the correct fuel PSI for the carb, and that you are supplying enough fuel to the carb. Low float-bowl levels will lean it out also.

Switch to a Holley carb. There are so many parts and so much information available, it will really make your life easier in the long run. A square bore 650 double pump would work well. If you are determined to run a Quadrajet, find an expert who does high performance mods. Be careful with the boat until you get this sorted out. Running lean could destroy your new engine.