Need help with new motor...
 

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.

My 18' Formula weighed 3500# with full tank and small block. Yours is much heavier, really should be a big block boat with bravo. Friend had one on Cayuga lake like yours and believe with the 260 hp the most he saw was 43.

Jasper's rating did not include water pump, accessories, and probably used dyno headders, I think your combination with these losses would bringe you down to the 300 hp level.

Merc used to rate the standard 7.4 liter carb engine at 330 HP, but that was at the crank, when they switched to propshaft rating (all accessories and drive losses) the new rating was 310 hp.

My avaitar shows killer 406ci small block with Brodix Track II 2.02 aluminum heads, single plane manifold, 750 dual line holley, solid lifter Ultradyne cam, and Stainless Marine manifolds. It would pull a 27 pitch 4 blade hydromotive prop like it was nothing. It killed the drive in the second season even when babying the throttle. Top speed was 70 to 72 at 4600 rpm, but the boat chine walked badly. Pulled all the cam out of it, went down to a 600 cfm carb and then sold it with a top speed of about 60, just so the new owner didn't kill themselves.

I am starting to think you guys are right, that it just needs a big block. I thought that upping the small block from 260 horse to 325 horse would do the trick, but I guess this thing was absolutely horrible with the original 260.

I am going to try and step down to a 17" Mirage prop and see what it does. This motor needs to turn RPM to make power. I just don't understand the white plugs, thats why I wanted to try a Holley 750.

Will overloading the motor with too much weight and too big of a prop cause lean white plugs???

Well, I decided to try and step down to a 17 pitch prop, to get the RPM's up. I guess this motor needs to really spin to make power. I picked-up a Mirage 17 today, and hopefully it will help. I'm sure my holeshot will improve. I'll post the results tomorow.

Thanks again guys for your advice, I appreciate

I think you need a good holley 600 and put the timing to atleast 36 or 37 degrees. Hell on my old 355 with steel dart heads and almost 11-1comp I ran 38 degrees and it made an honest 450hp.

Well, I stepped down to a 17 pitch Mirage prop, and it made a huge difference. Now it turns 4800-4900 RPM's at 47 MPH on the GPS. It comes out of hole ten times better also. Now when I nail the throttle it actually takes off, and has some balls.

I think with some more timing and a different carb, (I agree 100% niceguy) I can get a little more out of it. And, I am having the bottom paint soda blasted, and hopefully that will help a little. Right now it has several cotes of old "shark white" paint on it, and it looks like crap. If I can get 50 MPH out of the small block, I will be happy.

Thanks again for all of the help and advice guys, I appreciate it.

I have the 242 with the BBC and only see 55 gps, so 50 with a sbc should be about right.

Good luck