racinbird

Could use some suggestions. 97’ 232 boss, carbed 502 (475hp?), bravo 1, running bravo1 24p 4 blade. Best top speed I’ve seen is 69.7 mph @5000-5100 rpm. To achieve this trim needs to be more than half way up. Any more trim and I start to chine walk. Also the more weight in the boat the faster it goes. Most responses about top speed say they get more the lighter the boat, opposite for me, that 69.7 was with four large adults and 60 gallons of gas. With just me, passenger and ½ gas it gets some crazy chine walk past 67 mph.

With this size and weight boat should there be more top speed? Stock 232’s with 496 HO run upper sixties. Is the 4-blade prop lifting the transom out of the water? Would a 23p or 25p 3 blade help by keeping the boat down at more trim? Adjusting the trim tabs just slow me down. Should I look into changing stock X-dimension? Or maybe look into an out drive extension, would dropped the drive down help this? Or do I just have less horsepower than I think? Any help would be greatly appreciated. Anyone with a hopped up 232 or 252 have a combo that works? Thanks in advance, Derrick.

mcollinstn

#1) what "flavor" of 502 are you running? You mention 475 hp, but that is not a stock flavor. Without knowing what setup is on your motor, we can't accurately guess the power peak to help you prop for top speed.

#2) without knowing the flavor, I'm going to pick 5100 rpm as a peak. Since you are already turning 5100 with throttle left in the stick, you need to prop up a size for further testing.

#3) If you are experiencing chinewalk that you are uncomfortable with, then you need to enlist the assistance of an experienced driver to determine if you have some weight distribution or setup issues that need dealt with. An inexperienced driver attempting to drive through chinewalk can have disastrous consequences.

Chinewalk can be aggravated by many factors, some of them being:

side-to-side weight distribution
free play in the steering system
choice of propellor
existence of irregularities in the running surface of the hull
propshaft height
air in the trim system
worn gimbal components
manufacturing defect (driveline mounted offcenter, etc).

An experienced driver can check out a boat and decide whether to attempt to drive further into chinewalk. I drove a 280 Baja with twin 502's that nobody at the dealer had been able to drive WOT without using tabs to combat porpoising. I was able to drive it tabs up and trimmed out to WOT and was able to help them pinpoint a weight distribution issue that tamed the boat.

If you have been unable to drive the boat WOT with tabs up and fully trimmed (not overtrimmed, but able to find the sweet spot), then your boat definitely has more in it. Find some experienced help before going further.

racinbird

Mcollinstn, bought the boat used earlier this year. The engine is a built setup, starting with a GM Gen6 502 short block, Merlin oval port 254cc heads with extreme duty valves. Has 1.8 crane gold race roller rockers. The cam is the BIG mystery, was told from old owner that the cam selected was more for low-midrange use; it’s a special comp cams grind. I was not able to get a grind build card and he can’t remember the specs. So with out pulling the timing cover to get a stamped number, I have no idea. He did say though that the setup should be close to the HP500 specs, but still guessing. Eldebrock air gap manifold, Holley 750 carb, lighting magnum water-jacketed headers, Msd ignition. Yada, yada yada.

When I hit the 5100 mark, I am at WOT, its just that the more I trim up, the faster it keeps going, and the faster I go the more chine walk I feel. I don’t have external steering yet, but it does have a sidewinder strut system on it, I have heard they don’t do much, but better than nothing for now. As for the side-to-side weight issue, there really isn’t too much on this boat, unless it’s a poor structured or damaged hull, I have a hard time seeing that as a problem, I always try to even out passenger and gear load.

I can’t feel any free play in the steering, its as solid as I’ve seen, unless only at high speeds/loads. Is there a way to really check it out thouroly?

Choice of prop is what im really curious about. I have heard that bigger 4-blades can tend to pull the transom out of the water more than a 3-blade, and with this being such a light boat already, is that the issue?

I have played with the trim tabs a lot, they don’t change the ride much other than lower the speed when down, moving up doesn’t change anything at high speeds, I leave them parallel to the hull.

As for the “sweet spot” issue, any other 232 owners out there may be able to help, depending on load weight changes my trim max sweet spot. With a light load I can trim about to the half way mark and ride smooth, that’s right at 67 mph and close to 4900 rpm, if I have four adults and some gas I can trim up 1/8 more and get 5000-5100 and 69-70 mph, I still have trim left, but the ride gets scary from there, a lot of side-to-side (chine walk?) action, so I really don’t know how much more I have left.
Any more ideas or thought?

russ

Sound like you got the wrong prop. I had a 98 232 with 454Mag (385HP) at 5200 RPM's with 23P prop, 1/2 tank gas, 2 people, cooler running 68 on GPS.

You need to do some prop testing. Try a 25P 3 blade. You should at least be seeing 74 to 76 MPH.

I also had problems with chin walking. I always had to steer to the right to correct it.

Steel Outlawed

Was this boat originally from Greenville, SC. Sounds like a boat I looked at about four years ago. E-mail me I might be able to give you some more information on the boat. Few things that might let you know if this is the same boat, are it had switchable external diverters on the exhaust, external steering stabilizer (sidewinder brand), I think he had added a couple guages to the right of the helm.

[email protected]

Madmax

I've got a 97 232 with a lightly modded stock 454. It runs right at 68gps. I'm figuring i'm making about 375-385hp. You should be going ALOT faster.

Mine also chine walks like crazy with a light load and a lot of trim. I haven't dove into the problem much because trimming it back down below the halfway mark on the gauge brings it right back around. I'm running a 25pitch 3 blade mirage +. I tried a 24pitch bravo prop and it porposed insanely, plus it went about 4mph slower. I put the 25 back on and have left it alone.

I told the dealer about the porpose and the chine walk, and they suggested having the hull blueprinted to correct any problems. Their opinion was since i store it on a lift and a trailer year round, the bunks could be causing the bottom of the boat to distort a lil bit over time. I don't know if this is crap or not, but it kinda sounded logical. Maybe yours being older also, the bottom isn't perfect anymore either??

Sorry, just rambling.....Sounds like the chine walk is normal, but the speed is definately NOT if you are making the power they claim you should be making....

racinbird

jeff, you have mail

mcollinstn

If it were mine, I'd pull the timing cover. I'd want to know what I had. It's not nearly as bad as a smallblock timing cover (in case you were dreading it already).

Also, oval Merlins are 269 runners (and are good heads) for a medium flavor 502.

Custom Comp Grind?
If you can get a valve cover off, you can measure cam lift easily enough with a dial indicator.

When a motor has an unknown content, it is impossible to determine how it should be performing. A stock Mercruiser hydraulic flat tappet 502 cam is 224/224 @050 and .511 lift (or somewhere around there). This is good for 400hp on a carbed stocker. Depending on cam choice, you may still be in that ballpark.

racinbird

Mcollinstn, you're right, pulling the cover to get the cam grind is the best place to start. This could easily be a lower than thought engine horsepower rating situation. I may do that this week.
Also, not that it matters, but according to the original merlin instructions, the ports are 262cc, or at least back in 98' they were.

So if the cam is smaller than thought, any ideas on a cam choice to run around 500-550 horse, the rest of the engine should be more than able to handle the upgrade. Thanks again.