I run electric Mallory 140's 600HP/side on stock 3/8" 6-9psi with no issues.

Thanks for every ones help, i will try and find a 850

contact Himrod67 on here. he has my old boat and i know he went to a dominator. he will prob get rid of the 850. it was dialed in incredible. started and idled like a efi. it wasnt very pretty of a carb but it worked awsome!! pm him and see if he still has it

if it has been the same cylinders, check intake surface, like mentioned. fix problem before you doctor over it and do more damage.

make sure you carry more than a quarter tank of fuel when trying to bust the speed record.

i highly recomend checking your air-fuel ratio ,espically at wot.

If you had the motor dynoed the dyno shop had to have had a EGT system or air fuel ratio meter on it. What were those readings? Were you ok or at the very edge of being lean. What size fuel lines and pickup do you have in the boat? I would compare all the fuel lines, pumps, and filters used on the dyno v/s what you currently have in the boat. I'm running a 850 on a 468 with 320 cc heads and it made 450hp and 512 ft/lbs on the dyno and all the EGT's looked good, I also have overkill on the my fuel system with everything being 8an lines and fittings.

While I agree the 750 carb is too small for a 548CI, I dont believe thats why you burned pistons.

You need to check WOT fuel psi. It should not fall below 5.5lbs. If fuel psi is holding ok at wot, I'd be looking at the jetting. Too small a carb will starve the engine for air ,but not fuel. The 850 carb doesnt have larger needle and seats, larger bowls, or anything really to allow it to flow more fuel.

Your pistons got burned up from fuel supply, or lack there of. I'd still go to the larger carb, better pump, and make sure there are no restrictions in the fuel supply. The holley pump you are using is marginal at best for what you have.

wouldnt you see a poor fuel delivery on other cyls too not just 4 and 6??? you would see it on ALL your exhaust valves not just 2 cyls.

ninja any updates or findings??

Most of the valves were tuliped on the #2-8 side head, I cant remember if any on the other side was, I will check and get back to you.