548 fuel delivery
 

I just burn 2 pistons (second time) in my 548. The bearings look ok so am assuming that it was not a timing issue. I guess it can only be a fuel delivery problem. Can anyone recommend a electric fuel pump and fuel lines that I should use? It was dynoed at 560 hp, no fuel problem at that time.

If you are running this in your checkmate with a stock fuel configuration the first place to start is probably the fuel line and pick up from the tank.

I think most will agree aeromotive has one of the best electric set ups.

Are you running a mechnical at this time? With. the right lines a mechanical pump should deliver all the fuel you need. Just switching to electric will not help you if you have a volume delivery problem. A fuel pump gauge on the dash with this much power is a must as well, IMO

i agree i would start with your tank pick up and supply lines. no need for a aeromotive or some crazy pump. your not making nearly enough power for that. i rigged some pretty big cubic inch and hp stuff this year and we are running mechanical pumps without a hicup. what # pistons are you burning up? might want to look into your carb. i ran a 850 holley on my old 548 and made great power. current owner of the boat switched to a dominator.

running a 750 holley right now and had a holley 110 electric pump. number 4 and 6 cylinders.

check your intake make sure your not sucking air on that side. these motors dont get hot enough to expand and seal up intakes if they have a little warp in them. you will be able to see it in your intake gaskets if they are leaking. ive seen problems with that with aftermarket intakes. going to an 850 carb wont hurt you either. you will make more power for sure than your 750.

What is your fuel pressure at wide open throttle?

What is your jetting?

If the "548" is cubic inches a 750 holley seems small to me.

What did the new owner see with the dominator? We are tuning a 540, and running an 850, but have a 1050 on the shelf we may throw back on.

ive heard that a 1050 will give you another 20hp but judging by his speed numbers he didnt gain much compared to when i had the boat. i did 2 boats with 548's this year. both had dominators. one had 320cc heads and made 650hp and the other 548 with dart 335 cnc heads made almost 700. my 548 in my old pantera supposedly made 650. the 850 really ran great. it had great midrange where a dominator wont. dominators are made for idle and WOT. they are a headache to tune the midrange and i dont think your gonna see a difference of 20hp in a big single boat mph anyway. also if your not using a dominator flange intake your pissing in the wind. a 4150 intake is still a 4150 hole. like pinching off a garden hose

You are correct on tuning the mid with the DOM. We had it on there, and couldnt get the boat tuned. Went back to the 850 and within a short time had it running right, getting the timing curve in it now, and was thinking of giving the dominator another shot, but heck if it's only 20 horse probably leave it be. Boat is a 26 American offshore cat so it runs well once it gets going.

i would run the 850 too. the driveability is worth it imo. as for ninjaturtle throw a 850 on it and put a straight edge on your intake. you might find a surprise. if so go get it milled a touch. it seems big blocks burn headgaskets between cyls 3-5 and aftermarket intakes are a major culprit for leaning out and burning pistons and valves

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.

need more info on engine..thats not a lot of power to be killing pistons..