Help with performance problem!!!!
 

Big problem with the T-Bred, I was running a few days ago and pushed about 5500 with the BBC, Popped and skipped, THough it was rev limiter so i didnt over twisted it. Throttled down and then back up was fine. I was out coming back from Block Island, 1. I was pushing 4600 and could not turn the motor any fast dont know why, when i was running it popped threw the intake on one cylinder then didnt, i got back to the dock smelled antifreeze, Lost all coolant, Filled it ran it again turned 5200 but still feels like its holding back. I could only get about 72 out of it. ran 81.7 so im lossing about 10 mph. I had a fuel problem i need a reg. im putting that in wensday, but could just the fuel pressure make it feel like im pulling an anchor? Any and all help is greatly appreciated, also i will be out thursday so if anyone can help and want to ride along to help please do!!! thanks guys

Maybe a nead gasket went south:(

$h!t because i was thinking along those lines, the coolant ended up in the bilge still dont know how or why, but wondering why i couldnt get any rpm i mean this was like pulling a parachute in 50mph winds u could feel it wasnt right. was making pleanty of boost just not going anywhere

were you running hot when the coolant was low, check the plugs also, if coolant is in the bilge that sounds like a leak under pressure maybe. mine popped last yr and a stud broke from ex side and popped out the carb:eek: easy fix no bented valve:D .I am on cruchers but will stop by on thurs. art

Thanks art, not sure about the hot and popped out the card i tried to look at theh the gauges at one but didnt get to happend all to fast, sure stop by i hope i can resolve this, sux, it was sunnin so good to

This is a blown motor? If you lean it out it will be a non running blown motor. What type of blower? Carbed or F.I.? Fuel supply is critical. How much for max boost? Check your plugs, was the motor hot? What does it have for an ignition system box and distributor? I've built a few boosted motors and have blown up more.
Josh

This is a 250 B&M running between 4.5 and 5 p.s.i. depends on how hard i run it and how the weather is as u know hot or cold. Im going to look at the plugs tomorrow and the ignition system is stock. its the thunderbolt 4 with an msd coil. I know leaning it out will pop it for sure. i always have my eye on the psi just because i felt there was a prolem from day one. What should my pressure be for fuel at idle and WOT, i was thinking idle 7 to 7.5 and WOT like 4.5 to 5

my 509 runs 7,5 to 8 perset all the time. I was told to never let it get below 5. I have to get my stitches out of my knee thurs morning so I will call you tomorrow to see if we can hock up. just bought a new bravo 1 x drive :D , I am slowly buying parts:p .

Sweet art hoping to hear from you hope all go well nice grab on the X Drive

How long have you been running this combo? Who put it together? What carb or carbs? Fuel psi should be a MINIMUM 5 I like 7. Is it an electric or mechanical pump? Is it a locked advance on the distributor? You could get a lot more out of that motor with good electronics, boost referenced distributor, big carb or carbs, and change the pulleys for more BOOST.

STITCHES OUT AT 930,I'll call yah, art

The motor was put together in 1998 by JB MArine and Automotive. The carbs are 750 Mech. Double Pumpers. This si a mechanical fuel pump running off the sea water pump. has a stock pulley on it and also the ignition is stock also thunderbolt 4 system want to upgrade to an MSD. Im running 5 psi of boost. thanks HYDRO. Any and all help much appriciated

if thats the stock pump you need to get the upgrade or a elec pump I also have a new black holley marine set up I never installed. I think I bought the upgrade kit from cp, but fred might have them to at trick. call me its 2pm, I called you at 12 my doc was late taking out the stitches. worst case we can strip mine off the water pump and try it. ART aka ARTIE or ARTIMUS

Art just talked to you sounds good about the pump we will slap that in and also the reg and blast from there it might be a little jimmy hacked until i get my normal BG reg back but hopefully rungs great and good to block with eveyone else

Yup, definately upgrade the fuel system and the electronics if you got the doe. Do the carbs have the marine kit in them? The MSD systems are good see if you can get a boost referenced system then it will become more snappy retards ignition as boost goes up. Do you have any cooler on the intake? Did you check the plugs and or do a comp test to see if you popped a gasket? You know at 12lbs you volumetrically double your cubic inches.... just for info's sake. :cool:

Imm doing the fuel system with art (airtime)today, I rebuilt the cars before i dropped it in the water for the sencond time to, they were dripping fuel so i just made them new again, there is not chiller on the intake, plugs look fine and i havent done a compression check yet, i dont see anythign out the exhaust, water dumps or on the plugs. I do see water/antifreeze in the bilge but the pressure testing didnt reveal anythign so looking more i do.

[QUOTE=when i was running it popped threw the intake on one cylinder then didnt, i got back to the dock smelled antifreeze, Lost all coolant, Filled it ran it again turned 5200 but still feels like its holding back. [/QUOTE]

Check timing also. Is the timing fixed or referenced?
Could have backed off and that would cause the popping overheating all kinds of bad crap.

Its a fixed timing

jb marine installed cheap valve springs after i paid for hp springs.
long story short the valve floated destroying the motor. if jb touched
this motor look out.

Coolant still blowing out seems to be external but not 100% sure

I was forwarded this thread from a friend who saw me go through some of this... I bought a boat with a 502 with a 250 B&M on her. I leaned out and blew the blow off plate on the side of the manifold and waisted a valve. I ended up ripping out the motor punching it to a 509 and putting J&E pan pistons in her. I junked the Thunderbolt 4 and put MSD in with Crain Fireball coil and MSD 6 box. locking her out a 28 degrees total, no initial. I run a Nickerson 1050 carb and I ended up having to make 2 dips into the tank running the stock fuel pump and one electric fuel pump. I ran them into the fuel separator and then into the regulator, with separate fuel lines to each bowl. I run 7.5 pounds of fuel pressure. I run 7lb of boost on the blower, the fuel pressure never drops lower then 5.5 lbs. The B&M intake is kind of thin and could crack very easy... I hope some of my info may help... Its not much but the motor runs and performs awesome now.

Thaks H2O mine is performing pretty well gonna play with the props a bit this wekeed hopefully and get a little more speed from it or at least a better rpm range. Just looking to find the coolant leak thats my maine objective.

Glad to hear you got her running good...I hope you find the coolant leak soon...and its a cheap fix!

Me to but main thing is just to find it the money thing nothing really can be done what it is it is

What manifolds are you running... I fond a leak between my manifold and my riser.. It leaked down in between the black.. what had happened was I tightend down the riser to much and caused the middle of the riser to lift up letting the gasket leak...I was not an easy find cause at idle it would only drip down out the bottom...

ME....

Im runnong stainless marine. This boat was already put together for a while just happen to happen just as i got back from block as i entered the marina (thankg god it wasnt in the middle of the ocean) Yea idlea its fine and under pressure i cant find anything either, holds presure its just as i run it but under load not just the engine running, o well hopefully found soon.......

It won't be the manifolds raw water goes through them. I was thinking what if you or us take my old video camera and aim it at the tank tape it down leave the lights on and run up and down the river smooth water and watch the tape if the camera breaks no big deal its 4 or 5 and it took a beating last fall on my boat:eek: :p . so we can zoom in and watch the hoses at different spots or I will crawl in side with the lights on and feel for leaks:D and mike I GOT A CD WITH YOUR BOAT ON IT AND NAME:p :D ART

That would be raw water in there this is a hose, hose clamp, cap, or tank, engine block shut off on either side lower block. art

MIKE THATS IT what about the screw in sea cocks on each side of the block they are lower by the stringers we or I was thinking high by the hoses or tank, LIKE I said I can come down and lay in the bilge and you run it or the camera in there:D :evilb: I always wondered what a bilge felt like at 80plus:rolleyes: . art call me

Thanks art checked them, all tight i cleaned the coolers we'll try that