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sherman51

need some advice on 350 mercruiser

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i just bought a 25 ft boat that has had the engine changed. i need some help and advice. the owner changed the motor about 5 yrs ago. he put about 20 hrs on the motor then died. so the boat has set for 5 yrs.

first off does anyone know how to tell if its a std 350 or a vortec motor?? it does have the serpintine belt on it, it has a 2 barrel carb.

here are some of the things i plan to do. i am going to borrow a oil pump tool and prime the oil. i am going to hook a electric fuel pump to it and pump out as much old gas as i can get out, then add fresh gas and carb cleaner. i plan to look at the plugs and decide if i want to change them. i plan to replace the wires and rotar and cap. i plan to start and run the engine on the old oil then change the oil and filter. i was going to change the outdrive waterpump impeller. then i decided to change the upper housing as i will have it off anyway.

does anyone have any more suggestions or advice?? this is an older boat an 86 sea ray. it looks alittle rough, but it was cheap. if the motor is good then i should have a really good boat for erie. it is 25' x 8'6" and it trailers good.

i do already have a 86 28' x 10' sea ray amberjack that i got mostly for my little brother and my next best friend and me to use on erie. but they both died this last spring. and one engine lost fire and wont run. and i just lost interest in it. and plan to sell it this spring when i get the engine running. it has a brand new tandem axle trailer and tows good. but it is 335 miles each way for me to tow. and without my crew i just dont want to be towing that far. it has had the engines changed. it has twin 4.3 mpi engines. when it died it was like you shut the key off. i just wiggled all the wires and it started back up and run good. then we went fishing and run the motor all day, then it died again. i just had it winterized and parked it. i havent even tried to get it running. but im sure its just something simple. a loose wire or maby the coil. i have already bought a new coil for it. and i bought 2 brand new 4 blade props for it before my brother and friend died. so next spring look for this boat to be for sale. now i just need your advice on my new 25 ft sea ray.

sherman

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real easy if its a older model 350 chevy it will have 4 valve cover bolts 2 on the top 2 on the bottom if its a vortec it'll hace 4 through the center of the cover

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Two things are for sure on the new 25', the gas is real old, and you should change out all the water and gas filters, plus rebuild the carb. Next I would advise that the oil has definitely lost it's viscosity setting up 5 years too, change it twice, once before you fire it up, and again after about 10-20 hours to be sure it's clean and has it's proper weight. When you put new gas in, try to find non-ethanol grade to ensure you don't repeat the old gas problems into the future.

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thanks so much guys for the information and suggestions. it must be a vortec engine it has the valve cover bolts through the center of the valve pans.

and 2 oil changes isnt going to kill me. does anyone suggest i put some oil in the cylenders and turn the motor over a few times then let it set for awhile before starting it?? or maby take the plugs out and fog the engine and then let it set for awhile?? i,ll be honest im not much of a mechanic, i just do the best i can. and with my health i have most stuff done at the marina. but this spring im going to make my 2 sons help me do the stuff i think we can do.

any more info or suggestions are welcome.

sherman

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Good luck with the new boat Sherman.

On the old boat, make sure the plug that plugs into the motor is making a good connection. Mine kept coming loose, and it would do just as you described. A hose clamp took care of the trouble.

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I would also spray some oil or fogging oil into the cylinders and let it sit. Then turn it by hand with a socket and breaker bar on the front of the engine before trying to turn it over with the starter.

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Good luck with the new boat Sherman.

On the old boat, make sure the plug that plugs into the motor is making a good connection. Mine kept coming loose, and it would do just as you described. A hose clamp took care of the trouble.

thanks for the tip. i had the mechanic at our local marina tell me the same thing. he said he runs into this problem all the time. it make me feel alittle better hearing it from someone who has had this problem. it will be the first thing i check come this spring.

sherman

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real easy if its a older model 350 chevy it will have 4 valve cover bolts 2 on the top 2 on the bottom if its a vortec it'll hace 4 through the center of the cover

thank you. it does have the bolts in the center of the pans. so that is good news. atleast i know now what type engine i need to get parts for.

sherman

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I agree with the rebuild the carb 100%, but I would start checking into any possible gains with 4 barrels.

What gains would you think might be possible considering the heads are 2 barrel size?

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most 4bbl and 2bbl use the same heads. The big advantage to a 4bbl would be in getting a spread bore carb then you can have economy at idle and part throttle and performance when cruising and getting up on plane. Biggest gains would be fuel injection and a cam. Affordable Fuel Injection has a Marine kit for SB Chevy that includes a electronic dist and GM computer which you can get hundreds of programs for. If it is a 350 and not a 305 putting 300 plus to the prop is not a problem just spend money LOL.

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small block chevys use same heads for 2 barrel carbs as 4 barrel carbs the intake is diff. for best fuel eco. i would stay with a 2bbl

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Personally I would get the fuel injection and modern computer and have the best. Heck If i keep my 26 and go with the fuel injection I will make him a great deal on my 4bbl and manifold.

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I am guessing the the motor is free and not froze by the way you are posting . you have asked about oil in the plug hole. If it was me I would us about a half qt of tranny fluid split between all of them . It is a old trick that we used back in the day for motors that have been sitting around,the inside walls still do rust just by the heating and cooling of the casting.(summer winter) which makes rust,and if you have a ring that is froze it normally frees up. I would fill them till they are full and let it sit a few days, the longer the better. then slowly roll it over by hand with the plugs out. After that prime the pump and fire it for a few min's so you have pressure shut it down and change the oil. Use a High grade straight weight oil with a rust retarder. rebuild the carb and water sep. If you don't have time to drain the tank use a 5gal outboard tank.

hope this helps

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What gains would you think might be possible considering the heads are 2 barrel size?

from my understanding and from changing many old cars from 2 to 4 barrels you gain about 15 to 20 hp, depending on the type intake and carb you change to. but you also use alot more gas with the 4 barrel. so for now i just plan to use the 2 barrel carb and see how the boat performs.

im not a speed freak, so if the boat planes off good and i think it will then i,ll stay with the 2 bbl carb. i plan to start out with a 17 pitch high five 5 blade prop. that will take care of my hole shot. and i have found that most days you dont want to run full throttle on erie anyway. so i,ll just take it a day at a time. but i,ll probably keep an eye out for a good intake and 4 bbl for a vortec engine.

sherman

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Personally I would get the fuel injection and modern computer and have the best. Heck If i keep my 26 and go with the fuel injection I will make him a great deal on my 4bbl and manifold.

let me know, i might just buy it.

sherman

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most 4bbl and 2bbl use the same heads. The big advantage to a 4bbl would be in getting a spread bore carb then you can have economy at idle and part throttle and performance when cruising and getting up on plane. Biggest gains would be fuel injection and a cam. Affordable Fuel Injection has a Marine kit for SB Chevy that includes a electronic dist and GM computer which you can get hundreds of programs for. If it is a 350 and not a 305 putting 300 plus to the prop is not a problem just spend money LOL.

It has been many moons since I have done any engine rebuilding and most of that was with Fords. I did a Olds 350 once. These all were done in the late 70's-early 80's. My recollection is that the heads on those engines were specific to the carb.

Now I understand why people liked working with Chevy....

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