rssteiny

my 2000 500hps have 380 hrs on them they still run awsome and oil pressure is still same as when new , i did new valve springs at 240 hrs and i change oil every 20 hours since new with royal purple race 51 only. my question is should i refresh now for the upcoming season or can i get 1 more year out of them and then refresh, as i only put about 40 hours per summer on it and only run hard 10% of the time. i would like to here from anyone who has run 500hps 400 plus hours and there thoughts and results. i do want to build more power when i refresh like 600 hp thanks

nocigarette

Keep running the sheet out of them and save your money you have two you have to go through when one weakens..............

rssteiny

thanks any other input

jryan26

New springs. Maybe valves?

stevesxm

take a few hours and do a proper leak down. thats going to tell you if you have any pending issues... any thing less than 20 % anywhere will indicate some meaningful wear somewhere that you might care about. if its the rings then you can do another year but just be down on power, if its the valves then you might consider if its just one or all... just one might mean its bent or has a bad seat... and you don't want to run that... if its all the i would have the heads off before you made yourself very unhappy some day at speed. the way youve been maintaining the oild would mean that all the bearings are still perfect... what you are up against with those hours are simply pending sealing issues.

npartin

I wouldnt use the Race 51 oil.... those engines were built as tight tollerance engines and the use of heavy oils like the race 51 actually REDUCE oil flow in GPM and can actually cause a reduction in actual over all lubrication, which can actually rob power, and hurt the motor, keep the royal purple but go to a 10/30 or evn 5/30 weight versus the race 51.. the reduced drag on the oil pump and the added lube flow at the same pressures will allow the motor to last ALOT longer than it would on the Race 51 due to more oil passing over the bearings puling more heat away from them.... todays engines are no longer the loose tollerances that the old engines are... now the rules are as tight as physically possible under heat so long as they dont actually make contact, and because of it lower weight oils and higher GPM flows through existing oil pump designs are starting to show up on the market.


You NEED to do a leak down. NEVER jst assume that becasue your motors have X hours on them they need to be rebuilt... also use a spring tension checker, why spend 10K or more to freshen a set of motors when you may actually have 1000-2000 more hours in them.... there are actually SEVERAL 525's out there with more than 1000 hrs and BTW MERC has schedualed maintance scheduals printed all the way to 2000 hrs and no where in that schedual is a rebuild at 380,500, 1000, or even 1500 or 2000 hrs... as long as CYLINDER compression and leakage is within Spec and consistant year to year, mechanically the engine is capible of producing X HP MOST HP loss is fuel system and ingition system related, as an engine ages carbon deposits in the intake and exhaust disturb the flow of air through the motor and a ctually slow down the incoming intake charge, plus carbs and injectors clog up and because of their change in spray pattern or fuel flow through the jets become rich in mix because the dropplet size increase relitive to the area that the air around it occupies... what I wold do if my boat started slowing down slightly is check the hull, any flaws there, or did I leave it moored for the summer and does it have marie growth on it causing drag?? then lok at the prop, is it scratched warn ect, then move to the drive,, do things move freely or is something binding... then on to Alignment, then to the Plugs on the motor, plug wires dist ect.. then compression check. then leakdown... if leakage exceeds 10-15% i would find WHERE.. if leaking around rings pull out injectors and check flow, if bad there is a carbonissue so the motor needs some top end attension... your motors are Roller cam equiped (as well as roller rockered) so the springs and related valve train shouldnt really show that much wear or loss of seat pressure versus the impact that mechanical flat cams take that were known for wearing out valvetrain parts..

to me I would say your waisting your time if things look good and its a known fact that 500 HP from a BBC is NOTHING...

pretty much ANYONE even if they dont really know what they are doing can make 500 hp out of a 502 and make it last A LONG TIME if they atleast use good parts...

npartin

Ideal Leakdown is 0-10% with readings consistant from cyl to cyl.. any more than that or a large (more than 5%) actoss all cyl then its worth finding where the leakage is comming from.... with respect to oil i would actually look to the beerings for excessive wear.... heavy ol doesnt flow very well through tight tollerances.... that motor was built around 10-30 or at most 25-40W not 50W oil... tollerances are tight and wear actually could be increased as the pressure spring opens before full oil FLOW through the motor occurs.. and the pump will bypass most of the oil back into the pan...

Phazar454Mag

Are you really sure about this ?
It would surprise me that a 10W-30 or 5W-30 is the oil to use in a 500HP engine. Is the 500HP engine really built with very tight tolerances ?

rssteiny

i will do a compression test/leak down and if all is good maybe i will pull the heads and replace valves , springs and a little head work along with a bigger cam and new lifters and a cloyes roller chain & gears. would like to make more power like closer to 600hp so if the bottom end is ok will me doing the top only put more stress on the bottom end. as for oil weight most evertbody runs a 50w of some sort.

thanks

stevesxm

let met this straight.... you are going to do all that work if the leakdown is GOOD ? why bother w/ the leakdown at all ? the only thing standing between you and a complete freshening at this point is a handfull of oil pan bolts and a set of rings. the logic of doing all the diagnostics just so you can rattle it almost all the way to pieces anyway escapes me.

as far as the leak down numbers go , you can believe what you want... sure... single digit numbers are wonderful but a good solid motor when cold will give you some numbers in the 12 and 15 % range which wouldn't bother me in the least... and if you are telling me that you are going to warm this thing up in the boat, then strip the plugs out and get the leak down done in any reasonable sense without really having a miserable day... well youre a better man than i.

it sounds to me like your mind is made up to go for more power... just make the decsion, take them apart and do it. thats going to be anall or nothing deal...

why would you think of going thru all the work you are discussing just to leave old bearings and rings in it ?

not trying to give you a hard time... just don't understand your approach.