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If I had to make up a rating it would be
1a. 502 mag 1b. 496 2. 500 efi 3a. 525 3b. 520-565 I suspect the 520-565 have the 525 cam so valvetrain life would be similar. But mercs seems to have cut cost in the bottom end of the 520-565. Maybe the new machining processes of the 520-565 helps them, but they just haven’t sold enough to have a great idea how they last compared to 525s. 520s at least have cast exhaust manifolds, which helps a lot. |
Originally Posted by 1MOSES1
(Post 4827653)
griff I’ve been meaning to ask this question…agree on need to refresh top ends on blue motors every 300 hours. the stock springs are prettty weak. Coupled with junk head gaskets…it’s probably a good idea.
what I don’t understand is rebuilding a bottom end on a 500efi at 600 hours. Everything is more stout than say a 496 and it has a lower compression ratio. Why do black motors get a 1000 hour pass but we say blue motors need a full refresh at 600? |
Originally Posted by 1MOSES1
(Post 4827668)
i personally wouldn’t consider carb power in todays day in age. The fuel consumption alone is enough to make the decision.
with that being said fuel injection idle better, run better, etc. Start easier.... Thanks. Brad. (937)545-8991 |
Originally Posted by hogie roll
(Post 4827683)
Supposedly the 496 passed mercs 100hr peak tq to peak power endurance test.
I don’t really have a dog in this fight, but I do think Merc racing’s valvetrain service interval is ridiculously short. The 500efi with its milder cam seems to last a lot longer than a 525 I’ll put $50 down that 525efi owners are heavier on the throttle. I never looked into it, but wonder how different the spring rates are, if they are. |
Originally Posted by SB
(Post 4827752)
500efi exhaust lobe is the 525efi’s intake lobe. :)
I’ll put $50 down that 525efi owners are heavier on the throttle. I never looked into it, but wonder how different the spring rates are, if they are. |
Broke a valve on my 500 efi close to 900 hours
the other 2 engines had 1100-1200 hours untouched and still ran fine, but rebuilt them anyways |
Originally Posted by hogie roll
(Post 4827753)
And an exhaust valve is much lighter. Unserviced 500s seem to make 800-1000 hrs. 50-100% more than a 525
i’ll stand by 525efi’s being run at a little higher rpm then. Did some quick digging on oso and saw both 500efi and 525 efi use weak psi springs. Maybe 525’s running into soring fuss more. Seems likely. That’s my story and i’m sticking to it. :wink :lol |
33-36 baja is a great boat but man that engine compartment is tight .
Replacing sea pump impeller is like getting your teeth pulled with no novicane. |
Originally Posted by jeff32
(Post 4827756)
Broke a valve on my 500 efi close to 900 hours
the other 2 engines had 1100-1200 hours untouched and still ran fine, but rebuilt them anyways |
Originally Posted by SB
(Post 4827758)
True. okay……
i’ll stand by 525efi’s being run at a little higher rpm then. Did some quick digging on oso and saw both 500efi and 525 efi use weak psi springs. Maybe 525’s running into soring fuss more. Seems likely. That’s my story and i’m sticking to it. :wink :lol |
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