Why 50 weight oil?
05-05-2017, 10:55 AM
#31
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Running a bronze gear, is a thing of the past unless you are just turning a distributor for cam sync or spark with a external oil pump. 20/50 shouldn't be wearing gear out. A steel core cam gear requires a steel gear. Better check distributor end play at gear out of engine and tightened down, sometimes the gear bottom interferers with block at bottom of block.
05-05-2017, 11:02 AM
#32
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what is the 6 digit number?if it is 139691 it is a hyd roller with a pressed on iron gear and uses a melonized gear,make sure you measure the shaft dia of your dist to make sure you get the correct gear.in using the bronze gear you have not damaged the gear on the cam and once you install the melonized gear you won,t ever need to replace it.make sure you coat the new gear with a high pressure grease before dropping it in.
05-05-2017, 11:11 AM
#33
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Running a bronze gear, is a thing of the past unless you are just turning a distributor for cam sync or spark with a external oil pump. 20/50 shouldn't be wearing gear out. A steel core cam gear requires a steel gear. Better check distributor end play at gear out of engine and tightened down, sometimes the gear bottom interferers with block at bottom of block.
05-05-2017, 11:37 AM
#34
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05-05-2017, 11:57 AM
#35
what is the 6 digit number?if it is 139691 it is a hyd roller with a pressed on iron gear and uses a melonized gear,make sure you measure the shaft dia of your dist to make sure you get the correct gear.in using the bronze gear you have not damaged the gear on the cam and once you install the melonized gear you won,t ever need to replace it.make sure you coat the new gear with a high pressure grease before dropping it in.
05-05-2017, 01:39 PM
#36
I only use Mercury semi syn 25W-40. Have had 1 V-6 get 600 hrs before sale, 2 350 MAGS get 300 and 500 hrs before sale, 2 496 HO's get 300 hrs before sale, and currently own 1 350 MAG with 255 hrs and two 525s with 343 hrs. Change every motor at 25 hrs regardless of high-po or low-po. Never an oil related failure. Never any mechanical work on any of them. Only the 525s had gauges and they run 65-70 psi at cruise.
05-05-2017, 02:25 PM
#37
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mark,correct me if i am wrong but a crane 8620 core hyd roller cam has a pressed on iron gear and using a steel dist gear will quickly ruin the iron gear pressed on to the steel core.i got this information from the crane cams tech guy but maybe he was wrong.he told me a melonized or a bronze gear will work but the bronze gear will wear out fairly quick because it is so soft.the bronze gear is what was used before gm started using steel core cam,s in oe production engines,they started the use of melonized gears then and have used them on anything with a dist driving the oil pump.
05-05-2017, 02:35 PM
#38
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Iron cam gear = melonized distributor gear.
Steel cam gear = bronze distributor gear.
Most Crane hyd rollers have pressed on iron gears, but others will have to verify that part number.
Merc 25/50 marine oil is NOT 25W50 (a 25 weight base stock with viscosity improvers added), but is instead a mix of straight 25 weight and straight 50 weight with full string olefin strands.
The problem running conventional multi viscosity automotive oils in a marine performance engine is that the constant heavy duty cycle of the marine engine causes premature breakdown of the viscosity improvers, leaving the oil very quickly at its base rating (a 15W40 will quickly break down into a 15 weight oil).
Mixing 20 and 50 weight stocks remains pretty much a mix of 25 and 50 weight stocks long into the useful life of the oil.
SYNTHETIC "multi vis" oils perform differently than conventional muulti vis oils.
A Synthetic 40 weight stock will generally yield the same cold performance and lubricity as a 10 weight conventional oil, so the straight full-synthetic 40 weight is labelled 10W40 but it contains nothing but full 40 weight (hot) synthetic stock.
A 5w40 synthetic is pretty much straight 30 weight synthetic with some viscosity improvers added. If it breaks down, it will still only break down to a 30 weight lube.
0W30 is more like 25W synthetic with some viscosity improvers.
At least that's the best Layman's explanation I can give,
m
Steel cam gear = bronze distributor gear.
Most Crane hyd rollers have pressed on iron gears, but others will have to verify that part number.
Merc 25/50 marine oil is NOT 25W50 (a 25 weight base stock with viscosity improvers added), but is instead a mix of straight 25 weight and straight 50 weight with full string olefin strands.
The problem running conventional multi viscosity automotive oils in a marine performance engine is that the constant heavy duty cycle of the marine engine causes premature breakdown of the viscosity improvers, leaving the oil very quickly at its base rating (a 15W40 will quickly break down into a 15 weight oil).
Mixing 20 and 50 weight stocks remains pretty much a mix of 25 and 50 weight stocks long into the useful life of the oil.
SYNTHETIC "multi vis" oils perform differently than conventional muulti vis oils.
A Synthetic 40 weight stock will generally yield the same cold performance and lubricity as a 10 weight conventional oil, so the straight full-synthetic 40 weight is labelled 10W40 but it contains nothing but full 40 weight (hot) synthetic stock.
A 5w40 synthetic is pretty much straight 30 weight synthetic with some viscosity improvers added. If it breaks down, it will still only break down to a 30 weight lube.
0W30 is more like 25W synthetic with some viscosity improvers.
At least that's the best Layman's explanation I can give,
m
