A stock BBC will have no issues with a 40, but a 50 could possibly be questionable, depending on how hot the oil gets. In a marine engine, things are different, as they get the oil HOT, no matter how big the coolers are, due to sustained 2/3+ throttle running.
71 SS Chevelle 454
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Originally Posted By: electrolover
i dont think the compression makes that much difference but you dont need 20/50 in a tight engine, it wont flow properly. and the engine is not going to be making that much oil heat so there is no need. in this case it would do more harm than good.
if you wont to throw 20/50 in your stock daily driver thats fine, but dont tell someone else to do things that will harm their engine. thats just wrong!! it wont move threw the tight clearances well at all, the pump will go into by pass, and the lack of oil flow will spin a rod bearing. go tear your own [censored] up and keep the ignorant advise to your self
I recommended 20W-50 after an easy break in period with SAE30. The reason why I recommended that thicker oil was because the OP said the engine has a stage III camshaft in it and in which case I suspect has stiff valve springs to prevent valve float at higher RPMs should the OP choose to take the engine there. The stiff high rate valve springs are going to exert a reasonable amount of pressure through the valve train and onto the camshaft lobes. How well is a modern SN 30 weight oil with next to no ZDDP going to protect those camshaft lobes? We're not talking about a roller camshaft in this case either; just roller rocker arms. And you say the engine is tight. How tight is a freshly machined 1971 Chevy 454 going to be? Is it going to have the tight clearances of a 2011 Honda Accord V6 engine?
i dont think the compression makes that much difference but you dont need 20/50 in a tight engine, it wont flow properly. and the engine is not going to be making that much oil heat so there is no need. in this case it would do more harm than good.
if you wont to throw 20/50 in your stock daily driver thats fine, but dont tell someone else to do things that will harm their engine. thats just wrong!! it wont move threw the tight clearances well at all, the pump will go into by pass, and the lack of oil flow will spin a rod bearing. go tear your own [censored] up and keep the ignorant advise to your self
I recommended 20W-50 after an easy break in period with SAE30. The reason why I recommended that thicker oil was because the OP said the engine has a stage III camshaft in it and in which case I suspect has stiff valve springs to prevent valve float at higher RPMs should the OP choose to take the engine there. The stiff high rate valve springs are going to exert a reasonable amount of pressure through the valve train and onto the camshaft lobes. How well is a modern SN 30 weight oil with next to no ZDDP going to protect those camshaft lobes? We're not talking about a roller camshaft in this case either; just roller rocker arms. And you say the engine is tight. How tight is a freshly machined 1971 Chevy 454 going to be? Is it going to have the tight clearances of a 2011 Honda Accord V6 engine?
Given the BBC Chevy's rep for oil consumption, a 40 weight wouldn't be a bad idea, and ZDDP is a must-why not a 15W40 HDEO such as the (near-syn quality) Mobil Delvac 1300? Tough as nails & CHEAP too!
It definitely needs a lot of ZDDP. HDEO, or a high-ZDDP racing oil, or a ZDDP additive is needed regardless of oil weight.
8000 rpm ???
Originally Posted By: crazyoildude
8000 rpm ???
yeah and with stock 3 thou rod clearances to boot. and some how MAGICALLY nothing distorts and it doesnt throw a rod
also not tp mention its hard to turn a PROPERLY BUILT bigblock 8000 with stock rod sizes because the journals are so dang big. i can imagine what would happen if you did it with stock clearances on top of that
dont get me wrong some people do run tight with high rpms but they have billet everything so nothing distorts. not to mention they run amazingly awesome oils
ya know im no lee sheppard but i have built more than a couple small blocks and my brother is one of the best engine builders in north texas so i have picked up a few things....at least enough to know when im being [censored]'d
8000 rpm ???
dont get me wrong some people do run tight with high rpms but they have billet everything so nothing distorts. not to mention they run amazingly awesome oils
ya know im no lee sheppard but i have built more than a couple small blocks and my brother is one of the best engine builders in north texas so i have picked up a few things....at least enough to know when im being [censored]'d
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Originally Posted By: electrolover
Originally Posted By: crazyoildude
8000 rpm ???
yeah and with stock 3 thou rod clearances to boot. and some how MAGICALLY nothing distorts and it doesnt throw a rod
also not tp mention its hard to turn a PROPERLY BUILT bigblock 8000 with stock rod sizes because the journals are so dang big. i can imagine what would happen if you did it with stock clearances on top of that
dont get me wrong some people do run tight with high rpms but they have billet everything so nothing distorts. not to mention they run amazingly awesome oils
ya know im no lee sheppard but i have built more than a couple small blocks and my brother is one of the best engine builders in north texas so i have picked up a few things....at least enough to know when im being [censored]'d
Not to mention, anything running in that RPM range with 8 cylinders usually doesn't have a "stage anything" camshaft. It would be a custom billet piece.
Originally Posted By: crazyoildude
8000 rpm ???
dont get me wrong some people do run tight with high rpms but they have billet everything so nothing distorts. not to mention they run amazingly awesome oils
ya know im no lee sheppard but i have built more than a couple small blocks and my brother is one of the best engine builders in north texas so i have picked up a few things....at least enough to know when im being [censored]'d
Not to mention, anything running in that RPM range with 8 cylinders usually doesn't have a "stage anything" camshaft. It would be a custom billet piece.
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