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Ingine Clearances

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    Captain Rehab swampfox44's Avatar
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    Default Engine Clearances

    Sorry 'bout the mispelling "engine",it was another 20 hour day.....my bad.
    I'm about to assemble my 388 Stroker Small Block Chevy. I bought a balanced complete rotating assembly (Scat crank,rods,pistons,rings,bearings,flexplate & balancer). What is a a good clearance on rod and main bearings as well as piston to wall clearance and also ring end gap. Also,what is a recommended oil viscosity and brand. I'm putting the engine in a 1968 16' Cheetah with a 12JG pump and "B" impeller. Figure it is going to be spinning maybe in range of 5000-5400 RPM. (This is just a guess,may not be accurate).Running 9.7 compression,hydraulic flat tappet Comp XM278 cam.Aluminum 64cc heads2.02/1.60,750 Holley,Edelbrock RPM air gap intake,stock volume,high pressure oil pump, 8 quart pan and Rewarder headers.

    Thanks
    Last edited by swampfox44; 07-26-2009 at 12:56 AM. Reason: mispelled title.
    SwampFox
    '68 CHEETAH
    383 STROKER

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    Sit N' Spin Jetaholic's Avatar
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    Quote Originally Posted by swampfox44 View Post
    I'm about to assemble my 388 Stroker Small Block Chevy. I bought a balanced complete rotating assembly (Scat crank,rods,pistons,rings,bearings,flexplate & balancer). What is a a good clearance on rod and main bearings as well as piston to wall clearance and also ring end gap. Also,what is a recommended oil viscosity and brand. I'm putting the engine in a 1968 16' Cheetah with a 12JG pump and "B" impeller. Figure it is going to be spinning maybe in range of 5000-5400 RPM. (This is just a guess,may not be accurate).Running 9.7 compression,hydraulic flat tappet Comp XM278 cam.Aluminum 64cc heads2.02/1.60,750 Holley,Edelbrock RPM air gap intake,stock volume,high pressure oil pump, 8 quart pan and Rewarder headers.

    Thanks
    Go high volume on the pump. Looser clearances need more oil volume than stock clearances.

    0.002" - 0.0025" on the rod bearings

    0.0025" - 0.003" on the main bearings

    With these clearances I'm running Valvoline VR-1 20w-50 oil and seeing about 25-30 PSI hot idle, 55-60 PSI at cruise and 70-75 PSI at WFO.



    Quote Originally Posted by HammerDown
    Kendall L-427 Super Blu...extreme-pressure (ep) lithium complex keeps my thrusting balls happy
    Quote Originally Posted by back2k5 View Post
    Well I am putting in a nice stereo system in the Carrera...maybe Ill put on some rap and turn the scoop sideways

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    Quote Originally Posted by swampfox44 View Post
    I'm about to assemble my 388 Stroker Small Block Chevy. I bought a balanced complete rotating assembly (Scat crank,rods,pistons,rings,bearings,flexplate & balancer). What is a a good clearance on rod and main bearings as well as piston to wall clearance and also ring end gap. Also,what is a recommended oil viscosity and brand. I'm putting the engine in a 1968 16' Cheetah with a 12JG pump and "B" impeller. Figure it is going to be spinning maybe in range of 5000-5400 RPM. (This is just a guess,may not be accurate).Running 9.7 compression,hydraulic flat tappet Comp XM278 cam.Aluminum 64cc heads2.02/1.60,750 Holley,Edelbrock RPM air gap intake,stock volume,high pressure oil pump, 8 quart pan and Rewarder headers.

    Thanks
    Go high volume on the pump. Looser clearances need more oil volume than stock clearances.

    0.002" - 0.0025" on the rod bearings

    0.0025" - 0.003" on the main bearings

    For the initial startup and break in, I recommend the Joe Gibbs Performance Break In Oil. It's got lots of zinc for that flat tappet cam. Run it for break in and the first two hours of engine operation, then change the oil and filter.

    With these clearances I'm running Valvoline VR-1 20w-50 racing oil and seeing about 25-30 PSI hot idle, 55-60 PSI at cruise and 70-75 PSI at WFO.

    I'm running that exact same cam. You'll want springs with about 120lbs seat pressure and 310-315lbs open. Also, if you got the high energy lifters, take them back and get the Pro Magnum lifters. They're only about $10-$15 more and the retaining clips on those High Energy lifters have no place in a jet boat engine.



    Quote Originally Posted by HammerDown
    Kendall L-427 Super Blu...extreme-pressure (ep) lithium complex keeps my thrusting balls happy
    Quote Originally Posted by back2k5 View Post
    Well I am putting in a nice stereo system in the Carrera...maybe Ill put on some rap and turn the scoop sideways

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    Captain Rehab swampfox44's Avatar
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    As far as pump volume,I've had alot of guys swearing the high volume will suck the pan dry and wipe my bearings. They keep recommending stock volume,high pressure. I've built many street engines as well as mud drag/bog engines and run high volume pumps and have held engines at 7200 rpm for a 12+ seconds and never dropped pressure or wiped bearings.

    Thanks
    SwampFox
    '68 CHEETAH
    383 STROKER

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    Sit N' Spin Jetaholic's Avatar
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    Quote Originally Posted by swampfox44 View Post
    As far as pump volume,I've had alot of guys swearing the high volume will suck the pan dry and wipe my bearings. They keep recommending stock volume,high pressure. I've built many street engines as well as mud drag/bog engines and run high volume pumps and have held engines at 7200 rpm for a 12+ seconds and never dropped pressure or wiped bearings.

    Thanks
    As far as pumping the pan dry, in regards to a Chevy that is pure BS. If it were an Olds I'd say yes. But Chevy's never had the oil drainback issues that the Olds has...on top of that you have an 8 qt pan, which I seriously doubt that it would pump THAT pan dry.

    You will have to change the intermediate pump shaft (i.e. the shaft that connects the distributor to the oil pump) to the severe duty chromoly shaft (ARP makes them...shouldn't be more than about $15). Also make sure whatever distributor you use has a brand new cast iron gear on it.

    Most high volume pumps only pump about 25% more oil than stock anyway, so are you saying that a stock pump is 25% away from pumping the pan dry? I highly doubt it.
    Last edited by Jetaholic; 07-24-2009 at 07:35 PM.



    Quote Originally Posted by HammerDown
    Kendall L-427 Super Blu...extreme-pressure (ep) lithium complex keeps my thrusting balls happy
    Quote Originally Posted by back2k5 View Post
    Well I am putting in a nice stereo system in the Carrera...maybe Ill put on some rap and turn the scoop sideways

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    Quote Originally Posted by swampfox44 View Post
    As far as pump volume,I've had alot of guys swearing the high volume will suck the pan dry and wipe my bearings. They keep recommending stock volume,high pressure. I've built many street engines as well as mud drag/bog engines and run high volume pumps and have held engines at 7200 rpm for a 12+ seconds and never dropped pressure or wiped bearings.

    Thanks
    You do not need a high volume pump with those clearances.

    I run .0025 (aprox) all over mine, and have no trouble maintaining 58psi on 10w-50 synthetic above 4,000RPM, all the way to 5,400+.

    Idle hot pressure is 23, plenty.

    I've run this engine WFO for as far as 8 miles, not 12 secconds, 7 minuites.

    Standard 5-quart pan, 2-quart K&N oil filter (I THINK it's the 6002 p/n)
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    Smokin' is right...you don't ABSOLUTELY NEED a high volume pump. You CAN run one though and IMHO it is the better way to go. However, unless you're running an oil pan with stock capacity, the whole "pumping the pan dry" on Chevys is simply a problem that doesn't exist.



    Quote Originally Posted by HammerDown
    Kendall L-427 Super Blu...extreme-pressure (ep) lithium complex keeps my thrusting balls happy
    Quote Originally Posted by back2k5 View Post
    Well I am putting in a nice stereo system in the Carrera...maybe Ill put on some rap and turn the scoop sideways

  10. #8
    Captain Rehab swampfox44's Avatar
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    Thanks JetAholic,I'm still thinking 8 quart pan,the large K&N 2 qt filter,I've got an oil cooler with 3/4" water in/outs and 1/2" oil in/outs and HV/HP oil pump.

    Thanks
    SwampFox
    '68 CHEETAH
    383 STROKER

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    Quote Originally Posted by swampfox44 View Post
    Thanks JetAholic,I'm still thinking 8 quart pan,the large K&N 2 qt filter,I've got an oil cooler with 3/4" water in/outs and 1/2" oil in/outs and HV/HP oil pump.

    Thanks
    IMO you don't need the high pressure pump. A high volume/stock pressure pump pops off (bypasses) at 60 PSI and will allow the pressure to increase another 10 PSI on top of that (mine hits 70 PSI).
    Last edited by Jetaholic; 07-26-2009 at 01:16 AM.

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    Quote Originally Posted by swampfox44 View Post
    Sorry 'bout the mispelling "engine",it was another 20 hour day.....my bad.
    I'm about to assemble my 388 Stroker Small Block Chevy. I bought a balanced complete rotating assembly (Scat crank,rods,pistons,rings,bearings,flexplate & balancer). What is a a good clearance on rod and main bearings as well as piston to wall clearance and also ring end gap. Also,what is a recommended oil viscosity and brand. I'm putting the engine in a 1968 16' Cheetah with a 12JG pump and "B" impeller. Figure it is going to be spinning maybe in range of 5000-5400 RPM. (This is just a guess,may not be accurate).Running 9.7 compression,hydraulic flat tappet Comp XM278 cam.Aluminum 64cc heads2.02/1.60,750 Holley,Edelbrock RPM air gap intake,stock volume,high pressure oil pump, 8 quart pan and Rewarder headers.

    Thanks
    Id be interested to know how that cam idles with your set-up. I'm currently running a very similar build with cast (sportsman) heads and an xm270... and am very tempted to go bigger

    You're having the rotating assembly balanced by a machine shop, right?

  13. #11
    Captain Rehab swampfox44's Avatar
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    Yes,everything is balanced.
    SwampFox
    '68 CHEETAH
    383 STROKER

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    Sit N' Spin Jetaholic's Avatar
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    I run the XM278 on my big block and I'm seeing about 5200-5300 RPM on an A impeller with an RPM Air Gap, Performer RPM heads and a Holley 750dp, 10:1 compression.



    Quote Originally Posted by HammerDown
    Kendall L-427 Super Blu...extreme-pressure (ep) lithium complex keeps my thrusting balls happy
    Quote Originally Posted by back2k5 View Post
    Well I am putting in a nice stereo system in the Carrera...maybe Ill put on some rap and turn the scoop sideways

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