71 440 build ? grooved bearings mains and rods

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flathead31coupe

flathead31coupe

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I know it has had to be covered here just cant find it... how do I know witch to use.. full 3/4 or 1/2 grooved bearings...the ones I took out were 1/2 grooved on the mains with a thrust flang dia of 3 9/16 = 3.5625 looking for the right bearings.... crank is 30/30...thanks
 
Unless you're racing it, the 3/4 or 1/2 grooves will be fine assuming the clearances are all in spec.
 
Did you guys have any oil pressure issues with the full grooved bearings? I did. It made exactly 10psi per 1,000 rpm when hot and that was with 20/50 oil.
 
roccodart440 said:
Did you guys have any oil pressure issues with the full grooved bearings? I did. It made exactly 10psi per 1,000 rpm when hot and that was with 20/50 oil.
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Probably more to do with loose lifter clearances than main bearing grooves, imo.
 
I have fully grooved main bearings. The oil pressure is reduced. Remember oil pressure is the resistance to flow. Reduce resistance and oil will flow more easily. I also use a Melling Hi-volume oil pump with an extra capacity oil pan with windage tray. Works great, revs like crazy. Good luck
 
383Scampman said:
I have fully grooved main bearings. The oil pressure is reduced. Remember oil pressure is the resistance to flow. Reduce resistance and oil will flow more easily. I also use a Melling Hi-volume oil pump with an extra capacity oil pan with windage tray. Works great, revs like crazy. Good luck
Click to expand...
can I use the hi volum pump with a 7qt pan....and should I?
 
The top shell has a groove that goes up and tapers away about 1/4 of the way up each side of the shell... The grooves in the mains reduce the load capacity of the main bearings by giving that space to oil flowing to the rods. If you have sustained high rpms, they (and wider clearances) are needed. If you're just drag racing and running up to 6500 - they aren't.
 
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