when are 3/4 grooved main bearings needed for bbc ?

[John Wallace]

Thanks, tuffxf!

[swampbuggy]

To whom it may concern: I was determined to see where my Winberg crankshaft was (is) in relation to all of the numbers/degrees that have been displayed in this thread. After close checking with a degree wheel and rechecking and rethinking it all, i get the same numbers that Rick posted on page 8 i believe it was on his Bryant crankshaft. When the hole in the front (near the snout) main journal lines up with the feed hole in the block the rod journal center line is real close to 45 degrees ATDC. I made a drawing with a protractor which is 180 degrees to study more fully. Here are the results-----at 45 deg. BTDC the feed hole in the #1 main journal is at the parting line (or) the start of a 180deg. groove. At TDC the hole is 45 deg. through its trip and is 45 degrees before lining up with the incoming oil. At 45 deg. ATDC the holes line up, the main journal hole has now turned 90 deg. At 90 deg. ATDC the hole has moved 135 deg. of the 180 deg. groove. At 135 deg. ATDC (or) 45 deg. BBDC the hole in the main journal has traveled 180 deg.'s Mark H.

[tuffxf]

Gday Mark,
Awesome thanks for doing that, great info!
My stock cleveland crank all journals except 2 and 7 turn on, ie the start of the 180 groove at around 4 o clock position and 2 and 7 turn on at around 3 o clock.
Lost my original notes, will have to do a mock up and do it properly as you have done.
Cheers
Paul

[swampbuggy]

I for one am always trying to learn facts. Meaning of fact/s = something that is really true---reality---actuality. After reading Ricks data on his Bryant crankshaft and doing a study on my Winberg shaft, and reading Warpspeeds as well as other peoples comments, i have come to a complete and total belief that if there is adequate and constant quality oil (minimal aeration) at the bulkhead oil exit hole and in the main bearing groove, the degrees after top dead center in which the holes line up is not super critical. Most of us know that Bryant and Winberg crankshafts are used in some of the highest RPM engines in different forms of Motorsports, so go figure.

To the original post: I owned a 516 c.i. 855h.p. BBC , GM Bowtie block, wet sump Stef's pan with baffling and windage screen, melling 77 hi-vol. pump, blueprinted, it employed 180 degree top main bearings. This was a street driven vehicle and every outing when it fried the rear tires the tattle tale tach would say 7500. When the drag racer i know and sold the engine to freshened it up, the rod bearings looked almost new. So to answer your question, if all parts of the engine are correct you do NOT need 3/4 grooved bearings. Mark H.

[Little Mouse]

Thanks swapmbuggy, after all the arguing back in forth you came up with useful info.

[cjperformance]

I for one am always trying to learn facts. Meaning of fact/s = something that is really true---reality---actuality. After reading Ricks data on his Bryant crankshaft and doing a study on my Winberg shaft, and reading Warpspeeds as well as other peoples comments, i have come to a complete and total belief that if there is adequate and constant quality oil (minimal aeration) at the bulkhead oil exit hole and in the main bearing groove, the degrees after top dead center in which the holes line up is not super critical. Most of us know that Bryant and Winberg crankshafts are used in some of the highest RPM engines in different forms of Motorsports, so go figure.

To the original post: I owned a 516 c.i. 855h.p. BBC , GM Bowtie block, wet sump Stef's pan with baffling and windage screen, melling 77 hi-vol. pump, blueprinted, it employed 180 degree top main bearings. This was a street driven vehicle and every outing when it fried the rear tires the tattle tale tach would say 7500. When the drag racer i know and sold the engine to freshened it up, the rod bearings looked almost new. So to answer your question, if all parts of the engine are correct you do NOT need 3/4 grooved bearings. Mark H.

There is a chalk and cheese difference between zinging a street driver to 7500 in a skid where its not seeing full load and or any rpm duration compared to even a drag race situation where the entire run starts nearing peak tq then spends the rest of the run smewhere between just below and past peak Hp but all the while at full load, let alone any other form of endurance engine where it is spending time on/off the throttle and fully loaded at these rpms for extended periods of time.
Im not saying that all you have observed is incorrect, only that there is more to think about when looking at examples.

[swampbuggy]

I agree with what you said Craig. Be it known, Mike P. my long time friend who ended up with my old engine did 1/4 mile drag race the engine in a top shelf Horton rail type racing machine for quite a while running high 7's before they freshened it up. Mark H.

[novafornow]

Thanks swapmbuggy, after all the arguing back in forth you came up with useful info.

Warp answered the question on the first post.

[ClassAct]

To whom it may concern: I was determined to see where my Winberg crankshaft was (is) in relation to all of the numbers/degrees that have been displayed in this thread. After close checking with a degree wheel and rechecking and rethinking it all, i get the same numbers that Rick posted on page 8 i believe it was on his Bryant crankshaft. When the hole in the front (near the snout) main journal lines up with the feed hole in the block the rod journal center line is real close to 45 degrees ATDC. I made a drawing with a protractor which is 180 degrees to study more fully. Here are the results-----at 45 deg. BTDC the feed hole in the #1 main journal is at the parting line (or) the start of a 180deg. groove. At TDC the hole is 45 deg. through its trip and is 45 degrees before lining up with the incoming oil. At 45 deg. ATDC the holes line up, the main journal hole has now turned 90 deg. At 90 deg. ATDC the hole has moved 135 deg. of the 180 deg. groove. At 135 deg. ATDC (or) 45 deg. BBDC the hole in the main journal has traveled 180 deg.'s Mark H.

Where is the hole in the block?

[Cubic_Cleveland]

Hi, Cleveland with any aftermarket crank i have used is fine, wether its cross drilled or not there is no issue any more and in this im talking when using 1/2 groove bearings.
Wet sump N/a clevo stroker street/strip is no major ask. The minimum I do in this typical instance (not because its a must, just because it makes me feel good) is match the hole in the block for oil feed(where the pump bolts on) to the pump, then that hole quickly goes near 90* out to the filter feed, i get right into this hole from both sides and smooth out the 90* intersection and port/lay down the 'short side' of this intersection and get it as smooth flowing as i can, then at the filter boss chamfer this hole out, i just dont want any hard sharp edges/turns.
Then same with the feed from filter to block, take out the filter adaptor, chamfer the block side of it out as much as possible while not weakening it, get into the block under this adaptor and smooth out that shitty intersection. I almost always use a grooved back cam bearing with oiling set at 2 to 3 o clock, this does restrict oil to the cam bearings (which saves any excess for main/rods) but improves the delivery point and the bearings look great all the time. That's it for the basics that i do and its quick to do as well.
If im spending a bit more time i then match up/elongate the main bearing galleries at the main bore to the bearing and match the bearing back to the hole as well.
So im not reinventing the wheel here, all im really trying to do is smooth up the oil flow path wherever i can, improve delivery quality.
If youre then going to turn the same stroker combo to 7500 assuming the hardware is able, oiling wise a rear oil feed line is in my opinion helpfull as feeding the gallery from both ends simply slows down the supply oil speed where it has to turn thru 90* into the rh lifter gallery before it can feed #'s 2,3,4,5 main bearings, you dont change the oil demand/quantity but by having 2 feed points you slow down the oil speed where it has to turn at every point until the oil in into the galleries that meet the bearing.
I do like to chamfer the crank main to rod oil feed holes at the journals with a heavy leading chamfer on the main journal and trailing chamfer on the rod journal, BUT i often wonder about the effect of the leading chamfer on the lower main as it runs over the non grooved surface, as in am I creating more of a pressure drop here and causing localised vaporization? I havmt seen any ill evidence on the bearings so maybe not, someone else may have more thoughts on this? Id be happy to hear them.

Craig, would you have a part number and supplier for these o.d grooved cam bearings?
Cheers,
Mick.

[cjperformance]

Hi, Cleveland with any aftermarket crank i have used is fine, wether its cross drilled or not there is no issue any more and in this im talking when using 1/2 groove bearings.
Wet sump N/a clevo stroker street/strip is no major ask. The minimum I do in this typical instance (not because its a must, just because it makes me feel good) is match the hole in the block for oil feed(where the pump bolts on) to the pump, then that hole quickly goes near 90* out to the filter feed, i get right into this hole from both sides and smooth out the 90* intersection and port/lay down the 'short side' of this intersection and get it as smooth flowing as i can, then at the filter boss chamfer this hole out, i just dont want any hard sharp edges/turns.
Then same with the feed from filter to block, take out the filter adaptor, chamfer the block side of it out as much as possible while not weakening it, get into the block under this adaptor and smooth out that shitty intersection. I almost always use a grooved back cam bearing with oiling set at 2 to 3 o clock, this does restrict oil to the cam bearings (which saves any excess for main/rods) but improves the delivery point and the bearings look great all the time. That's it for the basics that i do and its quick to do as well.
If im spending a bit more time i then match up/elongate the main bearing galleries at the main bore to the bearing and match the bearing back to the hole as well.
So im not reinventing the wheel here, all im really trying to do is smooth up the oil flow path wherever i can, improve delivery quality.
If youre then going to turn the same stroker combo to 7500 assuming the hardware is able, oiling wise a rear oil feed line is in my opinion helpfull as feeding the gallery from both ends simply slows down the supply oil speed where it has to turn thru 90* into the rh lifter gallery before it can feed #'s 2,3,4,5 main bearings, you dont change the oil demand/quantity but by having 2 feed points you slow down the oil speed where it has to turn at every point until the oil in into the galleries that meet the bearing.
I do like to chamfer the crank main to rod oil feed holes at the journals with a heavy leading chamfer on the main journal and trailing chamfer on the rod journal, BUT i often wonder about the effect of the leading chamfer on the lower main as it runs over the non grooved surface, as in am I creating more of a pressure drop here and causing localised vaporization? I havmt seen any ill evidence on the bearings so maybe not, someone else may have more thoughts on this? Id be happy to hear them.

Craig, would you have a part number and supplier for these o.d grooved cam bearings?
Cheers,
Mick.

Hi Mick, T Meyer in USA do them. I do mine myself simply because im in Australia and i just order the bearings i need and machine them as required, using preferably FP26 or FP26T coated durabond bearings depending on what cam in using. Steel core i use the coated bearings, cast core the plain unless it has very heavy valve springs.
Cheers,

[swampbuggy]

Classact: In response to your question above " Where is the hole in the block? " The 1/4" holes in my Dart Iron Eagle are at 12 o'clock (or) straight up with the engine positioned in the normal running position. Is this not the position of 90% of the blocks made ? Just to be clear, this is the point in which the oil exits the block and enters into the main bearing groove. Mark H.

[ClassAct]

Classact: In response to your question above " Where is the hole in the block? " The 1/4" holes in my Dart Iron Eagle are at 12 o'clock (or) straight up with the engine positioned in the normal running position. Is this not the position of 90% of the blocks made ? Just to be clear, this is the point in which the oil exits the block and enters into the main bearing groove. Mark H.

Correct. That's the postion of all the SBC's but not any Chrysler with the exception of a few R blocks and I don't remember about the KB stuff for the big blocks or the Indy either.

I need to go back and look at some other things because with the oil hole in the crank at 12 o'clock it sounds like 45 degrees after TDC is early.

[Rick!]

Here is the best write-up I've found for the 351C oiling thing.
https://pantera.infopop.cc/topic/351c-l ... lubricants

[Cubic_Cleveland]

Hi, Cleveland with any aftermarket crank i have used is fine, wether its cross drilled or not there is no issue any more and in this im talking when using 1/2 groove bearings.
Wet sump N/a clevo stroker street/strip is no major ask. The minimum I do in this typical instance (not because its a must, just because it makes me feel good) is match the hole in the block for oil feed(where the pump bolts on) to the pump, then that hole quickly goes near 90* out to the filter feed, i get right into this hole from both sides and smooth out the 90* intersection and port/lay down the 'short side' of this intersection and get it as smooth flowing as i can, then at the filter boss chamfer this hole out, i just dont want any hard sharp edges/turns.
Then same with the feed from filter to block, take out the filter adaptor, chamfer the block side of it out as much as possible while not weakening it, get into the block under this adaptor and smooth out that shitty intersection. I almost always use a grooved back cam bearing with oiling set at 2 to 3 o clock, this does restrict oil to the cam bearings (which saves any excess for main/rods) but improves the delivery point and the bearings look great all the time. That's it for the basics that i do and its quick to do as well.
If im spending a bit more time i then match up/elongate the main bearing galleries at the main bore to the bearing and match the bearing back to the hole as well.
So im not reinventing the wheel here, all im really trying to do is smooth up the oil flow path wherever i can, improve delivery quality.
If youre then going to turn the same stroker combo to 7500 assuming the hardware is able, oiling wise a rear oil feed line is in my opinion helpfull as feeding the gallery from both ends simply slows down the supply oil speed where it has to turn thru 90* into the rh lifter gallery before it can feed #'s 2,3,4,5 main bearings, you dont change the oil demand/quantity but by having 2 feed points you slow down the oil speed where it has to turn at every point until the oil in into the galleries that meet the bearing.
I do like to chamfer the crank main to rod oil feed holes at the journals with a heavy leading chamfer on the main journal and trailing chamfer on the rod journal, BUT i often wonder about the effect of the leading chamfer on the lower main as it runs over the non grooved surface, as in am I creating more of a pressure drop here and causing localised vaporization? I havmt seen any ill evidence on the bearings so maybe not, someone else may have more thoughts on this? Id be happy to hear them.

Craig, would you have a part number and supplier for these o.d grooved cam bearings?
Cheers,
Mick.

Hi Mick, T Meyer in USA do them. I do mine myself simply because im in Australia and i just order the bearings i need and machine them as required, using preferably FP26 or FP26T coated durabond bearings depending on what cam in using. Steel core i use the coated bearings, cast core the plain unless it has very heavy valve springs.
Cheers,

Thanks Craig