SoCal Jet Boats
Tech Talk => Engine Mechanical / Electrical => Topic started by: 69kona on May 27, 2015, 05:32:58 PM
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Has any one seen this done before ? Got complete motor for a 100 bucks ...
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Not on purpose !!!
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Lol! man looks machined I never seen that before....
Crank .020 rods .010 mains I thought u were supposed to turn down equal?
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Where do all the oil galleries go? Hard to tell if the groove in intentionally machined. I am going to guess intentionally because of the surface finish. Looks like tool chatter instead of galling.
Grooving main journals was a common method of attempting to get 360-degree oiling to the connecting rods. The down side is that it reduces the surface area of the journals in contact with the bearings, reducing their load carrying capabilities.
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They just dead end ... Holes evenly spaced. should I start looking for another crank or is it ok to turn down to .030? Thanks for helping!
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What is the price of an aftermarket crankshaft vs. all the work to that one?
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450 for a eagle crank ....
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Or $200 for a factory original standard/standard crank.
Contact me if you are interested.
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Ready to run or still needs machining?
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Holy funky crank Batman.
As for the rod and main bearings being the sane undersized, why? We used to cut one main, all of them, one rod.... lol. As long as it balanced, who cares.
I even had a big block Chevy with two larger pistons. ...hahaha. .. hillbillies be hatin'.
GT
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Ready to run or still needs machining?
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Will need a polish, add 35 if you want me to do it.
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Has any one seen this done before ? Got complete motor for a 100 bucks ...
Grooving the mains is an old racer trick that came about in the late 1960's when the Fuel guys hit a brick wall of sorts--they all started kicking their rods out of the pans due to lack of lubrication because of the half-groove main bearings. Back then, there were no fully-grooved main bearings and so the next trick was to groove the main journal (ie, put the oil path in the journal instead of the shell) so as to get continuous, 360-degree oil feed to the rods. Oilah--Fuel guys got faster again because their con rod bearings got the oil they needed.
I've never seen that in an Olds crankshaft; today almost all Olds bearings are full-groove (exception: Speedpro offers a 3/4-groove bearing), which makes that modification pointless.
My guess that full groove in the main journal was added decades ago. Your crankshaft is perfectly usable with the added feature...it's just not necessary anymore.
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Lee, did you hurt the boat motor, or is this a different one.
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Many Olds cranks (and others in the old days, like some Cadillacs) have the blind holes in the crank. The thought was when the holes passed the oil delivery slot in the upper bearing, the blind hole would fill with oil, and when it was in the lower part of the bearing the oil would centrifugally be thrown out to help with lubrication. The rod bearing size and main bearing sizes can be and often are different when remachined. No sense in removing good bearing surface of the mains if not needed to clean up the main journal with less grinding. You would grind all the mains or rods the same, but not more than needed and not necessarily the same amount for the rods and for the mains. TIMINATOR
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Lee, did you hurt the boat motor, or is this a different one.
. Different one.
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So it would be fine to have the crank turned 0.30 on rods ? And thanks for the info from everyone
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So it would be fine to have the crank turned 0.30 on rods ? And thanks for the info from everyone
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No. Imho if it's needing to go more than .020" under, it's a wind chime. Maybe even a mailbox stand.
The hard facing is only so deep.
GT
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Cast cranks are not hardfaced, grind it to what it needs. Many bearings are supplied not only in .010, .020, and .030, but .040 and .060 also. Before cheap stroker cranks were common, we offset ground 460 Ford crank rod journals to use Pontiac rods (.250", yup that's a quarter inch undersize) to stroke them out to near 500", depending upon bore size. We used 403 Olds pistons and rings, that gave us a completely off the shelf 498" Ford. We had a ton of them in 4x4s and boats, they lived fine at over 500 HP. With custom oversize pistons they would be around 512". I suppose that we shouldn't be offset grinding 500 Cadillac crank rods down to BB Chevy size, (that's 3/8", yup .375" under) either. We have another one in here now that we are doing. Eagle rods and Ross pistons in this one. Incidentally, with the overbore this Caddy will be 548". And if we are the only people making this mistake can anyone account for the bazillion 383 Chevys out there with the mains cut from 400 to 350 size? As far as steel cranks go, other than the BBChevy 454 LS cranks from the 1970s (those had black counterweights from the Nitride hardening), I can't remember many factory steel cranks that were hardened at all. TIMINATOR
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Wow.
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GT call me sometime and we'll talk, no hard feelings here. Just differences of opinion and those bring out better info for everyone. I'll explain my thoughts on discussions too. TIMINATOR
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GT call me sometime and we'll talk, no hard feelings here. Just differences of opinion and those bring out better info for everyone. I'll explain my thoughts on discussions too. TIMINATOR
I may take you up on that.
In the mean time.
Here is where I live.
If the crank has had to be cut once, something took a crap to cause it to need to be cut. How hot did that rods journal get? How long did it hammer?
If it had to be cut twice, obviously it took another crap. Let's spend another $250 and cut it again, we still don't know what exactly happened either time, but what the heck. Cut it again, have the indexing checked, throw some bearings at it. Ok fine. The third time, this is three times now it has been cut, same thrust areas, same crank gone through who knows what for a heat cycle.
At what point to you cut your losses and throw that piece of shit away? The metallurgy is going to be screwed up. Your pouring more money into something that can be replaced fairly economically. Not to mention installing more and more soft metal between two pieces of iron.
If the crank was uber rare and a replacement could not be found. Fine. But this is not the case.
The harmonic snout is likely worn. The threads on the flywheel have been abused.
I am a cut your losses and move on guy. I'm not going to spend a lot of time messing with something I can easily and economically replace for something better.
Not saying my way is the only way, just saying use common sense.
GT
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All points taken and valid.
If its blue, don't use it!
Any crank grinder worth his title will fully inspect the entire crank, including the snout and threads and advise before the grind.
Most Olds cranks were in little old ladies Vista Cruisers that never or rarely had the oil changed, so they had surface wear only. Many of those same old peeps, like my grandfather (1964 Pontiac Star Chief, bought new) kept their cars for 20 + years and still never changed the oil even tho he had the engine rebuilt twice. I believe his quote was: "all oil is 20 million years old, what's a year or three in an engine? It gets freshened when more oil is added."
Take it in to a professional and let him decide.
As far as multiple grind go, is it a race boat or lake boat? Stock crank or aftermarket? Chinese aftermarket or Callies $2600.00 crank? What can you afford? Does somebodies life depend on it working? Food for thought, only. TIMINATOR
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What happen to this motor was the seats fell out and it made metal from
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What I see.
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I
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