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#61
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At the end of the day those sharp 90 degree edges worked (accomplished the task on hand) so please explain how they are wrong?
Last edited by PAUL K; 06-05-2021 at 11:17 AM. |
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#62
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So 8500 rpm is just a rpm number that my company used as we had lots of track data that matched the dyno data saying we would be safe to run there. But back on the sharp corners of the modified oil pump shaft for clearance. Common knowledge from crankshaft experience that you do not cut a crankshaft with sharp corners where the rods are mounted. Always a radiused fillet there. That radiused fillet is there for a reason, which I think TAFF2 is also saying. As far as what you can get away with in production, If the spring loads on the valvetrain in a Pontiac head were not higher vs the force required to remove the pressed in stud from the head, no worries. But then you have to ask, why were lots of performance pontiacs in the old days running either pinned studs or aftermarket threaded studs vs the press in studs once the spring loads and camshaft lift numbers went up. Same question on why any later pontiac head had threaded studs IF there was not an issue at higher spring loads. So your example/ ouestion has holes in the logic Paul. Tom V.
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"Engineers do stuff for reasons" Tom Vaught Despite small distractions, there are those who will go Forward, Learning, Sharing Knowledge, Doing what they can to help others move forward. Last edited by Tom Vaught; 06-05-2021 at 12:03 PM. |
#63
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Why is it that some of these posts turn into pissing contests of who's engine did this and who's engine did that and I knew a guy who.........
Isn't this on a street engine and not a 200,000 RPM race engine using a 500 mega GPH oil pump, 140 weight gear oil, and a modified 3" dia. oil pump drive shaft taper ground in the center and made in China? Why not just just point out what the HO engine build book shows and make your own shaft that seemed to be the answer for their record holding engines? Man, if Mickey Thompson were alive today............ Moderator, please add a new category titled "Theory, Maybe?" Then some of you can really dig into metallurgy, cohesion, fluid dynamics, hardening treatments, inertia loads at speed, torsional stresses and breaking points of metal compounds, and race engines I have known, known about, or had a buddy who knew a guy who had a race engine. |
#64
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The point was use parts designed for the actual application. In this case, another used oil pump shaft might give a bit more clearance vs the one he currently has and then you are done with the exercise. Tom V.
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"Engineers do stuff for reasons" Tom Vaught Despite small distractions, there are those who will go Forward, Learning, Sharing Knowledge, Doing what they can to help others move forward. |
#65
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Well lets not forget Studebakers and pre-1966 Mopars (AAAAARRRRRGH)
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#66
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What about how far it's engaged? Looking at this pic shows it to not be fully engaged. I think a shim or two in the distributor would help.
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“Nothing in the world can take the place of persistence. Talent will not; nothing is more common than unsuccessful men with talent. Genius will not; unrewarded genius is almost a proverb. Education will not; the world is full of educated derelicts. Persistence and determination alone are omnipotent. The slogan Press On! has solved and always will solve the problems of the human race.” ― Calvin Coolidge |
#67
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Shaft is all that stressed. It's running at half crankshaft RPM and cushioned from torque by the compressible oil in the clearance between the oil pump gears.
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#68
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Same for the oil pump driveshaft with the "sharp corners", is that the wrong oil pump drive shaft for the job? Does all the effort put into winning the Championship that year get disqualified because the oil pump had "sharp corners"? Quote:
This oil pump drive shaft (with the sharp corners) was designed for a reason. It did it's job and never failed. FACT |
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#69
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It's to bad because I believe most of the time the OP is looking for some useful advice. Remember that thread when the guy was a bit disappointed with his 496 dyno results and there were a bunch of "Interent Experts" giving poop poor, unrealistic, ridiculously expensive, ideas for fixing his issue and most likely their ideas never would've helped.... Sad deal. |
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#70
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These parts are not designed for a perfect .00001" fit, they can't be. If I had to guess on the shaft pic posted, there is where on that edge because the shaft was working beyond its limits trying to either spin a HD pump, like an 80 PSI pump, thick oil - which is worse when cold/start up, or it had a lot of miles and simply reached peak cycling. Appears the broken side simply twisted off. Looks to be a stock piece. Bottom line is that ANYTIME you rebuild an engine, replace an oil pump, or simply have an engine out for rework, replace the oil pump and install a new hardened oil pump shaft as insurance - which is cheaper than an engine. The prices can vary depending on type/style of pump shaft. |
#71
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LIFT HEAVY, LIFE IS TOO SHORT TO BE SMALL! |
#72
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Tom V.
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"Engineers do stuff for reasons" Tom Vaught Despite small distractions, there are those who will go Forward, Learning, Sharing Knowledge, Doing what they can to help others move forward. |
#73
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#74
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I agree, sad deal. There is a lot of good information on this sight if you do a search.
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#75
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With the tangs, it looks like an OEM or Melling shaft? I recall from my previous days working with OEM parts, that the stock driveshaft had a lengthwise witness mark suggesting that it was made from extruded bar stock vs. the Ram Air/SD engines had a shaft that had subtle spiral colorations which made me suspect it was some sort of rolled alloy steel. I agree with the statement that on a street engine, the stress should be pretty moderate. I'd wonder if there was an unusual event? For instance, maybe the oil pump ingested a metal chip or something that caused a momentary spike in load? Just pondering..... Eric
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"Everybody has a plan until they get punched in the mouth" noted philosopher Mike Tyson Life begins at the end of your comfort zone. “The mind, once stretched by a new idea, never returns to its original dimensions.” |
#76
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72 lemans,455 e-head, UD 255/263 solid flat,3.73 gears,,,10" 4400 converter,, 6.68 at 101.8 mph,,1.44 60 ft.2007 (cam 271/278 roller)9"CC.4.11gear 6.41 at 106.32 mph 1.42 60 ft.(2009) SOLD,SOLD 1970 GTO 455 4 speed #matching,, 3.31 posi.Stock manifolds. # 64 heads.A factory mint tuquoise ,69' judge stripe car. 8.64 @ 87.3 mph on slippery street tires.Bad 2.25 60ft.Owned since 86' |
#77
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wow.......alot of "mine's better than yours"....lol
the broken tang looks to be an anomaly. Yes it happens but without a full "investgation" into the remains of the engine it would be difficult to determine was it the CAUSE of death or the RESULT from something else that failed. A typical machinist would radius all cuts and edges because it has been proven XXXX times over that ALL edges create stress risers. How much??? who knows..who really cares...its just what we do. As a Toolmaker i've NEVER been accused of UNDER designing something...lol |
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