Slant Six Forum :: Oil pump gear failure -- theoretical possibility

Hi Kevin. I have been interested in all kind of technical information all my life, and I know there is a 99.99% chance I will never experience a distributor axle breakage of the kind you refer to. But I have all my life also been able to combine the specific knowledge of technology in one area in dealing with problems not related to that original problem at all. I lost interest in the last thread as the words shrunk to unreadable size, so I hope my question is not already answered. Do you know if anybody actually measured the line-up of the bore for the distributor shaft in different slant blocks, regarding distance between centerline of the axes involved, and also if the angle between them are measured to a true 90 degrees, and what could a misalignment lead to? I would be interesting to hear if such information is available. And Kevin, don't mind the calluses, keep feeding the hungry ones. Olaf.

Author:	Kevin Johnson [ Thu Dec 10, 2009 9:37 am ]
Post subject:	Oil pump gear failure -- theoretical possibility
I have been advised not to mention outside material in the forums. I apologize for doing that.

Author:	madmax/6 [ Fri Dec 11, 2009 9:00 pm ]
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Think I figured it out.About a month ago you got some REALLY good pot.How else do you come up with this stuff?Have read all your posts and have refrained from chimeing in,but this is over the top IN MY OPINION.My neck is sore from sitting here shakeing my head back and forth.I have not heard of 1 problem with a Dutra blueprinted pump with hardened drive gear.I have over 100 runs on mine and have been over 6,200 rpm quite a few times.I also have only 1 pin in my dist gear.My car only runs high 12,s with stock baffled pan,and windage tray,no scraper.ALL Motor Guzzi Mark

Author:	Fopar [ Fri Dec 11, 2009 10:21 pm ]
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Mark :tsk:

Author:	Kevin Johnson [ Sat Dec 12, 2009 3:14 am ]
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You're so right.

Author:	Charrlie_S [ Sat Dec 12, 2009 4:31 am ]
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Mark, I have been racing slant sixes since 1974, and I have never had an oil pump failure, either. BUT some people have had failures. To the best of my knowledge, there has not been a definative answer on the cause/cure, just theories. What Kevin is posting is just that, another theory. It may or may not be correct. Your option is to consider it as such (a theory), or dismiss it out of hand, but not to "kill the messenger".

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Oil pump gear failure -- theoretical possibility https://www.slantsix.org/forum/viewtopic.php?t=38269	Page 1 of 3

Author:	stonethk [ Sat Dec 12, 2009 7:00 am ]
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There's a guy on e bay selling bars of titanium in various diameters, 1-1/8", 1-1/4", etc. I have been thinking about this thread and the possibility of different materials. If there are any machinists out there with the capability of machining a gear I will buy the Ti and send to you. Regardless of what anyone thinks I would like to try this.

Author:	Kevin Johnson [ Sat Dec 12, 2009 8:36 am ]
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Quote: There's a guy on e bay selling bars of titanium in various diameters, 1-1/8", 1-1/4", etc. I have been thinking about this thread and the possibility of different materials. If there are any machinists out there with the capability of machining a gear I will buy the Ti and send to you. Regardless of what anyone thinks I would like to try this. Sounds cool. Go for it.

Author:	olafla [ Sat Dec 12, 2009 5:51 pm ]
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Hi Kevin. I have been interested in all kind of technical information all my life, and I know there is a 99.99% chance I will never experience a distributor axle breakage of the kind you refer to. But I have all my life also been able to combine the specific knowledge of technology in one area in dealing with problems not related to that original problem at all. I lost interest in the last thread as the words shrunk to unreadable size, so I hope my question is not already answered. Do you know if anybody actually measured the line-up of the bore for the distributor shaft in different slant blocks, regarding distance between centerline of the axes involved, and also if the angle between them are measured to a true 90 degrees, and what could a misalignment lead to? I would be interesting to hear if such information is available. And Kevin, don't mind the calluses, keep feeding the hungry ones. Olaf.

Author:	madmax/6 [ Sat Dec 12, 2009 9:57 pm ]
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Yes,EVERY slant six person I know,knows that about Porshe 928 rods... I owened one of those turds and didnt know that,,,,pass the joint dude.Wilfred

Author:	Kevin Johnson [ Sat Dec 12, 2009 10:49 pm ]
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Quote: Yes,EVERY slant six person I know,knows that about Porshe 928 rods... I owened one of those turds and didnt know that,,,,pass the joint dude.Wilfred You're so right.

Author:	dakight [ Sun Dec 13, 2009 4:18 am ]
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I was under the impression that these failure began to show up in high numbers in the 90s. To me that would point to something that occured after intial manufacture by Mopar. We may never know with certainty, but if the cause was misaligned pump shafts, harmonic stresses or any other such design factors wouldn't the failures have occured from the get-go? Some have suggested improperly hobbed gears on aftermarket camshafts, while others have pointed to inadequate hardeness pump gears. I realize that it's possible that a basic design flaw could be exacerbated by later inadequacies in aftermarket parts but still It looks to me that the major issue(s) arose at some time well after the initail manufacture of these engines.

Author:	olafla [ Sun Dec 13, 2009 6:29 am ]
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It would be interesting - but perhaps too time-consuming - if every slant-owner that perform an overhaul or dismantle of the engine could do some measuring and report the findings back to the forum. That way we may see if there is simple solution to a problem that not many have, but one that makes the consequences to those who have it very expensive. It would mean that a standard procedure in taking those measurements needs to be developed, so that an individual without sophisticated measuring equipment easily can do it themselves. Alternatively a procedure that a machine shop easily can do in the process of taking other measurements needed for machine works when overhauling, without adding much to the price. There may also be other block/head measurements that may be interesting to log.

Author:	olafla [ Sun Dec 13, 2009 6:49 am ]
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I comment on myself! One way to do a survey, is that we make a standard blueprinting form for the slantsix. That form must be published for download, and each and every point must also contain a detailed description, with pictures/drawings, on how to take the measurements. An electronic version of the form can then be filled in online and stored, and over time be a database where changes easily can be read and analyzed. It all depends upon the interest of the members to take their time to do it, though.

Author:	slantzilla [ Sun Dec 13, 2009 8:30 am ]
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Failed parts have been inspected, cataloged, and talked about to death. Doug was keeping a list at one time. Failures do not seem to have one single common denominator. There have been different gear types tried, different cam grinders, cam buttons, oil pressure lowered, oil pressure raised, squirters designed, oil control tricks to make sure the gears are oiled well, and so on. I have a pump in my motor that has a Dutra hardened gear that has been on 2 different camshafts (one new and one used) and is not worn at all. I put one of the cams in a buddy's motor with a new MP high volume pump and it started eating the gear in less than 300 miles. I had a complete failure in one of my motors with an MP .528 cam and a stock Autozone pump. The pump had been on a Racer Brown cam for 50,000+ miles with a cam button and showed no wear at all. It took less than 800 miles on the Mopar cam and the teeth were razor sharp and 2 broke off. Some people have never, ever had a gear failure, even under race conditions.

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