Slant Six Forum :: Oil pump gear failures -- revisiting the Matrix

More people raced Slant sixes in the 60s than anytime since. I was around then and as far as I know OPDG failures were not a problem. In the 90s and afterwards there were a rash of these problems especially with aftermarket cams. The number of people who ever used rods without oil holes until just recently is miniscule. I believe this points to the camshaft as the source of these problems. One thing that was never done in the original investigation was to identify the cam blank that was used in failure situations. Like Doug says there is only one source of cam blanks now and they have EP7 cast into them. This wasn't necessarily the case back in the ninties when there were several sources of blanks. It would be most interesting to know what casting marks were on the blanks involved in failures. If anybody paying attention to this subject still has a failed cam it would be interesting to try to determine where the blank came from. Maybe Frank could do this with the engines he has.
As Frank would say... my 2cents.

Author:	Kevin Johnson [ Wed Nov 25, 2009 6:45 am ]
Post subject:	Oil pump gear failures -- revisiting the Matrix

Author:	sandy in BC [ Wed Nov 25, 2009 7:04 am ]
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I believe the matrix predates the aftermarket rods with no oil holes.

Author:	66aCUDA [ Wed Nov 25, 2009 7:16 am ]
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Quote: I believe the matrix predates the aftermarket rods with no oil holes. Sandy that is correct. I have 2 engines that have had OPG failures, both were running MP cams. I would have to look at the cams to see which model. Unfortunately I did not own these engines when the failure occured. The rods were stock reconditioned. Frank

Author:	SlantSixDan [ Wed Nov 25, 2009 7:33 am ]
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Slant-6 oil capacity with most passenger car oil pans is quoted as 4 quarts plus one in the filter. Adjust your water tests accordingly.

Author:	ceej [ Wed Nov 25, 2009 7:48 am ]
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I noticed that one of the criteria that was not listed was whether the cam was used in a previous engine, or with another build. Fopar lost a gear this year that was on a cam previously used in his other race engine. Likely a contributing factor in the failure. Where a cam is moved from one block to another, that data would need to be captured since the wear pattern would have to be re-established, and the contact path would likely be different. CJ

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Author:	sandy in BC [ Wed Nov 25, 2009 9:07 am ]
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Another factor I looked at was cam drive (chain and gears) and the possibility the cam could be pulled forward by a roller chain vs stock chain. I also played with chain slack .....and the effect of abrupt cam movement during shifts. After much angst and reasearch coupled with parts swapping my conclusion was that my much travelled Comp cams poor gear machining was the LARGEST of many contributing factors. .....in this situation and usage in my location that day. By searching the site and asking questions I found a bunch of effective ways to reduce the possibility of a third failure. My favourite: Lighter oil . Best money spent: Oil pump/gear from Doug Dutra Best time spent: Dailing in all aspects of pump drive from crank to pump during assembly. This included dressing the cam gear, Clover lapping in pump and cam gears and cam end play adjustments. Cam and gears/chain is a whole nother topic.

Author:	Exner Geek [ Wed Nov 25, 2009 12:19 pm ]
Post subject:
More people raced Slant sixes in the 60s than anytime since. I was around then and as far as I know OPDG failures were not a problem. In the 90s and afterwards there were a rash of these problems especially with aftermarket cams. The number of people who ever used rods without oil holes until just recently is miniscule. I believe this points to the camshaft as the source of these problems. One thing that was never done in the original investigation was to identify the cam blank that was used in failure situations. Like Doug says there is only one source of cam blanks now and they have EP7 cast into them. This wasn't necessarily the case back in the ninties when there were several sources of blanks. It would be most interesting to know what casting marks were on the blanks involved in failures. If anybody paying attention to this subject still has a failed cam it would be interesting to try to determine where the blank came from. Maybe Frank could do this with the engines he has. As Frank would say... my 2cents.

Author:	sandy in BC [ Wed Nov 25, 2009 1:18 pm ]
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My gear eating Comp 264s-10 is an EP-7 . However that is a casting number. You could have several different machining companies working with EP-7 blanks. One guy ....one day...on one machine ...could screw up a lot of gears.

Author:	SlantSixDan [ Wed Nov 25, 2009 1:38 pm ]
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Quote: One guy ....one day...on one machine ...could screw up a lot of gears. Very, very true. And that one guy could easily account for the whole, entire problem, given the low volume of new slant-6 cam production by all grinders combined. (On the other hand, I was on the UM Solar Car team with a guy who had the bizarre and well-practised ability to get so drunk he couldn't walk steadily, then sit down in front of a lathe, mill, or whatever and turn out beautiful, accurate, perfect part after part after part.)

Author:	Kevin Johnson [ Wed Nov 25, 2009 1:51 pm ]
Post subject:
Quote: More people raced Slant sixes in the 60s than anytime since. I was around then and as far as I know OPDG failures were not a problem. In the 90s and afterwards there were a rash of these problems especially with aftermarket cams. The number of people who ever used rods without oil holes until just recently is miniscule. I believe this points to the camshaft as the source of these problems. One thing that was never done in the original investigation was to identify the cam blank that was used in failure situations. Like Doug says there is only one source of cam blanks now and they have EP7 cast into them. This wasn't necessarily the case back in the ninties when there were several sources of blanks. It would be most interesting to know what casting marks were on the blanks involved in failures. If anybody paying attention to this subject still has a failed cam it would be interesting to try to determine where the blank came from. Maybe Frank could do this with the engines he has. As Frank would say... my 2cents. What were the typical ETs in the 1960s for the slant six and then in the 1990s? From this you can calculate average acceleration and apply it to the sump. If you know the 60 foot times, even better. Edit: I went to this article: http://www.moparmusclemagazine.com/proj ... index.html ... and entered 14.190 seconds into this 60 ft time estimator: http://www.wallaceracing.com/calc60ft.php ... and entered 1.97241 sec into this average G force estimater: http://www.wallaceracing.com/g-force-60foot.php and this yielded .48 G Edit: I briefly searched the board for some more 60 foot times: 2.4 sec = .33 G 1.79 sec = .59 G 1.70 sec = .65 G 1.67 sec = .67 G http://www.dragtimes.com/Fiat-1100-Timeslip-3619.html 1.220 sec = 1.26 G Edit: For .33 G tilt the pan rearward ~18 degrees. For .65 G tilt the pan rearward ~33 degrees.

Author:	sandy in BC [ Wed Nov 25, 2009 2:29 pm ]
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No 60 ft times here. We measure travel in hours. Here is some anecdotal evidence of my experience. I have also heard similar stories posted over the years. We play a game here called "Top Ending" the car. Starting from a fixed point (burnout optional ...it can be part of the run) the vehicle accelerates for about 1/2 mile across the causeway till you hit the bridge. You record either a time or MPH. Thats 5 gears. It went soft at about 105mph....both times. The car is a 16 (mebbe even 15) second car with 5 speed and 3.55 gears. Mebbe 175 hp. 3000lbs/driver. Dennis blew one up between toll booths as I recall. That was a MP cam. If acceleration is a factor (and of course it is) then it would seem to apply to slower cars as well as the way fast guys.

Author:	ceej [ Wed Nov 25, 2009 2:33 pm ]
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There are a few times down in the 1.50's as well. Take a look in the racing results area. There are threads that list times for 60', 1/8 and 1/4 mile there. CJ

Author:	Exner Geek [ Wed Nov 25, 2009 4:37 pm ]
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Except for nitrous and supercharged cars, racing slant 6s in the old days didn't run that much different than they do now. Drag tires are better so the 60 foot times are probably better but not a big difference. OPDG failures are not corrolated with high G drag cars, they have happened to many cars that are never raced and often just going down the road. I am not sure I remember any really fast drag car having a failure but I will have to say that many are not using the stock type oil pump. Mike Jeffrey, Dale Rose, and others never had a reason to use anything other than a stock type oil pump and they know how to generate some Gs. The frequency of failures with Mopar Performance cams is definately higher than average but the gears were already finished before whoever ground the lobes on those cams had at them. Thanks for the blank info Sandy, maybe some others can check their broken pieces and post.

Author:	GTS225 [ Wed Nov 25, 2009 5:11 pm ]
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I would appreciate a touch of clarity, here. The subject seems to be jumping between the pump-mounted gear and the drive gear hobbed into the center of the cam blank. Are we trying to discuss the *driving* gear or the driven gear? Roger

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Author:	sandy in BC [ Wed Nov 25, 2009 6:06 pm ]
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Clarity..... I always look at meshed gears as a single entity.....hence lapping. The cam gear is cut as is the pump gear. The pump gear is the one that fails. The pump gear gets hardened. I think its cam gear machining thats at primarily at fault but that is purely a personal opinion based on my own experience and observation. I also feel there are at least 6 factors related to or contributors to failure. My cam and pump gear are available to anyonewho wishes to analyze them.