only an old beater,but theres # 5 again.
regards,Rod
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| #5 rod bearing https://slantsix.org/forum/viewtopic.php?t=25920 |
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| Author: | 66aCUDA [ Mon Nov 19, 2007 11:20 am ] |
| Post subject: | #5 rod bearing |
Over the past 6 months I have disassambled a number of / engines. Most if not all have had problems with the #5 rod bearings. As I am getting ready to build 3 motors does the oil mods done on Twiggy address this? Are there other things that need to happen? Thanks Frank |
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| Author: | Doc [ Mon Nov 19, 2007 2:19 pm ] |
| Post subject: | |
I feel that #5 rod bearings fail more frequently because that cylinder tends to run leaner then the others. (cylinders 2 & 5 are typically the lean cylinders on a Slant) Lean cylinders tend to detonate and detonation really "pounds" on the rod bearings. Good oiling helps but getting even cylinder pressures and even fuel mixture distribution across all 6 cylinders are also important goals. DD |
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| Author: | Aggressive Ted [ Mon Nov 19, 2007 7:05 pm ] |
| Post subject: | |
Quote: cylinders 2 & 5 are typically the lean cylinders on a Slant)
Lean cylinders tend to detonate and detonation really "pounds" on the rod bearings. Given that, how can we improve fuel flow to 2 and 5????? Do we have to run a fatter jet? or is there something we need to do under the carb? like build dams to direct flow? if so do you have a template, drawing or picture? Thanks, |
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| Author: | Charrlie_S [ Tue Nov 20, 2007 5:49 am ] |
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I will add something to this. In the 70's I ran a 65 Valiant with a 170 engine, in NHRA stock eliminator. This started as just a "rebuilt" motor. After the first season, the motor got a complete NHRA legal "blueprint" build, including the crank being indexed, balanced, and the bearing clearances set. Ran the motor for two more years, and had zero problems with bearings. At that point I could no longer run stock, and did some "cheapy" mods. Milled the head .100, Modified the stock cast 1bbl manifold for a 500 holley 2 bbl carb, and installed a Crane s-264 (264 adv dur 222* at .050, with .434 lift)cam. After a little while found number 5 bearing with excessive wear. Over about a two year period, I had to replace the #5 several times. I talked to Larry Sheppard (Chrysler engineer) about this, and was told "I was doing something wrong, it is not a symtomatic problem, with the engine" (yeah, right). During the off season rebuild, I did some oiling system mods, some of them similar to what Doug reccommends (I did not know any other slanters, including Doug, at that time). I opened up the main galley, the pasages to the main saddles and ran full groove main bearings. I have not had a bearing problem since, and I still have that same engine running the same crank, now on NOS. And yes, I also have seen many slants with bad #5, in the salvage yards. |
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| Author: | Rob Simmons [ Wed Nov 21, 2007 1:48 am ] |
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Good real-world feedback Charrlie. Thanks. The wheels are already turning on how I want to build my next Slant 6 race engine and I will keep the oiling mods in mind. |
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| Author: | walpolla [ Wed Nov 21, 2007 3:14 am ] |
| Post subject: | |
only an old beater,but theres # 5 again. regards,Rod
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| Author: | Charrlie_S [ Wed Nov 21, 2007 5:00 am ] |
| Post subject: | |
Quote: Good real-world feedback Charrlie. Thanks. The wheels are already turning on how I want to build my next Slant 6 race engine and I will keep the oiling mods in mind.
I will add a little more info. I have never had an oil pump gear failure(now I will probably have one  ), but I have also never run a cam made newer then about the mid 80's. Also have never run a high volume oil pump. Even on my turbo engine, where the turbo requires about 1/2 gal of oil per minute, and the engine had full groove mains, I used the Stock replacement pump, which is a higher capacity then the factory OEM pump, but not as large as the "high volume" pump. Oil pressure was a little lower at idle, but was up to the relief valve setting, of 50-60 PSI from about 1500-1600 rpm up, with 10-30 oil. I also groove the rear cam journal (very slightly) for more valve train oiling. One thing Doc does, that I do not do, is put a oil nozzle in the front oil galley plug to lube the timing chain. The factory used a different front main bearing, with a champher on the edge (current aftermarket main bearings, do not have this) to spray oil on the chain. I file a champher on the edge of the bearing, to lube the chain, and run an oil slinger. Not saying Doc is wrong, just giveing another way of doing it.
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