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By famdoc3 - 14 Years Ago
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Don't know if anyone else has faced this problem. I just finished the rebuild on my 312 with a brand new isky cam. I was really worried about a dry start and made sure I loaded the cam with their moly lube and also lubed the cam journals with the high pressure moly lube. After start up had no oil coming to the rockers. Pulled the motor to look at the completlely wiped out bearing 2, 3 and 4 for the cam. My machinist talked to comp cams guys and they said you can't use the high pressure moly lube on babbit bearings and they suspect it blocked the oil holes. So started over. My rebuild is almost done and I'll pt it back in in the next coulpe of weeks. Did spin up the oil pump today and I am getting plenty of oil up there now. Wish me luck. Always a little stressful dropping the engine plus long tailshaft super t-10 into an old t'bird. Posted this because I had never heard of this problem before. MIKE
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By kevink1955 - 14 Years Ago
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I never heard of that either, hope someone comes along and explains it. I do not see how any lube that flows at all could plug oil feed to the cam bearings. Are you sure the oil holes were in proper alignment from the start. Most of the lube on the bearing surfaces should have been scraped off when the cam was inserted. I would think any prelube (by spining the oil pump) would have pushed the rest of the cam lube right out.
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By Grizzly - 14 Years Ago
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Mike, That's hard luck. Firing a new engine for the first time is supposed to be an exciting time. I've most certainly used assembly lube on rebuilt engines. Makes me wonder if something else was a miss. cheers Warren
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By PF Arcand - 14 Years Ago
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Hopefully some of our engine gurus can help explain how that could happen. Reference is made to Babbit bearings. In the past there has been a reference to undesirable soft cam bearings being available for Y Blks. Are they babbit type? Can someone in the know elaborate on this problem?..
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By charliemccraney - 14 Years Ago
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Moly lube is not designed to be used on the bearing journals, only the lobes. It's pretty much a thick grease, thick enough that it can block oil passages restrict or prevent oil flow. I believe it has a warning on the packaging about using it on bearings.
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By Ted - 14 Years Ago
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There are two basic types of cam break-in lube; one being the black moly lube and the other being the red high viscous lube. My own preference is the red lube over the black as I’ve experienced just enough ‘grittiness’ in the black lube to be concerned with this being recirculated in the oil and back onto the main and rod bearings in particular. For the camshafts though, I only use the cam break-in lube on the lobes and the bottom of the lifters. I either use engine oil or Torco lube on the bearings and journals. The soft cam bearings are a major problem though and if you’re buying a cam bearing set based only on the price, those soft bearings come to the forefront. I’m having good results using the Durabond brand of cam bearings. The other key to a good camshaft break-in is to have the camshaft rotating freely within the bearings once it’s fully installed. If the cam does not turn freely or ‘drags’, this must be addressed before going any further. Where cam tunnel hole alignment is typically not a problem with the 292 blocks, I’ve found a number of crooked cam tunnels on the 312’s. This has to be corrected for the camshafts to be expected to last for the long haul.
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By mctim64 - 14 Years Ago
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I too have had nothing but good luck with Durabond and you do need the cam to turn freely when assembled. As for the lube the only pre-lube that I've seen clog oil holes is white grease but I wouldn't call that a pre-lube anyway. I use the Moly lube on the lobes and the lifters and oil on the journals, always prime the engine and see that oil is getting to the top before you light a fire to it.
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By pegleg - 14 Years Ago
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How do you straighten the bores. I understand line boring and/or honing, but where would you find bearings with an oversized OD to compensate?
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By 46yblock - 14 Years Ago
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I had an Isky cam for a new motor that had too much run out. Didnt think it could be returned due to the time lapse since purchase. The cam was hard to install and turn in the new bearings. Taking it out the bearingings showed the points of interference. Using 0000 steel wool on the interference marks I worked the areas down, gradually. If I remember there were two bearings with the wear marks. It was a long, worrisome process, with at least a dozen cam in-outs. Then of course the washing of the block was done afterward. This was probably all wrong, but it worked. The engine is running very well 3 (or 4?) years later. If something similar should ever happen again, a new cam would be ordered even if the "bad" new cam couldnt be returned.
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By Pete 55Tbird - 14 Years Ago
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Mike When you lost the 2,3, and 4 cam bearings in your rebuild was the cam damaged too? The reason I ask is that on a lot of the English cars of the 50`s and 60`s the cam bearings were designed to be " scraped" to size after being installed. So was it just a total lack of engine oil for a short period of running that destroyed the bearing and did this show up as just a low oil pressure issue or were there other symptoms. Thanks Pete
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By Ted - 14 Years Ago
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pegleg (5/26/2011)
How do you straighten the bores. I understand line boring and/or honing, but where would you find bearings with an oversized OD to compensate?For the really crooked cam tunnels, I get a local shop to rebore the cam tunnel holes to a larger diameter. Lonnie Putnam then makes new bearings using bearing brass for those enlarged bores. The issue is bad enough with the 312’s that Lonnie has built a straight shaft to use as a bore checker that slides in the cam bores to check straightness of the bores prior to doing any machine work. This bore checker works on all the ’55 and later Y-Blocks and as a general rule, 292’s always pass with flying colors. It’s just some of the 312’s that this issue comes to the forefront on and must be addressed appropriately.
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By famdoc3 - 14 Years Ago
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sorry to be so late in getting back. I did check the cam for run out was ok. Journals were clean as it wasn't run very long. Cam bearings were in properly located but wiped out. I forget the brand but didn't buy crap as bearings seem like a foolish place to save money. Only symptoms were from noisey rockers and several bent early flimsy style push rods. Have put the motor back together (red lube this time) and will hopefully get it back in this weekend. Will let you know how it works out. Couldn't find any other problems. MIKE
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By famdoc3 - 14 Years Ago
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So finally got running today. It's great to have it back. Lopey idle from the Isky cam. Pulled the valve covers to adjust the valves and there is now so much oil flowing it over flows the heads. Now it's on to injection tuning and the laptop. MIKE
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By PF Arcand - 14 Years Ago
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Mike: re oil overflow. Are your rocker assembly overflow drain tubes block off? If so, you might want to re think that mod. It's somewhat controversial.. Likely to get different opinions on that here..
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