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one mistake we know of is the pressure guage was hooked up at the back of the block and that is straight across from where the feed went in. So i believe the reading was inaccurate because it was reading from the pump and not through the bearings. All the other bearings just had some scuffing from debris. Also never showed loss of pressure on oil thats why i believe reading was wrong. Originally only caught the problem because there was a drastic drop in HP from one pull to the next.
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i agree w evrbody else i see no real prob w oils system except the oil press guage deal. its kinda wierd to do it backwards but i see no real problem. sounds like your figuring it out. prob a case of the brand new blues... rarely have i bought all new stuff and not have to "fix" something. sorry to hear that thoComment
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shouldn't make any difference where the gauge is in the system. pressure is pressure, if there's no resistance on the other end (ie an open hole, etc), you won't build pressure. So if you didn't see a drop, you didn't have an oil pressure problem (supposing there was no blockage somewhere). You can verify that there wasn't a blockage by pumping some oil through the inlet and see if you have oil coming out at the mains.Originally posted by DoubleD View Post
More likely (though not sure how this would hurt the lifters, unless that was unrelated), you just got a bad set of bearings. Have a buddy that built engines that had problems with coated bearings he was getting for a while. switched types/brands and hasn't had problems since.Comment
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Could be something as simple as the wrong bearing clearance on #8Comment
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Thanks again everybody. Builder swears he checked all clearances and mic'ed everything as he was building it so just looking for other thoughts.Comment
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i reading and thinking this may sound stupid but here we go, did you prime the system with a drill 1st and get good pressure before you started cranking her,ive seen that before with all new parts and no one primed the system real good before cranking it,if she fired up real quick and rpms got up to 5000 it may have hurt it right from the get go,just a thoughtComment
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Originally posted by grt74 View Post
or didn't use good enough assembly lube. always a possibility, though less likely.Comment
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DD,
I think you can break it down to a couple main things that made #8 fail. Too much oil pulled from that main, or improper bearing clearances or bad bearing. I would have to see the bearing to make a better guess. How was the rear main?
Billet,
I appreciate the primer on how dry sump systems work. I well know how a dry sump system operates as I have built tankless dry sump systems ( saves 50# ), segmented pan systems as well as the cam tube oiling system along with submerged valve train systems, well before many Cup teams even heard of it. My first dry sump NASCAR 2-bbls had these systems in place in the late 80's. Upon race winning tear downs I was asked not to bring some of these systems back although they were 100% legal by rules. Following rule books had rules in place to prevent me from running this stuff again.
My point is; since there are 3-4 suction stages and only one pumping stage. it can be possible to over scavenge certain areas of the engine while not losing visible oil pressure on the gauge.Comment
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Dyno,
You may be the smartest engine builder ever but you are talking out your a$$ when you say you can over scavenge on a drysump system.Anyway how in the world could you possibly pull vacuum on a main bearing? Segmented oilpan maybe but I'll bet you he didn't have a segmented pan.3 or 4 scavenge stages and only one pressure stage is s.o.p. for dirt track.Beside all that,if it were possible to over scavenge,he would also had trouble out of #7 rod bearing also and the #4 and #5 main bearings.That is if he had a segmented oilpan.Otherwise its physically impossible.Last edited by perfconn; 07-12-2012, 07:52 PM.Comment
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The exhaust fan must be off in the dyno room again!Comment
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Not a chance Jedclampit, the only real reason would be a half filled windscreen washer bottle, that will cause low oil pressure in a SBC DLM engine any day of the week. I have tested this on my dyno 400 hundred times in just the last week alone !!!Originally posted by jedclampit View PostComment
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LOL! Yep!Comment
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He put in a fan??? Must be why he was looking at the posts for so long without posting anything, OR he was hoping some things would go away!Originally posted by jedclampit View PostComment
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Thanks Again for all the input guys. Engine just had a simple pan with screen in it. I do have alittle more info. This is a spec engine just as my last. The old engine had 60-65psi oil pressure with a 5-stage SCP pump. Put the same pump on the new motor and when i was @ builders when first fired it had right at 100 psi @ idle. I questioned about it , just got a " well its fresh just need to turn the pump down." Well forward several months ,builder still hasnt fixed it and after sitting in stands all summer, a buddy offered me his spare engine . Went and got my oil pump, cleaned it out, put it on borrowed engine....60-65 psi as soon as fired. Am i reading too much into this that builder just plain f**cked -up and had something too tight in the new one?Comment
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Hard to believe a competent builder wouldn't know the cause upon inspection. Hope you get it ironed out. The oil pressure deal seems fishy to me.BUCKLE UP NOW, YA HEAR?
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