It was pulled because I had the same engine builder, build me a 540 and I stuffed that in the nova. I honestly never drove it because I just missed the blower sticking through the hood. So, someone bought the 540 and I decided to go back to the blown small block. Im running an MSD 6AL tied to a MSD 8977 timing computer that references boost from under the blower. From that you can program a timing curve to pull timing out per LB of boost. Sadly they dont make the 8977 anymore but they do make a digital 6AL along with a MAP sensor to accomplish the same thing. I'll keep using the 8977 with the 6AL until they puke. The 11% overdrive is a direct result of a BIG cam in a small block. It needs to be overdriven that much to produce 8-10lbs of boost. Theres a lot of overlap in that cam so its bleeding off cylinder pressure up the ass. I know its not the right cam for a blower if you are going for max HP, but I sure do like the blower surge it produces. 93 octane pump gas has not been an issue. The STD on the bearing means the crank journals are OEM size and in this case - .001 for clearance. Im going to talk to the engine builder tomorrow and see if I can just run standard OEM without the -.001 . that would put me somewhere between 2.5 and 3 thou. I would NEVER take emory cloth to a crank journal. Those journals are slick as glass right now and look like mirrors. Im not going to screw that up. I really didn't want to pull the crank as im going to have to pull the comp cams belt drive to do it. its turning into a huge pain in the ass but its looking like I need to pull the crank to make the job easiest . It would be completely stupid to NOT replace the rear main seal at this point. Im already in there. Im just not comfortable in the bottom yet. I'll get there. Anywhere up from the crank and rods, im completely comfortable with. Im an old man with little experience with the rotating assembly. Ands it clear as day I dont know how to interpret the bearing wear. My gut is telling me that those chatter marks are not a good thing. We shall see.
before I would go to all that trouble on a 1975 truck block, id throw the money at a dart little M block and eagle rotating assembly and just write off the old truck block. its been good to me for almost 20 years. I have not put thousands of miles on it but its stayed together this long. the builder told me he exclusively sets up engines at 3 thou unless the customer requests different. I think its the drag racer in him. He races division 4 top alcohol and a lot of people are running his big blocks. I wonder if the 4 thou im seeing is a mis measurement from the plastigauge or 1 thou wear on the bearing. Just curious, why do you think its shoddy machine work ? When I told him I was going to plastigauge it to see where I was he said " get some fucking tools and do it the right way. plastigauge is for working on a fucking tractor out in a field ". LMFAO.... unfortunately, currently thats my limit and abilities...
Here is the link to an excellent article on types of bearing wear. https://www.speedperf6rmanc3.com/content/Engine Bearings.pdf Bob I remember an article by Bobby Unser, that stated a lot of the wear
The thing about grinding a crankshaft is that even though you can't see them without magnification, there are little teeth on the crankshaft that are kicked up by the grinding wheel. They all face one direction. When you use emory paper or crocus cloth you cut in the opposite direction to remove the microscopic teeth. A professional crank polisher uses a lathe and a belt that is under power. Homebuilders use a stationary method as shown in one of the videos below. It also insures that oil hole chamfers don't have a small burr that can ruin a bearing. Your choice as to whether you do it or not, but just because a journal looks smooth doesn't always mean that it couldn't be even better. Professional Polishing Amatuer Polishing
Just one last comment. You are probably aware already, but you can mix and match bearing halfs to taylor clearance if needed. Halfs should stay within 0.001" of each other. So by example, on the main you measured 0.004", what were the bearing halfs? Both +0.001? If so you could replace one half with a standard and reduce clearance by 0.0005. It's your deal, but for your application I would be more comfortable with an accurately measured 0.003" to 0.0035" on the mains. Good luck with getting it sorted out.
What is the best way to get plastigauge off the bearing surface and surface of the journal ? I used a plastic spudger and just kept rubbing until I could no longer feel any of it. I then wiped the journal down with acetone and put on some assembly lube but just wiped the bearing surface with a clean cotton rag and then assembly lube before putting the cap back on. That stuff is a pain in the ass to get off.
Seems like you spent a lot of money on this car and saved it on the gasoline. Put in 110 octane instead of the 93 or go back to the under driven set up. Pat
the gas is not the issue. that's what a boost referenced timing curve is for. considering this is a street car and it spends most of its life at part throttle and mostly on the primaries, 93 octane is fine. putting 110 octane in it at $7 a gallon is not the answer unless you have unlimited funds. which I dont.
I'm just curious as to what you are running for an air filter as those look like scratches from dirt/grit getting in.
I agree with your engine builder on the clearances. Too tight is always a problem. Too loose has low oil pressure but doesn't lock up. I have 20 years exp. with blown alky. As I recall, the small block racers ran their blowers at 11 over at denver and around 4 over at sea level. Now, what I don't know is how good your blower is. If you remove it and check the clearance between the rotor and the bottom of the case, I would have an idea. If your blower is weak and you're driving it harder to make boost, you put a lot of strain on your components. My guess on the skipping pattern on the bearing is crank flex. When you really start to make serious power, you will see the main caps and block brinelling metal onto each other. I didn't see that in your pics. From what I see, you need at least 50lbs. of oil pressure to be safe at low speeds and more at upper rpm. Many will dispute that but this isn't a naturally aspirated engine. If you turn this over 6 grand, you need some oil pressure. I would install the new bearings and seal and go enjoy it.
I agree with polishing ....as to the video , if I saw the snout of a crankshaft held in the hard jaws of a vice like that , I'd be really upset !
I agree with Mr48Chev, looks like particles scratched and embedded in the overlay. I don't like the dark color of the bearings, they look stained as if from heavily oxidized oil. How often do you change the oil?
That's a new one on me. Are you referring to "caviatation erosion", which can occur on bearings, but it doesn't have to to with hydraulic shock, or due to full flame propagation.
Nothing wrong with the oil, but skip the Lucas oil stabilizer, not a great idea to blend your own formulations at home, the chemical engineers did a lot of R&D at Castrol, the Lucas product is not helping, at all, may even be hurting.
That was a simplified explanation that Henri at ACL's lab gave me. The top coating was literally delaminating [oil was being forced under the coating] It was happening on the upper rod bearings and lower main bearings. The maximum cylinder pressure is at TDC when the rod and crank throw are alligned straight. All these forces are transferred through the bearings. We also had the same issue with a TRD engine in a touring car. The life expectancy for the bearings was 1 meeting [Nobody makes H series bearing for Toyotas] Believe it or not, It doesn't matter. Many members of the HAMB have a good working relationship with their engine builders, but not many have gone into the R & D depts or Labs of the component manufacturers. As the late Bruce McLaren said "The real cost of racing isn't the parts you use, but the parts you throw away"
I ordered the bearings today and am installing a Melling shark tooth high volume / high pressure billet pump. It had a Melling M55A standard volume / high pressure pump on it. After talking to Melling again today they insisted that for my tolerances and application, its needs to be the high volume / high pressure pump. I had ordered the standard volume pump and now its going back. I already ordered the high volume one from summit.
The motor is so clean inside you could eat your lunch in the lifter valley. I really mean that. the builder saw the pics today and told me it looks like crank flexing or block movement and possibly detonation. he said to put the exact same bearings back in it and put that shark tooth high volume pump in it. he said the back side of that main looked to be overheated. he stated that I should throw as much oil at it as possible. it was also stated that switching to synthetic would be a positive move.
Bearings have been overheated and are badly scored. The engine will need a full overhaul and cleaning.
the engine is going to get new bearings , oil pump and valve springs and its going to get run until its done. the new oil pump will go in a dart block and the heads will go right on also. im done worrying about every little nuance of imperfection . I'll run it till it pukes. I'm an old man in my 60's. I suspect it will outlive me.
The options are extremely limited for something that will fit under that blower hat. Is there something that size that filters better ?
I don't recall that you mentioned what the capacity is of your current oil pan. That high vol oil pump will move some oil and it doesn't always drains back to the pan fast enough at sustained higher revs, like on the expressway.
its a 7 quart T sump I did ask Melling about that issue and they said its a non issue with a 7 quart pan.
So, what clearance do you plan to run when you replace the bearings and use a higher volume/higher pressure oil pump? I'm also curious as to how the bearings could overheat and/or delaminate and the journal be in perfect condition. Seems strange...... Something else to consider, given the restrictions within the oil passages of an OEM smallblock around the cam bearing, how much additional oil will pass thru to the crank and how much will divert to the upper end?
Im going to do exactly as the builder instructed and put the exact same bearings back in it and put the high volume shark tooth pump in. I suspect that with new bearings, the clearance will be between 3-3.5 thou looking at that pic, I have only one choice, the high volume model of the shark tooth. after talking to Melling yesterday, the standard volume shark tooth pump has the exact same flow as the Melling M55A that I just pulled out of my motor except in a billet format. I see no sense in putting it back together with that volume of pump. The high volume model has 25% more volume of flow than the stock M55A. The info on summits website is incorrect when it states that the 10055ST has 25% more flow than stock. The 10050ST is the high volume model that has 25% more flow. The info on Mellings site is the correct info. its really my fault for not figuring that out. I just read the info for the 10055ST on summits site without looking closer at the specs. Here is that info on summits site that was clearly just a copy / paste from Melling " Smoother, tighter, and quicker--Melling Shark Tooth oil pumps utilize helical asymmetrical technology to improve the heartbeat of the traditional internal gear pump. The use of this new gear design feeds your engine an increased flow of oil without the usual pulsing. How much more? About 10 to 25 percent more volume! Equip your setup for a powerful bite of high performance; install one of these Melling Shark Tooth oil pumps."
is there an easy safe way, other than a plastic tool, to get plastigage off bearing surfaces. sometimes the plastigage sticks to the journal and sometimes the bearing surface or in my case, both.
The Jalopy Journal
