I built a sbc 355 and it’s hardly run at all just was braking in the cam and noticed the oil pressure dropped to probably 15 psi at 2000 rpm, shut it off drained the oil and filter and cut the filter open there was a few and I mean a few like 3 or 4 small pieces of what looked like bearing material. I figured I better open it up so I pulled the pan off and pulled the main bearing caps and this I what I saw, you can just catch your nail on a some of them. I didn’t pull the rod caps yet but there was no knocking or anything sounded fine Sent from my iPhone using The H.A.M.B. mobile app
Looks like debris scratching the bearings. If all the bearings look like that, more likely junk in the block. How well did you clean the block and passages before assembly?
I’m with Mike on this. What are the details on the build? New crank? Old crank? Crank turned? How well did you clean everything up? Sent from my iPhone using The H.A.M.B. mobile app
What's the crank look like? Did you use assembly lube? Did you clean out the oil galleys with a wire brush? Was the block "boiled". Did you prime the oil system before you started it the first time?
It’s a block I got from my dad that was bored 30 over already so I never took the block to the machine shop myself and neither did he bought the block like that, but anyway full build with new eagle cast steel crank, scar rods, srp pistons all balanced. It’s got smelling m55a oil pump, milodon oil pan think its 8 quart. Comp xs274s solid cam and aluminum blueprint heads to top it off. I thought I had cleaned it well but maybe I didn’t do a good enough job Sent from my iPhone using The H.A.M.B. mobile app
Okay,,,,45 psi is pretty good . But,,to drop to 15 is pretty bad,,,,,but,,I don’t see that much damage to the mains to drop 30 psi ,,that quickly. I suspect you have some more stuff wrong as well,,,,look further. Check the rod bearings closely . Tommy
Pull the 3 oil galley plugs, get a shotgun cleaning kit, knock the plugs out on the other end of the block and push the wire brush through there. Seen more than one that ate the main bearings up on its initial brake in due to the crap in those oil galleys.... some machine shops clean them, some don't.
I would check/Mic. The main cap's to make sure they all belong to there location as you installed them, also... One should Never assume when building an engine..., Clean,Clean, Clean Good Luck
I have heard of some of those new cranks with oval / out of round journals. I’m not saying that is it,,,just another thing to look at . I know the first pic is #5 main cap,,the second looks like #1,,,,the third pic is #2-3-4,,,,,it’s a 4 bolt main looks like . Tommy
Ok thanks I will, I have the oil gallery plugs tapped for plugs also Sent from my iPhone using The H.A.M.B. mobile app
This probably isn't what you want to hear, but you might want to pull it all down and clean and check EVERYTHING. You can never be too sure, or clean. I'm with Tommy, I've also heard of ovaled journals on new cranks.
Check the oil pump for junk, verify the bypass is not jammed open. BluePrint does the machine work but I'm fairly sure the heads are eVil imported heads. https://www.alibaba.com/product-det...pm=a2700.7724857.normalList.26.59164795PIp459 *Ford heads, but they have Chevy and other makes as well* A block is not really clean unless you've washed and hosed it out about three times with good detergent and various brushes to clean out every port, orifice, and bore. Same with all components, oil pump, camshaft, pushrods, etc. Even when new, clean them so there is no chance of contamination from machining or filth from dusty warehouse storage. Pull the oil pressure sensor/gauge off as well. You may have had adequate pressure but junk may have been blocking the port.
Can’t remember off the top of my head think I wrote them down somewhere they were with in spec though I spent a lot of time time checking and rechecking them with a dial bore gauge Sent from my iPhone using The H.A.M.B. mobile app
They’re stamped with the numbers 1-5 on them starting front to back right? Sent from my iPhone using The H.A.M.B. mobile app
That’s possible there wasn’t when I shut it off, it sounded fine Sent from my iPhone using The H.A.M.B. mobile app
Was the block washed with hot soapy water and bottle brushes ? If not it was full of trash and now it is for sure ....what type of cam , hyd. Solid flat tappet or roller ??did you replace the cam bearings ??
I washed it with hot water but didn’t use any brushes. It’s a solid flat tappet and yes it had all new bearings Sent from my iPhone using The H.A.M.B. mobile app
Hot Soapy water with brushes !! Rinse with a pressure washer . old blow dryer to dry it, then oil....
Junk in the oiling system stowed away down stream from the filter gets my vote. Back in the last milennium A friend paid plenty of his hard-earned bucks for new parts and to have an engine "built" by an "expert" in Alfa Romeos. Among the other screw ups, the expert left the crank full of grinding debris. His story was he did not clean the crank because the crank grinder " does that." (Alfas have a complicated cross drilled crank with plugged holes that require heroic measures to remove, but if left in place make thorough cleaning impossible. ) It made a HUGE mess of the entire lower end. Got any pictures of the "3 or 4 small pieces of what looked like bearing material." ? For me, complete disassembly and 100% inspection including careful measuring is in order. At the very least the crank needs a thoughtful, directional polishing to knock down any raised scratches. The bores may show some scratching and the pistons may have some embedded grit too. I'd also check the ring faces using magnification and a bright light. The cam bearings may need replacing on principal, but I'd measure them and the cam journals first to see if they were involved in the low oil pressure.
there’s the cam bearing and cam. Does the cam look alright? Doesn’t look like it wiped any lines to me. It did take the bearings though Sent from my iPhone using The H.A.M.B. mobile app
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