max71
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This is going to be bit long so be warned. :fat:
I had the engine rebuilt about 35K ago. Supposed to have been done perfectly. Everything save for the pistons was renewed, balanced, line bored, etc. VP-11 cam new billet. Rods and mains sized (supposedly). Head by Huffaker and touched up with larger valves eventually by Sean Brown. Supposed to have lasted over 100K.
Its a 1971 daily driver with over 500K on the odometer. I just restored it again around the time of the engine.
With the electric gauge I showed a steady OP of 70-75 lbs even in traffic and the heat of L.A.
Moved to Oregon which is much more MG friendly weather. A couple thousand miles ago I suddenly saw the oil pressure drop 25 lbs + Obviously, I was immediately concerned.
Went through everything I could prior to pulling the pan including buying a cheap sun pro mechanical gauge. That gauge showed the electrical gauge was WAY off. Changed the oil/filter but that wasn't it and only 4000 instead of 3500 interval. Even put in a larger oil filter.
Bought new tri-metal bearings and a new oil pump. Pulled the pan and the caps on the rods and 3 mains I could get to. Plasti-gauged a couple rod journals. One was .0018 and the other was a depressing .003 Top of one rod journal had a slight score. The fingernail test showed the other were fine but #3 main had micro grooved and a slight burr which I carefully sanded down with 600 solvent soaked sandpaper as per crank grinding sites. None of the rods had any crush to the bears which sucked. Also found a dingle berry from a hone in the oil pan. Otherwise no metal or metallic substances.
The uprated oil pump was fine but the part that goes into its housing was heavily scored. The rest was perfect. Put in another one just in case.
The rod bearings looked like the came from a 100K+ engine and the backs clearly showed they had been moving within the caps. Naturally the tops were worse than the bottoms.
Followed the manic no dust policy using dust free wipes and carefully cleaned and dried the journals and caps/rod tops. Proper use of assembly lube.
Crank was polished and not turned. I had at one point put in a new crank and helping mechanic though it was better to polish than turn. STD beading but I think it should have been turned. Oh well.
Reassembled and let the car get oil pressure prior to firing. No change in oil pressure. Yesterday was a hot day here and was stuck in freeway traffic. The SunPro read at the worst 48 speed and 25 idle. Once it cooled down on the road it went up to 54/35.
Got a used mechanical Smiths oil pressure gauge (thanks Rut!) and the associated line/junction. Its having some teething but when checked was in perfect calibration. Just dealing with a sticky needle right now.
I'm at a complete loss why the oil pressure didn't get any better. Spoke to one person who insisted it was the cam bearing but the cam looked fine and I'm pretty sure I had them line bore it but with what I saw I think the Speed Shop in Burbank CA just charged me and didn't do much of anything they were paid to do or did it very badly. Head came off twice and I finally gave up and sent it to Sean Brown who said guides were in backwards and wrong like intake in the exhaust etc. Once fixed the car ran and still runs great.
The only reason why I didn't put in new pistons was because one previous mechanic's shop made a mistake and instead of skimming the block they decked it. Compression is high and I didn't want it any higher.
Hot compression is 190/187/204/192
I did the math on the compression table on the net but it shows about 9.1:1 which can't be with the compression. The head is 42.6cc. The piston dish is 6.5cc. The pistons are .015 below the deck.
No rod knocking. Car runs great but oil pressure is freaking me out. Being a daily driver I can't put it down for a month or more waiting on a machine shop. Plus I think the block is toast with almost zero deck. Oh, and no budget since I put so much into the car to make it new.
So, um, help?
I had the engine rebuilt about 35K ago. Supposed to have been done perfectly. Everything save for the pistons was renewed, balanced, line bored, etc. VP-11 cam new billet. Rods and mains sized (supposedly). Head by Huffaker and touched up with larger valves eventually by Sean Brown. Supposed to have lasted over 100K.
Its a 1971 daily driver with over 500K on the odometer. I just restored it again around the time of the engine.
With the electric gauge I showed a steady OP of 70-75 lbs even in traffic and the heat of L.A.
Moved to Oregon which is much more MG friendly weather. A couple thousand miles ago I suddenly saw the oil pressure drop 25 lbs + Obviously, I was immediately concerned.
Went through everything I could prior to pulling the pan including buying a cheap sun pro mechanical gauge. That gauge showed the electrical gauge was WAY off. Changed the oil/filter but that wasn't it and only 4000 instead of 3500 interval. Even put in a larger oil filter.
Bought new tri-metal bearings and a new oil pump. Pulled the pan and the caps on the rods and 3 mains I could get to. Plasti-gauged a couple rod journals. One was .0018 and the other was a depressing .003 Top of one rod journal had a slight score. The fingernail test showed the other were fine but #3 main had micro grooved and a slight burr which I carefully sanded down with 600 solvent soaked sandpaper as per crank grinding sites. None of the rods had any crush to the bears which sucked. Also found a dingle berry from a hone in the oil pan. Otherwise no metal or metallic substances.
The uprated oil pump was fine but the part that goes into its housing was heavily scored. The rest was perfect. Put in another one just in case.
The rod bearings looked like the came from a 100K+ engine and the backs clearly showed they had been moving within the caps. Naturally the tops were worse than the bottoms.
Followed the manic no dust policy using dust free wipes and carefully cleaned and dried the journals and caps/rod tops. Proper use of assembly lube.
Crank was polished and not turned. I had at one point put in a new crank and helping mechanic though it was better to polish than turn. STD beading but I think it should have been turned. Oh well.
Reassembled and let the car get oil pressure prior to firing. No change in oil pressure. Yesterday was a hot day here and was stuck in freeway traffic. The SunPro read at the worst 48 speed and 25 idle. Once it cooled down on the road it went up to 54/35.
Got a used mechanical Smiths oil pressure gauge (thanks Rut!) and the associated line/junction. Its having some teething but when checked was in perfect calibration. Just dealing with a sticky needle right now.
I'm at a complete loss why the oil pressure didn't get any better. Spoke to one person who insisted it was the cam bearing but the cam looked fine and I'm pretty sure I had them line bore it but with what I saw I think the Speed Shop in Burbank CA just charged me and didn't do much of anything they were paid to do or did it very badly. Head came off twice and I finally gave up and sent it to Sean Brown who said guides were in backwards and wrong like intake in the exhaust etc. Once fixed the car ran and still runs great.
The only reason why I didn't put in new pistons was because one previous mechanic's shop made a mistake and instead of skimming the block they decked it. Compression is high and I didn't want it any higher.
Hot compression is 190/187/204/192
I did the math on the compression table on the net but it shows about 9.1:1 which can't be with the compression. The head is 42.6cc. The piston dish is 6.5cc. The pistons are .015 below the deck.
No rod knocking. Car runs great but oil pressure is freaking me out. Being a daily driver I can't put it down for a month or more waiting on a machine shop. Plus I think the block is toast with almost zero deck. Oh, and no budget since I put so much into the car to make it new.
So, um, help?