I have a 1971 Ford 360 cid 8 cylinder engine mounted in a wood chipper. The oil pressure was running low at 10 psi @2000 rpm hot using 10w-40w oil. The engine was previously rebuilt with .020 undersized bearings. The engine oil pan was removed and the bearings inspected. #4 cylinder bearing was well worn showing copper all around, and #8 cylinder worn but not as bad as #4. The rest were only slightly worn. The sump pick up strainer was somewhat clogged and that maybe the origin of the low oil pressure. It is hard to imagine the sump strainer starving the oil pump, but I have limited experience to make any determination.

I replaced all the rod and main bearings with .020 under size and checked clearances with plastigage. All journals measure around .002 clearance except for cylinders #4 and 8 which share the same crank journal. #4 measures .003 - .004 inch clearance and #8 measures .002 - .003 clearance.

The Ford manual says allowable clearance is .001 - .0025 clearance. So I am within allowable clearance on all journals except for rod journals #4 and 8.

The sump pickup was cleaned with gasoline and compressed air. Seems okay now. I would have replaced it but do not know what vehicle it came out of.

Options I am debating:
1. Leave it as is and reassemble with a high volume oil pump and run a heavier weight oil like SAE 30. Is .003-.004 inch clearance that bad?
2. Find an .021 and .022 undersize connecting rod bearing. Has anyone ever heard of this odd size and where it might be obtained?
3. Place a strip of shim stock under the bearing shells and trim the shell end to make up for the reduced circumference.
4. Install a new reground crankshaft with appropriate bearings.

Option 4 seems over kill, since this engine is in a wood chipper used for my own personnel needs, the engine will see little use compared to a truck application.
Option 2 seems unattainable.
Option 3 is not worth the trouble is option 1 will work. But has anyone tried shimming and what were the results?
Option 1 is best option if the engine will survive with a high volume oil pump and more viscosity. Has anyone tried it? What were the clearances?

Any suggestions on what to do would be appreciated.
Thanks for reading.

 

Option 1. If it doesn't have lifters clacking and bad sounds up to, it was getting enough oil with the old bearings and it will get plenty with the new. Maybe try 20w50 so your cold starts are easier than with straight 30.

 

If it's for personal use I would assemble it, install a new HV oil pump. I say no to shim stock under the bearings, it's been tried and the end result is always spun bearings.

 

The engine sounded okay last it was running. I only dropped the pan because of the low oil pressure, When cold the pressure was about 35 psi, but when it got hot, pressure was only 5-10 psi at 2000 rpm. I thought the engine would seize. I had cheap 10w-40w new oil in it, but still I thought the engine must be totally worn out. This wood chipper is a new acquisition. It had been sitting in the woods for 15 years. It surprised me that it started right up. It is actually a 330 cid Medium Duty low compression truck engine. I called it a 360 so as more people are familiar with that.

 

Thanks for that feedback. I was fearful that shim stock under the shells would produce a spun bearing. A big reason for posting was to get an opinion from someone who had some knowledge of the practice.

I was reading in the Ford manual that the bearings are selective fitted with .001 and .002 undersized shells used in conjunction with standard shells. So a standard size lower shell could be mated to a .002 under size upper shell to take up the clearance on a worn journal. I would never thought that was possible, but there it was in the Ford manual. Problem I have is my journals are ground .020 under size but .022 bearings don't seem to exist.

I infer from your's and 85e150 reply that .004 clearance on one journal is not that much concern for a lightly used engine.

 

I've seen a few engines wiped out from a clogged oil strainer, also #4-8 bearings are the last to get oil and will show the most wear from low oil pressure.
A 330 MD truck engine has a different oil pump than a 360, it uses a 5/16" drive were a 360 oil pump has a 1/4" drive.
Stock oil pump will be all you need but I'd pull the valve covers and rocker arms, then install restrictors in the oil passages in the heads.
Also check the oil drains in the corners of the heads for blockage, I've seen those get plugged and hold the oil up on top of the heads.

 

X2. This is a simple mod that requires NO drilling or tapping. Get 2 #70 Holley jets (Summit is one source), remove the rocker arm assemblies and insert the jets in the oil feed galleys in the head. That's all that's required. The FE/FT series is notorious for flooding the heads with too much oil.

 

I have strong suspicions that the strainer was the source of the problem. It appeared completely blocked with flaky particles made of sludge/rust. It took a lot of effort to clear it out with compressed air. Thankfully the screen did not get damaged.
My engine has a 1/4 hex drive shaft to the oil pump. I had ordered a replacement 330 distributor from RockAuto with 5/16 drive shaft and was surprised to find it did not fit. So I returned it and got one for a 360 which has a 1/4 drive and it fit. I also did the same for a timing chain cover gasket and crank seal, 330 no fit, 360 fit. My conclusion was that RockAuto 330's are all heavy duty but 360 will fit my 330.

There is a lot of confusion as to what this engine really is. My evidence of it being a 330 MD is: the intake and exhaust valve stems measure .370 - .371 inch diameter. Seller said he measured the piston bore as 3.92 that would correspond to .050 oversize 330 engine. Compression test reveals low PSI (100) on all cylinders. Normal engines are usually around 150 psi, so I conclude it is a low compression ratio engine. Crankshaft snout is 1.375 inch diameter which corresponds to 330 MD FE engine. Water pump bolts on to engine block which is FE style, and not the timing cover which is FT style.

The wood chipper title is 1971, but the engine probably is not original. The previous owner said the title may not be true to the chipper. There are no number stamps on the chipper. So the year of the engine is really unknown. I have been using 1971 Ford 360 cid with 100% success, and 0% success using 330 from RockAuto.

 

Thanks for that picture. I had read about this procedure in the FAQ section of this forum but no description of it's implementation.

I removed the valve covers to inspect and found rust in the rocker arm push rod joint area of cylinders #4 and 8. Not a good sight. And probably a sign of inadequate oil reaching the rocker arms. I think it is another low oil pressure symptom. The inside of the engine appears nice and clean, no sludge. The bottom of the oil pan was also relatively sludge free except for the sump pick up screen. Go figure that! The oil return passages in the heads were clear.

 

Didn't have my brain completely in gear last night!
Your correct, 330 MD uses components that fit the FE series engines, I was thinking 330 HD which uses all FT parts.

 

That's OK, my brain's clutch has been slipping almost my entire life

These guys got you covered...

 

btw - my Motor's manual says for 330 (both MD and HD), rod clearance is .001-.0029

So .004 is not that far off - I bet in a worn engine, it's much higher than that anyway...

 

I was wondering what clearance a worn out engine has just before it starts knocking or seizes or other catastrophic failure. How far can the clearance go? What is the typical worn out clearance when the owner says enough is enough and replaces or rebuilds the engine?

 

Tried to find that--no luck. If OP runs the HV pump and 30w to 40w oil he may be good. Probably should restrict the heads too.

 

I've never gave clearances much thought until we had the engine torn down for a rebuild, if it'll hold at lease 30 psi hot at cruising speed, doesn't burn oil to the point it fouls plugs or smokes like a freight train and doesn't leak oil out as fast as I can pour it in, we keep on using it.

Max recommended is .0029, yours is .004 on one journal, the average human air is .003 so you less the half a hair out of spec, that's not much.
Another way to look at it is a 428 CJ race engine gives bearing clearance specs of .003 -.0035, so yours is like a low performance race engine with a few passes on it.