engine refreshening help

DukeGnarley · Dec 12, 2010

So, today I spent $130, and picked up a '90 short block 5.0 with 61k miles on it.

The bores look to be in pretty good shape, but before I start building it up, i figured I should freshen it up a bit.

My current plans are to replace the cam, main, and rod bearings, Then hone the cylinders and put new rings on the pistons. At the same time I will replace the rod bolts with arps.

what I'm trying to do is figure out how much of this I can do myself. From looking around it seems like I'm going to need a ring compressor, hone, bore mic, and cam bearing installer.

Does anyone know if napa/oreillys would have any of these tools to rent? Or am I better off just taking it to a machine shop for the hone and cam bearings?

hungrymonkey · Dec 13, 2010

machine shop for the cam bearings. fwiw, they normaly do not wear very fast.

You are on the cusp of the "might as wells"

IE, might as well have the crank journals ground, and the crank, and might as well have the cylinders bored, etc.

Next thing you know, you will be 3k into an engine.

DukeGnarley · Dec 13, 2010

with only 61k I don't think there would really be THAT much wear on the engine, but I figured new bearings wouldn't hurt. I'm not going to bore it because i don't want to have to buy new pistons. Do you know about what a machine shop would charge for the cam bearings and a hone job?

Realmongo · Dec 13, 2010

If you are going to change the rod bolts you will need to have the rods resized at a shop.

Pony66 · Dec 13, 2010

You looking at around $100 for a bore and cam bearings. If you dont need to bore and only need to hone, rent the tool free at Autozone. But you will need a ball hone to put the crosshatch back on the cylinders. Buying one of those is around $50.

You can get a ring compressor free at Autozone as well.

I spent about $500 to have by block honed, cam bearings installed and rotating assembly balanced. They also put in freeze plugs and cleaned the block way better than I could.

brianj5600 · Dec 13, 2010

That motor is just getting broken in. Look at the bearings and if they are OK just run it. There are guys running 10s with turbos on motors with 3x that many miles.

DukeGnarley · Dec 13, 2010

The people I bought it from mentioned that the oil pressure was a little low, so that's part of why i want to put new bearings in it. the local shop wants $5/bearing if i buy the bearings from them, or $7.50/bearing if i don't. They also charge $10/cylinder for honing. seems pretty reasonable to me.

brianj5600 · Dec 13, 2010

It is your money and time. Those are some durable motors. I would not assume that the motor is worn out. If there is not sludge in the engine, I would be surprise if it is not ready to go for another 100,000+ miles.

PoppyMod · Dec 13, 2010

I agree.
R&R the Rods and mains. You can learn a lot from their wear patterns. If you decide the R&R, then check the end play of the cam and crank. 61K should be no evident wear, if true.

rbohm · Dec 14, 2010

my advice is to NOT hone the cylinders, as all you do is leave a lot of microscopic junk that will hurt the bearings in the long run. clean the block really well, and use a set of moly faced rings instead as they will seat on smooth cylinder walls.

if you do decide to hone the cylinders, clean the bores to the point where you can run a clean white cloth through the bores and have NOTHING come off on the cloth.

DukeGnarley · Dec 14, 2010

Well, I just disassembled the engine. The main bearings all looked pretty good, but the #7 rod bearing had a groove in it. The corresponding journal on the crank had a ring around it that i could just barely catch my finger nail on.

Do you think I'd be ok with running the crank as is?

I'll have to look into the moly rings. It would be nice to be able to re-ring it without honing.

PoppyMod · Dec 15, 2010

DukeGnarley said:
Well, I just disassembled the engine. The main bearings all looked pretty good, but the #7 rod bearing had a groove in it. The corresponding journal on the crank had a ring around it that i could just barely catch my finger nail on.

Do you think I'd be ok with running the crank as is?

I'll have to look into the moly rings. It would be nice to be able to re-ring it without honing.

Hi,

Without a doubt, you should plan on having the crank turned to the next under size. This is not an area to cheap-out on. Also, not knowing what caused that grove, the engine should be completely diss-assembled and thoroughly cleaned.
I can understand, you may not have the money now, especially this time of the year, so , hold off until you can get the money together to do it right the first time...and for the last time.
It would be nice to have the shop chamfer the oil holes, micro polish the journals, and balance the rotating assembly as a minimum part of your build plan. A good shop can check those bores and advise on their finish.
Good Luck!

rbohm · Dec 15, 2010

PoppyMod said:
Hi,

Without a doubt, you should plan on having the crank turned to the next under size. This is not an area to cheap-out on. Also, not knowing what caused that grove, the engine should be completely diss-assembled and thoroughly cleaned.
I can understand, you may not have the money now, especially this time of the year, so , hold off until you can get the money together to do it right the first time...and for the last time.
It would be nice to have the shop chamfer the oil holes, micro polish the journals, and balance the rotating assembly as a minimum part of your build plan. A good shop can check those bores and advise on their finish.
Good Luck!

i completely agree with having the crank turned. anytime you can catch your fingernail on a crank journal, you need to have it turned, otherwise it becomes a point where a bearing failure can occur.

as for the cylinder bores. check then for roundness and taper. if they are with in factory spec, you are good to go. if not then have the cylinder bored to correct the issue.

DukeGnarley · Dec 16, 2010

I dropped the block off at the machine shop today to be hot tanked, honed, and have new cam bearings and freeze plugs installed. They are going to check out the cylinders before cleaning, and if they need to be bored they will call me.

If the cylinders need to be bored they will "shake and bake" the block instead of hot tanking it.

PoppyMod · Dec 16, 2010

"Shake and bake"! Where did I go wrong/

DukeGnarley · Dec 16, 2010

I'm almost positive they do the hand signals every time they clean a block that way.

rbohm · Dec 16, 2010

DukeGnarley said:
I dropped the block off at the machine shop today to be hot tanked, honed, and have new cam bearings and freeze plugs installed. They are going to check out the cylinders before cleaning, and if they need to be bored they will call me.

If the cylinders need to be bored they will "shake and bake" the block instead of hot tanking it.

when you get the block back, clean the cylinder bores thoroughly. you want them cleaner than a hospital operating room. also did the machine shop guy ask what rings you plan on using? it does make a difference in the bore finish. moly rings need a smooth bore, where as chrome rings need a coarse one, and iron rings fall in the middle.

DukeGnarley · Dec 16, 2010

He did not, and I totally forgot while I was down there. I'll give them a call tomorrow in the morning. Is there any reason not to go with moly rings?

DukeGnarley · Dec 23, 2010

Ok, so i got the block back from the machine shop. The cylinder bores have 0.002" of taper. According to my engine building book, the most you want for a rebuild is 0.004, so I should be good to go without having to bore the cylinders and buy new pistons. I just need to get the crank turned and I should be ready to put it all back together.

PoppyMod · Dec 23, 2010

DukeGnarley said:
Ok, so i got the block back from the machine shop. The cylinder bores have 0.002" of taper. According to my engine building book, the most you want for a rebuild is 0.004, so I should be good to go without having to bore the cylinders and buy new pistons. I just need to get the crank turned and I should be ready to put it all back together.

Do you want to explore a more performance machine turning of that crank? Ask the shop about cross drilling, chamfering the oil holes, micro-polishing the journals. These attributes add a little better oil delivery to the bearings. Also, there are a few tweaks to the oil pump that are easy and improve the delivery, as well. Granted, they may seem beyond a standard rebuild but, these enhancements will add value down the road.
Good Luck!

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