273 Cylinder Bore .004 over spec

[Bossanova5]

I measured my cylinder bores today and the worst cylinders are close to being .004" over the allowable 3.6270" maximum measurement.

How much oil will this thing burn, and compression lost (With it being .004 out of tolerance) if I put it back together?

Thanks

 

[RustyRatRod]

Don't know but it surely won't be as good as with fresh bores, new pistons and rings.

 

[Bossanova5]

Trying to prevent spending $2,500-$3,000

 

[RustyRatRod]

Trying to prevent spending $2,500-$3,000

Well.......you'll do it later if not now.

 

[kick]

I don’t know your shop rates but I’m thinking you should be able to get new pistons, rings and a bore and hone for less than $2500.

 

[67Dart273]

The bigger question is "how is out of round and taper?" People used to knurl piston skirts. I know it ain't the best, but...................

 

[junkyardhero]

I don’t know your shop rates but I’m thinking you should be able to get new pistons, rings and a bore and hone for less than $2500.

he's doing this up 100% OG commando, so with that comes $700 in pistons. that other 1800 goes quick: hot tank & mag for 175, bore & hone 350, square deck it and align hone 300, install cam bearings and plugs 150, tank, mag, straighten & polish crank 125 rod bolts + resize rods 100, and that's supposing everything is hunky-dory and it doesn't need a full battery of stuff.

around here you *might* be able to do it for about 2K

but then are you gonna put some unknown tired heads on that fresh bottom end?

there's another smooth G to go thru those.

 

[TT5.9mag]

he's doing this up 100% OG commando, so with that comes $700 in pistons. that other 1800 goes quick: hot tank & mag for 175, bore & hone 350, square deck it and align hone 300, install cam bearings and plugs 150, tank, mag, straighten & polish crank 125 rod bolts + resize rods 100, and that's supposing everything is hunky-dory and it doesn't need a full battery of stuff.

around here you *might* be able to do it for about 2K

but then are you gonna put some unknown tired heads on that fresh bottom end?

there's another smooth G to go thru those.

There’s always basket weaving.

 

[RustyRatRod]

There’s always basket weaving.

Or Tiddly Winks. Or stamp collecting. Or baseball cards. You've seen me say it before!

 

[Syleng1]

Pay to have block sonic tested first.
Make sure the walls can take the .004” over bore. Honestly those blocks can handle a lot. I know because my 66 is bored that much. The issue with mine was the head gasket surface area were not square and not parallel to the crank bore. That cost a bunch to straighten out. Most people focus on cylinders being square- but not if the whole block is square. Camshaft bore square to crank, crank square to bell housings and head surfaces. You get my point.

 

[junkyardhero]

There’s always basket weaving.

you know i did my undergrad in underwater basket weaving, why must you always poke fun every chance you get?

it's a legit career path turbo mike!

 

[TT5.9mag]

you know i did my undergrad in underwater basket weaving, why must you always poke fun every chance you get?

it's a legit career path turbo mike!

Legitimate yes. And cheap!! For those who want to avoid machine shops while building engines it’s a great alternative.

 

[junkyardhero]

Pay to have block sonic tested first.
Make sure the walls can take the .004” over bore. Honestly those blocks can handle a lot. I know because my 66 is bored that much. The issue with mine was the head gasket surface area were not square and not parallel to the crank bore. That cost a bunch to straighten out. Most people focus on cylinders being square- but not if the whole block is square. Camshaft bore square to crank, crank square to bell housings and head surfaces. You get my point.

the last 340 i did got the full boat just like that. sonic, squared, decked, align honed, bored with torque plates, one sleeve.

with the work on the rods and crank, the machine shop bill was over 3K and all i got was a clean block that was ready to build with cam bearings and plugs in it and a pile of parts.

 

[junkyardhero]

Legitimate yes. And cheap!! For those who want to avoid machine shops while building engines it’s a great alternative.

why must you besmirch the rattle-bomb rebuild?!

live by ghetto fabulous rules, die by ghetto fabulous rules.

caveat: they never die, they just run poorly forever because they don't make enough power to hurt anything.

 

[TT5.9mag]

Certainly not against the rattle can rebuild at all. What I do advocate for is not even measuring those. Why take it apart and measure bore wear, taper, out of round etc if you’re just going to slap it back together and not fix anything? Just leave it together, spray bomb it and run it.

 

[TT5.9mag]

By my math his .004 past limits puts the skirt clearance somewhere near .012-.015 and that’s if the piston isnt worn. I build **** loose. Real loose and I wouldn’t put that back together.

 

[Dart Frog]

As long as you're bores are round close to spec you'll be okay till your RPMs get higher than you will most likely begin to build crankcase pressure and lose oil.

 

[Desoto291hemi]

Isn’t the standard bore for a 273,,,,3.625 ?
So no way is this block at the maximum bore already !

Tommy

 

[junkyardhero]

Certainly not against the rattle can rebuild at all. What I do advocate for is not even measuring those. Why take it apart and measure bore wear, taper, out of round etc if you’re just going to slap it back together and not fix anything? Just leave it together, spray bomb it and run it.

*hits it with brake clean*

looks good SHIP IT!!

 

[RustyRatRod]

By my math his .004 past limits puts the skirt clearance somewhere near .012-.015 and that’s if the piston isnt worn. I build **** loose. Real loose and I wouldn’t put that back together.

So do I and I agree! Loose always runs better and makes more power....but that would be sloppy like a hooker on payday. In a Navy port. On the weekend. Runnin a 50% off sale. With free Viagra samples.

 

[RustyRatRod]

Isn’t the standard bore for a 273,,,,3.625 ?
So no way is this block at the maximum bore already !

Tommy

That's not what is being said. It's BEYOND the maximum spec for a STANDARD bore. He's not wanting to bore it. Get it?

 

[RustyRatRod]

As long as you're bores are round close to spec you'll be okay till your RPMs get higher than you will most likely begin to build crankcase pressure and lose oil.

He's already said. They are .004" PAST maximum spec. That's a mile.

 

[RustyRatRod]

By my math his .004 past limits puts the skirt clearance somewhere near .012-.015 and that’s if the piston isnt worn. I build **** loose. Real loose and I wouldn’t put that back together.

See? This ^^^^^ is being said by someone who GETS what's going on here.

 

[Desoto291hemi]

That's not what is being said. It's BEYOND the maximum spec for a STANDARD bore. He's not wanting to bore it. Get it?

Yes,,,,I understand completely !
But in post #10 it was stating to have the block sonic checked to be certain the bores wouldn’t be excessively bored over .

Tommy

 

[RustyRatRod]

Yes,,,,I understand completely !
But in post #10 it was stating to have the block sonic checked to be certain the bores wouldn’t be excessively bored over .

Tommy

Maybe the poster didn't understand we are dealing with a standard bore block. Although badly worn.