Multiple repair sleeves on big bore Dart Big M BBC

[Pontiac_Puller]

I have available to me a Dart Big M BBC tall deck that needs repairs. Price is right, free. The hang up is that it's at a 4.625" bore already, and two cylinders will need repair. They are also right next to each other. I believe the other 6 are fine, and will clean up with a light hone (I hope), but the other 2 will need sleeves. To achieve the same bore, and give the sleeve any thickness, I need an outside diameter of 4.750". This leaves just 0.090" between the blocks bores, and I'm concerned of the block splitting under hard load. I'd consider filling the block if that would help support the bores.

Let's say for the sake of argument that all 8 will need to be done, to bring the bore down to a smaller size allowing for multiple rebuilds. Has anyone done this, or anything similar? Cost is a non-issue, I can perform all machining myself, and like I said, free block. Otherwise I'd never try this, and I'm sure that's why he doesn't want anything for it.

Please don't tell me I'm a fool, I already know I am.

[tenxal]

Before doing anything, call Dart and get their recommendation.

My thought is sleeve all eight and start fresh.............

[PackardV8]

X2 on sleeving all eight.

From a previous thread, someone said Melling makes a 1/16"-wall sleeve in 4.500" bore. You'd have to get an exact OD from Melling, but one might be lucky enough to able to just whang them in the existing bores. Wouldn't that be nice?

Every time I look at one of those 4.625" blocks, I'm amazed the headgaskets hold in that narrow space between the cylinders at the horsepower levels they make. It's a tribute to how far the block and gasket technology has come.

[Wolfplace]

I have available to me a Dart Big M BBC tall deck that needs repairs. Price is right, free. The hang up is that it's at a 4.625" bore already, and two cylinders will need repair. They are also right next to each other. I believe the other 6 are fine, and will clean up with a light hone (I hope), but the other 2 will need sleeves. To achieve the same bore, and give the sleeve any thickness, I need an outside diameter of 4.750". This leaves just 0.090" between the blocks bores, and I'm concerned of the block splitting under hard load. I'd consider filling the block if that would help support the bores.

Let's say for the sake of argument that all 8 will need to be done, to bring the bore down to a smaller size allowing for multiple rebuilds. Has anyone done this, or anything similar? Cost is a non-issue, I can perform all machining myself, and like I said, free block. Otherwise I'd never try this, and I'm sure that's why he doesn't want anything for it.

Please don't tell me I'm a fool, I already know I am.

It can be sleeved but,,,
You would need to sleeve that whole side if you want round bores when you are done if going back to the same bore size because the bore next to the ones you sleeve are going to distort even with a light press fit
If you go to 4.630 you could probably get away with sleeving just the two & end up reasonably round

Also are the bores just damaged or are they cracked or is part of them missing?
60thou is not much cylinder wall without some support behind it

Personally I would pass even if it were my own project

[CNC BLOCKS]

I have available to me a Dart Big M BBC tall deck that needs repairs. Price is right, free. The hang up is that it's at a 4.625" bore already, and two cylinders will need repair. They are also right next to each other. I believe the other 6 are fine, and will clean up with a light hone (I hope), but the other 2 will need sleeves. To achieve the same bore, and give the sleeve any thickness, I need an outside diameter of 4.750". This leaves just 0.090" between the blocks bores, and I'm concerned of the block splitting under hard load. I'd consider filling the block if that would help support the bores.

Let's say for the sake of argument that all 8 will need to be done, to bring the bore down to a smaller size allowing for multiple rebuilds. Has anyone done this, or anything similar? Cost is a non-issue, I can perform all machining myself, and like I said, free block. Otherwise I'd never try this, and I'm sure that's why he doesn't want anything for it.

Please don't tell me I'm a fool, I already know I am.

It can be sleeved but,,,
You would need to sleeve that whole side if you want round bores when you are done if going back to the same bore size because the bore next to the ones you sleeve are going to distort even with a light press fit
If you go to 4.630 you could probably get away with sleeving just the two & end up reasonably round

Also are the bores just damaged or are they cracked or is part of them missing?
60thou is not much cylinder wall without some support behind it

Personally I would pass even if it were my own project

X100000 I can see why its free.

[machinedave]

I would have a lot of concerns about the block being to thin in between the cylinders at .090". I think it could only work if you sleeved the bore sizes down to 4.500" or less to keep the block strength. If the was block filled and all cylinders sleeved then I wonder how well the block would cool. Maybe not an issue in a drag only car.

[machinedave]

I found sleeves with a 4.628" O.D." x 4.470" I.D." x 8" length. If you installed them in your 4.625" block you could probably just lightly hone your original cylinders to install them and if you bored the new sleeves to 4.500" then you would still have a sleeve thickness of .064". There may be an issue with not having a ledge for the bottom of the sleeve to rest on unless you could go further down into the mains and manually grind clearance to flush with the bottom of the cylinders. I cannot say that I have tried this but it's something to think about.

[cgarb]

Do they make sleeves with a flange at the top? You could bore a small counter bore up on the deck surface that would be the stop for the sleeve.

[Pontiac_Puller]

If I decide to through with this, it will be using a full diameter sleeve, at 4.7525" OD. I don't plan to go to a 4.625" bore right away, or even a 4.600", but am looking to neck down to 4.560". I spoke with a knowledgeable gent today who claimed to have done this before, and not having issues. Despite having 0.090" between the bores, there is still over 0.200" cylinder wall thickness everywhere else after the overbore, and are designed to be repaired in this manner. I'm still going to call Dart and get the low down from them directly. I pick the block up on Saturday, so I'll be able to see just how bad things really are.

At this point it's a learning job, as I've never heard someone doing this. Maybe there's an obvious reason for that, but I'd still like to see what is possible.

[Chipped tooth]

I would check with some sleeve manufacturers, don't they make thin wall sleeves that are more durable than a normal sleeve?

Use some Seal-Lock on them before ya put them in?

[Pontiac_Puller]

I'll be using Melling sleeves, and yes, their centrifugal casting process yields a much tougher iron than anything mold cast, such as a block, even a ductile iron one.

[Alan Roehrich]

Darton has a nice off the shelf flanged sleeve for your application. And a top quality flanged sleeve is what I'd use, were I repairing that block.

If weight does not matter, it won't hurt to pour it with Embeco 885 to the bottom of the water pump holes. But that will make that block real heavy.

[wyrmrider]

I usually use LA Sleeve as they are really local to me
thanks for the tips on the other vendors

[Racing68]

Any results from this project? Had a customer bring one in 4.625 bore needs one sleeve and then hone all bores to 4.635 as the others are scuffed pretty bad.

[Racerrick]

i would sleeve the two holes and hone the block to the next available ring size. To hold the sleeves in I would taper pin them at the bottom