Boring bar

[capt_tjm]

I need to bore out 1 cylinder of a 4 cyl. aluminum block angine and press in a steel sleeve.
I'm looking to make my own boring bar since this is a one shot deal and I have all winter to do it, engine came out of my boat.
Can anybody refer plans for a bar and recommend how much interference to use between sleeve and block.?
I'll need 4.390" diam x 6.00" depth.
I have a CNC with 14" of travel on the Z axis but the whole head moves, no quill so the bar itself would be at least 6" long.
Any suggestions would be appreciated.

[docsteve66]

Capt: Can't help on the bore bar plans.

May be able to find info on pressing sleeve in. E mail me engine specs.

We usualy sleeve an engine (al to iron) by heating the block to 650 deg F ALL over. Then drop the cold iron into the hot block. measure temp with crayons, at least three crayons 625, 640, 650 to be sure the whole thing is hot and evenly hot. Then drop the cold iron into the hot aluminum, in one smooth motion and let it drop to proper depth. all must be set up right cause when you begin the drop there is no backing out (pun intended).
Cold press scares me. Some times the sleeve works down, catches a ring and the top of the piston stays up while the rest goes down, hard on crankshafts etc. but I think I can find specs for you.

I sure advise you considering farming the sleeving job out. Around here (Jacksonville fla area), the sleeve is expensive, labor is less than the cost of the sleeve. Cost goes up if the engine is not stripped and clean.

Steve

[Gary Reif]

capt_tjm
I worked in a automotive machine shop for 25 years reboring and resleeving blocks. I never sleeved an aluminum block with a (castiron) sleeve unless the sleeve was made specificly for the purpose i.e. the chevy vega, if you remember it. I never felt you could the proper interferance fit without heating the block which brings up the need to linebore and resurface the block. Even these things need to be done on a castiron block to do the job right. Also, Can you get pistons that are compatable with castiron cylinders? Is your block not able to be rebored? IMO this would be a much simpler fix. It would have to be honed to get the proper finish though. Most engine rebuilding shops can do this.
Just my 2 cents worth.
Gary

------------------

[Thrud]

capt_tjm:
I would use as large a boring head as you have and take your time.

The cast iron sleeve should be cold soaked in Liquid Nitrogen and dropped into place. It should just slide in and once warm it will either be seated or will split the Aluminum block. It would need a rim around the top to allow the head to apply retaining pressure to the sleeve.

You may have big problems as Gary suggests. The only aluminum blocks that chevy made successfully with iron sleeves were the LS-7 engines. The Iron Sleeves can be pulled and special pistons & rings run in the aluminum bore for upto 572Cu.In.

Good luck with your project.

[docsteve66]

Dave, Have you ever tried the liquid nitrogen method? I have used the heating several times (probably over 100) and I sure would not have wanted to do it on my own the first time. Its scary and dangerous and needs good preplanning at best.

Reason i ask about the nitrogen as a means of making temp difference is that with crayons we get up to 650 F (which is as hot as we dare go) and make the bore/ sleeve as close as we dare and still have time to get it all together (takes a fast lick of the hammer some times to be sure it is seated) before the sleeve is grabbed by the block. Around here the sleeve starts at say 80 DegF, the block is 650 f so delta temp is say 570. The man who taught me said he tried 450F and had sleeves slip (unless restrained by block design). I would think the nitrogen/ ambient delta temp would be marginal. But one experiement (or more) beats all opinions- I wanted to try dry ice on sleeving but i havent.

I did shink a collar on a pto shaft once- the shaft was from a Ford 8 0r 9 N, the shaft from a Massey Ferguson. Supposedly the two would fit. I did some calculations, measured as best I could, Put one in oven, other in freezer. Slipped the collar on shaft and down as fast as i could. It froze up short of the goal.

Took it to work, asked one of the men to "press" it on to the mark or press it off and return the parts to me. He had to cut it off! neat little ring around where the collar had been. man asked me how did I get on in the first place. I told the truth (partially) that I hit it with a hammer. Man did not accept that story (cause it did not fit the evidence he could plainly see. Both pieces were iron, Delta temp was maybe 500 degrees and diameters were around 1.125. Sure impressed me with the forces involved. The intended interference fit was what ever the books suggested for a cold press, but i did not measure well or some thing. There is a lesson there some where- and i suspect Capt is well advised to have experienced help on hand. Just from the questions , I suspect he is beating a new path (for him) alongside well worn paths.
Peace, Steve

[capt_tjm]

Thanks to all for the prompt replys.
I'm putting together a quick website with photos to document progress.
Check back next week!
-TJM

[chief]

Alot of good info here but stay away from N2
(nitrogen) unless you have experince, it is dangerous.Not only can you really screw up yourself but you can also damage the part.
We used to use N2 to freeze fit stainless steel valve seats into valves for liquid oxygen plants used to make air for fighter pilots. drop an apple or quarter into the N2 then pull it out with tongs and throw it on the deck, it shatters like glass. Big fun
until the Chief caught us, same with using
freon or CO2.

[tonydacrow]

Hey, Guys.

If you want to experiment with low temperatures, try dry ice in acetone. It'll get you down to about -78C (-108F). Not quite the -196C (-320F or so) for Liquid Nitrogen, but still respectable.

BTW, if you want to try stupid things with LN2, try this site. [http://www.physik.uni-augsburg.de/~ubws/nitrogen.html] There are others out there as well. Just be careful.

Capt, a combination of heating the block and cooling the sleeve in acetone and dry ice may work...

Oh, yeah. Almost forgot. Chief is correct. LN2 (dry ice and acetone for that mater) is very dangerous if you don't take the proper precautions and don't know what you're doing. Losing a digit or your eyes to this stuff is no fun.



[This message has been edited by tonydacrow (edited 10-17-2002).]