Healey 3000 cylinder bore

[davidb]

I was discussing the maximum cylinder bore on Big Healey engines the other day, with a neighbour of mine who has an MG. I seem to recall seeing rings at .060 over. What do you do after that? Any one out there have an idea what is acceptable? A lot of our cars are getting up there in mileage and many/most have been rebuilt at least once. Are liners available, as in TRs?

Just so you'll wake up screaming in the middle of the night, I should add that when I rebuilt my engine years ago, I found - get ready for this - <span style="text-decoration: underline">chunks</span> of rings in the oil pan from the previous owner's total neglect. I bought it without a compression test. Nice shiny red paint, and love at first sight.

And the thing still ran.
Cheers,
Dave

 

[Jerry]

There are 0.60 over pistons and rings available. You can also put in liners, they are readily available. I have them in 3 of my bores.

Jerry

 

[Randy Forbes]

As Jerry says, sleeves are available to bring an excessively scored cylinder back to the size of the others, or you can put six (6) sleeves in and rebore to original stock bore diameter.

Sleeves for a Healey or MG would be "dry" whereas the TR's are "wet" (touched by coolant. The Healey block would be bored out enough to allow the sleeve to be pressed in (ledge left at bottom to seat sleeve, ground flush with the top deck and secured by the clamping of the cylinder head).

My third (3rd) MGB's engine, upon disassembly, yielded three (3) completely different types of pistons, three (3) were short-skirts (and a couple of them knurled) and one (1) long; no wonder I couldn't get the thing to rev (about 87MPH was top speed). You just never know what you're going to find until you open them up.

 

[BUNDYRUM]

Hello davidb,

Generally it depends on what size you want to go to within the confines of the engine block casting.

You can always fit a piston from a different engine.

This means comparing compression height (the distance from the center of the wrist pin to the top of the piston), and wrist pin diameter between the original and the new pistons.

Best regards,

bundyrum.

 

[Michael Oritt]

I sleeved the bore of #3 cylinder in the MGA engine in the Elva after a dropped valve roughed up the bore. Luckily there was enough material in the block to permit the boring/sleeving, so as others say it depends how much meat is left in the block.

 

[Barefoot]

My first Healey got 25 miles/quart when I bought it. (no need for a compression test there...)

When I pulled the pistons, they were all knurled, the tops were going away from detonation (especially at the edges) and the top rings were pretty much non-existant.

 

[roscoe]

YIKES! What's next? Knurled crank journals? I have to say, I am a big fan of stuff that you pull apart and wonder how much longer it could have run without a serious "that's not right", followed by a quick shutdown. Great photo. Planes, trains, automobiles, and ships. It would make a great coffee table book.

 

[Legal Bill]

I remember when a buddy of mine knurled his Jaguar pistons about 34 years ago. We tried to talk him out of it, but he said it would cost a lot less than new pistons. I have to say, the engine ran great!

 

[Randy Forbes]

Wow, that's a beaut!

I think you should cast it into a clear polycarbonite cube and keep it in a place of prominence.

 

[Patrick67BJ8]

I remember when a buddy of mine knurled his Jaguar pistons about 34 years ago. We tried to talk him out of it, but he said it would cost a lot less than new pistons. I have to say, the engine ran great!

I've had good success with knurled parts a long time ago. It was a favorite thing for early hot-rodders to do especially for pistons. My Healey's valve guides wre knurled back in '76 because we couldn't find any guides at any price. They're still installed in the head.
Patrick

 

[Michael Oritt]

The articulated steering column in the Elva goes through a couple of heim joints and the point of wear on the uppermost one was worn down to the point where there was enough play to convince tech inspectors that my steering box was worn. I gave the shaft and joint to a machinist friend who has a "knurler" and he transferred enough metal to where the fit is now perfect and all play at the joint has been eliminated.

In my next life I want to come back as a machinist.

 

[davidb]

Thanks to all for your valued coments on the Healey cylinder bore. I wasn't aware that you could get Healey cylinder liners.

Thanks Randy - I always wondered what a "wet" liner was.

Thanks Barefoot for the disturbing photo. I had to lie down for awhile.

Cheers Dave

 

[Randy Forbes]

I remember when a buddy of mine knurled his Jaguar pistons about 34 years ago. We tried to talk him out of it, but he said it would cost a lot less than new pistons. I have to say, the engine ran great!

I've had good success with knurled parts a long time ago. It was a favorite thing for early hot-rodders to do especially for pistons. <span style="font-weight: bold">My Healey's valve guides wre knurled back in '76 because we couldn't find any guides at any price. They're still installed in the head.</span>
Patrick

That might actually be preferred, as the grooves will retain more oil for cooling and lubricity than smooth-bore guides.

Knurling is a proven way to raise the metal to save an otherwise unavailable part. I'm not sure, in today's marketplace, if there's much money to be saved in the labor versus replacement parts cost. My stand on the subject, is that the parts will stay with the car (or whatever) and the labor is a fleeting expense; I'd rather spend the money on what I get to keep :wink:

 

[Randy Forbes]

The articulated steering column in the Elva goes through a couple of heim joints and the point of wear on the uppermost one was worn down to the point where there was enough play to convince tech inspectors that my steering box was worn. I gave the shaft and joint to a machinist friend who has a "knurler" and he transferred enough metal to where the fit is now perfect and all play at the joint has been eliminated.

<span style="font-weight: bold">In my next life I want to come back as a machinist.</span>

Yes, BIG difference between owning machine tools and being a machinist.

I own machine tools, but I wouldn't consider myself to make a pimple on a (real) machinist's a$$!

But, it has been (mostly) fun to learn the things I don't know!

 

[GregW]

but I wouldn't consider myself to make a pimple on a (real) machinist's a$$!

Yes, but with your mill, you could lance it easily.

 

[BUNDYRUM]

Hello davidb,

I went back and re-read your original post and saw where you were discussing maximum cylinder bore on a Big Healey.

As far as I'm aware for the BN1/BN2 the largest bore size with an original block I've heard of was 3 5/8" (92mm). My BN1 has a bore of 3.583" (91mm).

With the 3000 block the largest I've heard of was 3.500" (88.9mm).

No Austin/BMC didn't make pistons that size but luckily someone did.

Best regards,

bundyrum.

 

[JamesWilson]

With the 3000 block the largest I've heard of was 3.500" (88.9mm).

No Austin/BMC didn't make pistons that size but luckily someone did.

I think it was Volvo with their B20/B30 engines... not sure if the stroke/top of piston-wrist pin distance, etc. are right....

But I'm kind of thnking about it....

 

[Johnny]

Interesting thread Dave, thanks for posting.
I guess I'm a little lost as to why would you only replace one liner? Why not replace all six? Also, why would you bore out a new liner unless you're trying to match the others?
Or, does the liners come in different sizes?

Another question for those who have done this;
Are the liners notched at the bottom to align properly? I've seen inline six big bore diesel engines that have replaceable liners that are easy to put in and they are notched.

 

[Randy Forbes]

Johnny, a cylinder sleeve for our engines is strictly a repair operation to prevent scrapping an otherwise good block. Not the same as a diesel where sleeves are maintenance items.

One (1) reason for only sleeving a single cylinder would be because that bore was scarred (dropped valve, broken ring__cause doesn't matter) and requires boring beyond the largest oversize for currently available pistons.

Sleeves really don't care what size they are when supplied (okay, within a certain O.D. range they do). The block is overbored to accept a press-fit sleeve, then the internal bore of the sleeve is machined to the size of the rest of the cylinders.

Let's say that five (5) cylinders will "clean up" with a + .020" overbore, but one (1) had standing water in it and left a patch of .040" deep pits. That one (1) damaged cylinder would require that all six (6) be cut to +.080" or more, and specially obtained pistons would be required.

Instead, the builder can buy a set of off the shelf +.020" oversize pistons and repair the bad hole with a sleeve. On a scale of economies, this would be cheaper AND allow the block to be built to the next available oversize at it's next rebuild.

Make sense?

 

[davidb]

Interesting how these threads often "wander" off topic when they get going. It's a good thing - always something new to learn from other guys' experiences.

Randy - Good explanation of cylinder re-boring/liner use. In fact, when I rebuilt my engine, one cylinder was badly scored from a broken ring. But rather than sleeving, the machine shop bored all cylinders. Based on your comments I now recognize that this was possibly a mistake. Should have perhaps sleeved just the bad cylinder. That was 25 odd years ago however, and perhaps things have since changed. I wish I'd had this website back then.

Johnny - good looking Healey. That's the "evil red" that got me into this mess some 30 years ago. You buy with your eyes - not your head.

Cheers Dave