Boring Over size

B

Bluebell

Well-known member
Which blocks can be bored over size (to 3+5/16")?
Is it all blocks that started out at 3+3/16" or is it only certain models
I am assuming no issues with water jacket corrosion or off set casting faults
What is the normal deal?
If they can all go 3+5/16" what is the risk at 3+3/8"?
At what size should I get sonic testing done?
I am interested in the views of those who know.
Thanks in advance.
 
I dunno anything about 8BA stuff, but it is my experience that the best blocks are the C69A's. They undoubtably have thick cylinder walls. However, in saying that, I just bored what appeared to be an outstanding [no issues- no rusty water jackets, every thread was perfect] C69A out to 3 11/32 and got a pinhole in one cylinder- bugger!! hours of work went into it. now it's destined for scrap I guess; my machinist refuses to sleeve it! I doubt a sonic test would've even picked up that one pin hole.
I even had a late model french flathead and you could tell it had a coreshift; one side of cylinder walls was way thicker than the other, indeed, I ported into the water jackets with that puppy; another one bites the dust!
Anyway brother, try and access a C69A, and check out how massively thick the walls are. i doubt you'll find any block with thicker walls. But, be aware, you could still hit water! good luck in your search, Brian
 
During my racing years, I had several blocks bored to 3 7/16. I also built one for George over 20 years ago that's still running. But I guess, sonic testing is the best bet, then cross your fingers.
 
Scrapping a block for a pinhole :eek:

The cheapskate in me just screams...lol

Sleeve it back to a smaller bore and run it in a milder engine instead of scrapping it.
 
Brian,

Just curious, what reason did your machinist give you for refusing to sleeve that block?

Tubman
 
Boring it out for a sleeve to fit the large bore may have been difficult ?
But if it wasnt the final cut on the bore i be tempted to weld the pinhole if it was low in the cylinder.
 
tubman said:
Brian,

Just curious, what reason did your machinist give you for refusing to sleeve that block?

Tubman
Click to expand...
I too have scrapped blocks for precisely this reason. "Why" you ask?
There will be a "hot" spot where the bore cast is thin. This can and often will create an issue later. To me, it is simply not worth the gamble. I "cut my loss" and move on to a better (hopefully) bock.
 
With all the other tests (mag, pressure) a sonic test will tell you how far you can bore it and leave sufficient walls. Core shift makes it necessary to do this as not all blocks were exactly the same. Water jacket deep rust pits can cause problems as described above.
 
What about blocks that have a chunk broken out of a cylinder? Are we saying 'don't do it' ?
I have a 59A, which is otherwise a good, crack-free block. It has one cylinder with a chunk broken out. I took it to one of the 'big-time-advertisers', a guy with one of the bigger ads in the V8 Times. He didn't even hesitate when he quoted the 'regular' maching work, plus one sleeve. Should I not have it done?
(I'm not thinking 'performance', just a simple stocker - or at least, close to stock.)
 
What? A sleeve is OK to repair a chunk out of a cylinder, but not a rust pinhole? Either I don't understand what is involved, or we are getting mixed messages here. I'd still be interested to hear what Brian's engine builder said.
 
bobH said:
What about blocks that have a chunk broken out of a cylinder? Are we saying 'don't do it' ?
I have a 59A, which is otherwise a good, crack-free block. It has one cylinder with a chunk broken out. I took it to one of the 'big-time-advertisers', a guy with one of the bigger ads in the V8 Times. He didn't even hesitate when he quoted the 'regular' maching work, plus one sleeve. Should I not have it done?
(I'm not thinking 'performance', just a simple stocker - or at least, close to stock.)
Click to expand...
I would not even think of using this block. Yikes!!!
Is your rebuilder going to warranty against any adverse effects?
 
tubman said:
What? A sleeve is OK to repair a chunk out of a cylinder, but not a rust pinhole? Either I don't understand what is involved, or we are getting mixed messages here. I'd still be interested to hear what Brian's engine builder said.
Click to expand...

Sleeving either a chunk or a pin hole problem will work fine, If done correctly.
Look at the article Ronnie posted a link to, that is a 318 (compared to a flathead from stock to high horse power) short stroke high rpm and therefore needs good cylinder walls. You should be able to see this sleeving business is completely fine.
Martin.
 
Sleeving has its advantages because resent manufactured sleeves will have a higher quality steel / nickel content ,Ted
 
No-one was more pissed off than myself, after the pinhole was discovered. I'd put a lot of hours into this seemingly 'mint' block. I have a nos set of .020" 239 pistons, so thought I could utilise sleeves to bring the block back to suit, My machinist refuses to do so, for the reason JWL above states. Honestly, I thought there would be a reasonable wall thickness in the sleeve .068" to permit this, but he said no!
Years ago, I broke a piston in a flathead, holing the cylinder wall. A machinist [a different one] bored that cylinder and fitted a thin sleeve. I ran than engine for a few more years, but the sleeve eventually failed where the hole was; the sleeve sort of distorted and ultimately cracked because it had no support in that location. That was a hole though....not just a little pinhole.
Maybe this C69A block with the pinhole would be a good candidate for a dragster engine; fill it with filler and run it.
This thread has got a bit off topic, but does illustrate that there are no guarantees, when boring this old iron.
 
Brian said:
No-one was more pissed off than myself, after the pinhole was discovered. I'd put a lot of hours into this seemingly 'mint' block. I have a nos set of .020" 239 pistons, so thought I could utilise sleeves to bring the block back to suit, My machinist refuses to do so, for the reason JWL above states. Honestly, I thought there would be a reasonable wall thickness in the sleeve .068" to permit this, but he said no!
Years ago, I broke a piston in a flathead, holing the cylinder wall. A machinist [a different one] bored that cylinder and fitted a thin sleeve. I ran than engine for a few more years, but the sleeve eventually failed where the hole was; the sleeve sort of distorted and ultimately cracked because it had no support in that location. That was a hole though....not just a little pinhole.
Maybe this C69A block with the pinhole would be a good candidate for a dragster engine; fill it with filler and run it.
This thread has got a bit off topic, but does illustrate that there are no guarantees, when boring this old iron.
Click to expand...
Brian, While I sympathize with you in the fact you are out some monies and labors with this block, I still feel you made the correct decision in not throwing more good money after the bad.
Chances are that "pinhole" you describe is the proverbial "tip of the iceberg".
As you most certainly realize, anything can be repaired with enough time and money tossed at it. However, repaired correctly? Repaired to last?
 
I have no clue where all this bull about a sleeve not working comes from.
Right sleeve with the right interference will work as good as anything.
If its a pinhole and your concearned about it weld it up bore and sleeve.
All the pins NI-FE Weldingrods and sleeves i put in should scare the daylight out of some around here :D
Then again if not done right...nothing works.
And Sleeving cost money so if you have a better block at hand...just dont scrap out the blocks...we will run out of them...
 
Installing sleeves was near $100 per bore for a long time. I don't know what they charge currently but it should still be near this figure, at least not more than $150 yet. With this in mind, it is possible to bore plumb through the cylinder walls to get a good sleeve in an old block. Especially the old 221 blocks that are getting harder and harder to find good ones.

More than one block has been successfully modified for larger than stock sleeves by leaving a step at the bottom of the bore and using epoxy resin to set & seal the top deck and bottom step areas. There is always a risk when machining old cast iron parts and the top deck is somewhat thin so it could be torn plumb to pieces by someone that didn't know there machine well or had little experience to start with. At some point in time there will be more of these type repairs performed as the old blocks become harder and harder to find. That is unless some company will reproduce them some day. There aren't as many shops that are well experienced in old machinery as there used to be but they are still out there. They might get a customer to sign a waiver of liability if they don't want it to come back but if done correctly they won't need one.
 
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