My "B" Block needs a bit of work.

[Purdy Swoft]

As Jim Brierly says , there is nothing wrong with a 4 inch bore . If it was mine and I could use the block without sleeving I would, even if it was just a little lose . If the valve seat crack could be done without having to sleeve the cylinder I would do that . Even if you had to sleeve one cylinder , it wouldn't be as bad as sleeving 4 . It may hold up better and run faster this way.

[Marshall V. Daut]

"There is no replacement for displacement." Say that out loud to get the full effect.

This is an old hot rodder's axiom from 3/4 of a century ago and it still rings true today. Extra displacement is FREE horsepower in the form of additional torque. Another axiom along these lines is: "You build horsepower into your engine, but you DRIVE torque." True in hot rodder Grandpa's day and still true now. I love the extra "umph" that 0.125" overbore Model A engines have given me over the years. The strongest Model A engines I have owned were 0.125" over. Just ensure that there are no engine block sand casting pin holes in the cylinder bores. Listen to Jim Brierley! He knows what he's talking about.
Marshall

[Railcarmover]

That all depends on how it was hogged out.a stocker or .020 over punched once to .125 for a hotrod is one thing..if it was done .010 or .020 at a time the odds of the bores being true to the crank diminishes. an engine rebuilt four or five times prior isn't the best candidate.

[Chris Haynes]

Originally Posted by Marshall V. Daut

"There is no replacement for displacement." Say that out loud to get the full effect.

This is an old hot rodder's axiom from 3/4 of a century ago and it still rings true today. Extra displacement is FREE horsepower in the form of additional torque. Another axiom along these lines is: "You build horsepower into your engine, but you DRIVE torque." True in hot rodder Grandpa's day and still true now. I love the extra "umph" that 0.125" overbore Model A engines have given me over the years. The strongest Model A engines I have owned were 0.125" over. Just ensure that there are no engine block sand casting pin holes in the cylinder bores. Listen to Jim Brierley! He knows what he's talking about.
Marshall

It is .125 over with a large lip. It obviously would need another bore to clean it up making it .135 or .145. Both are beyond the limits of safety.

[Marshall V. Daut]

"It is .125 over with a large lip. It obviously would need another bore to clean it up making it .135 or .145. Both are beyond the limits of safety."

Yes, indeed. Time to re-sleeve the cylinders. I should have been more specific in your case. Since you are building this engine as a high performing animal, once new sleeves have been installed, my comments were intended for you to take advantage of cubic inch displacement and bore the cylinders back to .0125", or if you are concerned about going too thin, out to .100". No sense in sleeving the engine back to standard or even a few thousandths over and then putting all those speed goodies on it. Let the larger cylinder displacement work for you with some minimal horsepower gains, but with free extra torque.
Marshall

[Ryan]

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I cleaned this thread up a bit... Please be respectful of each other.

Thanks!

[Chris Haynes]

Marshall,
I not looking to build a racer. Simply a good runnig' street engine.

Originally Posted by Marshall V. Daut

"It is .125 over with a large lip. It obviously would need another bore to clean it up making it .135 or .145. Both are beyond the limits of safety."

Yes, indeed. Time to re-sleeve the cylinders. I should have been more specific in your case. Since you are building this engine as a high performing animal, once new sleeves have been installed, my comments were intended for you to take advantage of cubic inch displacement and bore the cylinders back to .0125", or if you are concerned about going too thin, out to .100". No sense in sleeving the engine back to standard or even a few thousandths over and then putting all those speed goodies on it. Let the larger cylinder displacement work for you with some minimal horsepower gains, but with free extra torque.
Marshall

[Chris Haynes]

Originally Posted by hardtimes

HEY TOD...where the heck are you with the 5x5 new iron blocks !!
BTW Chris...I've sent you a PM.

Tod tells me he has plans to make an A block set up for a B crank. Sounds like a good idea.

[Chris Haynes]

Originally Posted by Ryan

I cleaned this thread up a bit... Please be respectful of each other.

Thanks!

Thank you.

[johnneilson]

Originally Posted by Chris Haynes

Tod tells me he has plans to make an A block set up for a B crank. Sounds like a good idea.

I have put "C" cranks in "A" blocks before, not a race motor but stout.

It requires insert bearings and full oiling but is much stronger than the "A" noodle Henry provided.

J

[40 Deluxe]

Originally Posted by johnneilson

I have put "C" cranks in "A" blocks before, not a race motor but stout.

It requires insert bearings and full oiling but is much stronger than the "A" noodle Henry provided.

J

Is not a 'C' crank in reality a 'B' crank with factory counterweighting? Thus, no such animal as a 'C' engine? There was a plain head for regular 'A's and a 'B' head for police Model A's, so the heads for 'B' engines had to be 'C' but the engine assembly was still a 'B'.

[johnneilson]

The "C" crank is the last version of "B" crank.
It has the counterweights integral rather than added on.

A good piece if not ruined by a unknowing grinder.

[Chris Haynes]

Originally Posted by johnneilson

I have put "C" cranks in "A" blocks before, not a race motor but stout.

It requires insert bearings and full oiling but is much stronger than the "A" noodle Henry provided.

J

His block will accept a B crank without resizing the mains.

[Flathead]

Originally Posted by Chris Haynes

Tod tells me he has plans to make an A block set up for a B crank. Sounds like a good idea.

I think that would appeal to the most people.

[Jim Brierley]

A comment on sleeving only 1 cyl. A friend had that done years ago on a race engine. First run at the Lakes the adjacent cyl. got hot enough to cook the paint on it. The new sleeve distorted the adjacent cyl. Moral of the story, check clearance on all cylinders when making changes. BTW, I don't recommend sleeving then boring to 4", too much of the block is lost, bore to 4.030" or sleeve to standard.

[ursus]

Originally Posted by Jim Brierley

A comment on sleeving only 1 cyl. A friend had that done years ago on a race engine. First run at the Lakes the adjacent cyl. got hot enough to cook the paint on it. The new sleeve distorted the adjacent cyl. Moral of the story, check clearance on all cylinders when making changes. BTW, I don't recommend sleeving then boring to 4", too much of the block is lost, bore to 4.030" or sleeve to standard.

I have a worn block that is at 0.125 over and a new set of the old "SEMI" marked pistons, which measure about 0.140 at the skirt. Could I bore it out further and fit the Semi pistons? The cost of sleeving back to standard has kept this block on the sidelines.

[johnneilson]

Originally Posted by ursus

I have a worn block that is at 0.125 over and a new set of the old "SEMI" marked pistons, which measure about 0.140 at the skirt. Could I bore it out further and fit the Semi pistons? The cost of sleeving back to standard has kept this block on the sidelines.

I think it depends on the intended purpose of the final assembly.
If trying to build a full race motor, forget that block, even sleeved.
If a hot flathead motor, you could probably get away with it.

One problem is the bore spacing, when you bore them big the sealing area between cyls gets marginal. Then you start playing with wires to get the gaskets to seal.

By boring to .140 over, you are getting to the edge, if sleeving is prohibitive at least you can use the block.

I had a block here that had been brazed up internally to seal up the water jackets. The deck had been welded and stud holes fixed, someone spent some money on it to use it. It came over here because it no one wanted to gamble on it. Decided the only use for it was a full race monster. Filled the deck with aluminum solid, no water to leak and moved valve positions and modified ports. Put sleeves in it to stop the deck cracking into bore and run nitro in it. See, intended purpose, it runs, gets horrible mileage and requires valve job every 3 miles.

YMMV, enjoy the hobby, speed cost money and imagination is limitless, well within the realm of physics and the law.

Enjoy, J

[zzlegend]

Originally Posted by johnneilson

I think it depends on the intended purpose of the final assembly.
If trying to build a full race motor, forget that block, even sleeved.
If a hot flathead motor, you could probably get away with it.

One problem is the bore spacing, when you bore them big the sealing area between cyls gets marginal. Then you start playing with wires to get the gaskets to seal.

By boring to .140 over, you are getting to the edge, if sleeving is prohibitive at least you can use the block.

I had a block here that had been brazed up internally to seal up the water jackets. The deck had been welded and stud holes fixed, someone spent some money on it to use it. It came over here because it no one wanted to gamble on it. Decided the only use for it was a full race monster. Filled the deck with aluminum solid, no water to leak and moved valve positions and modified ports. Put sleeves in it to stop the deck cracking into bore and run nitro in it. See, intended purpose, it runs, gets horrible mileage and requires valve job every 3 miles.

YMMV, enjoy the hobby, speed cost money and imagination is limitless, well within the realm of physics and the law.

Enjoy, J

John, I think I know a guy like that. LOL.
Again, thank you for the top.

[Jim Brierley]

ursus, You can use the semi pistons but first check to see they are completely finished, i.e. they should be cam ground (oval shaped) tapered top to bottom, and rings available. .140 can safely be done on the block.

[Tom Wesenberg]

Originally Posted by Jim Brierley

ursus, You can use the semi pistons but first check to see they are completely finished, i.e. they should be cam ground (oval shaped) tapered top to bottom, and rings available. .140 can safely be done on the block.

I also have some semi pistons. Who can cam grind pistons?