Why do Flathead V8 Blocks Crack?

[Mike51Merc]

When it comes to exhaust pulses, 90 degree crank V8s have a syncopated rhythm. What I mean is that regarding left and right banks, there isn't a left-right balance to exhaust beats (like there is with a 180 degree crank in many European V8s). The result is a loss of scavenging, but the benefit is a smoother engine.

Looking at the flathead firing order, the middle cylinders (with the shared ports) are separated in order by a cylinder on the opposite side, which is pretty much the same as you'll find on a more modern overhead valve Ford V8.

[Tom Walker]

Its interesting that when Cadillac produced the ground breaking OHV V8, they compromised with a centre siamesed exhaust port. It works fine till you want to squeeze the last few hp out of it.

[Lawrie]

Poor design my a**,the flatheads in my 33,34 and dragster perform as good as or better than most engines of the day,my 33 tows a caravan all over Australia no drama,what other old car can do that reliably,
Lawrie

[Henry Floored]

Originally Posted by Lawrie

Poor design my a**,the flatheads in my 33,34 and dragster perform as good as or better than most engines of the day,my 33 tows a caravan all over Australia no drama,what other old car can do that reliably,
Lawrie

I agree with this. My 75 year old Ford hauls the balls! At 73 years of age I replaced the rod bearings while the engine was still in the chassis. The main bearings,oil pump, pistons, rings, valve train and valve seats are still original. She still runs like a top.

[Flat32]

While I'm certain there are various causes for various Flathead block cracks it is fairly certain stress does it.

For the particular intake port to cylinder ones I have a suspicion they are primarily caused by overheating like happens during a common boil over, but with the real stress being caused by relatively cool air coming into the port if the seriously overheated is restarted too quickly and worse if trying the restart with a wide open throttle.

I can easily see a poorly maintained cooling system car boiling over going up a steep hill and the driver continuing to the top when he should just stop.

I was taught to shut down and let the engine cool without doing anything and not to add water until I could lay my hands on the heads.

As far as the 337 engine goes I had one that I picked up in a scrap yard back in 1960 and before I took it apart my car mechanic uncle told me it will be cracked at the intake ports and most of them were in his experience. He was right. Every one was cracked.

I put that cracked engine into my father's F-8 dump truck and he ran it around his place for years with no real problem.

On Henry's Flathead design I'm intrigued by it to the point I'm making a 1/4 scale model of it and working on making 1/4 scale molds to attempt casting the block in bronze. This project has given me a very intimate appreciation of how it was done.

This is a link to my drawing file of the cores and mold as I am building it. Following what I can see in the River Rouge Tour video on Youtube.

https://www.dropbox.com/s/jdm9pf08cu...0mold.exe?dl=0

Flat32

[FrankWest]

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Interesting thread...
I know it has nothing to do with flatheads but It always amazed me the Volkswagen aircooled engines? My brother always has volkwagons and I took my driving test on a volkwagon bus in 1977. The motor always seemed to run smooth. I wonder how those blocks held up to cracking?

[19Fordy]

I have a spare, used, magnafluxed 8BA block with no cracks. Bought it in the 1980's from Doug Shull who was an advisor in the V-8 Times magazine many years ago.

[tubman]

I just sold an uncracked 8BA to a fellow up here building a hot rod. It came out of a 41,000 mile '50 Ford that a tree fell on in a storm in 1954. Someone tried to repair the damage by using a cutting torch to cut through the windshield posts and ended up setting the interior on fire. The car sat in a garage until the late eighties, when I bought it. I parted the car out and saved all of the good parts. A couple of months ago, this guy called me, hearing I had some engines. We made a deal on this one, because I had come to the conclusion that I'll never get around to using it. We pulled the heads, and there were NO "part number" or other cracks. A subsequent magnaflux and pressure test confirmed that this was a completely crack-free block.

My theory is that this was an almost new car when it was damaged and put away, and had never had a chance to overheat or be abused. This leads me to believe that the cracks are caused by abuse (overheating) when the cars become older and less valuable, and that properly maintained flatheads will probably not be cracked. This is confirmed by the fact that the engine that I pulled out of my 82,000 mile '51 Ford shows no "part number" or other cracks either. This engine came out of a "Sunday car" purchased originally by two bachelor farmer brothers to go to church in. After the last brother passed, the car was left to their elderly cleaning lady who couldn't drive. I bought it from her nephew and can assure you that that car was never abused or overheated either.

I pulled the engine from that car because it started making a funny noise I could not track down. I checked a number of things, including the fan bearing and throwout bearing and still couldn't find the noise. Although the engine ran good with excellent oil pressure, I decided to replace it before something bad happened. I replaced it with a '51 Mercury engine I had. Fords and Mercury's used different oil pans, so I removed and cleaned them so I could put the Ford pan on the Merc. In the bottom of the Ford pan I found a chunk of the thrust surface of the rear main bearing lying in the bottom of the pan. I am sure that is what it is because I had a set of new main bearings "in the box" to compare it to. In talking to my machinist we came to the conclusion that it had to be either a defective bearing or more likely an "assembly error".

I think Ford did a better job on these castings than anyone gives them credit for these days.

[RKS.PA]

I agree with you, tubman, that Ford's castings were better than we give them credit for in the breach. I remember my dad's flatheads, bought new, never had a cracking problem discovered on rebuild. And, I don't every recall vapor locking and we were using them hard on the farm in N.J. in the summer heat. As you noted above, it's what happened later in their lifetimes that causes the cracks. Of course, our gasoline didn't have any "corn" in it either!!!

[rotorwrench]

Man this is an old one. I must have missed it a few years back.

About the only thing I can add is that the flathead V8 was one of the most compact and simple design engines of its type ever made (just not simple to cast). I beg to differ on comments about poor design. For the price and reliability they had when properly cared for, they were one of history's better designs. It's limitations are what made it obsolete. Ford just wanted larger engines that were lighter weight and cars were not getting smaller or lighter in the mid 50s.

If a person compares the average size and weight of the cars & trucks of the 8BA era to the earlier types, a person can see why the 8BAs were wearing out a bit faster. Excessive heating and lack of proper anti freeze in freezing temperatures were the two big killers of flathead blocks. This had more to do with poor maintenance than it did with design.

[tubman]

Also, consider the thousands (actually, probably millions) of Ford V8's that passed through the re-builders in the forties thorough the sixties. I don't think they would have rebuilt an engine with a cracked block. It's only when they got to be old neglected "beaters" that got no care or consideration at all when the bad things started to happen.

[Bored&Stroked]

I saw a couple earlier comments about 8BAs seeming to be more cracked than earlier models - my observations would conclude the same thing. However, this thread also made me wonder if by the time they were using flatheads in the early 50's, maybe they were really flogging them in heavier cars, with automatic transmissions and maybe inadequate cooling systems?

Was wondering if more of them overheated due to the more extreme conditions they MIGHT have been subject too? Anybody have any comments to ponder? I've never owned a flathead powered car that was newer than 1940 - so I have no experience to work from.

Also, then there is the load-o-matic situation . . . one where in 100% stock form, it works well . . . but the minute you put dual carbs on a 49-53 engine, then the situation gets worse than the earlier front-mounted models. Without the correct/stock vacuum signal, there tends to be too little advance - which also contributes to over-heating in certain cases.

Just pondering this stuff on a Sunday . . .

[richard crow]

the simple fact is the eng. was a poor design. the big flaw was the exhaust gases going through the block. if thick head ford would have improved it with an over head design like the arden heads the eng would be made to this day.

[harleyjohn45]

I had a 1953 ford in 1953 and drove it fast, cruising at 65-70 mph. Top speed was 85 mph. It had overdrive and got 20 mpg, I drove it until 1959 and traded it in with 135,000 miles. I never had an over heating issue. I now have a 1953 8BA in a 1930 ford, and if I drive it too hard it tends to heat up. I intend to use evapo rust to clean the block and then install a fan shroud. I believe a fan shroud would eliminate a lot of over heating problems.

[Admiral]

Originally Posted by Bored&Stroked

I saw a couple earlier comments about 8BAs seeming to be more cracked than earlier models - my observations would conclude the same thing.

This has been my experience as well. The late-run blocks seem to have more cracking issues than earlier examples; casting quality also appears a little rougher, with far more flash and core wire hanging around.

[tubman]

Originally Posted by richard crow

the simple fact is the eng. was a poor design. the big flaw was the exhaust gases going through the block. if thick head ford would have improved it with an over head design like the arden heads the eng would be made to this day.

This has been bothering me for a day. It mystifies me why someone would post something like this on a board dedicated to flathead Fords.

[Henry Floored]

Originally Posted by richard crow

the simple fact is the eng. was a poor design. the big flaw was the exhaust gases going through the block. if thick head ford would have improved it with an over head design like the arden heads the eng would be made to this day.

I happen to think that the exhaust port routing is the best possible compromise in a single camshaft side valve “V” engine.

If you place the exhaust port exits in the valley you are forcing the exhaust gasses to do nearly a 180 degree turn at max velocity and expansion.

In the case of the Ford design the exhaust exits the valve pocket then gently falls downward and away. I spend a good amount of time cleaning up the exhaust port opening and exit to maximize this efficiency and minimize turbulence through the port.

If one concentrated on those areas you would realize that a Flathead Ford has high volume exhaust porting. Much higher than engines with greater displacement. This was no mistake. I think Ford engineers did it this way to remove back pressure and hence heat from the exhaust seat quickly and efficiently.

The engines that I have built here in Florida that I still have contact with consistently run 170 - 180 degrees water temperature. In the heat of the summer in stop and go traffic maybe they tickle 185 -190. The thermostat in my modern vehicle doesn’t even open till it reaches 197 degrees.

So I gotta say there is more to the Ford V8 than meets the eye. That’s why I think it was an overachiever of an engine.

[rotorwrench]

Originally Posted by richard crow

the simple fact is the eng. was a poor design. the big flaw was the exhaust gases going through the block. if thick head ford would have improved it with an over head design like the arden heads the eng would be made to this day.

By this analogy, any engine becomes a poor design when it reaches obsolescence. Ford and Cadillac both made larger engines in the valve in block design but one was a good tank engine and the other was just plain too heavy to be a long term product. The 337 only lasted four years but it did the job they wanted it to do. The Cadillac 331 was already in production when the 337 came out. But look at the size of those old Cadillac cars too. The 331 didn't last a long time either.

I can't poo-poo the Duntov brothers but they really just made a band aid to get more power from the Ford flathead V8 engine for truck applications. It made it a lot more complex and heavy. The Y-blocks only lasted a little over 10-years so what kind of design is that. A Ford 302 V8 would have more power and be a lot lighter. The Ford 289/302 was in production longer than the flathead and is a better design for functionality plus light weight but is came along almost a decade after the flathead was dead and buried plus it is only available as a crate engine now. We have more modern aluminum computer controlled V8 engines available for certain applications but whether they are a better design or not is moot. This is over 50 years after the flathead was in production. You would expect better designs with that much water under the bridge.

When you compare the flathead Ford V8 engine to other prewar engines, it was like a rocket compared to anything else and it was less expensive than most other brands. It wasn't till 1948 that the old flathead was showing its age and it still kept up with the competition fairly well.

[Art Newland]

Hey Richard Crow,

[40 Deluxe]

As I remember, by the mid to late '50's, the 8BA style engines were known for cracking. As we know, ignition timing that is retarded causes overheating, AND, Loadomatic distributors often had ruptured diaphragms. Ergo, cracked block! In addition, many people still ran plain water in the summer. Thus, mucho scale in the cooling system.