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Old 07-27-2010, 10:00 PM   #41
Henry Floored
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Default Re: Boring a flathead

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Originally Posted by Ol' Ron View Post
I like the 258ci engine because the port valve area can feed this to a higher RPM. WITH POWER. Having run a number of Dyno ests on Flatheads, they all seem to fall off after 45-4800 RPM. Sure they'll turn 55-6000 but the torque is gone. Very long cams with hi lift, and you can push this up abit, But the ports are th limiting factor. That's why Kong Jackson and Dick landy built their 16 port blocks. In Landys case the engines were supercharged and produced over 500 hp.

Back in the real world we have to use what Henry gave us. Porting and reliving work well at hi RPM, but offer little in the way of performance in a street engine.
I have a 3 3/8X3 5/8 crank assy and if I can find it , I'll sell it Cheep. Tell us how it works.

Ron, the statement you're making about the Flatheads falling off at 4500 rpm is the exact reason why I think there is an inherent "dam" in the performance arena of the Flathead Ford. As you know at low engine speeds the Flathead's intake port/transfer area can easily cope with flow requirements. As engine speeds rise the port I feel either works pretty well or can be made to work pretty well. It's just that it's flipped on it's back and directing that airflow smack dab into the wall created by the cyl head. I'm convinced that by raising the dome over the cylinder significantly one could then significantly raise power due to less of a "flow dam" effect. I don't think trying to get the charge to make an abrupt turn like a stock or hi compression head does is the way to go at hi engine speeds.

I'm absolutely aching to test this theory. I realize that some racers of the past have done this with great succes but I would like to see what this can do on a street engine. I am seriously thinking of 3 5/16" x 4 1/4" or maybe even a 3 3/8" bore if my block checks out.
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Old 07-28-2010, 03:00 AM   #42
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Default Re: Boring a flathead

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Ron, the statement you're making about the Flatheads falling off at 4500 rpm is the exact reason why I think there is an inherent "dam" in the performance arena of the Flathead Ford. As you know at low engine speeds the Flathead's intake port/transfer area can easily cope with flow requirements. As engine speeds rise the port I feel either works pretty well or can be made to work pretty well. It's just that it's flipped on it's back and directing that airflow smack dab into the wall created by the cyl head. I'm convinced that by raising the dome over the cylinder significantly one could then significantly raise power due to less of a "flow dam" effect. I don't think trying to get the charge to make an abrupt turn like a stock or hi compression head does is the way to go at hi engine speeds.

I'm absolutely aching to test this theory. I realize that some racers of the past have done this with great succes but I would like to see what this can do on a street engine. I am seriously thinking of 3 5/16" x 4 1/4" or maybe even a 3 3/8" bore if my block checks out.
If i would build another BIG engine i would go 4 3/8 x 3 5/16.
Scat makes a crank and rods and Ross the pistons.
makes 302ci.

I know there is alot of talk about these long strokes about siderocking
the piston , but there are so many other engines that have a way worse
stroke/rod length ratio that i think it will work fine!
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Old 07-28-2010, 08:51 AM   #43
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Default Re: Boring a flathead

The biggest problem with the long stroke is piston speed. As the valve opens it shouls reach max lift at about 70 degs after TDC. This is when the piston is reaching max speed. the valve begins to close at around 135 degs and the piston begins to slow down. At very high RPM's the piston runs away from the intake charge, effectively de-stroking the engine. I di believe a pop-up piston will breath better. There are a coupla things you can do to do this without spending allote of money. Using a 3 3/4 strole piston on a 4" crank, then recessing the piston .125 into the head. Now remove the lip created by the transfer area. This can give aprox 9:1 in a 276 engine. After you build a few dozen engines, you'll learn allote.
Good luck.
PS Just remember, ALL the power the engine makes has to come through those ports.
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Old 07-28-2010, 09:13 AM   #44
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Default Re: Boring a flathead

I've heard of engines punched out to 3 1/2 - 9/16. The cost and reliability of these along with a 4 1/2" crank?? I have a friend that runs a 342ci flathead at the drags, runs in the 10's. He admits he didn't think it would last as long as it has..
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Old 07-28-2010, 10:27 AM   #45
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Default Re: Boring a flathead

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I like the 258ci engine because the port valve area can feed this to a higher RPM. WITH POWER. Having run a number of Dyno ests on Flatheads, they all seem to fall off after 45-4800 RPM. Sure they'll turn 55-6000 but the torque is gone. Very long cams with hi lift, and you can push this up abit, But the ports are th limiting factor. That's why Kong Jackson and Dick landy built their 16 port blocks. In Landys case the engines were supercharged and produced over 500 hp.

Back in the real world we have to use what Henry gave us. Porting and reliving work well at hi RPM, but offer little in the way of performance in a street engine.
I have a 3 3/8X3 5/8 crank assy and if I can find it , I'll sell it Cheep. Tell us how it works.
Ron, I agree the 258 is the way to go. Just go with a light car to get performance. We are never going to beat the modern motors.
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Old 07-28-2010, 11:17 AM   #46
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Default Re: Boring a flathead

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Ron, the statement you're making about the Flatheads falling off at 4500 rpm is the exact reason why I think there is an inherent "dam" in the performance arena of the Flathead Ford. As you know at low engine speeds the Flathead's intake port/transfer area can easily cope with flow requirements. As engine speeds rise the port I feel either works pretty well or can be made to work pretty well. It's just that it's flipped on it's back and directing that airflow smack dab into the wall created by the cyl head. I'm convinced that by raising the dome over the cylinder significantly one could then significantly raise power due to less of a "flow dam" effect. I don't think trying to get the charge to make an abrupt turn like a stock or hi compression head does is the way to go at hi engine speeds.

I'm absolutely aching to test this theory. I realize that some racers of the past have done this with great succes but I would like to see what this can do on a street engine. I am seriously thinking of 3 5/16" x 4 1/4" or maybe even a 3 3/8" bore if my block checks out.

I'd be curious on this because if you look at a Model A head, that dome area can't be any more open and thusly the 4.5 or 5 (don't quote me on that) to 1 compression.

I'm really curious on what you have in mind to cope with the loss of compression if you open up that area in the head?

I also believe the flathead is a engine of compromises. You can certainly do a lot of tricks to it, but those trick come at a cost by impacting performance in other areas.

95% of the guys running a flathead in their car would be tickled pinked with a nice, stout (+/- 276 c.i.) street engine after compared to a stoker. These engines can still be built to stay together for many years for $5K or under.

Anything more in the realm of tricks that you can't do yourself, the costs start to multiply quickly.
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Old 07-28-2010, 02:36 PM   #47
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Default Re: Boring a flathead



This is the size of a stock port, not much to work with.
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Old 07-28-2010, 06:41 PM   #48
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Default Re: Boring a flathead

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This is the size of a stock port, not much to work with.
'Ol Ron:

Thanks, great picture.
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Old 07-28-2010, 11:07 PM   #49
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Default Re: Boring a flathead

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I'd be curious on this because if you look at a Model A head, that dome area can't be any more open and thusly the 4.5 or 5 (don't quote me on that) to 1 compression.

I'm really curious on what you have in mind to cope with the loss of compression if you open up that area in the head?

I also believe the flathead is a engine of compromises. You can certainly do a lot of tricks to it, but those trick come at a cost by impacting performance in other areas.

95% of the guys running a flathead in their car would be tickled pinked with a nice, stout (+/- 276 c.i.) street engine after compared to a stoker. These engines can still be built to stay together for many years for $5K or under.

Anything more in the realm of tricks that you can't do yourself, the costs start to multiply quickly.

Tim the lost compression is gained back by using a very hi dome piston which tightly fills the raised combustion chamber.

Yes the Flathead Ford certainly has some compromises compared to later engines. For example the small diameter camshaft combined with equally small diameter lifters. Makes agressive cam grinds a little tough. Combine that with the lack of a rocker arm to multiply lift, that's a big compromise. But yet the lack of rocker arms is one of the reasons why Flatheads are so simple and endearing.

But compare the Flathead Ford to many other antique engines and quickly we see that our beloved Flatty's have performance written all over them. They are compact and light. They have good fuel distribution with all the intake ports grouped near the carb. They have a good oiling system with insert bearings on most of them.

As far as 95% of guys being happy with a standard built 276" I would love to say you're right, but unfortunately what I really see is a lot of beautiful early Ford bastardized with all sorts of goofy GM and Mopar powerplants. Do I think that a Flathead Ford could ever compete toe to toe with a scrub 350? Heck no, but for me I'd like to suprise a couple of those guys with what a Flathead Ford can do. I guess I'd like more than just a strong cruiser. I'd like a stoplight bandit, one that could at least give a lazy crate 350 a run for it's money. That might be fantasy, but the idea of it is really cool to me.

As far as a pop up engine goes, I don't think it's all that exotic. There are only two components that deviate from an average build and that's the pistons themselves and the cyl heads that compliment them. I'm certain those items could double the cost of my theoretical engine but I'm determined to try it at least once. This engine could be built in any bore/stroke configuration including stock 221 or 239. It's just the pistons and heads and the machine work to make it happen.

Ron has shown us an excellent cross section of a Flathead Ford intake port. It definately could use a better short turn radius and a little more cross section. But if you look at the flow path it seems Ford designed the bottom of the port as a ramp directing about 80% of the incoming flow right under the far edge of the intake valve and straight up into the transfer area. In my humble opinion the transfer area is the single biggest cork in the process. As the piston races down the cyl you'd think that it would just suck the charge right down with it, but actually I believe that in fact a column of air moving that fast just can't get turned that abruptly. It bangs into the cyl head, piles up and get's bounced around till finally heading down to fill the cyl. By moving the combustion chamber up and increasing it's volume that same column of air now has a space to flow to. Backpressure in that area is relieved and we should see a corresponding increase in volumetric efficiency.

A Flathead Ford has an inherant advantage over almost any ohv engine in that it does not need a fancy combustion chamber shape to swirl or rotate the intake charge when the piston comes up to suspend the fuel droplets. The Flathead's piston pounds the mixture from over the top of the cylinder to the valve chamber and when the mixture is lit it is pretty well mixed by all that natural movement. This gives a pretty efficient combustion process. Another advantage is the ability of a Flathead to swallow huge crankshaft strokes. A scrub 350 has less than a 3 1/2" stroke while a standard Ford has 3 3/4" and a Merc a full 4". Then there are all the stroker combos that can be had at a decent price like 4 1/8", 4 1/4" even 4 1/2" are all in the realm of real possibility. They are cost effective too. Those big levers can provide a lot of grunt. That's another Flathead advantage.
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Old 07-29-2010, 12:56 AM   #50
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Default Re: Boring a flathead

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Tim the lost compression is gained back by using a very hi dome piston which tightly fills the raised combustion chamber.

Yes the Flathead Ford certainly has some compromises compared to later engines. For example the small diameter camshaft combined with equally small diameter lifters. Makes agressive cam grinds a little tough. Combine that with the lack of a rocker arm to multiply lift, that's a big compromise. But yet the lack of rocker arms is one of the reasons why Flatheads are so simple and endearing.

But compare the Flathead Ford to many other antique engines and quickly we see that our beloved Flatty's have performance written all over them. They are compact and light. They have good fuel distribution with all the intake ports grouped near the carb. They have a good oiling system with insert bearings on most of them.

As far as 95% of guys being happy with a standard built 276" I would love to say you're right, but unfortunately what I really see is a lot of beautiful early Ford bastardized with all sorts of goofy GM and Mopar powerplants. Do I think that a Flathead Ford could ever compete toe to toe with a scrub 350? Heck no, but for me I'd like to suprise a couple of those guys with what a Flathead Ford can do. I guess I'd like more than just a strong cruiser. I'd like a stoplight bandit, one that could at least give a lazy crate 350 a run for it's money. That might be fantasy, but the idea of it is really cool to me.

As far as a pop up engine goes, I don't think it's all that exotic. There are only two components that deviate from an average build and that's the pistons themselves and the cyl heads that compliment them. I'm certain those items could double the cost of my theoretical engine but I'm determined to try it at least once. This engine could be built in any bore/stroke configuration including stock 221 or 239. It's just the pistons and heads and the machine work to make it happen.

Ron has shown us an excellent cross section of a Flathead Ford intake port. It definately could use a better short turn radius and a little more cross section. But if you look at the flow path it seems Ford designed the bottom of the port as a ramp directing about 80% of the incoming flow right under the far edge of the intake valve and straight up into the transfer area. In my humble opinion the transfer area is the single biggest cork in the process. As the piston races down the cyl you'd think that it would just suck the charge right down with it, but actually I believe that in fact a column of air moving that fast just can't get turned that abruptly. It bangs into the cyl head, piles up and get's bounced around till finally heading down to fill the cyl. By moving the combustion chamber up and increasing it's volume that same column of air now has a space to flow to. Backpressure in that area is relieved and we should see a corresponding increase in volumetric efficiency.

A Flathead Ford has an inherant advantage over almost any ohv engine in that it does not need a fancy combustion chamber shape to swirl or rotate the intake charge when the piston comes up to suspend the fuel droplets. The Flathead's piston pounds the mixture from over the top of the cylinder to the valve chamber and when the mixture is lit it is pretty well mixed by all that natural movement. This gives a pretty efficient combustion process. Another advantage is the ability of a Flathead to swallow huge crankshaft strokes. A scrub 350 has less than a 3 1/2" stroke while a standard Ford has 3 3/4" and a Merc a full 4". Then there are all the stroker combos that can be had at a decent price like 4 1/8", 4 1/4" even 4 1/2" are all in the realm of real possibility. They are cost effective too. Those big levers can provide a lot of grunt. That's another Flathead advantage.
I believe that haveing no rocker arms is a big advantage as you have
a very light valve train and can use single springs.

Then you can run wild cam profiles

People say you have to watch lifter bores with a Isky 404A , but who
has seen oval ones in real?

I`ll try a 404A in a 284ci next year and then we will see!
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Old 07-29-2010, 01:29 AM   #51
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Default Re: Boring a flathead

"For example the small diameter camshaft combined with equally small diameter lifters. Makes agressive cam grinds a little tough."

You really should gather more reliable information before making such statements...It has been shown in dynamic testing that the flathead Ford cam does NOT deflect enough when running to change the timing enough to record on a dyno..You can see absolutely NO deflection with a strobe while it is turning 7000 rpm on a test stand... It may be deflecting but you cannot see it...If you are familiar with strobe testing, you can easily see a deflection of .002...It is a commonly known fact that everything else in the engine will be worn out before the cam bearings....Deflection of the cam would show very early in worn cam bearings.
As far as lifter diameter goes, check the diameter of a Chevrolet V8 lifter and compare it to a flathead Ford lifter..Flat lifter Chevys will turn 8000.
Flathead Fords will turn that also on a test stand but guess which one will last longer due to much lighter valve train.
Plain old rocker arm engines such as the common V8 are a poor compromise as far as performance....They were built that way to sell many units and build CHEAP AS POSSIBLE.
In the past, desmodromic valve train was the hot thing as far as high performance went...F1 engines both in cars and motorcycles have always been on the leading edge of development and they both had that technology...When that became obsolete, electronic valve train was the new technology....No cam, NO ROCKER ARMS, no lifters, no push rods...Only valves.
GP engines nowdays turn 19000 rpm....they idle at 7000...
Rocker arms are Mickey Mouse as far as efficient technology goes.
Your mileage may vary.

Last edited by Pete; 07-29-2010 at 01:36 AM.
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Old 07-29-2010, 06:34 AM   #52
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Default Re: Boring a flathead

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The biggest problem with the long stroke is piston speed. As the valve opens it shouls reach max lift at about 70 degs after TDC. This is when the piston is reaching max speed. the valve begins to close at around 135 degs and the piston begins to slow down. At very high RPM's the piston runs away from the intake charge, effectively de-stroking the engine. I di believe a pop-up piston will breath better. There are a coupla things you can do to do this without spending allote of money. Using a 3 3/4 strole piston on a 4" crank, then recessing the piston .125 into the head. Now remove the lip created by the transfer area. This can give aprox 9:1 in a 276 engine. After you build a few dozen engines, you'll learn allote.
Good luck.
PS Just remember, ALL the power the engine makes has to come through those ports.
If you say "high RPMs" how high are we talking?

The 4 1/4 x 3 3/8 with the Potvin 425 won`t stop revving....
Have no tach but for a Flathead it revs high....

The 4 3/8 x 3 5/16 i would build as a torque motor anyway...
with a 404A for example....

That popup 276 sounds like a good Idea
Do build that often?
Which heads can take a 0.125 CC cut?

I know Sharp can but they are hard to come by....
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Old 07-29-2010, 06:47 AM   #53
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Default Re: Boring a flathead

Pete, my statement about cam and lifter diameter is not about a deflection problem. It simply means it would be nice to start with a larger diameter blank with which to cut the more aggressive profiles. It simply would give the cam designer more to work with. As far as lifter diameter goes a little more footprint, while stock works 95% of the time, could be beneficial in not exposing the edge of the lifter to the camshaft lobe lifting ramp in the most radical racing cam designs.
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Old 07-29-2010, 07:03 AM   #54
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If you say "high RPMs" how high are we talking?


That popup 276 sounds like a good Idea
Do build that often?
Which heads can take a 0.125 CC cut?



I know Sharp can but they are hard to come by....

Two production heads that I know of. Navarro Hi- Domes and Baron Racing Equipment pop- up heads.
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Old 07-29-2010, 07:54 AM   #55
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Two production heads that I know of. Navarro Hi- Domes and Baron Racing Equipment pop- up heads.
I`m aware of both. But both are very expensive .
I thought more of a more common head.

I like Barons chamber design.

I`m not so sure about Navarros hi-dome piston.... i don`t see an advantage over Barons etc....

Michael
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Old 07-29-2010, 08:28 AM   #56
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Two production heads that I know of. Navarro Hi- Domes and Baron Racing Equipment pop- up heads.

Henry Floored:

Regarding the pop-up idea. I got it and I must have missed the piston/hi-dome head part of your idea/post.

When I looked into doing this, Arias was the only company making pop-ups for this application. They were $125 a piece + the $875 for Navarro hi-dome heads so you'd be into $1,875 before anything else.

I believe someone mentioned Ross is now also making pop-ups but I don't know for certain.

If you're going this far, you may want to atleast look into using some Scat H-beam rods @ $425 [cheapest H-beam rod-albeit off-shore *YUK* made] a set.

This is what I meant by entering into the exotic side of flathead engine building. A lot of guys balk at spending $250 for a set of pistons.

Some of these guys would have a heart attack if you told them the pistons for their engine was going to cost them $1K.

Once recovered, they'd then go into a hour long story about how they bought their first car for $10.00, fought too dang hard in Korea to let something like this happen and how spending $1K for a set of pistons would be a crying shame.

Also, when I said 95% of flathead guys would be happy with a 276 c.i., I meant the guys who actually keep a flathead in their old Ford.

I'm not even interested in old Ford with a small block anything in it.

To me, the parts just don't fit. But, as with most thigns in life, to each his own.
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Old 07-29-2010, 09:57 AM   #57
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Well that's allot of information to follow. I don't have that much knowkedge in cam design, I'll leave that to Pete. I ran a 404 for a while ans switched to a 400jr which ran much better in our application. The last cam I used in a racing engine was an Errson D410, it replaced the 400jr. Over the years I tried many cams in a racing application. I was also more knowledgeable about intakes & exhaust, combustion chambers. Light weight crank assys and rear brake drums and wheels. over a period of 8 years we took a 258ci engine with 2 bl carb from 22 sec lap time to 16sec. HOW?? Well let's say we learned alott from our mistakes.
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Old 07-29-2010, 10:29 AM   #58
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Default Re: Boring a flathead

I was thinking Ron said use regular 3 3/4 stroke pistons with a 4" crank for the pop-up setup, that still leaves the cost of special heads?
Guess I won't be building one unless could find some heads within reason.
Had a friend in about 1960 with a '32 cpe had a 3 3/8 X 4 1/2 popup engine,.
Red Cornett Summerset Ky built that engine and welded Merc crank and he proly made the pistons, can't remember what brand aftermarket heads he used.
Sure ran though, faster than my chev powered '34 pickup.
This is great stuff, keep it going.
Seems like he wanted a block stamped with Z?
marvin
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Old 07-29-2010, 10:37 AM   #59
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I believe, the "Z" blocks were one of the military versions with high levels of nickel in the mix.
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Old 07-29-2010, 12:38 PM   #60
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"could be beneficial in not exposing the edge of the lifter to the camshaft lobe lifting ramp in the most radical racing cam designs. "

That doesn't happen in any cam I have ever seen...It may appear to but actually does not touch the edge...If it did the cam and lifter would be toast in a short time.
The reason for using a larger diameter cam blank in a flathhead is because at anything over .420 lift on a stock core you can't get the cam in the block..To get "more cam" you need to increase the lift along with the RATE OF LIFT...On the Isky 505A and several other manufacturer's cams with more lift they either run the cam in the block or bore the cam line and put inserts in.
It is possible to design a cam with a rate of lift so high that on a graph the accelleration curve would be a vertical line..This would require spring pressures so high in order to work that the system would fail mechanically.
Isky found that .011 per degree squared was the practical limit for the 505A...In order to get more it would require an inverted flank acceleration ramp..That is not practical with a radius lifter....Many modern roller lifter racing cams have inverted flanks but they require spring pressures that are hard to imagine....In some cases 800 lb on the seat..1200 open...The springs are 2 inches in diameter, have 3 coils and are made from 5/16 diameter wire.
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