Rod-K, agreed. Also, all Blocks need to go to a reputable builder/shop anyway for correctness/imperfections. Even the new blocks have imperfections/problems & need work.
I do like sleeves. (correct ones) We can change a cylinder out right at the track.

They are "improved", but I wouldn't qualify that as a significant improvement. For 99% of those running one, the improvement's are meaningless. What can you do with a modern 427 block that you can't with an original block, that is "significant" to the average Cobra owner?

The cool factor and bragging rights are highly subjective depending on one's point of view. Some may well see an original side oiler as exceeding the "cool factor" and "bragging rights" of a Shelby. Other's see great value in the Shelby name. There is no right or wrong position on that issue, it is what it is.

If I may suggest some things you could with a modern block over an old one.
1. Save time and frustration looking for a nice original block. Buying new takes less energy and generally speaking is a better gaurentee of getting a good block the first time.
2. Build a stronger, higher horse power motor. To realize the benefit, new vs old, I think you would need to be approaching 900 to 1,000 horse power.
3. Run it at a higher rpm than an original block and expect it to live longer while doing so? #3 is kind of iffy, most folks are going to stroke the motor, often to the max, and a big strock and high rpm are not generally two compatible goals. More stroke, less rpm is the rule, a nice fit for a hydraulic roller cam.
4. Bigger bore, in some cases than is possible with an original block, within safe paramenters. Now THAT appeals to me! My prefered recipe is more bore, less stroke, higher rpm. High rpm rules out the hydraulic roller, due mostly to additional expense and ultimately just the limited rpm range of a hydraulic cam in general. A solid roller would not be my first choice for a "street" engine, so your left with a flat tappet as the most logical reasonably priced, street friendly cam choice. And it's pretty clear most folks have moved away from flat tappet (not me, I think they are an excellent choice for many reasons). The benefits of a flat tappet out weigh the negative aspects. So, that which remains is a low rpm, hydraulic roller cam, stroker motor. A recipe I'm not real excited about, new or old block, same same, no significant advantage...

Ernie, I've got a low rpm, hydraulic roller, stroker motor. It's not the same same, especially in a street car. How about 638 ft. pounds of torque at 2700 rpm. How's that for same, same?!:D

But Mick, the question is: Can that be done with an original side oiler block? Not that I'd want to, just askin'...

By the way, is that motor in an 18 wheeler? Because with that kind of torque at that rpm, it would serve a Peterbuilt well. :) :)

I personally don't consider these improvements to be meaningless to 99% of us.

Priority main oiling.

Thicker decks.

Billet steel main caps.

The Shelby head stud configuration delivers maximum gasket seal/retention and minimum cylinder bore distortion when the head is torqued to the block.

Extended skirts.

Thick oil pan rails.

Up to 527ci and saves 75 lbs.

There are reasons why the original blocks need sleeves and welding on pan rails.

Unlike the Shelby blocks, all of which require sleeves, a good side oiler block does not. Nor does it require welding anywhere. Mine is neither sleeved or welded on, it's all "natural", right down to it's Le Mans rods and iron heads. :)

There is no question the Shelby block is stronger than an original side oiler block, OK, and that means...?

There are many that make the same argument for a center oiler vs a side oiler. Do you really NEED the extra strength of a side oiler? Do you really NEED the priority crankshaft oiling system? Most of us don't, we would do just fine with a center oiler (limiting rpm to 6,500 or less). Want to turn 7,000? Better get the side oiler, more strong. OR, if you plan to run 500 miles at elevated rpm at Daytona Speedway (NASCAR style), or Le Mans, then you will need the side oiler.

We really choose the side oiler because it is legendary. It's association with racing history, for some, a center oiler just won't cut it. Gotta be a side oiler.

Same reasoning applies to the Shelby. It's association with the legend and that extra strength is part of the "new" legend in the making. Not that most of use will plan to run 500 miles at Daytona, or Le Mans, but if we DID, well by golly we could!

So either way, new or old, we choose based on what we can afford, what we want, what makes us happy. The strength issue is really more about bench racing, for most of us, than a real world application, new OR old block!

Priority main oiling
The oiling system in the sideoilers was never a problem

There are reasons why the original blocks need sleeves and welding on pan rails.Yes B/C someone blew them up

It means that, whether it be a Pond or Shelby aluminum block, ME, MYSELF and I, all three of us, are comforted by the fact that the newer block with all the improvements and newer and better technology as well as metalurgy will increase the chances of my engine's survival over a very good sideoiler block, which is now 40-45 years old.

I know you like your sideoiler a lot, but I like my CSX block alot. If I build another FE, like a SOHC engine, then I may buy the Pond block for the bottom end, because I know that's an excellent choice as well.

my head hurts...

One of the cool things about the Kirkham is that it can be a light weight car with the billet suspension and such. It will certainly be lighter with an aluminum block motor.

Another cool thing about the Kirkham is that it can be very authentic with the expensive and heavier original style suspension.

When you are going for authenticity in a Kirkham, an original 60s side oiler makes perfect sense to me.

When you are going for the high tech light weight billet suspension the modern aluminum block side oiler makes sense to me. In that case who cares if you are not building to block to it 1000hp potential, that is irreverent. It is the light weight block fits into the light weight replica equation.

Since we're talking about "period corectness"...

Let's take example from the "period".

The small block cars won all the races, because they handled better. The big block cars were in essence an "attempt" to get the car past the 160MPH "air wall" on long runs, at the sacrifice of handling. (IE: "the turd")

Drop the weight and keep the power of the BB? = Priceless.

And to address the comments that 100lbs on a 2300lb car makes no difference, B.S. that's 100lbs off the front end weight of ~1150lbs. Handling is just as important on the street as the track.

And to think in the "period" they shifted the motor off-center, mounted the batteries opposite the driver. The old man himself only sells aluminum block 427's and now 351's. Wonder what he'd have wished for back then.

As far as over-kill for the 600hp build, well yes, but it's relative: in the "period" production 427's were 450hp (max), the Shelby engines 480hp. A 1500hp rated block is not very stressed which means (hopefully) it's that much longer before stuff starts cracking. A vintage block in the same scenario is definitely "stressed".

From what I've heard the side oiler did little if anything to effect main bearing failure rates except in the most severe racing applications. (quite possibly a fix for a non-existant problem)

Ernie, I think the OP made up his mind about eight pages ago...

"And God looked down from the heavens and saw the Iron man Cobra sporting a nice new CSX alloy block and said "It is good".

Ford never released any specific horse power numbers for the side oiler, but it's clear estimates of 400-450 horse were under rated by a bunch. Well in excess of 600 horse can still be done today using only period correct parts, not a single modern component is required.

This book spells it out on page 33 really well, 410 HP for the 4V and 425 for the 8V:

http://www.mustangtek.com/Library2/1...rfCatalog.html

Personally I do not think the numbers were under-rated, I think Ford was pretty accurate and Ole Shel was BS'ing for sure. I read where he said the 428CJ was rated at 335 HP and he said it was more like 500 HP. I ain't buying it. If a stock 1966 R-code 427 made the 425HP as advertised, that's about all it made. If anyone can tell me how to get more than 475 HP from an otherwise stock 8V non-stroked 427 c.i. side oiler with stock MR heads as came from Ford, lay it on me now.

Again, just my opinion based on my build.

I totally stand by the above statement. Using parts readily available in the 60's for an FE block that could make well over 600 horse power can be duplicated today. Piece of cake in fact.

It's a valid comparison because there is no "stock" modern FE to compare to. A wide variety of cam's, heads, induction systems and a slew of modern parts make up a typical FE of today.

I wasn't arguing with you, just speaking within the confines of a stock setup. :)

425 horse was the accepted "politically correct" number widely used, often quoted, written in books, acknowledged by NASCAR and often seen today in various reference manuals. It was never officially confirmed or denied by Ford.

Many believe the center oilers of '63 and '64 were making a true 500 horse, "stock", as delivered in a Thunderbolt anyone could buy at their local Ford dealer. That 500 horse number is supported by 1/4 mile calculators using known Thunderbolt ET, trap speeds, weight, gear ratio's and tire size.

In 1965 and later, with the new side oiler, it is estimated some T-Bolts were making close to 650 horse, all though, not "stock" at that point. But using parts available at the time.

Then along came the tunnel ports and the SOHC, either of which I suspect will flow more air than a Stage 3 Edelbrock head worked over by the masters. But I could be wrong about that, perhaps they are equal in that regard?

Medium riser and hi riser OEM heads flowed squat.. Maybe in the 250 cfm to 270 cfm range. You are NOT going to get 600 fwhp out of a 427 unless (1) the heads are HEAVILY massaged (2) you got a real big mechanical roller (3) 12-13 to 1 compression (4) big cubic inches ..... AIN'T GONNA HAPPEN.

Have you had your engine dynoed? What'd it make?

Well, I am not sure who we were counting on to officially confirm or deny, but Ford's lawyers and their marketing department (who as well all know love to lie UP and not DOWN) publicized 410/425 in at least a half a dozen pieces of literature that I have found between 1965-1968.

Exactly.

It made 451 on the dyno at 5800 rpms, which is the basis of my point. My engine as-built is 100% original medium rise except with a bigger cam and some valve work. So if Ford said these engines made 410-425 and mine made 451, then anyone who thinks Ford was hedging or holding back 100+ HP in the ratings is full of crap. Find me a bone stock MR side oiler with 10 or 11:1 to compression who is running over 450 HP with completely stock heads. Ain't happening.

Whenever I get around to it, I'll let you know what I dyno at. My build is similar to yours. Although my builder said it should make closer to 500hp and wasn't a BS type of guy. But the dyno will tell.