'60s 427 FE 425 Hp side oiler......mpg?

[AC Ventura]

Originally Posted by olddog

I have no clue the value of your car or what changing the engine would do to that value. That said you could pull the original engine (after fogging it with oil), then properly store it, so it could be put back later, thus preserving the value of the car.

Now you can install another engine for fun. However to keep with planning to re-install the original engine some day in the future, you need to minimize changes required to fit the new engine.

That would tend to make me go for a 347 stroker. If your budget would allow, I would go with an aftermarket 4.125 bore block which gets you a little over 360 cid. Go with the best heads you can afford and keep the cam more to the mild side. You should be able to make somewhere near 400 Hp and still get decent MPG.

Is the car EFI now? If it is, stay EFI. If not, stay with a carb.

I'm not unduly worried about value, other people are. It took me 22 years to be in the right place at the right time to be able to acquire this car. It won't be sold and my kids will inherit it.

Do you think the 347 can be made to sound like a big block and still keep 17" of vacuum? Or do you guys not run power brakes?
Is the argument about the 331 being a better set up from an engineering perspective, nonsense?
EFI is obviously already installed, but as nothing on it can be used, what's the difference?

[1795]

I cannot speak to the vacuum issue, but I can let you know that it is rare for a cobra over here to have power brakes. Just no real need for power brakes in a car so light. Good luck in your decision making process.

[olddog]

Originally Posted by AC Ventura

I'm not unduly worried about value, other people are. It took me 22 years to be in the right place at the right time to be able to acquire this car. It won't be sold and my kids will inherit it.

Not "Unduly" worried. Hmmm. I take it, it is still a factor in the equation. Plus the ease of staying with the same block.

Originally Posted by AC Ventura

Do you think the 347 can be made to sound like a big block and still keep 17" of vacuum? Or do you guys not run power brakes?

I do not have power brakes. My engine idles around 13-14 in Hg. I have had many people swear my 347 is a big block, when they hear it. Plenty of folks on here will say they can tell a BB from a SB by sound without fail. Personally I cannot do it without fail. Generally BB will sound like they have a fairly mild cam at the London Ohio Cobra show, when compared to SB engines. Partly because you have to go more radical with a SB to get the power, and Partly because a BB will sound milder with the same cam.

Originally Posted by AC Ventura

Is the argument about the 331 being a better set up from an engineering perspective, nonsense?

I think the concerns about the 347 is all theoretical. When a bunch of people who never assembled an engine in their life are sitting around trying to sound like they know something, long stroker engines are junk, but they seem to work just fine.

Originally Posted by AC Ventura

EFI is obviously already installed, but as nothing on it can be used, what's the difference?

I'm not sure it cannot be used. My EFI is from 1989 - 1993 Mustang GT manual transmition. It is an EEC4 A9L box code. You can put a Moats Quarter Horse chip on it, and tune it to do anything you want. Then burn the tune onto a EPROM type chip. If you have an older set up that was Speed Density, but multi port, you can do the same thing, but you have to be much more careful on the cam shaft with speed density.

[Dwight]

most people mistook my 347 for a big block.

a little over 400 rwhp - rwtq

.590/.595 lift cam EEIV processor with a SCT chip to make all the mismatch parts work.

20 to 22 MPG

Classic Cobra Pack 3" side pipes

I put 30,000 miles on the 347 with no problems

Dwight

[Bernica]

It's all in what you want. There are no rules. I have seen and heard SBF's roar like a BBF and wasn't sure until they popped the hood. But then, we go into the entire other discussion, which will just dilute this thread.....

I would say "bring what you have and be proud of it, it's yours". Plenty of both recipes out there and many more ad nauseam...

[patrickt]

The trick to telling the difference is to stand with your butt facing the engine. This allows the vibrations to hit the back of your ear flaps, as opposed to entering directly in to the canal. When done this way, the distinction is readily apparent to the trained ear.

[Bernica]

Originally Posted by patrickt

The trick to telling the difference is to stand with your butt facing the engine. This allows the vibrations to hit the back of your ear flaps, as opposed to entering directly in to the canal. When done this way, the distinction is readily apparent to the trained ear.

I can tell the sound of a Chrysler or Chevy from a long ways away, even the sound of them starting. But the way guys are building the Ford SBFs now with the "Ca-Chunk, Ca-Chunk" noise and big stuff makes it harder. I will try your scientific method!

[olddog]

Most people who have concerns on stroker engines will talk about or look at the Rod Ratio, which is the length of the rod divided by the stroke. Here are some rod ratio to compare.

Ford SB 260 and 289 rod ratio is 1.8
Ford SB 302 and 351W rod ratio is 1.7
Ford SB 351C rod ratio is 1.65
Chevy SB 350 rod ratio is 1.64
Chevy SB 400 rod ratio is 1.48
Chevy SB stroker (350 rods with 400 crank) rod ratio is 1.52
Ford FE 428 rod ratio is 1.63

Now what is the 347 rod ratio? A reasonable 1.59

PS
That said I try to keep my 347 below 6200 rpm, but it has hit the 7000 rev limit a couple times. I have a fairly standard rotating assemble with "I" beam rods. With better rods and zero balance, I would not be afraid to turn it 8000 rpm all day. It is how it is built that limits the rpm, not the rod ratio. In fact, keeping the valves under control (not floating) is much harder to do than building a bottom end for high rpm.

I have seen ~430 cid Small Block Chevy running the 1.52 rod ratio run in dirt track cars at 8000 rpm. Run the same engine 3 years at a time. Very common. I have also see the Chevy 383 stroker (350 block with 400 crank and rods) with the 1.48 rod ratio ran in dirt track cars at 6000 rpm without issues.

Ford 347 Strokers are very common around here.

[Mark IV]

I have seen Mk IVs converted to FE power and unless ordered from Autokraft that way the swap requires a LOT of cutting/fabbing to work. I hate to see a MK IV chopped up in a way that precludes return to factory condition.

A stoker 302 (331/347, etc.) will be a quick and much easier swap but a stroked 351 will allow you to got to the magic "427" number and not require the footboxes to be chopped if you run an undercar exhaust. The extra height/width of the 351 works on the MK IV and several were powered that way (like Jack Roush's car, Mike Kranefuss's car and Bob Negstead's MK IV).

Negstead told me if he, Jack and Mike revved to 6000 and dropped the clutch together "we can change the Earth's rotation!"

Look at the MK IV lightweight that Alan Faulkner-Stevens changed over to a 351 stroker with a TKO600 gearbox featuered in the ACOC ACtion magazine in May of 2009.

[wkooiman]

Well put.

[olddog]

If the 351W block fits with only minor exhaust modifications, by all means stroke it out and drop it in.

I would not stay with the standard 351 cid. You might as well go with the 347 and not have to change anything else. The 5.0 ltr block is weaker. The 351W block can take much more beating. I would stroke it to at least a 392.

[AC Ventura]

I know the 351 is a more robust block, but I think it's just too tall. Click on the link (not the pic) and you'll see a well known and successful racing, 351 equipped Mk IV. I think you can see anti chafe rubber on top of the air cleaner and the oil pan dragging along the ground almost.

1987 AC Cobra MK4 6 litre 351ci For Sale on Car And Classic UK [C625850]

I went to see an FE equipped Cobra that doesnt overheat and the footwells are 29" apart. I measured my car up again tonight and that is an issue. Each footwell needs narrowing 1.5 - 2", which conflicts with the existing steering column and requires a pedal box mod which is no big issue.

The factory did it seems fit the FE in between unmodified footwells. How every everything is virtually touching as you can see from the pic of this, one of the 11 factory 427 BB equipped MK IVs.

[Bernica]

You mean like this? An early CSX 4000 series. Look at how close the linkage is to the header. Yes, footbox location!

[Bernica]

Not a good pic. Sorry, but that throttle linkage clears that header bolt by about 1/16".

[AC Ventura]

Yep that's officially snug and cosy....