I've been wondering (screams of pain and joy)

which would work better ?
for what applications and why?

4.13 * 3.78 = 406
or
4.05 * 3.98 = 410

Has anyone run the numbers by a "desk dyno"

FE parts down here are fairly scarce so I have lost of time to plan etc.

I will probably build a:
4.08 * 3.88 = 406
as that is the parts I've collected

(unless the new 4.125 cranks are released soon enough any one heard of a date yet)

 

I look at it like this. A longer pedal on a bicycle would equal a longer stroke. A stronger foot would equal a bigger bore. Desktop dyno shows a very slight difference in peak torque between the two. A 406 would be better for a motor that you want to make a high RPM screamer since it will simply hold together better due to less rod angle and less stroke. They would both make great engines for low end torque if built for it of course. Stroking an engine doesn't really do as much as a lot of people think for torque than boring to equal the same displacement. At very low rpm's the 410 will have a little more grunt than the 406 with all other parts being the same.

 

Wasn't the 406 an introduced street engine to satisfy Nascars (stock) rules, and was a race motor, and is even rarer that the mighty 427?
http://www.clubfte.com/users/jowilker/USFlag.gif
John

jowilker email me
[link:www.ford-trucks.com/users/jowilker|My Club FTE Page] Member since 01 01

[link:www.ford-trucks.net/users/jowilker/NCFTE.html|NCFTO] North Carolina Ford Truck Owners Group

In the cool still quiet of night, you can hear chevies rusting away.

 

You are correct John. Since most had crossbolt mains it definitely is a motor not meant to be mild but it could be that way. I would hate to see one wasted like that though.

 

Just a couple of quickies. The bigger bore will help in the breathing department by unshrouding the valves, the gains show up in the mid and upper rpms. Also, it’s a lot easier to get extra cubes by stroking rather than boring, it’s a geometry thing. Take for example going from a 352 to a 360, a .050” overbore only yields 8 cubes.

Barry

 

I dont have any exotic blocks to munge but I do have an FT block that may bore ok.

I was thinking about piston dwell and the influence on detonation and cam shaft selection and rpm, Rod stroke ratios and torque, and how this may interact with the FE's poor exhaust ports.

I'll be using 400 Clevland rods (on a 3.78 crank) if I can't get a 3.98 (or better) crank. I guess in the long run I'll be going as big as can be achieved with the parts i can get hold of.

 

Theoretically, the greater the bore-to-stroke ratio is, the quicker the engine will rev and the better it will perform at higher revs. The larger bore and shorter stroke of the 406 means that the pistons are travelling shorter distances for the same RPM, which of course means they are travelling slower. Slower piston speeds also mean lower friction. On top of all that, a longer stroke requires a larger crankshaft with more mass, which of course adds more inertia and makes it more difficult to quickly rev up.

The same basic theory explains the different characteristics of the FE 427 and 428 motors. The 427 is 4.23 x 3.78, which is seriously oversquare. The 428 is 4.13 x 3.98. Not surprisingly, the 427 made a great high-rpm racing motor, but was not well particularly well suited for low rpm, high torque duty. That's where the 428 came in.

The 406 was the original FE racing motor, and is extremely rare. I know that a lot of Cobra replica guys build them, though, as they are much cheaper to build than 427s (just bore a 74-76 truck 390 block .080 over), look identical from the outside, and perform almost the same. A well built 406 can easily generate 400+ horsepower without power adders and be comfortable running at 6000 rpm -- awesome in a light car like a Cobra.

Still, I'd take the 410 over the 406 in a truck, anyday.

 

 

I realize that this thread has gone stale but I thought I'd add this; I have heard that the 406 is often a cross-bolt, side oiled block like the 427 and that the later 406s were the same casting as the 427. This means that the later 406 can be bored to the 427's bore. Add a 410/428 crank and you have an FE 454!

 

I could see it now. A drag race between a Ford and cheby with a 454. The Ford blows it away, then the cheby guy asks what engine you got and you say a Ford 454. I would love to see that especialy the cheby guys face.

 

I have heard of very few stories where an FE other than a 427 has taken a bore to 4.23". Many FE blocks that share casting numbers have totally different cylinder wall thickness. The C6ME-A block is supposed to be a 428 but seems to be very commonly found as regular 390's. Core shift was also pretty bad on some of the blocks so that can even limit your boring abilities even more.

 

I don't believe that a 406 could be bored out to 427 dimensions. That's an overbore of 0.18", which would require massively thick cylinder walls. I've never heard of any block being capable of that much overbore. In any case, I'm not sure why you'd want to. 406s are rare and expensive, too, so you're not getting a cheap 427 that way.

 

Where did you come up with 0.18"?

406 = 4.13 x 3.78
427 = 4.23 x 3.78

That's a 0.100 overbore. Yes, that's large. If it's too large then go with 0.060. That's not unusual. But my point remains, what I read was that the late 406's, the ones made concurrently with the 427, were the same casting.

 

Duh. You're right. My mistake. For some reason, I was thinking 4.05, but of course that's the dimension for a 360/390/410. I should know, as I'm toying with the idea of building a 406 out of a '75 360 block for use in the Cobra replica my wife says I can build as soon as my college loans are paid off.

 

[updated:LAST EDITED ON 28-Mar-02 AT 01:35 AM (EST)]Cobra replia! Too cool Yup, FE engine is the way to go.

406, Maybe destroke a 428? Oops, you said you have a 360 already. Never mimd.

BTW, why are 406's popular with Cobras? I thought that the original Cobra big blocks were 427s.

Who's kit would you be using?