Single plane 427 inlet manifold

[Ant]

Has anyone tried fitting a manifold the same or similar to the Shelby single plane 427 inlet manifold to a Cobra, and is there room for an air cleaner, or would it require a large bonnet scoop?

[SCOBRAC]

Edelbrock has made several which fit as well as the standard Ford Manifolds. The question is why would you do this?

Most single plane manifolds are excellent performers over 3500-7000 rpm. They make very good power for high rpm engines. A good dual plane offers nearly as good, sometimes better performance and far superior drivability.

http://www.flatlanderracing.com/man_edel_ford332.html

[Ant]

SCOBRAC,

Thanks,

You have answered my question from what you posted its a matter of compromise, and if a dual plane gets me good power, and probably a heap more torque!

I noticed the manifold on Shelbys website and thought that looks a bit like a Victor Jur, and should be good, but now...........!

[SCOBRAC]

It would be very good. But it would be a huge compromise if you intend to drive it on the street, that isn't to say it cannot or should not be done. It can be. But at what cost? The upside is you can make more top end power... You know for al that time you'll spend at 7000 rpm plus

[SCOBRAC]

One very good alternative is the "tunnel wedge" intake. It is a single plane unit made near the end of the FE run. It offers a fairly good bottom end with the look and near flow characteristics of the tunnel port unit.

The real factor is heads. You will want to very closely match any intake you choose to the heads you have or will have. Getting a mismatch at the point the heads meet the intake is a huge power loss.

All the intake manifolds on the link I included are a perfect match for Edelbrocks heads. Dove is another company that makes heads / intakes which are an exact fit.

The importance of this can be found in the "parts for sale" section of this fourm. An engine builder named Kieth Craft has an FE engine for sale that made 650 horsepower and 555 ft pounds of torque. He did this by extensive porting, but more inportantly it was the flow characteristics of the porting and the smooth even (volume of the runners after porting) way the air flows.

If he reads this I have no first hand knowledge of his technique, it's an art as much as a science. It's what winning racers have known for decades, just know that it makes a huge difference.

[Ant]

SCOBRAC,

Thanks for your advice, so what you are saying is porting matching and good head work are the secret. From your post the
the middle performer manifold seems to be better suited to my application, as the bottom single plane is still to higher rev range, same as the shelby item. But I see the Edelbrock version fits under the bonnet, for what its worth!

Can someone downunder (NZ) buy heads that have that sort of work, because "all to often" in my build here I have been sent sh*t, and they have had to replace it. I think some outfits think we will send our seconds, he wont send it back, as it will cost to much in freight! Sorry about the gripe but its true.

Getting back to the KC engines an power, I would like to purchase an alloy block (std 427 size) and some good modified heads, and manifold, running between 10.1- 11.1 comp pending on how much avgas I want to use (hassle paying big $ and getting it) I want this engine to spin to 7000, but as you mentioned it would be silly to sacrifice mid range power for a bit extra up top! I should mention the car is being built for road racing, I originaly wanted to go SB but as the alloy blocks have come down in price ............!

[SCOBRAC]

I would look up Kieth Craft in the forum and have him build you something. I am sure there would be someone capable of doing this type of work for you but you will likely need to import the parts anyway. Have Kieth build it and ship it to you.

[PatBuckley]

IMO The amount of torque you give up at the lower end of the rev band with a single plane manifold is minimal - something like 30 ft/lbs - but the gains are way bigger at the upper end of the rev range over a dual plane manifold.

If you are going to set the car up for the track then a single plane is exactly what you want.

Cobras have a huge amount of torque - in fact, most could use a little less torque on the bottom end.

[Ant]

Pat,

I dont want to use over 7000rpm, and may even change at 6500rpm!
Would the single plane be more for 6500-7500rpm?

[PatBuckley]

Ant-

I think you would be ahead of the game from 3000 rpm up using a single plane...below 3K you will lose a little torque - probably not enough that you would notice though.

In a road race situation you will never see the low side of 3K, right?

Pat

[ENTDOC]

I tend to agree with Pat.This is much like the 4v vs. 2v heads on a 351 cleveland argument. 4v heads flow much better and make most hp at higher rpm,2v heads have beter low rpm torque numbers, however in a lightweight cobra the difference is minimal at the low end but dramatic at higher rpm. I like the high rev driving experience so I got a Victor for my 427. chuck

[PatBuckley]

On top of that, the single plane looks so much better!!

[Ant]

Pat, Chuck,

I agree they do look a lot better, and also I dont like the engine flattening out a bit over 6000rpm!

[Cracker]

I've had the benefit of owning/driving both on my 427 and it's hands down the single plane if... 1) you value performance over originality 2) you really want to rev your motor (6500 + - mine revs to 7600!) 3) you have a engine build to make use of the flow - ie. cam, springs, rocker arms, etc. etc. All in all I feel it is more tractable and a kick in the pants in a Cobra. I also had a 428 in my car for awhile - never again, I want horspower not excessive low/slow spinning torque. Rev it high and stroke it short and you'll have an absolute ball - guaranteed!

SOBRAC - The "parts for sale" engine is MINE - it's not being sold by Keith Craft - he just hand built it!

Enjoy your motor!

[Ant]

Cracker,

Originality in the inlet manifold department is not a priority but performance is!
I will be using good forged internals and rocker gear, maybe Carrillo rods, Shelby rockers, the best valve springs, dont know what crank or pistons yet. Solid flat tappet camshaft. May get Keith C to do an engine, or Gessford, not sure yet.

What manifold are you referring to is it the Edelbrock single plane, or the Shelby?

I like the Edelbrock due to it still fitting under the hood!

[Cracker]

Ant - your like all of the rest of us in a sense. We all think we know whats best and plan it out until you talk with a pro and your components list changes based on their recomendation.

For instance: Shelby Rockers - you can do much better for the same money; Carillo rods - why? same as above; etc. etc.

This should answer your question.



Enjoy your build, every minute of it!

[Ant]

Cracker,

That answers my question, nice package!

Regarding internals when I am nearer to buying a block etc will speak with Keith C or suchlike and get their recommendation on what will live for a while on the street and do some road racing.
I have heard some horror stories on CC of rocker gear only doing 1000miles.
On my old FE390 I used Isky rockers on good shafting, and the present owner has done heaps of hard miles, they were not the best available by any means.

Have you a build sheet, or recommend Crank/Rods/Camshaft/Rocker gear/type of Carb, any info gratefully appreciated!

[Cracker]

This will get you started - CLICK HERE!