Comp, S/C, Street 427 BB Engines

[jconley]

What is the difference between the competition, semi-competition and street 427 BB engines used in the CSX 3000 series Shelby Cobras? Is there a good reference (book, web) that describes the differences?

[Bernica]

I would start by getting ahold of the Shelby Registry for Cobras and GTs.
They came with everything from 428s to 427 center oilers and side oilers with single 4bbl to dual quad to Weber 8-stacks to supercharged.

[patrickt]

Originally Posted by jconley

What is the difference between the competition, semi-competition and street 427 BB engines used in the CSX 3000 series Shelby Cobras? Is there a good reference (book, web) that describes the differences?

Jeff, you have to think of the "outside" of the engine, and the performance of the engine, coming from the "inside," as two different subjects. From the outside, in a Cobra all FEs look the same -- you can't see the difference between an expensive sideoiler and a bargain basement 390. The only visible differences are going to be the parts you bolt on the top, and for the most part that's just the intake manifold, one or two carbs, and whether you have a Turkey Pan and what valve covers you like. From a performance standpoint, you can easily make any FE outperform, or perform more street-smooth, than any original CSX3xxx engine. If you're going to be driving mostly on the street, then you'll probably want a different engine build than if you're doing serious racing.

[ACademic]

I think the OP might be interested with the internal differences, i.e. compression ratios, camshaft profiles, etc. I'm pretty certain the full competition engines were running at least 12:1 compression and perhaps as high as 14:1. Would be interesting to see a comparison of the actual compression and cam specs for comp vs. S/C (to see how much Carroll had to detune the cars to sell them as "street" runners).

[Cobra #3170]

Originally Posted by ACademic

I think the OP might be interested with the internal differences, i.e. compression ratios, camshaft profiles, etc. I'm pretty certain the full competition engines were running at least 12:1 compression and perhaps as high as 14:1. Would be interesting to see a comparison of the actual compression and cam specs for comp vs. S/C (to see how much Carroll had to detune the cars to sell them as "street" runners).

They did not detune anything, they used stock dual 4 medium risers in the majority of SC's.

The race cars had single four NASCAR engines.

[patrickt]

Originally Posted by ACademic

I think the OP might be interested with the internal differences, i.e. compression ratios, camshaft profiles, etc. I'm pretty certain the full competition engines were running at least 12:1 compression and perhaps as high as 14:1. Would be interesting to see a comparison of the actual compression and cam specs for comp vs. S/C (to see how much Carroll had to detune the cars to sell them as "street" runners).

I have a book that has that -- and it's reasonably believable, not just made up. There were several configurations, as I recall. But remember, back then you could get Sunoco 260, with the little "Dial-a-Pump." I use a cam that is actually a clone of a cam that was swapped in by CS for several of the engines that were a step below what you might call full race. But Lykins will tell you that cam architecture has come a long way in 50 years, but it's what I wanted. The OP could easily build an engine that is, for the most part, pretty similar to what they were 50 years ago. He just needs to sit down with a builder that is familiar with what was being done back then, because gas has changed. He's probably better off just instructing his builder as to what his goals are, as opposed to telling him what specs he wants for the internals. I did that, and my builder decided to go with an original spec'd cam from "back in the day." Had Lykins built my engine, I would have had to of twisted his arm to do that. But, who knows, maybe Lykins would have been right and I would have liked his choice more?

[Bernica]

Originally Posted by Cobra #3170

They did not detune anything, they used stock dual 4 medium risers in the majority of SC's.

The race cars had single four NASCAR engines.

And the race cars had the big NASCAR 4bbl with unique (and rare) NASCAR float bowls.

[DanEC]

Colin Comer's book, "Shelby" has a breakdown of engines used in the 427 models listed by serial number groups on page 86 and some of the particulars of the engines on page 65. Probably the best concise breakdown and listing you will find.

[jconley]

I'm building an ERA Cobra, and initially I was think of using a 428 because it was used in the "street" version of the Cobra, plus because of it's reputation for high torque at low rom. My car will mostly be used for cruising, with some autocross, and may be a track day. So, I'm not necessarily looking for high HP numbers, but a car that is easy to drive on the street and highways, and with low end torque for autocross (60 mph max).

I was reading the book Shelby Cobra Fifty Years, and learned that there were actually "street" 427s (CSX3301 and later). So I was curious if there was a resource (book, web) that described the difference between the three 427 engines.

Heads and intakes: low, medium and high risers
1x4, 2x4 carburation
compression ratios
cams
etc

Perhaps there are too many differences to list, and I can understand that. I suppose the fact is that a 427 can be configured with the right components to be as streetable as a 428.

[jconley]

BTW, the current configuration I have in my head now is the 427 BB, aluminum low riser heads, dual four barrel carbs with a dual plane aluminum intake matching the low riser heads. I have no idea what cam to use, or more specifics on the heads. But part of the fun is learning this stuff.

[Bernica]

You are in the right place and welcome!
Any of the engine builders here can guide you to just what you want.
As always, your budget will be the factor. You can go from $6k to $40k and more on an engine. A nice clean 428...I would guess $10k or so.
My 2 cents...

[DanEC]

The 428 I had built for my ERA Street Roadster by Keith Craft sounds a bit like what you are describing. It's a 428 block with 4.25 inch crank and Chevy rods, 9:1 compression, early LR performance heads ported/polished/early 427 valves, 1963 427 LR dual-quad intake, 427 dual point distributor. Keith Craft had a custom ground, hydraulic, flat tappet cam with 230/236 duration and from memory about .570 lift. It has a little rump, rump to the idle but is a torque motor that makes max power around 5500 rpm. Before I completely got used to the shifter I took off several times in 3rd accidently and didn't even know it until I realized the rpm were climbing slowly and I didn't need to shift. The dyno guy said I probably could have made another 25 or 30 HP stepping up to massaged Edelbrock aluminum heads. Keith Craft didn't want to go much above 9:1 with iron heads but if you use aluminum then you can bring that up some more. The 427 aluminum LR, dual quad intake is known to make a lot of torque. My torque curve is really broad.

I don't think anyone is making an aluminum low riser head (?). But you can use a MR head with LR intakes if that is your desire. Are you planning to do your own build or planning to use an engine builder?

Are you planning to build a Street Roadster with a smooth hood? If so, you are correct that you need to use a LR intake. It takes a hood scoop to fit a MR intake.

Good luck

[DanEC]

A bit more time now and I can re-cap some of engine info in Colin Comer's book, "Shelby":

3001 - 3071 S/C and Competition models - not all numbers used. I believe the competition models used higher compression side oiler blocks, MR parts, single 4bbl and other changes and were rated at 485

3100 - 3200 cars with LR 427 center oilers with dual quads/425 HP.

3201 - 3305 +/- cars with LR 428 PI engines with single 4bbl/385 HP

3306 - 3360 +/- cars with 427 MR side oiler engines wth single 4bbl/410 HP

[jconley]

Dan,

I like the specs of your 428. Torque motor is what I'm aiming for.

The car will look like a S/C with hood and side pipes.

I haven't decided if I will build the engine myself or not. I am a mechanical engineer, and have messed with cars since the 80s. I've only worked on small block Fords and Chevys, and only on the top end. I've never taken a bare block and had it worked on and assembled from the bottom up. But, like building the ERA kit, I would also enjoy building the engine.

[patrickt]

There is a good bit of confusion in the literature regarding the cams that were available, and that came installed, in the different 427 engines. I have a lot of the original literature from Ford, and even some of the original Ford documentation came with typos. Plus, over the years, errors have been copied over and over and over again - especially on the 'net. On top of that, Ford engineering and Ford parts numbers have caused confusion because people mixed them up and sometimes they sounded the same or looked the same. But really, unless you're a nut on the subject, nobody gives a shi* anymore on exactly what cam came in, or didn't come in, an original 427-4v LR versus the 427-8v LR versus next year's MR.

[Bernica]

I have the entire Muscle Parts catalog from 66, 67 and 68 with all of their cams, parts and specs for the 428 back in the day if you are interested. Back then we just called them "A Cam, B Cam or C Cams" as I recall.
Just send me a PM.

[patrickt]

Originally Posted by Bernica

I have the entire Muscle Parts catalog from 66, 67 and 68 with all of their cams, parts and specs for the 428 back in the day if you are interested. Back then we just called them "A Cam, B Cam or C Cams" as I recall.
Just send me a PM.

All of that stuff, and wayyyyy more, is available here: Ford Mustang Shelby vintage Hi Performance parts catalogs and publications it makes for great reading. To the OP, if you have never built an FE before, practice on somebody else's build before you build your own.

[Dimis]

If torque is what you're aiming for, then cubic inches are your friend.

As Patrick has said - they all look much the same on the outside bar the dress up bits.
You could approach this in a couple of ways, $$$ dependent.

If you want it done on a budget a 390 block with a 4.25 crank (445 cubes) will do it for you nicely. Match the heads, intake and cam accordingly.

OR

If you'd prefer a hamburger with the lot.
Then go an alu Pond/shelby block with the larger bore and stroke it out to 482cubes or more.

I'm guessing that a LR intake may choke up your engine either way.
If you are opting for a hood scoop anyway, is there any reason you wouldn't go a MR intake?

Kind regards,

[Bernica]

Originally Posted by patrickt

To the OP, if you have never built an FE before, practice on somebody else's build before you build your own.

A big Yup there! Just read a lot. They aren't your Mom's kitchen table Chevy small block!

[66gtk]

Originally Posted by DanEC

A bit more time now and I can re-cap some of engine info in Colin Comer's book, "Shelby":

3001 - 3071 S/C and Competition models - not all numbers used. I believe the competition models used higher compression side oiler blocks, MR parts, single 4bbl and other changes and were rated at 485

3100 - 3200 cars with LR 427 center oilers with dual quads/425 HP.

3201 - 3305 +/- cars with LR 428 PI engines with single 4bbl/385 HP

3306 - 3360 +/- cars with 427 MR side oiler engines wth single 4bbl/410 HP

So...all the glory and folklore back in the day was predicated on these "humble" big blocks putting out a little over 400 HP (give or take). Ken Miles drove a street Cobra on street tires in the famous 0-100-0 run that stood the test of time for decades. I don't understand why today's builders are so intent on making 600 HP or more with these cars when they did just fine with more usable power. Lynn Park has stated on record that when built to stock specs, the cars perform at their best. Yet people can't seem to help themselves by over powering them.