Is the '68 Shelby J code eng. the same as the Cougar J code ? [Archive] - Classic Cougar Forums

: Is the '68 Shelby J code eng. the same as the Cougar J code ?



Scali62
January 6th, 2006, 06:34 PM
The 68 Shelby 350 GT has a 302 for '68 rated @ 250 HP { as well as a Paxton SC 302 version rated over 300 }
What i'm wondering is a couple things,
Are these 2 motors the exact same { Shelby & Cougar J codes } also what makes up for the extra 20 ponies for the Shelby motor assuming they are ?
Also, can a vintage { or current model } paxton supercharger be bolted on the the J code or does it need modifications .
thanks..
:beer:

rjf
January 6th, 2006, 08:31 PM
Very interesting. I went to the Branda catalog and it agrees with your info, a 250 HP J code in '68. The Cougar J code was 235. Maybe it was the aluminum hi-rise intake and 600 CFM Holley that made the difference. It sure as hell wasn't the pretty valve covers. Hah!

Scali62
January 6th, 2006, 08:42 PM
If I had to guess i'd say the dual exhast , headers & a litle carb tinkering, maybe ignition too..
But I wonder if the internals are the same, between the shelby & the merc J codes, also I wonder if they dropped the compression for the blown model from the J code's 10-1 comp. ratio....
If not I would seriously considering seeking a super charger { one of those vintage paxton's would be cool } to bring the HP up to 320 or so i think it is..
Another concern even though I'm getting ahead of myself is will my C 4 & 8 " rear handle the extra ponies..
I think so...:zap: { I have no idea what this icon means but it's cool }

Royce Peterson
January 6th, 2006, 10:37 PM
The Shelby J codes had an aluminum Shelby high rise intake and a Holley carburetor which gave them the extra 20 horsepower. Shelby did not offer headers or a Paxton in 1968 except as do it yourself at home kits.

rocket
January 6th, 2006, 11:09 PM
the 68 shelby came with a c8ze-b hipo or k code head has this part number as well as having 289 and 3024v on the same head and also had the 19 and 21 casting on the outside corner as so you no its a hipo head with screw in studs and cast in spring pockets under the covers from the R1 files BC SURREY this file is decated to shelby cougars ROCKET

Scali62
January 7th, 2006, 07:23 AM
so the '68 Shelby 302 has solid lifter's & the J code Cougar doesnt I assume ??

Royce Peterson
January 7th, 2006, 08:34 AM
No, the '68 Shelby uses the same lifters as any other '68 J code and the same hydraulic camshaft.

The heads used on the J code Shelby were the same heads used on California Thermactor smog equipped J code Cougars or Mustangs. The screw in studs appeared on service replacement J heads and made them an acceptable service replacement for the K code 289 engines used in Mustangs in 65 - 67. The studs are a nice feature but unnecessary in the relatively low performance stock 302-4V. The detrermining factor for screw in studs is the valve spring pressure.




so the '68 Shelby 302 has solid lifter's & the J code Cougar doesnt I assume ??

rjf
January 7th, 2006, 09:35 AM
Jeez Royce, is there anything you don't know? Hmm, come to think of it - how would you know? Hah.

Royce Peterson
January 7th, 2006, 10:02 AM
Had a set of those screw in stud 302-4V heads and was "educated" by someone on how stupid I was when I told him something similar to the first post on the subject. As it turns out the ones with screw in studs are all date coded too late for production, I think mine were 1969. Ones that come off of cars and have legit date codes have press in studs.

Scali62
January 7th, 2006, 11:09 AM
Thanks Royce, your a true Ford guru :smoke:
I like it when he chimes into my post's because I know I'll have the correct answer..
Only one little slip up I've seen from the Ace & it had to do with Barret Jackson auctions having a $ 30 K limit, I know I heard Brock say many cars sell for 10 grand.. :smoke:
As they say no one's perfect:lolani: ..

Just having a little fun, thanks as always chiming in & for the info on Shelby & Cougar J code's..

jshcobra
January 7th, 2006, 11:15 AM
I can confirm what Royce said is correct. I have a set of 302 4v heads that have been sitting on a shelf for many years. Because they have the screw in studs I also assumed they were GT350 items. After reading Royce's post, I went out and checked and see that the date code is also 1969-- obviously too late to have been installed on a 68 Shelby.

Thanks for shattering my dreams, Royce.

SuperCJcat
January 7th, 2006, 11:26 AM
The Shelby J codes had an aluminum Shelby high rise intake and a Holley carburetor which gave them the extra 20 horsepower. Shelby did not offer headers or a Paxton in 1968 except as do it yourself at home kits.

Early 68 GT350s came through with the stock intake because the alum hi rise didn't meet emissions requirments yet. The intake was put into production cars as of 3/15/68 with a service campaign of dealer replacing stock intake with shelby intake. Not all 68 GT350s came with holley carbs, termactor 4 speed cars could have either holley or autolite carb, but a autolite carb had to be used on auto with IMRO emissions system. Paxtons were a option on early literature but was dropped by the time 68 shelby production started but dealer literature was never updated. A old style paxton will work on a stock motor, but a special fuel pump and carb jets and floats that won't collaspe under pressure have to be used.

Royce Peterson
January 7th, 2006, 11:30 AM
Hey they are still an outstanding set of heads. A set of those on a 289 or 302 with some stainless 1.92 / 1.60" valves is a great place to start.


I can confirm what Royce said is correct. I have a set of 302 4v heads that have been sitting on a shelf for many years. Because they have the screw in studs I also assumed they were GT350 items. After reading Royce's post, I went out and checked and see that the date code is also 1969-- obviously too late to have been installed on a 68 Shelby.

Thanks for shattering my dreams, Royce.

Royce Peterson
January 7th, 2006, 12:30 PM
More info is here:

http://www.1968cobra.com/intakes.HTML

rjf
January 7th, 2006, 12:46 PM
The studs are a nice feature but unnecessary in the relatively low performance stock 302-4V. The detrermining factor for screw in studs is the valve spring pressure.


Hey they are still an outstanding set of heads.

So are you saying the screw in studs make the difference between relatively low performance and outstanding? Are the Thermactor heads so much better? I only ask because I have a stock '68 J code with IMCO - which is great for me since IMCO was just a ported vacuum switch. Those iron heads sure weigh plenty, but then it's only a small block.

Royce Peterson
January 7th, 2006, 12:55 PM
The screw in studs allow you to run stiffer valve springs. The stock press in studs tend to get pulled out if you install stronger vlave springs.

Mercougar67
January 7th, 2006, 02:10 PM
Jeez Royce, is there anything you don't know? Hmm, come to think of it - how would you know? Hah.

And to think so many of you laughed at my "Stump Royce" thread!

rjf
January 7th, 2006, 02:19 PM
The screw in studs allow you to run stiffer valve springs. The stock press in studs tend to get pulled out if you install stronger vlave springs.

So how soon in performance gain would you need the screw in studs? I'm getting way ahead of myself because I haven't even done a cam replacement before, but I am wondering what is the potential of my heads with the pressed in studs. Can they easily be modified for screw in studs? And what's the difference between Thermactor and IMCO from the standpoint of the heads? Golly, throw in the air speed of an unladen swallow while you're at it.

Royce Peterson
January 7th, 2006, 05:58 PM
I don't know the answer to the second question but Paul probably does.

Screw in studs are a good idea even in a stock rebuild. I have had the studs come out in a completely stock 289 a couple times. Once was while going 120 MPH.................:devil:

The Fab Ford
January 7th, 2006, 07:18 PM
So how soon in performance gain would you need the screw in studs? I'm getting way ahead of myself because I haven't even done a cam replacement before, but I am wondering what is the potential of my heads with the pressed in studs. Can they easily be modified for screw in studs? And what's the difference between Thermactor and IMCO from the standpoint of the heads? Golly, throw in the air speed of an unladen swallow while you're at it.
Press in stud installation was a way for the factory to save costs on machining. Screw in studs are a better way to go regardless of performance level. They become a necessity when running cams breaking the .500 lift threshold. At this lift, a typical valve spring "open" pressure on a flat tappet cam with average ramp speed angles, is in the 280 pound range. More aggressive ramp angles will increase spring pressure requirments, as will increases in lift.

Screw in conversions require drilling the stud bosses, tapping them and then milling them down ~.120" to allow for the thickness of the guideplate that you will need, if you intend to run roller tip rockers. This operation is best done on a Bridgeport type mill and is a much larger PITA on canted valve heads, such as Clevelands and BB Chevies. Labor cost averages around $250.00 for non canted valve heads. Since it is time consuming, many engine machine shops shy away from the job, especially if they don't have a vertical mill.

Once you add this cost to a pair of stock heads and then the possibility of adding some porting costs, it would take an "IDIOT" (no offense, it just seems to be the new word to use in this forum) to do this, over just buying a new set of World Products (or equivalent) heads.

Modern heads have spark plug locations and angles, port profiles, valve sizes, and combustion chamber shapes that would be impractical to try and duplicate into an old head. You will spend as much or more money rebuilding old heads and get half of the gains of buying new ones. Technological gains in new head designs creates more efficient burn characteristics, which boosts hp and fuel efficiency, simultaneously.
EFI is only one part of the gain in modern fuel economy standards; cylinder head design, camshaft timing and ramp speed, high power electronic ignitions, etc are also part of the equation.

Oh, and are you talking about the speed of an unladen European, or African swallow?

Tom

hawkrod
January 7th, 2006, 10:39 PM
So are you saying the screw in studs make the difference between relatively low performance and outstanding? Are the Thermactor heads so much better? I only ask because I have a stock '68 J code with IMCO - which is great for me since IMCO was just a ported vacuum switch. Those iron heads sure weigh plenty, but then it's only a small block.

You really are going to love this one, the IMCO system does not have a ported vacuum switch. My guess is that you are confusing the TVS in the thermostat housing for an IMCO device but the switch in the thermostat housing is not a smog device as much as it is a safety device. It has nothing to do with IMCO and was first used on 67's with AC. The TVS (Thermal Vacuum Switch) is there to advance the timing and to speed up the engine when it is overheating. Advancing the timing causes the engine to run cooler and at an idle raises the idle speed allowing more coolant to flow through the radiator. The TVS only functions when the car is overheating and thus is not a smog device as a properly operating engine is not too hot! Many people assume the TVS is an emissions device and on later cars they often are but on a 67-69 is was there to reduce engine damage and coolant puking problems caused by hotter running engines with more and more garbage on them, it was a fix for the damage the emissions sytems and emissions tuning were causing! It is actually a great device and I would never remove it as it works well. Hawkrod

rjf
January 8th, 2006, 12:32 PM
All good stuff to know and pretty specific, thanks guys. I do tend to spend money like an idiot, but wisely - if that makes any sense. I ditched the TVS and got an untapped thermo housing, but I saved the old stuff. I haven't needed it but I guess it should go back on now that I understand it better. I'm not contemplating putting money into the heads, just wondering about them in stock form. I agree the money would be better spent on newer technology. And on aluminum.