What is the biggest Cam to run with Paxton and automatic trans?

[TJinSA]

I have loved my C7FE le mans cam with standard transmission, bu I doubt the levels of vacuum would work well with a C4 hipo automatic.  I was pleased with the hydraulic hipo cam profile with my cruiser automatics, bu missed the seriousness of the Le Mans.  What has been the group's experience running something more radical than a hipo cam with an automatic?... brand... approx spec, please.

[zray]

What ? The answers on the VMF to the same question are lacking in...... something ?

As already pointed out over there, many people, myself included, have tried many exotic cam profiles in a 289 K code engine, with many different induction systems. Including vintage and modern Paxton's, 4 Weber 48 IDA's , etc.

The consensus was, and is, full race cams provide an abysmal street driving experience. The 289 K code does not have an abundance of low RPM torque anyway. Start camming it up and you lose even more low end torque. Not a factor on the race track, but a very big buzz-kill for street driving .

Z

[TJinSA]

Forgive my question, It's reference link I had was lost, I believe with either 1.0 or my own ransom ware. The point wherein I disassemble my hipos and switch parts among them for a proper Paxton configuration while returning the car from manual to automatic has arrived. I CRS, and look to be in only one last time.  Your repeated advice is understandably an annoyance.

[zray]

"...........  Your repeated advice is understandably an annoyance.

you think you're annoyed now, wait 'till later when you don't take the good advice FREELY offered, and you're driving that LeMan's (or worse) cammed K code in heavy traffic.

Best of luck in your quest to find a high rom cam that doesn't take away badly needed  low rpm torque. Now that I think about it, there  might be such a "defying-the-laws-of-physics" camshaft  buried in my back yard, right next to my hoard of Spanish gold.

Kind regards,

Z

[shelbydoug]

A stock hipo cam is probably as radical as you want to run with a stock c4. Maybe just go to 1.7 rocker arms? Maybe a C90Z-C?

A supercharger is supposed to eliminate the need for more camshaft. In fact at some point the supercharger starts blowing out through the exhausts.

You might want to investigate cam company offerings showing a specific cam for supercharged cars. They offer them for Webers on IR manifolds. Probably for supercharged as well?

[gt350hr]

    Tom,
      6S477 is an automatic Hertz car I've owned for the last 45 years. When I bought it it had the LeMans cam in the original engine.At the drag strip it ran ( disappointing) mid thirteens. My quick and easy "hop up" was to install one of my Paxton setups that I used on 6S240 when I drag raced it. With no other changes 477 was quicker by over six tenths of a second and ran high 12s instantly. The whole combination worked because the car already had a 10" ( down from 11" stock) higher stall converter. The longer duration of the LeMans cam WILL need a high stall converter. It is important to remember this was 45 years ago. Since then I have compiled a notebook of camshafts I have run in various combinations. My exact recommendation would vary with respect to the cylinder head being used and amount of air flow it can produce. In general I would suggest a short duration ( no more than 232*s duration at .050) flat tappet cam with high lift of .550 and a 1.7 ratio rocker arm might be required to get there. For the exhaust I recommend the LeMans exhaust lobe of 252 @.050 and .500 (net) lift. All of this on a 110*lsa . The longer exhaust duration is needed to allow the additional amount ( supercharged) of  gasses to get out of the cylinder. High lift is not needed on the exhaust side. A "race only" situation could use more but as mentioned the "street manners" suffer. My recommended cam has 500 HP capability with a high flowing ( aftermarket) set of heads. I use a custom cam grinder out here in California , Steve Long Racing Cams , Corona Ca. to make cams for me and have for over 40 years.
    Running the Paxton with the automatic is FAR different than with a 4 speed where you don't have to idle in gear. To make me work even harder , I switched to the small block with THE worst bottom end (Boss 302) and developed cams to make that work. I also ran a tunnel port 302 for a few years in front of the automatic , another challenge.
    Randy

[zray]

A stock hipo cam is probably as radical as you want to run with a stock c4. Maybe just go to 1.7 rocker arms? Maybe a C90Z-C?

A supercharger is supposed to eliminate the need for more camshaft. In fact at some point the supercharger starts blowing out through the exhausts.

You might want to investigate cam company offerings showing a specific cam for supercharged cams. They offer them for Webers on IR manifolds. Probably for supercharged as well?

This.

^^^^^^^ +1

I had a cam specialty ground for a '66 GT350H with vintage Paxton. For the same reasons ShelbyDoug outlined, it had no no more duration than the stock HiPo cam, but more lift.  The specialty cam performed no better than the stock HiPo cam. However, It did sound more aggressive at idle.

Z

[gt350hr]

   The 540 ( determined by 1/4 mile performance, 11.41 @ 124 mph) horsepower Paxton blown 289 I used to set a few AHRA drag race records in 72-74 had a Crane solid roller that was understandably bigger than a hipo or C9OZ-C cam. I ran about thirty different cams through that combination before I was satisfied. Few here have had the need or desire to do that . I realize the OP is looking for a street performance cam. A generic cam will get generic performance and that's fine if it makes you happy. A custom cam could easily add thirty over a generic.

  Doug the "point the supercharger starts blowing out through the exhausts" is the overlap cycle , present in "most" camshafts including your C9OZ-C which has 12* overlap at .050 tappet lift. Overlap by itself is not always a bad thing. Understanding how to use it to your advantage is key.
  Randy

[shelbydoug]

   The 540 ( determined by 1/4 mile performance, 11.41 @ 124 mph) horsepower Paxton blown 289 I used to set a few AHRA drag race records in 72-74 had a Crane solid roller that was understandably bigger than a hipo or C9OZ-C cam. I ran about thirty different cams through that combination before I was satisfied. Few here have had the need or desire to do that . I realize the OP is looking for a street performance cam. A generic cam will get generic performance and that's fine if it makes you happy. A custom cam could easily add thirty over a generic.

  Doug the "point the supercharger starts blowing out through the exhausts" is the overlap cycle , present in "most" camshafts including your C9OZ-C which has 12* overlap at .050 tappet lift. Overlap by itself is not always a bad thing. Understanding how to use it to your advantage is key.
  Randy

It's easier to just turn up the boost. Not many records are set on the street. A stock Paxton at 6psi is going to add about 30 or 40 hp and keep streetability. If you want the "as advertised" 100hp, now that's more involved.

Dealing with a 700 lift cam, a blower and an automatic on the street is kinda complicated. That's more of a Pro Street car and why not throw some nitros oxide into the mix?

If we were looking for maximum power a Paxton is hardly what to work with. It's kind of a nostalgia thing mostly.

The original Paxtons needed to be kept under 6,000 rpm and had this slight little problem of burning up the fluid in like an instant. In addition they were really designed to work with a Ford carb and just fitting a Holley with center hung bowls like is shown in the Shelby blue prints is a little tricky as well.

[gt350hr]

     OK , I'll give you a few things out of my history book because you are mixing "modern " possibilities with what was available "to me" in '72. My "289" had a .580 lift solid roller ( the "big stuff" had too much duration) , flat top TRW pistons , C6FE heads and an Offenhauser 360 single plane manifold. I modified my own Paxtons with the help of Vince Granetelli. We changed the springs in the pressure plate and used different pullies to get an unheard of 13psi. A full 5psi over his better units. YES it came with a cost. I chunked MANY bearing races before stumbling onto B&M Trick Shift fluid and a "top secret" cactus oil additive. This virtually eliminated the failures. YES I drove it on the street too.
    While NONE of the above applies to the OP's initial request , reply #5 does offer "my" suggestion for an "optimum" street Paxton cam which was the OP's original request. It is possible that if you had done as many trial and error cam changes as I had 47 years ago , you might have a similar opinion , maybe not. I could easily have hit "+1" on the C3OZ-C9OZ recommendations you and Ray gave  but "my" personal experience is different than yours and his. Your way is safe and predictable , nothing wrong with that.
    Respectfully to both you and Ray,
         Randy

[FL SAAC]

do you want to go fast ?

ditch the original motor and install the new ford coyote

[gt350hr]

 Nice Tony , stick to topic.

[FL SAAC]

Nice Tony , stick to topic.

will do sir,

kindest regards

[shelbydoug]

     OK , I'll give you a few things out of my history book because you are mixing "modern " possibilities with what was available "to me" in '72. My "289" had a .580 lift solid roller ( the "big stuff" had too much duration) , flat top TRW pistons , C6FE heads and an Offenhauser 360 single plane manifold. I modified my own Paxtons with the help of Vince Granetelli. We changed the springs in the pressure plate and used different pullies to get an unheard of 13psi. A full 5psi over his better units. YES it came with a cost. I chunked MANY bearing races before stumbling onto B&M Trick Shift fluid and a "top secret" cactus oil additive. This virtually eliminated the failures. YES I drove it on the street too.
    While NONE of the above applies to the OP's initial request , reply #5 does offer "my" suggestion for an "optimum" street Paxton cam which was the OP's original request. It is possible that if you had done as many trial and error cam changes as I had 47 years ago , you might have a similar opinion , maybe not. I could easily have hit "+1" on the C3OZ-C9OZ recommendations you and Ray gave  but "my" personal experience is different than yours and his. Your way is safe and predictable , nothing wrong with that.
    Respectfully to both you and Ray,
         Randy

I read reply #5 as just a general outline, not a specific cam profile. OP asked for a suggestion for a specific cam. Granted his guidelines for it are a bit on the vague side suggesting some lack of experience in that area ?

No one is questioning your experience(s) or expertise in this area. I certainly am not but not having the facilities of NASA or expecting the OP to, or the years of the school of hard knocks experience that some have. it's safer to put someone in range of the expected results rather then getting a call on "that blue printed engine you sold me just blew up". Once is enough on that one. 

I will also admit that what any one particular individual means by a "street car" is quite variable. I would not consider GT40s or Daytonna Coupes as streetable but certainly a bunch of folks do. Those same people might consider Webers un-streetable and not that I'd debate that, I'd just pry to figure out what their expectations were?

In the current reality we live in, some would consider the camshaft specifications an infinite variable of virtual reality. I just try and set a benchmark on specific known camshafts that many can relate to. Then someone can play with those numbers, successfully or not to their own interests.

The Paxton as originally offered by Shelby was a bolt on for whatever you started out with. Anything more then that was up to you to discover and cultivate. As offered. it was more bluster then fact with a bunch of pitfalls even if you didn't stray from "out of the box".  Why does anyone want to recreate that?

[TJinSA]

Randy,  Your came advise is exactly what I was looking for.  THANK YOU!  Neither I, nor anyone of reason, is looking to turn our vintage car into a race car, but I was looking for some baseline to establish the operating envelope the Paxton is functional, without going through all the permiatations your experience has taken you.  Perhaps I should have explicitly given more than an automatic transmission as a factor, but it's a pretty big one I thought.  I wasn't looking for something so well documented as a C3OE cam.  THANK YOU, AGAIN.  You provided those types of profile characteristics that can be varied, and those that must be with caution.  A career in aerospace engineering, test and evaluation tends to help one know the limitations their experience can take them.