i was wondering what cam i should install, i'm having troubles with my account at the fordsix website so i thought i would ask here, i was thinking of a comp cams 252 as it produces more torque lower or possibly a 260 as it is a close second (455 ft-ibs versus 426, these are real life numbers as each were tested in an engine) but the guy who tested them said nothing about streetability. thanks in advance

 

what are your thoughts for these
COMP Cams: High Energy™, 268H <BR> Strong Mid-Range RPM Power, Noticeable Idle
COMP Cams: High Energy™, 252H <br> Good Torque & Mileage, Excellent Throttle Response
COMP Cams: High Energy™, 260H <BR> Excellent Torque & Power, Smooth Idle
i wouldnt mind the noticeable idle but i dont want to to kill my torque or make it come on at 3000 rpm either. it would also be nice if it didnt affect mileage but if they all do then so be it, so do any of these not affect mileage

 

anyone have an idea?

 

All three of those cams have a Lobe Separation listed as 110 degrees. That is not going to work with your Speed Density engine control system. General rule of thumb is nothing less than 114 degrees.

 

You're gonna have to post up a link or something cause I don't see a stock 4.9 generating anything remotely close to that regardless what cam it has.

 

sorry guys i was off it was 345 ft pounds my bad, here is the link FORDSIX PERFORMANCE &bull; View topic - Stock 300 camshaft specifications you have to scroll down some. also who makes a towing came with nothing less than 114 degrees of LSA? comp has one but its power band is like 1500-6000 so that wont be of much use to me

 

okay i called comp today and the one cam that would work they dont make anymore, does anyone know of a cam that will meet the criteria and make power in the appropriate powerband

 

What is the stock I6 rocker ratio.. 1.6 or 1.7? All stock this motor makes all of 150 freakin horsepower at 3400rpm...there is no way it has a cam with 268 degees intake duration and 0.422" lift, I think those guys are assuming too much to think the later EFI motors use the same cam as the early carbed motors. If it did then the aftermarket cams mentioned would actually make less power.. not more. Did I misunderstand something in that thread?

 

stock is 1.6 this explains it
I realize this is an old thread, but...

The stock 300 six/4.9 efi cam has quite a bit of advertised duration (~268) but the ramps are very mild. I assume this is for longevity more than anything else.
When building my 4.9, I was initially going to use a Comp 260H. When I discovered (on this forum) that the stock cams have 268 degrees of advertised duration, I went for the 268H instead.

Observations:
The Comp 268H has a .050" duration of 219 degrees. That's a fairly aggressive lobe. Being a flat tappet cam, it has a faster off the seat rate than a roller lifter will allow. You can tell how aggressive a lobe is by the number of degrees between the advertised and .050" numbers. Tighter means more aggressive.

The lobe center of 110 degrees causes this cam to lope a bit at idle (overlap 48 degrees). But the tighter lobe center lowers the rpm at which peak torque and HP occur, too. These heads do not require split-pattern cams (both carb and EFI). The exhaust ports flow plenty of air compared to the intake side (and compared to 5.0L exhaust ports, which do favor a split-pattern cam with more exhaust duration and lift).


252H 204hp @ 4000 345 lb ft @ 2000
260H 217hp @ 4000 338 lb ft @ 2000
268H 225hp @ 4000 326 lb ft @ 2000


What this is telling me is that peak torque is below 2k. With EFI exhausts, the peak torque of the 268H was a bit higher (2500 rpm, I think). Obviously, the 252H would be best for mpg as long as cruise rpm was geared at or below 2k.


power numbers 252H 204hp @ 4000 345 lb ft @ 2000
260H 217hp @ 4000 338 lb ft @ 2000
268H 225hp @ 4000 326 lb ft @ 2000


What this is telling me is that peak torque is below 2k. With EFI exhausts, the peak torque of the 268H was a bit higher (2500 rpm, I think). Obviously, the 252H would be best for mpg as long as cruise rpm was geared at or below 2k.


so the cam has 268 degrees of duration but it has mildly sloped lobes that are not as agressive as say a comp cams 268h

 

I know this thread is a little old but ive been running into problems with my 1992 4.9, a little backround on it real quick... its a 92 motor with a recent rebuild. And by recent I mean about 10,000 miles. Then I wrecked the truck and pulled the motor to put it into another and since I had the motor out I put in a crane cam, new lifters, new pushrods, double valve springs new retainers and harland sharp roller rockers. Along with a fresh valve job and arp headstuds. So when I finally fire it up it doesnt run quite right and I read somewhere that my cam lobe seperation may be to low at 112 for speed density. So I found a whole wiring harness and obd1 computer for mass air. Installed that and an msd idnition ive had for it and now it seems to run better at base timing but as soon as I plug the little jumper back in to let the computer control the timing the truck almost doesnt stay running.