Agreed. Ford definitely got it right with the HO grind. A set of AFR 165's or TFS 170's would be a super street motor in a light car.
Here's some good info. http://www.crankshaftcoalition.com/wiki/Cam_and_compression_ratio_compatibility
the biggest problem with all the cookie cutter cams is that they are ground on wider LSA's. This is good for OEM style manifold vacuum and especially helpful with engine electronics related to EFI. BUT.. it hurts torque down low and in the midrange for a slight bump on the top of the rev range(if you could even say that a stock cam has an "upper rev range". Although it's not just the cams fault alone.. we used to joke about these old HO motors pulling like tractors until the fell over the cliff. Even the stang owners call them tractor motors due to the sudden falloff after peak. If you want another 10-15 free horsies(compared to another cookie cutter or alphabet cam)?.. go with a slightly tighter LSA and higher lift while keeping the duration very tight to preserve the already limited cylinder pressure of this little motor. Comp cams makes the Extreme Energy line that will bump up power in the low/mid-range and still rpm well beyond the factory stick. The faster valve action of those lobes and the tighter LSA is what makes them tick. If you really want to play with all these factory parts.. learn the limitations and weaknesses(exhaust is relatively weak) that exist and get a custom grind. Comp Cams will do it for free if you know what you want. Assuming a roller block.. something like a split duration cam ground on a 108 LSA with 206/212 @.050" and .510/.530" lift will get it done well beyond the other shelf cams. Ask for a faster lobe lift rate and they will set you up. Could also add higher ratio intake rockers to speed up the valve action of any chosen cam too.
I saw a test a while back between a thumper & 2 other cams which had wider lobe separations,the thumper made 20 more HP & more torque with the narrow lobe sep,Rob is correct.
That would be 224 deg duration, much like an Edelbrock RPM except it's a roller, probably with faster opening rate. Hot cam!
I think we need to narrow down what year your stock HO block and cam is because AFAIK the HO cam in your block is more aggressive than the two cams you described. MD
The block is at the machine shop so at the moment I cannot get the casting numbers. I measured the cam lobes and all of them are .278 lift. The original heads were the E7TE heads, which I think was the standard H.O. head from 87 forward. According to this https://drive.google.com/file/d/0B83kJI0YRpg6SHlMNUhKMlF1MEU/view?pref=2&pli=1 all H.O. cams were .278 lobe lift and either 266 adv duration or split adv duration of 276/266. I guess with a degree wheel the duration and lobe center lines could be determined to narrow it down. I think it was the wide LSA that made the duration acceptable while still maintaining manifold vacuum, much like groberts stated. One of my concerns was how far can you go with a cam using the stock gears, converter, limited heads before you are over cammed and daily drivability suffers. At this point it looks as if the stock H.O. will be as good a choice as any off the shelf cam, at least that is what I currently intend to use. I figure it will save money for the build and still be a big improvement over the current 1972 one. In the future if he wants to upgrade the heads, that will be when a more suitable camshaft could be explored.
I searched for the SAE duration (at o.05 ") for the roller cam for the 85 - 88 HO engines with the 266 deg advertised duration. This cam was part number E5ZE-6250-AA. Mustang360 says the SAE duration is 210/210 degrees which puts it close to the two cams you mentioned in the original posting. This would be a smooth running fairly mild cam using the attributes described by groberts. I wouldn't consider it to be over crammed at all.
I'll toss another of my dirty penny's into the mix here. First off.. advertised seat to seat spec's hardly mean squat when it comes to comparing one camshaft to another of similar spec's. It's well proven and any cam grinder will tell you.. the true overlap flow at that lift point is next to nothing and even more meaningless. The bigger overlap flow begins to happen at .050" and above. Which is of course why a tighter LSA cam of similar spec being compared to a wider one will have notable impact on idle quality.. changes rumpity rump and manifold vacuum. That tighter LSA's overlap flow is what helps scavenge exhaust(especially the weaker port/small valve designs like this head has) and pull fresh charge more efficiently to bump power output at peak torque rpm and below. Falls off quicker but gives a meatier range for a gear limited car like this. Using a reverse split duration design like the HO cam supposedly has.. only serves to help emissions and extend warranties(does a Mustang motor last longer if its powerband gets snuffed out at 5,200 rpm?.. or 6,200 rpm?) and is the entirely wrong direction to go on a cylinder head with known exhaust flow issues. Then add a more restrictive street header/exhaust system with chambered mufflers and you just killed even more power potential. Then there's the fact that the seat spec's are quoted from various lift ranges of .002", .006", and even .020" for the various designs. The little I've read and heard from reputable cam grinders is that the Ford cams are all over the place and serve a better purpose as cam cores than a drop in part for most applications. Just because the OEM designed it and millions have run decent numbers with them does not make them gold. Need to compare apples to apples. More aggressive lobe acceleration rate changes the TRUE overlap flow rate variables even more. Compare an HO cam to another more aggressive lobe profile @.200" tappet rise and you will see. Of course a roller cam is already more aggressive(greater area under the curve) than a flat tappet.. but you still leave much on the table compared to a more aggressive aftermarket lobe. You would be very hard pressed to open the valve too quickly for a valve size/induction limited motor like this one. Higher ratio rockers help to fix this issue. Just need to balance spring pressure(need more as the lobe/valve lift rate gets more aggressive) and parts longevity into the mix, is all. As for the phone tech guys selling you the right cam?.. laughable to say the least. The good tech guys and the custom grind shops will tell you straight out.. if you don;t like the recommendations those low ladder phone tech guys are giving you?.. just hang up and call back in 5 minutes to speak with someone else.. or phone them back another day until you get the spec' you think is right. I've gotten different spec's from the SAME exact rep.. how the hell does that work?! Far too much loss in interpretation for things like "street and strip".. or "lopey idle".. or even "max torque at lower rpm's". One man's "too mild".. is another mans "too wild". Many also don;t consider the chassis and drivetrain as well as they should either. So, the point is this. If you don't mind getting a cookie cutter cam they will just as quickly sell to another guys with a significantly different combo of parts.. simply because it "fits you rpm range".. and will only get you 90-95% of they way towards optimum power?.. most shelf grinds will easily suffice. BUT.. if you want that last 5-10%?.. talk to someone who will run your FULL engine spec's(AND consider the entire chassis/drivetrain) through an analysis software(Cam Doctor or similar). Oorrr.. talk with someone who understand the shortcomings of the actual motors collection of parts that your working on. Talking to a Chevy expert won't get you as far as you need to go on a Ford. Cookie cutter "fits all brand motors" cams get you cookie cutter performance. Some light reading with good diagrams. David Vizards books are also highly recommended to get a better grasp on how cam/valve timing affects engine performance. http://garage.grumpysperformance.co...fects-your-compression-torque-dcr.1070/page-2 And some reference material for comparing similar seat spec'd cams to others. Look at how the .200" spec's change as the lobe gets more aggressive. For your application, I highly recommend a relatively small custom XE lobe ground on a 108 or 109 lobe spread. Probably need better valve springs and fatter rear tire/s to really enjoy it though. lol http://www.compcams.com/Technical/Catalogs/CamLobeMasterCatalog.pdf PS. another trick that helps to prepare for future engine/drivetrain mod's is to choose one cam size larger(keep it minimal though) and advance it 4° while using a dual plane manifold and VS carb. Still makes nice fat torque numbers early in the rev range.. idles well enough with good manifold vacuum.. and rpm's well past a stock cam. As the motor/exhaust get's mod'd more heavily and the gears get steeper.. you retard it back to "straight up", add a carb spacer, and put a lighter spring in the VS carb to help it rpm higher and unleash more potential power. Lot's of ways to go about future proofing during cam selection. Hope that helps edumacate about cams a little more.
