pickin an SD friendly cam is quite the pesky task. . .theyre all so similar, im really wondering whether its worth doing at all. it seems like the aftermarket cams are almost dead on with the stock, especially if one opted to up the rockers to 1.7.

ive gone over the cam specs and cam cards (cam cards of the aftermarket cams only, cant find one for the stocker) over and over again, and it seems a bit ridiculous to me. maybe i got the wrong info? or seeing the stock cam card for the timing will shed some light on why the aftermarket is "better", but as of now i really dont see it that way. ive done a ton of searching, and cant find a thread that addresses the cam options thoroughly, and technically. so maybe we can get somewhere.

the things that bother me, and the cams in question:

1)stock cam
.440/450 int/ex
206*/221* int/ex duration @ .050
115LSA

2) crane cam 444232
.448/.464
206/214 duration @ .050
cam timing, from card, seems slightly less aggressive than the comp cam
114 LSA

3) comp cam 35-255-5
.478/.485
210/214
cam timing slightly more aggressive than the crane cam
114LSA

now, for the things that seem bothersome, and why selecting a cam is such a pain in the ***
1) exhaust duration is greater than any aftermarket piece - but then again, i have no idea where that duration lies on the stroke because i cant find a cam card for it. it might be that the duration is higher, but cam timing is not as "optimal". nonetheless, its awfully close to the others, with almost identical lift as the crane.

2)when comparing cam timing to the comp cam, seems like its a tad less agressive, and duration/lift is close to stock

3)seems like the most viable replacement option, bein the greatest lift of all with stock rockers, and the > duration vs crane, along with its "slightly more aggressive cam timing", based off the card comparison.

perhaps the reason its so difficult is because theyre all so similar, and none of them are "star" performers. if i could look at a cam card for the stocker, and compare the timing with the other two, perhaps it'll stick out like a sore thumb as to why the aftermarket will give a boost in power. squeezing an extra * out of the LSA suggests the aftermarket will offer a slight power bump in the mid-range, but is that enough to feel? im really starting to think the best option is to get the comp cam, and 1.7 rockers in order to feel anything. what are everyones thoughts on this? i clearly haven't done any real world testing on it, and i sure as hell dont want to be the pioneer testing all 3 to see which one is worth buying, just to find out theyre all virtually identical.

 

Here's some info...

http://www.roushyatesparts.com/v/vsp..._camshafts.pdf

 

What motor is the cam for , and what do you want performance wise.???

 

i shoulda said the stocker was what i found for the 351 flat tappet efi cam.

its 351 .060 over, i ported gt40p's, milled for ~10.5:1 compression.

i dont need advice on cam selection necessarily, i just want to figure out what specifically makes the available aftermarket SD cams a better choice than stock (both for myself and others that seek the same information). i think in a perfect world, i'd select a cam in the high 210's low 220's for duration, and in the low-mid .500's for lift for my particular setup. i think thats whats makin it so difficult to pick between these cams. before ya suggest that i swap to MAF, im gonna keep it SD for the time being, and have no problem with doing so, but i just wanna get the facts straight before i even bother choosin an aftermarket SD cam.

 

GT40P's, are you using a custom header? I thought they had a plug placement issue that made it difficult for use in our trucks.

If you're building a motor why not go to a roller cam?

 

No that's the old carbed 351HO cam, there is no EFI cam with that much duration or lift. The biggest stock cam ever installed in one of these EFI trucks is the '94+(F4TE) roller with 0.422/444" lift and 256/266 adv duration. From 1987-1991 the stock flat tappet truck cam generates a pathetic 0.379/0.395" lift and 244/256 adv duration with 0.050" duration down around 190 degrees! In '92-93 the trucks got a new roller cam but it was essentially the same grind as the earlier flat tappet cam.

Bottom line is even the Comp 31-255-5/35-255-5 cams are a healthy upgrade from the early stock cam.

 

^^^^ That explains why the "factory" cam specs looked so aggressive, LOL.
The one thing I would note (when comparing a stock & aftermarket cam with very similar or identical specs) is the ramp speed on the lobes. My guess is that most aftermarket cams would tend to have a faster ramp speed, thereby creating more area under the curve. I've been told that Crane uses more "conservative" ramp speeds, but I don't know if it's really true or not. Seems to me it would depend more on the specific grind. My brother built a 400M for circle track, and he used a Comp 260H due to lift restriction rules. As I recall, it was a single pattern profile with fairly conservative specs (almost a stock replacement). We did not expect much, but It was very impressive as well, despite it's conservative specs.

 

Yes, you can see this in the 0.050" lift specs where the aftermarket cams tend to have quite a bit more duration then the stock grinds... which have been compromised badly in the name of emissions compared to what they could be. It makes you wonder what in hell Ford was doing with these motors though when you can take an otherwise stock engine, install an "aggressive" aftermarket cam like the Comp Extreme Energy and a free flowing exhaust, and gain close to 100hp and still meet tailpipe emissions requirements.

 

I vote conspiracy....

 

Sounds good to me!

 

well that'd explain it. . .i sorta thought somethin was rotten with the factory specs, but there are so many cams used during this time frame during the transition from flat tappet to roller, that it was tough to figure out EXACTLY what i had stock ('93 flat tappet cam w/ roller ready block). combine that with misinformation associated with the internet, and me gettin sick of searchin (gettin sloppy), and it was gettin a lil ridiculous. i hate to make a useless thread, hopefully it helps others.

well that makes me feel a hellofa lot better, especailly since i actually had that absolutely horrendous cam stock. id still like to go a lil bigger than whats available, but i think ill be nicely satisfied with the brute grunt that the aftermarket has to offer.

 

this is what i thought initially, thats why cam cards (for timing) are so helpful to look at. unfortunately, the flat tappet lobe profiles cant be nearly as aggressive as their roller brothers, so i was really hoping that i was just makin a mistake with my numbers vs relying on more aggressive timing for my power gains.

 

i was aware of the "header issue" for the gt40's when i picked them. i did my homework to make sure everything work work out, and it did. i wanted to start with them for the smaller chambers, im gaining my added compression via head milling vs a piston purchase, so i wont have to shave as much off the "P's" to achieve my desired 10.5:1 CR. i didnt want to have to mill so much off the reg gt40's. the funky exhaust manifold ford put on the explorers (where i got them) made me a lil bit weary while i was pullin them, but it turned out they worked just fine, as i thought they would. it seems to me that people have the most trouble when using stock manifolds or shortys, since by nature, shortys require the primaries to stay "higher, longer", where longtubes have a much smoother transition away from the head which allows for plenty of clearance.

i would go roller, but the hp isnt worth the cost at this point. i'd have to go pick the roller parts off an explorer, and shell out the extra few hundred for a roller cam/lifter package. for the extra 5-10 hp it might free up, i cant justify spending that kinda money. especially cuz flat tappet lifter kits are $200 and under. taking all that into consideration, i might put the money saved w/ a flat tappet setup toward 1.7 rockers.

 

I know what you're saying about the added cost of going roller cam. Don't forget that in addition to a few extra HP, with a roller you'll also get reduced internal friction, cooler oil, increased cam life, smoother idle with more vacuum (as compared to an equivalent flat tappet grind), better MPG and less worries about modern oil compatibility with flat tappets. I realize you already know all these things, and they may not be of much value in your particular application. To me, the whole "modern oil eats cam lobes" thing really makes me consider converting to roller cam in any older flat tappet application....at least if it's driven a lot. Then again, maybe it's being blown out of proportion. I can't wait to see how your build comes out. I'd love to do something similar to my SD '97 5.8.

 

id absolutely love to go roller, believe me. but, ive done enough builds that have been plagued with "misewell" costs that ive actually learned to control myself (thank god). i just have too much money tied up into too many toys/projects to go all out with the spending. all of the points you made are valid, but one thing to keep in mind is the rpm range where the motor will spend its time. i'd be an idiot not to put a roller cam in it if i was building it to spin 6000+ and planned on sending it there often, but i can live with a flat tappet in my rpm range-which i project to be ~5300rpm and under.

ive learned a lot about SD and the options available since i got serious about a build. i plan on having some kinks to work out with my setup, and most likely some lean issues (ill be runnin a wideband), but i like these SD trucks and admire their cost/performance ratio. theyre simple, cheap, and i really like that even though i wont be makin incredible hp numbers. ill be postin up the results (most likely in the form of dyno #s) of the build and what i had to do to get there. im shooting to crest 300 hp at the crank (my 302 dyno'd numbers so low that i didnt even bother printing it. it was ~140 at the wheels) with a total cost of 13-1400. gonna be a budget build with a lotta junkyard parts- heads, computer, block (stripped a parts truck), and some other nonsense. its gettin there but, as always, not enough time in a day.