Iskwezm

When i was in school for Ford (A long time ago) i did a lot of tuning and parts testing.We used the off the shelf cam like the Ford B cam or F cam. We used World Products cast iron heads because back then there wasnt all the choices like now.We would easlily make a dyno proven 400 hp with basic mods like 1.7 rockers,Ford B cam and World product heads,9.7 CR and it was still very streetable.

Dennis Marks

My last engine build was in1966. That's why I am so totally lost in trying to get back into this. First question-wasn't all 1993 Mustang 302's built with Mass Air? This is what I deduced from my readings. I am planning on installing both cam, lifters, MSD distributor, and Meling oil pump but am not sure what cam and head to use. I wanted to use Edlebrock Performer RPM heads and cam because I know they are a matched set, but they will not work with EFI so say Edlebrock. I want to stay away from custom cams right now. I like a lopey cam (my "old school" mentality) and hate to get something I have never heard and I cannot find anywhere on the net to listen to anything that is recommended. I like the sound of the E303 but was told it was outdated and have no idea what aluminum heads will work with it. Any more suggestion?

67mustang302

RPM heads and a Comp ots grind would work. They have hyd roller cams for EFI. And 93 EFI should be mass air, though you may need a different tb, maf etc depending on the heads and cam you use.

JamesW

I've had a series of Holley 600's... your basic vanilla vacuum secondary, manual choke versions you buy off the shelf from Summit. Out of the box they run fine. But over time, my luck has been that they tend to gum up from the fuel sitting in them. They develop sticky floats and dirty idle circuits. As I said before, I'm a weekend or less driver.

EFI, especially the design of the early SD and MAF styles, is very simple. Much much more simple than the mid-late 80s factory carbs.

Another point about efi is that it is incredibly forgiving. you can have a vacuum leak, bad wires, bad plugs....and the the system will still compensate. I thought my son's truck was running rough...wouldn't accelerate like it used to, looked under the hood and the power brake vacuum hose had come off....

Norm Peterson

I can't see any reason why the heads by themselves would not be compatible with EFI. Only the cam, which probably doesn't make enough vacuum at a sane-ish idle speed for most EFI arrangements to work with. FWIW, there is a third type of EFI known as alpha-N that doesn't use manifold vacuum at all (just throttle position) that probably would work with a lumpy-idling cam.

Aluminum heads generally allow 1/2 a point to a full point more compression ratio.

From what I understand, MAF can adapt slightly to the actual airflow up to the point where the airflow through the meter maxes the transfer function (meter signal vs airflow calibration curve) out. Beyond that point, you probably have more 'headroom' with S-D by editing the fuel map.


Norm

Norm Peterson

I'm aware of most of that (including the NASCAR vs F1 comparison), and once you get good vacuum at the boosters and velocity elsewhere there is no argument. But I really doubt that you're going to have 10 psi differential pressure at idle or small throttle openings. Maybe by 50% throttle, but not at 10%. The best "evidence" I can think of offhand is the lack of stumble you get with EFI if you're caught seriously lugging the engine. That you're less likely to actually stall EFI is also related (as well as to the "stall-saver" that a carb has no equivalent mechanism for).



The throttle body on the SuperRam in my Malibu is rated at 1000 cfm. It would be stupider than ridiculous to put that much carb on a moderately built 350 (AFR, 10.2 CR, mid 2-teenish intake duration cam), but it ran fine as a S-D EFI motor everywhere from idle to somewhere past 6000 (once I slowed the initial throttle motion down a bit for better low-rpm throttle control).


Norm

Dennis Marks

I talked to Comp a few days ago and they recommended cam 35-351-8. I also talked to Edlbrock and they recommended the Performer heads and performer Plus cam. I am glad to hear the heads will work. I also talked to Holley at the Auto Fair today and got information on their computer and wiring harness. Cost is around $1500. Anyone know anything about it. Also want to check into Painless. Have any of you kept the stock EFI? If so, what harness and computer did you use and how much trouble to put in and tune? I read an article from Mustangevolution last night about using EFI and it seemed a lot of parts had to be swapped but from what I understood from the Holley people all I needed was their unit 550-604 which includes ECU and harness. Anyone used this unit? You are a very technical person and I need you to explain what all the cam numbers mean and what increases HP. I have been comparing the specs between the stock cam, the E303 Ford, the Comp and Edlebrock cams and it means nothing to me. Please explain in a way a new person can understand if you do not mind. The E303 and the Edlebrock Performer Plus that they recommend look identical. Any of you other technical guys please explain to us technically challenged. Thanks.

Dennis Marks

Norm, please see my last quote on 67 302 and help explain cam specs to me. I like the sound of the E303 and it has the same specs as the cam Edlebrock recommended. If this is the case, I will just use the heads that match it and not have to worry about it. Thanks

Dennis Marks

Great. Thanks. I need simple and forgiving until I learn what I am doing.

67mustang302

Right, which is why I said at lower rpm and throttle positions the boosters become much less efficient. Exactly how well they work is more a function of the engine characteristics and the carb design itself. My QFT will operate just off idle in 5th gear at high altitude without stumbling etc, but it's also a very sensitive booster/emulsion arrangement that's arguably the bare minimum cfm size. Larger carb, or a different carb, more cam, less gear etc and I wouldn't be able to get away with it. Certainly most of the standard 4bbls that were used over the years couldn't come close to something like that.

And yeah, that is another advantage to EFI. Since carbs are flow/size dependant and EFI is not, EFI is WAAAYYY more forgiving of an oversized throttle body etc. While both a carb and EFI may lose power from too large a throttle in some instances, EFI almost never has drivability issues as a result, whereas a carb can simply not even function. The disadvantage or relying on some measure of restriction to function.

One thing though on the newer carb designs, is the emulsion places an emulsion hole right at about float level. While the booster generated pressure difference is practically 0 at very low throttle, and certainly not enough to lift fuel out of the well directly....the slight pressure gradient does flow air through the main air bleed and across the emulsion and into the booster. That airflow actually picks up vapors and small particles of fuel(which has a lowered surface tension as a result of said airflow) and carries it in the airstream to the booster. It's perhaps the 1 "backwards" operation of the bleed, where a larger volume of airflow actually generates higher fuel flow(to an extent).