Does anybody know the specs on a stock 302 for '74?
The bore and stroke is the easy part. I'm looking for cam specs, cylinder head specs, compression ratio, etc. I'd eventually like to supercharge my 302 but it's good to know what I'm starting with.
There's no way to say without knowing what your motor contains. If it's all original then is it a truck motor or a car version, and if it was from a car what car? And then there's the strong possibility that something has been changed on it somewhere over it's 35year life which would make stock specs meaningless. The best place to start is with the casting numbers.. that will tell you the basics but the cam will have to be measured, any numbers you might find won't help in identifying it. The good news is the cam doesn't have to be removed to be measured, just need a dial gauge and degree wheel.
__________________
Paul O
1990 F150 4x4 XLT X-Cab 5.0, 3.55, Comp 35-349-8, Flowtech LT's to 3" single, FRPP Mass Air Conversion
Under construction: '85 351HO, Dart Iron Eagles, 1.6 RR, Typhoon intake, Crane 444232, 24lb Injectors, TweecerRT, Innovate LC-1 wideband O2
1990 Ranger 2wd, 2.3 Briggs & Stratten, 5-speed, 3.08 gears, and now power steering!!
Well it's in a truck so that would likely make it the truck block since it's original. It was rebuilt at some point during it's life, but knowing the guy who had it done, I'm sure he went the cheapest route possible. It may have just been a simple re-ring and bearing job. If it's overbored I'm sure it's done with the cheapest most stock like components that could be found.
I don't really need to know the specs of the cam that's in the truck, I plan to replace it anyway. I was just curious what the stock specs should have been for my own information. When I look at aftermarket cam specs I see all kinds of things that seem just absolutely tiny, but then I'm used to looking at cams for 350 Chevy's. I was trying to get an idea of what stock is so I could get some idea of how much bigger these "bigger" cams really are.
The engine runs great right now, but it's just anemic compared to my much more modern engines. The combination of low compression, extremely mild cam, lousy heads, 2bbl intake with lousy intake, and horrible exhaust is just choking it. The bottom end seems pretty solid though.
As such here's what I'd like to do:
Headers - Although it might not help terribly with everything else stock, it would be pointless for me to do a lot more to get air into the engine until I have a provision to get air out. A good set of headers and the accompanying exhaust will open it up for any future breathing modifications.
Most of the rest of these mods I would basically have to do together as they really all would require each other to work well.
Heads - Some CNC ported and polished heads with a large chamber for relatively low compression. I'd like to hit somewhere in the 7 - 7.5:1 area. I've seen really good things out of Trick Flow, they have lots of options for the 302. Much larger valves are a must as well. I did find that stock valve sizes for my heads should be 1.78" / 1.45". On a GM product, you can easily go 2.00" / 1.56" no problem with a 4.00" bore, hopefully Ford would be similar.
Cam - Hydraulic Roller Conversion. Hydraulic because I don't want to go solid roller and have to adjust them every weekend, roller because you can get more lift out of any given duration. Good heads usually really like lift, and with a supercharger I would hope to get as much possible out of any given duration. The duration and lobe separation I would of course get optimized for a supercharger for under 6000 RPM.
Roller Rockers - I'm very used to setting up and dealing with full roller rockers. They're a good compliment to the roller cam to help reduce wear. Different ratio's well also help me tailor the lift to the capability of the heads.
Supercharger - Weiand 174. This should be small enough to clear the stock hood and yet provide good power gains provided I keep the RPM's reasonable. A friend who works at Holley tells me that even though it is marketed for the 302, it's very hard to keep the boost low enough to work on stock compression, they usually want to run about 9psi on a 302. He said it can be done if you pull a ton of timing, however. To buy myself a little headroom and improve the breathing over stock, that's why I'm looking at large chamber heads.
Carb - Holly 750CFM supercharger carb. Holley makes carbs specifically for supercharger applications. Again I know a few guys who work there so they should be able to help me with any problems that might come up.
Ignition - I haven't completely decided what to do here yet. Weiand says that factory ignition is typically OK for low RPM's, but I'm not sure I believe it. I'd like to run a really hot ignition so I can run a decent sized gap. I've had really good luck with MSD products. I'm thinking replacing the entire distributor with an MSD unit, running an MSD coil, and possibly the 6-AL2 ignition box. It's supposed to have the capability for built in boost timing retard and the spark drop rev limiter would help me keep the blower under control and safe.
I'm sure there would be a billion other "little" items that I'm not thinking about, but those are the big ones.
Stock 302's seem to have lifts somewhere around .410"-.425", with durations @ .050" int/exh of around 208/212.
That's just roughly from memory. So, there's lots of lift to be desired, and duration is fine for pulling, but lots of improvement room is left if you want more horsepower.
__________________ 1986 F-150 5.0 EFI XLT Lariat 4x4 NP435/NP208/9" 3.50
"Custom Exhaust" and leaf spring overloads
31x10.50 15" Nothing special, but it's a damn good truck.
That duration doesn't seem real bad for a 302. I use an LT4 Hot Cam in my 350 in the Corvette. It's a 218/228 .525/.525 112 It makes great horsepower with just a good set of heads and headers.
Yeah the heads are key and the stock Ford heads are small compared to everybody elses. It certainly sounds like you have a truck motor since the car version had heads with 58cc chambers for a CR of around 10:1., the trucks heads produced about 8.3:1 CR. The stock cams were also WAY small and only managed about 0.380" lift and 244 Adv duration at the valve with 1.6 rockers.
For a blown application you definitely want to rebuild the bottom end with forged pistons and H beam rods, but the stock crank and block are fine for up to about 450hp. There are loads of aftermarket heads available for this platform now, some of them are capable of producing 400hp NA out of the box with sufficient cam, intake and exhaust, and they won't break the bank.
A roller conversion on an older block is expensive, maybe consider picking up a later block('87+) and use the factory roller cam assembly, brand new OEM style lifters go for about $120 a set new while the linkbar lifters for an older block can run close to $500.
__________________
Paul O
1990 F150 4x4 XLT X-Cab 5.0, 3.55, Comp 35-349-8, Flowtech LT's to 3" single, FRPP Mass Air Conversion
Under construction: '85 351HO, Dart Iron Eagles, 1.6 RR, Typhoon intake, Crane 444232, 24lb Injectors, TweecerRT, Innovate LC-1 wideband O2
1990 Ranger 2wd, 2.3 Briggs & Stratten, 5-speed, 3.08 gears, and now power steering!!
You think the stock pistons and rods wouldn't handle a reasonable amount of boost? I'm not looking for a drag truck, I'm just looking to make around 300-350 hp, and keep the RPM under 6000.
Stock pistons are cast and fine for NA apps as are the rods with ARP bolts but it's roulette with boost. You don't need a blower at all to get to that power level with decent heads and even the stock heads will flow enough to get close to 300hp with the right cam. Of course a NA motor benefits from more compression and most of the aftermarket heads have 58-62cc chambers since they were designed with the EFI 5.0 in mind. It seems with electronic fuel and spark control throwing 8-10psi boost on a motor that already has 9:1 CR isn't much of an issue.
There are a few examples of what aftermarket heads do for this motor floating around the web including this one...
Stock pistons are cast and fine for NA apps as are the rods with ARP bolts but it's roulette with boost. You don't need a blower at all to get to that power level with decent heads and even the stock heads will flow enough to get close to 300hp with the right cam. Of course a NA motor benefits from more compression and most of the aftermarket heads have 58-62cc chambers since they were designed with the EFI 5.0 in mind. It seems with electronic fuel and spark control throwing 8-10psi boost on a motor that already has 9:1 CR isn't much of an issue.
I know I could easily get that kind of horsepower with heads / cam / headers, but I don't want to give up the low end. Torque is where it's at with a truck motor, and short of replacing it, or making a stroker, a blower is the best way to increase low end.
Well in all honesty a 5.0 doesn't really generate much "low end" TQ and you'll still only be able to throw so much boost at it below 2500rpm before detonation becomes an issue. So if you really want a truck powerband maybe you should be looking at building a 351 instead... bolts right in where the 302 was and produces more TQ at 2000rpm than the 5.0 does at 4000.
__________________
Paul O
1990 F150 4x4 XLT X-Cab 5.0, 3.55, Comp 35-349-8, Flowtech LT's to 3" single, FRPP Mass Air Conversion
Under construction: '85 351HO, Dart Iron Eagles, 1.6 RR, Typhoon intake, Crane 444232, 24lb Injectors, TweecerRT, Innovate LC-1 wideband O2
1990 Ranger 2wd, 2.3 Briggs & Stratten, 5-speed, 3.08 gears, and now power steering!!
This forum is owned and operated by Internet Brands, Inc., a Delaware corporation. It is not authorized or endorsed by the Ford Motor Company and is not affiliated with the Ford Motor Company or its related companies in any way. FordŽ is a registered trademark of the Ford Motor Company.
