5.0 Rebuild Questions?
#1
5.0 Rebuild Questions?
History
I started rebuilding my 302 from my 1990 LX with the intent to keep it cheap but add a little horsepower so I intended to mock a 1993 Ford Cobra setup. The intent was to get some horsepower gain but still maintain the "daily driverness" I wanted. I have no intent to shave .5 seconds off the 1/4, just .5 seconds off the stoplight to stoplight times. With that in mind, I started looking at the specs for the 1993 Ford Cobra and found several upgrades others were doing, sooooo, I decided, maybe a slight upgrade from just what the 1993 Ford Cobra offered.
Planned Setup
Questions
* No matter what, I'll still check the PTV clearance and I will measure pushrod length and I'll be using harden pushrods.
I started rebuilding my 302 from my 1990 LX with the intent to keep it cheap but add a little horsepower so I intended to mock a 1993 Ford Cobra setup. The intent was to get some horsepower gain but still maintain the "daily driverness" I wanted. I have no intent to shave .5 seconds off the 1/4, just .5 seconds off the stoplight to stoplight times. With that in mind, I started looking at the specs for the 1993 Ford Cobra and found several upgrades others were doing, sooooo, I decided, maybe a slight upgrade from just what the 1993 Ford Cobra offered.
Planned Setup
- 302 block bored to 4.030" - (scored in one of the cylinders)
- Stock crank & connecting rods
- Speed Pro ZH273CP30 pistons
- Ford Racing M-6049-X307 heads
- Crane Cams 444225 (2031) camshaft
- Crane Cams 36530-2 roller lifters
- Crane Cams 44746-1 1.7 roller rockers
- Ford Racing M-9424-Z51 Cobra Intake - (if I can find/buy one)
- 24lb injectors, upgraded fuel pump, etc.
Questions
- Before ordering the pistons, is there going to be a PTV problem that I can take care of now instead of ordering the pistons and finding out later?
- Although Crane Cams specifies Crane Cams 44308-1 valve springs and retainers, can the valve springs and retainers on the X307 heads be used instead?
- Does anyone see any problem areas that I need to address?
* No matter what, I'll still check the PTV clearance and I will measure pushrod length and I'll be using harden pushrods.
#2
My suggestion to both your question 1 and 2 would be to ask Summit's tech guys. I had the same questions with Probe Industries when it came to how much lift the pistons could take. They'll be able to tell you. I ordered Trickflow heads with a Comp custom cam, my springs were fine for the cam. I would "assume" that yours would be the same.
One thing I would check on with that camshaft, it stated the lift is .513/.529. I would check to see if that is with a 1.6 or 1.7 rocker arm, as it states in the notes that its for a 1.7.
Other than that, I don't see anything wrong with the combination. I haven't seen anyone run those heads so I can't give feedback on them. They are nice heads for the price.
One thing I would check on with that camshaft, it stated the lift is .513/.529. I would check to see if that is with a 1.6 or 1.7 rocker arm, as it states in the notes that its for a 1.7.
Other than that, I don't see anything wrong with the combination. I haven't seen anyone run those heads so I can't give feedback on them. They are nice heads for the price.
#3
I ran that cam for years, with the 1.7 Crane Cobra rockers, and liked it a lot, good driveability and even gas mileage. I'd pick Trick Flow TW heads over the Ford X heads - bigger valves. I also ran the Cobra intake for a while, but switched to the Holley Systemax and liked it a lot better. The Edelbrock intake would also be a fine choice. You'll like the part combo you're putting together, it will make significantly more power than factory....
#4
Thanks for the help fellas. reldla1996, I'll definitely check those heads and intake out.
One more question though, biggers valves doesn't necessarily mean worse gas mileage, in most cases better gas mileage, correct?
I know it sounds funny to worry about gas mileage in a V8. I'm just trying to put together a good combination for what it's for, daily driver and some drag racing between stop lights.
I'd pick Trick Flow TW heads over the Ford X heads - bigger valves.
I know it sounds funny to worry about gas mileage in a V8. I'm just trying to put together a good combination for what it's for, daily driver and some drag racing between stop lights.
#5
Technically, with a bigger valve you're letting more air into the chamber. Therefore you can mix more fuel to get the proper ratio. However, its not enough of a difference that I think you'll be able to notice it in mpg's, especially in a smaller v8. The difference is probably balanced out w the weight savings you'll have w aluminum heads
#6
You should always use the valve springs that the cam grinder says to use.
He may know something about what he grinds.....
The PTV clearance issue is going to be solved by mocking up the engine and seeing what you get for the clearance.
I wouldn't be happy with less than .100" but I'd sure like to see .120"
He may know something about what he grinds.....
The PTV clearance issue is going to be solved by mocking up the engine and seeing what you get for the clearance.
I wouldn't be happy with less than .100" but I'd sure like to see .120"
#7
As I was adding engine modifications one by one in past years, I lost about 1.5 mpg when I added the 1.7 Cobra roller rockers, and then gained the 1.5 mpg back with the trick flow heads. The rockers effectively made the cam bigger (duration and lift), which hurt the gas mileage. I'm not sure why the heads helped, but that is what I consistently calculated. When I was done, I got the same 20 mpg around town that the car got factory stock.
#8
As I was adding engine modifications one by one in past years, I lost about 1.5 mpg when I added the 1.7 Cobra roller rockers, and then gained the 1.5 mpg back with the trick flow heads. The rockers effectively made the cam bigger (duration and lift), which hurt the gas mileage. I'm not sure why the heads helped, but that is what I consistently calculated. When I was done, I got the same 20 mpg around town that the car got factory stock.
I know that you can get more lift with a bigger rocker ratio but I want to know about the duration.....
#9
i would check the clearance on the valves and pistons they may need to be fly cut...I have a new cobra intake in box if you need one. i would buy a cam based on a 1.6 rocker...and later you can add 1.7 for more lift without making a cam change..you need to tell your machinist what rings your going to use so he can hone the walls with the right grit..
#10
When you increase the rocker ratio, it increases your cam lift everywhere, including at the common 0.006 advertised duration and 0.050 duration measurement points. For example, Going from 1.6 to 1.7 rockers, will increase the lift at what was .050 to .053, while the duration is unchanged, say 220 degrees. That means the new .050 duration is now something greater than 220 degrees, because it now happens both earlier and later on the cam. Not a big difference, but measurable, and on cam duration, it doesn't take much to be noticeable.