Hi All,

As you've read in my previous posts, I have a 93 F150 4x4 5.0 AOD 3.73ls with 36" (soon to be 35"). I have a problem with it downshifting often out of ODto keep highway speeds (55-70) when going over overpasses. I've had great suggestions on gearing to 4.10s front and back.

I don't normally drive deep offroad (in fact I haven't gotten to take it offroad yet). It has 200k miles on it. I want to rebuild the engine and convert the S/D to MAF and pull more power out of it, with a power cam, and ignition and probably injectors.

I have a couple questions here. Since I can't afford to re/build the engine and swap the gears I want opinions on what I should do first.

Second question is, can I build the engine for more low end torque and have that minimize my downshifting problem? I would think if I can change the torque curve to lower rpms then the engine shouldn't have to kick the tranny out of O/D to maintain speeds. Am I off-base in my thinking?

I am looking forward to all opinions, comments and suggestions here. You all have been great with knowlege and I've learned alot more about my truck in a short period of time.

BTW, once I get the engine rebuilt/built and the drivetrain solid, I am stripping the body off and building a complete new cage H1 replica on the frame. I know I'm going to get a ton of comments on that. I love the H1's and want to build a replica. I also prefer a Ford drivetrain underneath since I grew up in a Ford family. I can't wait to hear all your feedback. LOL

Rick

 

I vote gears, but don't stop at 4.10, go 4.56. You can't really get a lot more TQ out of a 5.0, and even if you did the tranny is programmed to downshift on throttle changes anyway, so it won't make any difference. Put lots of gears in the pumpkins, and bolt-on a set of 1.7 rockers until you can build the motor.

 

Conanski,
The 1.7 rockers will make a difference even without a new cam on the S/D, until I can convert it? That's good to know. I was thinking of going only to the 4.10 gearing due to the chart on here somewhere that showed tire size with gearing. The 4.10's appeared to stay toward the mileage improvement side. I plan to make this a regular driver when I'm done with it, so I wanted to compromise a little torque for mileage. What do you think?

Rick

 

With stock tires on your truck it would be turning 2200rpm at 70mph. With 35's you would need 4.88 to retain the factory gearing ratio, anything less hurts performance and milage considering the relatively poor low rpm power this motor generates. You're not going to get quite as good milage with the big tires just because of increased drag and weight, but milage is also related to throttle position and load on the motor. If you can relieve some of the load with bigger gears you'll see improved milage up to a point, but too much rpm begins to hurt milage again of course.
The 1.7 rockers will help and are compatible with the stock EFI system, you can also bolt-on headers and open up the exhaust without issue.

 

Paul,
After having done a major tuneup on the truck when I got it because it ran like crap, I found that the heads are not for an F150 but for/from a Crown Vic. I figured this out because the spark plugs for an F150 wouldn't fit. The guy at Advanced Auto went through the book with me and the only 5.0 that took these plugs were the Crown Vic. My question from that ramble is basically if the 1.7 rockers will still work on a "Crown Vic" head? Also, when I finally do cam it, will that lift and rocker combination put me in danger of damaging a valve on the pistons?

I'll look into the gears again, and going with the higer numbers. I basically went off the chart from http://4lo.com/calc/geartable.htm that showed 35" tires with a 4.11 gear having the rpms of 65. I'd be interested in how you figured out the rpms for me, because I'm trying to learn all I can about these things. I'm new to regearing and all.

I'm also surprised that no one else has commented or offered advice. Did I offend someone by my tearing down an F150?? LOL

Thanks for your advice. I'll be doing alot of research this weekend.

Rick

 

If your re-doing the engine...why not find a 351, rebuild it and drop it in (plus a few minor adj)

 

What you have uncovered is a dirty little secret. It seems there was a surplus of either E6 heads or complete car engines, and Ford threw them into whatever vehicles could take a 5.0 until they ran out. You are not the first guy here to discover they have heads that were never spec'd for the truck motor.


It depends. If you get a cam with big lift you could be in trouble. I don't believe the E6 heads present any more of a problem than the E7 heads as the valves are more recessed in the heads, but it will be necessary to test the combo if the total lift approaches 0.500". It's always a good idea to check for valve clearance when making valvetrain changes.

I simply used an online engine speed calculator like this one. http://www.csgnetwork.com/multirpmcalc.html

 

Bad idea unless you are thinking of some serious forced induction and/or over ~450hp. If thats not your plan stick with stock injectors.

 

Correct me if I'm wrong, but from what I've found, the 5.8 only had like 20hp more and a little more torque.

I wasn't planning on going very extreme. I had seen on here that the Comp Cam 35-308-8 was S/D friendly (until I can convert) so I was planning on that. Summit Racing list the lift as .533/.533 so it appears to exceed the .500 you mentioned.

I am also going to look at the calculator you mentioned.

Building up to 450hp doesn't fit in my wallet. I'm just trying to get hopefully into the 300s so the truck doesn't lug so bad with the weight of the new body. So I won't worry about injectors then. Thx

Paul, ssidney and eco, thanks for the replies.
Rick

 

The posted numbers you see for these motors are very misleading. Yes the peak HP numbers are almost the same, and they should be as both motors use the same heads and on later motors the same cam. What the number don't show you is the low rpm TQ advantage the 5.8 has over the 5.0, it's probably 100ft/lbs at 2000rpm.. hugh difference.


The 35-349-8 may be a safer bet, you'll be limited to 1.6 rockers with the other cam for sure.


The stock 19lb injectors won't support much beyond 300hp without increasing fuel pressure, and i doubt the pumps will go beyond this as well.

 

gears would be your best bet 4.10 or 4.56 but if u dont intend on doing much off roading then i would go with the 4.10's

 

to get the real difference between 5.0 and 5.8, drive one of each under same cond. and see, the hp and tq may be close on paper directly, but I'll bet the 5.8 has a much broader power band (ie you can get an easy 300 hp out of a 2.3l but would you want it in a truck?)

 

Good point. I'll look into it. Although I don't think there are many around here cheap. They seem to ask a premium for them still. I may get lucky and find an old Bronco with one. I would guess I should find one with EFI and preferably MAF so I don't have to go converting it. Could I use my 5.0 EFI setup on a 5.8 if I find an older carbuerated one? I am thinking not but I don't have much experience in that area.

Rick

 

for the price of a good rebuild you should be able to find a complete, used 5.8 and ecm out of a truck thats been wrecked...may just take a little time

 

No, you didn't offend anyone and at least you ask alot of questions...that's a good thing.People's answers to everything when it comes to a 302 is drop in a 351........with a little bit of work to a 302 with mostly just bolt ons you can get a good motor......the 1.7's would be a good investment until you can get the cam yes but Paul's right...with the advertised lift being that high it'd be a problem with a cam swap and ou'd have to go back to the stock 1.6's.....unless you decided on 1.6 rr's......If I remember right our trucks come with a low to mid .300 lift on em......another thing to think about with the Roller Rockers is they may not clear your Valve covers....I ended up using VC's from an 80's model 302 because they're nearly an inch taller than the ones on our trucks....and I STILL had to trim and re tack my baffles to clear the rockers.....A 351 swap may be easiest for you but I built my 302 a little bit so when someone asks what I did to that 351 I can smile and tell em what it really is.....I think I'll be cammin it soon though.....Good Luck and keep askin questions.

JR