Hello, I am new here and am seeking advice for a few upgrades to an F150 I recently purchased. A little about the truck and what I want to get out of it:

'94 F150, 302, MAF, 4370W, 4x4, 3.55 gears, stock 235/75/15 tires.

I've been doing a lot of reading to get ideas but wanted to run some of these ideas here to get your thoughts. This truck is my daily driver but am looking for a little more all across the board performance, especially in the low to mid end RPM ranges. I'm primarily on city streets with maybe 10% on the interstate. It will rarely tow anything, and the bed only sees occasional light hauling. Some of the things I've noticed suggested are:

Gears- lower to 4.10, 4.56. It has tires that are very low mileage and would like to keep them, at least for now but not opposed to going larger if need be but I only want to swap gears once. I live in the Denver Metro area so at 5,000' elevation this thing has a hard time staying in overdrive when approaching even the slightest incline. Are either of these two gears too low for stock tires? Maybe 4.30 is a good middle ground?

Exhaust- replacing stock manifold, y-pipe, and cats with LT headers, replacement y, new cats, muffler with a 2.5" pipes.

Engine- Replace with 1.7 rockers and leave the stock cam alone.

Does this seem like a good setup that will meet my expectations? I guess my biggest questions are with the gearing.

Any help is greatly appreciated, thanks!

 

That's a good approach if you're leaving stock heads on. I'm not sure I'd go 4.56 with stock sized tires but then again if you're mostly on city streets that might work well. 4.56 with 31s and the engine work you proposed would probably be a good combo for a reasonable price.

 

Thank you. Do you know what the appox RPS's would be with 4.56 and stock tires going highway speeds would be?

 

You would be doing right at 2k rpm at 60mph in overdrive with 4.10's. 2150rpm at 65mph and 2325 rpm at 70mph.

4.56's would be 2200rpm at 60, 2400rpm at 65mph, and 2600rpm at 70mph

My numbers won't be exact because tires differ from actual size and I rounded a little. But should be very close to actual.

You can do it yourself here...http://www.crawlpedia.com/rpm_gear_calculator.htm

 

4.10's for sure..

The other stuff is subject to personal opinion. If you're going to do more I'd go a step further and do heads and cam as well

 

Yeah, I was thinking about doing the cam also. It seems to be the Comp Cam 35-320-8 and 35-512-8 are the two recommended for the 302, I just don't understand the difference between them and which would be more appropriate for my application. Would one be preferred over the other if I do GT40 heads? Either way, I just want to make sure my stock EFI system can handle the cam and GT40 head upgrade if I decide to got that route. Thanks guys for all your responses thus far.

 

I like to use this gear calculator.
Gear Ratio Calculator
It will show you the current setup on one side and you can play with the gearing and tire size on the other side and compare them. For power your 302 will like higher RPMs after it breathes better.
Speaking of that, you didn't mention putting a K&N air filter in the stock airbox or changing to a I6 or 460 intake tube.

 

If I do GT40 heads in combination with full exhaust, cam upgrade, 4.56 gears and 31" tires, this will put me around 300hp at the crank? Will my stock EFI and fuel systems be able to handle that?

 

I would go to 4.10s on stock tires as you say now it hunts overdrive on a hill. Then you said something about 31"s if you of to them you need a 4.56 gear. Simply for the fact that 4.10 is about a 13% jump a 31" tire is a7.9% jump in height and a 12% jump in width. Pretty much negating the gear change and putting you back where you started. With 31s 4.56s are where I would go if I was in the mountains. Now if you have a manual instead of the auto I'd say 4.10s since the overdrive is about 10% higher, which is why the 3.55 and 31 combo I have isn't horrible on the flatland highway drive I have.

 

Some big picture questions before I tell you my thoughts...

How devoted are you to this truck? How much do you want to invest into making it the truck you want? How many miles on on the truck/power train? Edit - Sometimes the most effective way to improve is sell what you have and buy a better platform.

If it were mine, and the truck and power train seemed to be healthy as is, I would swap gears before getting into the engine. On the gearing front I probably wouldn't go deeper than 4.10 on stock tires. If you don't tow, the deeper gears will just be a waste to my mind. As already stated if go to the 31"s you will need more gearing.

If it was mine, and wanted to put some real coin into the truck I would do a full tear down of the block and rebuild as appropriate. Don't go through the trouble of putting power adders on a block that isn't solid. The GT40 heads, improved cam, and appropriate exhaust will net you real gains that you will notice but I don't think you will see 300hp. But you aren't after horsepower anyway, you are after low end torque improvements. An edelbrock performer intake or clone may help to maximize the combo, but they are spendy for a marginal improvement over stock. Considering, you want to stick with the stock efi, the GT40 heads may not really be necessary. The GT40's won't hurt anything, but stock heads are good for 275hp or so I believe.

Keep in mind more output from the engine will put more wear on the rest of the drive train, and anything coming to the end of their service life will get there sooner. This tends to exacerbated by "enthusiastic" driving that comes along with performance improvements.

 

Thank you everybody for your input, it is really helping make sense of things and deciding what I want to do.

So the truck is in really good shape. Engine/transmission has 164k miles. Front end has recently been rebuilt, smaller components (plugs/wires, hoses, belt, filters, etc) were all recently replaced by previous owner. The interior and body are in immaculate condition. I bought it at a very good price, so there really isn't anything that NEEDS to be done. I'm looking for more performance, but not so much where I need an upgraded tranny, EFI system, etc.

A complete tear down, while a fun project and most beneficial, isn't going to happen as its my daily driver, and only vehicle I own. General consensus here seems to be with a new exhaust with headers, high flowing cats, and 2.5" pipe. GT40 heads may be a step too far and keeping stock heads but adding 1.7 rockers will get me close to the same result? 4.10 gears recommended if keeping stock tires, and 4.56 if moving up to 31". As for tires, my question is what is the advantage of getting bigger tires? It's a street vehicle, that won't be seeing any off road action. The stock tires on it are practically brand new. Do people get 31" tires because it looks a little better, or is there something else that I am unaware of? I don't mind getting 31's if it's more practical, but only want to regear once.

Thanks again guys, you've all been a big help!

 

At 164k miles I don't know if adding 1.7 rockers is a good idea without going through the heads. At that mileage parts are pretty much worn into a pattern, other guys with more experience may have better info.
​​​​​​​As for the tires, of you aren't going to off road, stay with the stock size and go to 4.10s. The 31s look good but if you don't need them its then they just hurt mileage. But, always your choice.

 

Tire height is important to the overall performance and visual of a vehicle.

At equal rpm shorter tires cover less distance than taller tires. Shorter tires are more advantageous to in town driving as they accelerate quickly but punish you at high speeds as they need to spin faster. Taller tires are slower to accelerate but require less rpm's at highway speeds.

Changing tire height affects the overall gearing of the vehicle, which is why you would need to change your ring and pinion gears to compensate for taller tires and keep your power train rpm's in an ideal range. If you aren't satisfied with your trucks performance now you will hate if you get taller tires and don't compensate with a re-gear.

Bigger tires typically provide more contact patch surface area, but less contact pressure, a give and take which is important in different driving conditions.

Not a rule by any means, but larger tires tend to have higher load ratings. Different tires also induce height and weight changes to the vehicle as a whole and to the rotational mass at the end of the axles impacting mileage and performance.

I think that for a lot of folks the 31's provide a good middle ground on the above conditions, and provide a good look. They fill the wheel arches well and provide a little lift without needing to modify the truck.

If you have a good set of 235's now, don't plan to do a lot of highway driving, and think the truck looks good don't worry about taller tires.

 

With the stock tire size id go with 4.10. Also if you go lower then 4.10,such as 4.56 I believe you will have to change your front carrier for them to fit. I am not positive, hopefully someone who knows will chim in.

Replacing the exhaust would be the next easiest thing to do, I went with longtubes going into 2.5in Y-pipe to a 3in single. Get rid of the factory catalytic converter and either put a highflow or delete it depending on your emission laws.

Since you recenetly tuned it up, If you have not already, bump the timing up from 10 degrees to 12-14 degrees. Easy way to wake up the 302 a little bit.

 

The carrier break on the TTB D44 is 3.73/3.92
Differential Carrier Breaks | West Coast Differentials