302 needs more power

[Johnnewc]

I have a 69 f100 with the stock 302 in it. It is fully rebuilt and had to take it 0.030 over bore. It has a autolite 2100 on it rated at 300 cfm. No other modifications. Want I want to know is if anyone has put an original cast iron 4 barrel intake on it with a 4 barrel autolite? If so what was the power like and how did it run? The reason why I ask is that this truck can't get out of its own way. It is slow. The engine runs great and sounds good there is just no power. Thanks for the help and suggestions.

[cep62]

What gear ratio do you have? if it's 3:00-1
that could make it sluggish.
A 3:50-1 gear is a good all around gear , depending on your tire size.

Holley makes a 500 cfm 2bbl that will bolt on to your stock intake.
That might be an economic way to wake it up .

[Johnnewc]

It has a 2.91 gear in it now. I have the original 3.50 gear. It came with the truck when I bought it. I didn't change it the previous owner did. I guess I didn't realize that the little bit of a difference between gear numbers can make so much of a difference.

[cep62]

It also depends on how much hi-way driving you do.
If you're going 70 plus every day the 2:91 would be a better choice.
If not you need to decide what your priorities are.
Maybe a looser torque converter will help off the line but lock up when rolling down the road.

[jamesdfo]

John: Well, a 2.91 gear is great......if you're running it downcourse @ Bonneville:)

If you have 3.50's, I would try them, but depending on tire diameter, you may find them a bit much @ freeway speeds. If 3.50 is too much, I can tell you from personal experience that the 3.25 works well all around:)

I wouldn't bother with a cast iron 4bbl intake, keep your eyes on CL, etc for a dual plane aluminum intake, and a Holley 390 4bbl carb. These days the intake should be pretty reasonable, the 390 may take some digging to find, but again, from personal experience, it will work well for your application.

The gears, intake and carb will make a difference, but you're leaving a LOT on the table if you're using a "stock" type cam, and presumably OEM cast exhaust manifolds and a single exhaust.........

HTH
James

[Johnnewc]

Thank you everyone for your help and advice!

[jamesdfo]

John: Link below will let you do the calcs to see what your RPM is with an alternate axle ratio. For trans ratio, assuming high gear is 1:1, enter 1, if you have an OD trans, enter a decimal number, eg 0.7.......

If you have any trouble calculating your tire diameter from a metric sidewall size, I have a crude spreadsheet I cobbled together that does the math, PM me with an email address and I'll send it to you.
OR, just post your size and I'll tell you the diameter.

https://spicerparts.com/calculators/tra ... calculator

[My427stang]

Fun with math

3.50-2.91=.59

.59/2.91=.20=20%

20% more torque multiplication with the gear change, 20% higher cruse RPM

I would likely do that first, then I would consider having the distributor recurved. It won't help WOT that much, but it will help part throttle significantly. Stock distributors are set to let anyone run any fuel anywhere, which means you trade performance

Then the 4 barrel, the stock one isn't a high rpm powerhouse, but if the 302 is pretty mild, it'll help. Headers wouldn't hurt, the but three things above will help more.

[jzjames]

The autolite 2100 is fine, I wouldnt mess around with carbs, but I would put the 3.50 gears back in.
Keep it simple.
Headers would be nice, a little more power. The differential is your problem.

[mbloes]

I have the exact same truck with the same motor. It's essentially stock but here is what I've done so far:

Holley 2300 carb. I believe this is 550 cfm. Works great but I can actually watch my fuel gauge drop as I drive.
Pertronix electronic distributor / coil / etc.
I also went with a 3.0 rear end to give it more "freeway". I can cruise at 65 without feeling like i'm overreving.

It's still a work in progress but I believe I'm moving forward with it.

[image]1472[/image]

[Johnnewc]

The positive part about having the 2.91 gear in the differential is the 13.7 mpg I got while driving around in town. Which I think is great. So I guess I shouldn't complain too much about the power. I'm 23 and plan on driving this truck daily like I do now into the foreseeable future till I die basically. So I might as well keep it as economical as I can. Who knows what cars will be like 50 years from now.