Im getting ready to rebuild my 300 and was wondering what all i could do to give it some more power. So far i have put headers on and a holly 390 carb on it. and during the rebuild its going to need to get over board. what else should i have done to it while its apart?

 

It really depends on what you are trying to do. What age is the engine you are rebuilding? A EFI engine has a different head then a carbed 300. What is the engine going in? What are you using the vehicle for? A daily driver/work truck is going to be a different build then a light weight car that is going to be drag raced.

If you want a mild engine with a little more go for your truck then here are a few suggestions.

A slight bump in compression will help. But you just have to be careful not to raise it too high. If you go high then premium fuel or race fuel becomes mandatory. To accomplish this you can swap on a 240 head. The 240 head will give you roughly a 0.5 bump in your compression ratio over a carbed 300 head. That means if your compression ratio was 8.5:1 it would bump it up to around 9.0:1. You can also accomplish this by going with a piston that has a slightly smaller dish.

Next would be upgrade the camshaft. What cam depends on what you are using the engine for.

And if you want to improve the power you can't over look the head work. At the minimum do some bowl work. At the other end of the spectrum a full port and polish job with larger valves. Again how far you take this goes back to what you are going to use it for and what you want out of it.


And it doesn't help much with the power but I like to install ARP rod bolts if I'm rebuilding the engine.

 

its an engine from a 1983 f150 that i want to be my everyday driver and have some more power when i go off-roading. not looking to throw to much money into it but since its going to be apart just wanted to up grade it a little.

 

Since you're rebuilding I would keep the head you've got now (assuming it's not cracked or anything) and raise compression by having the block decked to put the pistons at zero or .010" below deck. Stock the pistons sit ~.0433 below deck so taking it to zero would bump compression to right about 9.0:1.

Decking will also improve quench in the chamber which should help low end and ease potential for pre-ignition.

Porting the head would be a huge plus, but at the very least have them cut a 3 or 5 angle valve job and backcut the valves.

And, of course, a cam upgrade will make a big difference as well. The Comp Cams K-kits are a good value - comes with springs, timing gears, lifters, etc.

 

I agree with everything Fordman and Baron said. Furthermore, I would add four other things to consider: Intake manifold, carburetor, ignition system, and exhaust. All of those, dependent on your intention, could be upgraded, and there are positives and negatives with each increment of each upgrade. Your needs and wants will determine what sort of performance 'pie' you come up with. You just have to add the correct pieces for the desired pie.

Read a lot before making choices. Good luck.