First post for me on this forum. I've been skimming for the past year and have finally made an account. Anyways, I bought a 68 F100 with a freshly rebuilt 300. I was wondering what all I could do to build a hot street motor out of it? I've heard you can use Chevy 292 roller rockers, but can they clear the stock valve cover? I'll be ordering a header, 4bbl intake, and cam soon. I just wanted to stay with the Six for one because everyone and their dog would or has switched theirs over to a v8, and it's freshly rebuilt and cheaper than buying an building a v8. Planning on swapping in a 5 speed and 3.73's with lockers also. And high comp pistons out there for the 300? Thanks in advance.

 

If you can find an early 240 head, they had smaller combustion chambers. It's been so long since I put one together that way, but I want to say it was 63cc vs 74cc chamber. The exhaust ports can really use some work, there is a giant bump for air injection that can go away, and there is about 1/8" of material that can come out to gasket match. On mine, I also hogged out the intake ports and added a diagonal groove to give the charge some spin. Along with late 60s small depression pistons, you're compression will be fairly high but the power is quite good. Dual EFI exhaust manifolds, and a larger Motorcraft 2BBL on an Offenhauser C series intake and the thing was able to pretty easily spin 35s on dry pavement through a freshly built C6.
The last one I built was bored to .080 over, and i used .030 oversized flat top 360 pistons. I also used a stock intake and exhaust with a Delta reground cam for mid range torque, and advanced the cam timing about 4*. This in a 78 E150 with a C6 and 2.75 gears was able to run 75mph into a 30mph headwind, and turned in high teens for mpg typically. I was very happy with this build.

 

if you had the time and money anything can be done i have even heard of fellas using 351c heads that were cut down and brazed together and building custom intakes here's a couple links Ford 300 six cylinder custom head - Hot Rod Forum : Hotrodders Bulletin Board and FORDSIX PERFORMANCE • View topic - 300 w/cut-welded 351C Head Pic a little searching on google could probably yield more results

 

Lots of info over in the inline 6 forum HERE

 

WOW! E150's aren't just a brick, they are a wall going down the road. 2.75 gears going in to a 30MPH headwind still cruising at 75? WOW!

 

That was the 300 Ford should have built, it had no problems even at that high altitude running down the freeway. That van was a sail, the old engine was tired and it wouldn't do over 65 without wind, and it was always windy in eastern ID.

 

Have you considered getting the fuel injection stuff. Converting it to MAF, and adding a turbo?

When I got my C20 I was looking for I6 F150's, and every one I wanted was gone before I got there. Or they jacked up the price off some Nigerian letter.

I even considered putting a 300-I6 in my truck among a few easy options, but my time frame is to tight for it right now.

 

It's:

240 = 68cc
Carbed 300 = 76cc
EFI 300 = 68cc ( fast burn chambers ) .

The 240 head is good for a .5 bump in the compression ratio on a carbed 300.

 

Thanks. Yeah, I avoided the EFI head because the intake valve is much more shrouded and that head is more prone to cracking between the valves.

 

I avoid them too.

 

I think you've got some pretty good tips so far. I put the 240 head on my 300, 390 pistons and have 9.8:1 compression. That helps a lot. An RV cam with the torque grind, an offy 360 intake with a Holley Economizer 4bbl carb (replace the oddball metric threaded jets with standard Holley carb jets), and headers through a low restriction duel exhaust system. I kept the 3 on the tree because old school shifting is way cool. My '66 F-100 (with functional Super Duty scoop and side badges) will outrun all but the best 390s and beat them on gas mileage by double. There's a reason UPS still uses them.

 

Sounds cool!

But I'm pretty sure UPS is all diesel now.