So I have a 78 ford f150 with a 460 that I am rebuilding and the block is going to the machine shop and I can not figure out what to do about the fuel issue I am going to have because the parts I already purchased I did not realize that I am not going to be able to use pump gas because its 11.1 com ratio and now I just found out that with my new ported d3 heads I wont be able to use pump gas is there another alternative like aluminum heads

 

You can with the right camshaft choice to bleed off some of that compression. I'd go with a custom unit from Comp Cams, Howard's Cams or Buddy Rawls.

Also actual compression is usually lower than calculated, unless you actually measure head gasket crushed thickness, Piston-to-deck clearance, piston dish/dome CC and combustion chamber CC.

Look up Dynamic compression ratio, you should be able to make it work with the right cam.

My Aussie head 408 is about 10.25 : 1 static compression, Dynamic compression is around 7.8 : 1. On pump gas you want less than 8 : 1 Dynamic

 

Agree mixing race gas is no fun, especially on a PU. 11:1 just isn't going to work with pump gas. Your best bet is different pistons. That's far cheaper than different heads... besides 11:1 wouldn't work with even with aluminum heads.

I don't know what's available in "shelf stock" for that combo but Ross Pistons, Diamond Pistons, JE pistons or others will make a custom forged piston to match your head and desired CR for +/-$750. If you are working with a machine shop, they might have a bbrand preference.

With iron heads, I'd be looking for 9.0 - 9.5 compression. If there is a suitable stock piston, cost would be lower.

 

Agree mixing race gas is no fun, especially on a PU. 11:1 just isn't going to work with pump gas. Your best bet is different pistons. That's far cheaper than different heads... besides 11:1 wouldn't work with even with aluminum heads and anything short of a drag race cam.

I don't know what's available in "shelf stock" for that combo but Ross Pistons, Diamond Pistons, JE pistons or others will make a custom forged piston to match your head and desired CR for +/-$750. If you are working with a machine shop, they might have a brand preference or deal. If there is a suitable stock piston, cost would be lower.

With iron heads, I'd be looking for 9.0 - 9.5 compression.

 

This may sound dumb but could you use a thicker head gasket to knock it down just a bit?

 

I just rebuilt my 429 and I went with flat-tops. I have the old '68 heads and I calculated my CR to be 10.85:1. My engine just got to the point where I could start for the first time just last weekend so I have not really tuned it or driven it but the high CR did enter my mind when I was selecting pistons but in the end, I wanted the power! For the cam break in, she ran real good on some regular gas.

Here's a few things you can try doing IF detonation becomes an issue under normal driving:

Convert to E85 (need a carb and maybe some new fuel lines) You'll get the higher octane, MPG's will take a hit but you'll have the power!

Add methanol / water injection (fairly cheap and seems to work very well)
Back off the timing (MSD makes a control you can mount under your dash)
I discussed this potential issue with my machine and he also suggested I might try thicker head gaskets BUT there's this thing called quench that you really do not want to mess up.

Buy off the shelf flat tops and have the machine shop make some reliefs in the top to give you a few more CCs. There is usually enough material in there and can be done cheaper than ordering custom pistons and will drop your CR. You'll want to have the assembly balanced. Also, did you check the deck height on your 460? If it's a later model, they have a slightly taller deck and will probably yield a lower CR all else being equal.

I'll probably run premium in mine because it will be more of a toy rather than a daily driver. If you are looking to use your truck as a DD and are willing to sacrifice some power then drop the CR to 9.5

 

Those heads have 95cc chambers. Just wondering how you got to 11:1? Big domed pistons?

 

OK, There are a few myths here. 11:1 WILL work on pump gas. My 545 is 11.1:1 and runs fine on 91. I am at 6000 ft elevation and run aluminum heads. If I go to probably less than 4000' It is over for me on pump gas. Figure out every factor before you start giving advice. If you have good quench, run it cool, and run little timing and the right cam, it might be possible. Or, you might need lower compression. On another note, I have ran a 460 and a 390 that were also at 6000' that were north of 10:1, maybe close to 10.5:1, and they ran on 85 octane fuel. Iron headed. Do your research, and do a compression ratio calculation to figure out the actual numbers. People that say it is impossible probably aren't much help. How fast will it spin? How hot will it run? manual or auto? how heavy is the truck? will it ever tow? All factors for determining CR and pump gas territory. Elevation? Do your research before buying anymore parts. You probably learned a lesson here. Call Isky for a cam recommendation. They know their stuff.

 

flat tops, zero deck, and a slight cut on the D3 heads will get well over 10:1. Domes will go north of 11:1 with D3 heads.

 

If you can afford it, find someone in General Aviation and find a way to buy 100 Low Lead. I assume you will not have a catalytic converter, so this would be an alternative if it is not your daily driver.

 

.....how did you get the 11.1 number? What pistons did you get? There are too many variables here starting with the D3 heads. Try searching here.......460 Ford Forum I belong there as well and there is a lot of info that will pertain to your set-up.