Looking for info about 460 FI heads, are they all the same? Any aftermarket heads smog legal?
Getting ready to pull the heads to repair broken exhaust bolts.
Also looking for more performance.
Currently running a paxton supercharged 460 all else stock
except for cat back exhaust in a heavy crewcab 7400Lbs empty.

 

I'd look at some AFR's (if they make them) or Edelbrocks. Oh FMS makes some heads also. I do not know what years interchange, I'd assume most would be interchangable, just know what the cc size. Which ever you choose, expect HUGE gains in power over the stock iron.

If you are stuck with the old irons, first get them fully disassembled and cleaned to see what you have to work with. A full port job would do wonders for them. Gasket match to the intake and exhaust gaskets, clean up the valve throats, deburr the combustion chamber, etc.

If you want more performance for that blower do everything you can to uncork the intake and exhaust. Run long tube headers with 1.875" or 2" primaries, full 3" duals, with a large cased Magnaflow muffler(s) to flow and keep the sound down. You will mess yourself with the power gains of this alone. I'd say you will pick up an easy 35-50rwhp or more.

Intake wise...get a BBK twin 61mm TB, port match that to the upper plenum thing, if you have the lower intake plenum off, get it ported up also. That will increase air flow into the new heads.

Also if you have the heads off, you may as well install a new camshaft. A 224/234 would give you some hard-core power gains and work great with the supercharger being a dual pattern cam also.

 

93-97 factory 460 heads have bigger valves, but very restricting. I would recommend getting them ported. Hopefully the computer wont mind, if it does maybe an adjustable fuel pressure regulator would help with adjusting the fuel maps

 

Thanks guys,
Are there numbers on the 93 and later heads?
Sounds like a set of those ported with headers will work well and keep me smog legal.

 

I dunno, but even if you keep the stock heads that are on there now they will be VASTLY improved with a port job. I'd raise an eyebrow to if the later heads will work with the older intake manifold.

Depending on how much money you want to put into the heads, you could also stick in a slightly larger intake valve in too. But I'd do all that other stuff I mentioned if you keep them.

I'd try to figure the cost of: buying 93+ heads, rebuilding, porting them, etc. VS a set of Edelbrocks. It may be a $100-200 difference for the Edelbrocks (if so, go for them) and they would make more power out of the box than worked over stockers IMO.

FOR SURE add an exhuast of what I mentioned...long tube headers with 1.875" or 2" primaries, full 3" duals, with a large cased Magnaflow muffler(s) to flow and keep the sound down. Car Sound cat converters. This will make such a difference it isn't even funny. Heck you'll pick up some MPG too!

Freeing up that intake with an open K&N and that BBK TB will make a nice difference too.

Do you run a slightly lower thermostat also with your supercharger?

I am trying to think what else you can do to max out performance while you have everything apart and still keep the truck driving nicely.

 

Anyone seen a good rundown on interchangeability of 460 heads? The articles I have seen only mention heads up to 1979. Mine is a 1991. Somewhere I got the idea that the FI heads are different.

Seen any good performance articles that would apply to my truck?

Suggestions for searches? like 460 fi hop up - I am sure this has been covered.

Will my 1991 handle exhaust mods similar to those mentioned above or would it require a MAF conversion also?

I am not interested in building race truck, but as I replace parts I want to be aware of possible improvements.

 

I believe the intake ports wont line up and possibly the angle on the heads is different for the injectors. As long as you keep the EFI heads with the EFI intake I believe it will work on any 460 and possibly the 429

 

You don't need MAF for any reason with exhaust mods or intake mods...you may want it later on but even then if you aren't building something future high performance (just better power and economy) you probably don't need it. I have it now as it is easier to tune and more responsive to mods. Even with a cam change you can get a custom chip made for your computer and still run the Speed Density system.

I believe the differences between the heads are the cc volumes of the combustion chambers.

The 460 is like any other motor for performance... bump timing, use slightly lower thermostat, underdrive pullies, long tube headers, etc.

Doesn't your '91 have an E4OD auto if you have an auto? If so a TransGo shift kit will make that shift very nicely and a mild stall converter like 2400-2600 will get you out of the way faster and make sure to get a full lockup and keep the same economy as now.

 

Thanks again for the good info.
Just checked the edelbrock website and looks like the performer heads only fit up to 1987 models.
Looks like I'll be match porting my heads.

The only mods on my 460 for the supercharger is a different fuel pressure regulator. Thermostat is stock.
Just had the supercharger rebuilt with a higher output impeller.
I can feel the difference in power but starting to ping more in the middle.No change when you take some timing out. I think I need to bump the fuel pressure up some with a inline booster pump.
Thanks
Jerry Z.

 

Do more than the port match, if you spend a bit more on them (like the stuff mentioned in earlier posts) your gains will be far larger with the supercharger. Everything higher flow will let the supercharger work easier and make more power. Just like that exhaust system...forced induction works even better with very low back pressure (1-3psi max) and you don't need back pressure like you do on a naturally aspirated motor.

Depending on budget level and such, if you are going to keep this truck for a while (which it sounds like you are) I'd ditch that Fuel Managment Unit in place of the regulator and get some 42lbs/hr injectors and a custom tune for the ECU. I'd bet you are running very rich with that FMU and lots of power can be gained from a killer tune.

I'd toss in at least a 180* thermo or a 160* (lots of non intercooled S/C guys run a 160* due to pinging when on boost, of ~6psi). When you increase engine load via boost, nitrous, etc. You create lots more heat. If you radiator is looking quite poor consider an upgrade of a new 4 core copper brass or a 2 row aluminum. My F-150 has a 4 row copper brass, high flow water pump (30% more), and a 180* thermo....cools great but
not too cool either.

A larger exhaust system would drop under hood temps some too probably helping out that slight detonation problem you have. It will be easier for the motor to breathe.

For sure get a high flow inline pump. Not sure of your budget but I'd get around a 255-350lph pusher to fuel that 460. The high flow inlines do make a bit of noise when the Acc's are On but the motor is off...as soon as the motor is on you can't hear it. Sorta like a humming sound.

Either way, keep us posted on the progress...a supercharged 460 rocks! With some head work, intake/exhaust help, and a lil' tweaking of the tune you'll have one towing beast...or decent sleeper