A good option if you go with a 302 would be a '97-'99 Explorer engine. They are the most common of the higher-power 302s. Those GT40P heads are a serious improvement over all of the basic small block heads (excepting the Boss 302 and possibly the early 351W heads). Probably the next best head is the E7TE, but the GT40Ps (and probably the regular GT40) are still better.

The only thing I don't like about the EFI exhaust manifolds on the 300 is the sound - it makes them sound like a (just another) V6. That old restrictive log manifold from the carbureted Big Six provides such a nice smooth exhaust tone.

 

Some myths here the GT40P are decent heads but may need P exhaust manifolds to clear the revised spark plug angle. The difference between the P heads and the GT40 is not huge. The E7TE heads are= about the worst flowing standard valve size heads, unless you are just looking for compression bump from earlier big chamber heads they are not worth the effort. The 70's smog heads and basically any 2v non small valve (221 260 head) head will outflow the E7TE's, there were not a great head. But in the era of big smog chambers, they were a cheap and available and offered a badly needed compression bump on the smog motors as some of the 302's in the 70's were as low 7.4:1
The early 351W were the go to for many years before the GT40's came along. But today in the era of aftermarket heads you are better off just going that route unless budget is a concern.
The aftermarkets have modern combustion chamber designs and will handle a full point more in compression being aluminium.

 

I'd always heard that the E7TEs were about the same as all of the SBF heads before them, but more recently I'd read some statements that the E7s were better than the older heads. Probably that higher compression.

I think that the three bar Explorer GT40s are not very common, and one is most likely to find GT40Ps when searching for an Explorer engine.

 

I hear that a lot. Mostly from people that have either never owned one, or only owned a stock one. They never modified one. A modified 240/300 makes for a fun ride. Hell there are guys that drag race them. It's all about what you do to them.

He was also asking about fuel mileage. So that kind of rules out any big block engines unless it's a diesel.






The 240/300 are long engines. So when you run a single carb on them, you can run into the issue of having some cylinders run rich while others run lean. Running two or three 2V carbs gives you a more even air/fuel mixture distribution to all the cylinders. The 300 has some big cylinders. They basically have the same size cylinders as a 400 V8. So they can handle more carburation. A lot of people and carb calculators say the 300 should have a 4V carb in the 390-450 cfm range. I've built and ran 240/300's with a bunch of different carbs. They always seem to run better with a 4V carb in the 500-600 cfm range. On the 2-2V set ups If you go with a matched pair of Autolite 2100 ( 1960's ) or Motorcraft 2150 ( 1970's ) you are good to go. The Autolite 2100's are sized from .98 to 1.33. You will find the # on the side of the float bowl in a circle.

Here's how those #'s equate to cfm.

0.98 = 190 CFM
1.01 = 240 CFM
1.02 = 245 CFM
1.08 = 287 CFM
1.14 = 300 CFM
1.21 = 351 CFM
1.23 = 356 CFM
1.33 = 424 CFM

But 2V carbs are rated differently then a 4V carb is. Divide the 2V cfm rating by 1.41 to get it's equivilant to a 4V. On a stock or mild 300 go with Autolite/Motorcraft carbs in the 1.02-1.23 range. Stay away from the .98's ( too small ) . The 1.33's are harder to find and not needed on a stock engine.


Basically porting is just smoothing out/improving the air flow of a engine part. Most people use a die grinder ( either air or electric ) with carbide burs, sand paper rolls, grinding stones etc. But I've also used and seen people just use a drill with the same burs, sanding rolls,stones, etc. , it'll just take longer. You can do a search for porting on youtube. It's basically the same basic idea as porting a cylinder head. It's a lot easier to see some one doing it then to just reading about it. The goal isn't always just making the ports/passages bigger. The idea is to smooth out the path for the air flow. The 240& 300's are pretty restricted stock. I started out using the sanding rolls when I was first learning. They remove material slower. So you can get the feel of doing it without worrying too much. It is time consuming. I've got into porting a head and just kind of loose myself in it and before you know 5 or 6 hours have gone by.



A inline 6 will never sound like a V8 when you stomp on it. If you need the V8 sound, then swap to a V8. Otherwise you'll never be happy. I love the sound of a 240/300 with a big cam. They sound great. And during acceleration they kind of remind me of a old detroit diesel.

Here's a youtube video of a 300 with a performance cam and open headers. At idle it will confuse some people!








You don't need to run dual exhaust with the EFI exhaust manifolds. Just run a Y-pipe into a single exhaust. The 300 never sounds like a V6.



The P's are much more common. There are in a whole lot of 98-2001 Explorers. The explorer 3 bar GT40's are 96 & 97. But they are out there. I got a set for one of my 351W's. The 3 bars GT40 heads have larger exhaust valves then the 4 bar P's do.

 

Actual flow testing on the E7's has shown them to be the worst flowing small block heads after the small valve 221/260 heads.

The GT40 heads are not as common but also have no plugs clearance issues with standard style exhaust manifolds. They were used on the Lightning the Mustang Cobra and the Explorer. Ya not as common as the P heads but not uncommon either