I have an original non roller 302 in my 71 f100 and I have a burnt valve and need to get my heads machined. Will the heads off a 91 roller 302 fit my non roller block. Or should I just rebuild the 91 roller and put it in the truck although I want to keep as original as I can. Please help cant find any information saying yes or no about the heads. All I can find is what the difference is with lifter bores and spider plates and cthe cams and oiling.

 

Just now getting into motors and lack knowledge.

 

The new heads will fit, but they use pedestal type rockers, while the old heads have stud-mount rockers. Swapping them may require new pushrods.

The two engines have different balance, so you need to keep the harmonic dampers and flywheels with the engines that they came with.

The new engine uses a single serpentine belt for the accessories, so you will need to keep those with each engine as well.

The old engine has a mounting boss for the clutch equalizer pivot, while the new engine does not. If your truck uses hydraulic clutch, or you have automatic, that's not an issue.

Otherwise, the engines are interchangeable.

 

Ok so I should be able to get newpush rods and be ok with the heads? Because thats all im changing out. The roller I got is dis-assembled down to the block and lacks somethings like pistons mainly. I was just wanting to make sure if I bolted on those heads to my original 71 motor it wouldnt cause any issues.

 

And the motor is backed by a c6 automatic.

 

There is nothing carb or EFI specific about any of these SBF heads... they will work equally well on any motor as long the valvetrain is setup correctly.

 

The pushrods are the same length for both style rockers. The part about the serpentine belts is not true. You can use either style FEAD (Front End Accessory Drive) on either block, as long as you do not mix the parts. (timing covers, waterpump, brackets, etc) Now the question needs to be asked is, what heads are you wanting to use (casting numbers) There were two heads used in 91 (excepting the GT40's here) the E7TE's had 64 cc chambers, the E6SE heads had 68 cc chambers, your 71 heads are probably 58-60 cc. so you'll get some loss in the comp ratio in the swap.

 

Sorry, should have said "keep the accessories together with the belt types". That includes the front cover and fuel pump and eccentric on the cam. It seems a real hassle to swap these between blocks

 

It can be a hassle, very few parts can be interchanged. Like the timing covers. But there are reverse drive applications that used the std rotation cover.

 

Idk casting numbers at the moment I can get them tho and will post them up here. How much compression can I lose with the swap? Cause im not after power or anything use truck for cruising only. But I dont want to end up having a worthless motor and having to get another one again. But with the swap I only planned swapping just the heads. Unless I have to swap more.

 

You will drop 3/4 of a point in the ratio assuming a 6 cc increase in the combustion chamber. If it's 9.5 to one now, that'll drop to 8.86. If it's 9 to 1, then it'll go to 8.33. Acccording to the one book I looked up the ratio in, you've got 9 to 1 now. Of course you can always mill the E7's .040 to gain back the loss without getting into intake fit problems. The .040 mill will get E7's to 58 cc chambers.

 

Ok so how much of a difference will that make as far as performance and such. Will it affect anything such as fuel mileage or anything?

 

It will move the performance and fuel economy downward.. I would get the E7's milled before using them on that short block. After they're done, take a die grinder and a hone bit and take the sharp edges off the corners of the chambers to avoid having hot spots at the sharp edges. I wold also recommend using a porting bit and removing the Thermactor bumps from the inside of the exhaust ports. This is an easy operation to do that does a lot to open up the exhaust ports

 

Once I do that will it restore performance and fuel economy?

 

Milling will keep the comp ratio as it is now. So no change there. Removing the Thermactor bumps will allow it to breathe easier that will net you some gain, how much I cannot say, but the effort to remove them is minimal, so it's a win-win deal. With a good porting bit it takes all of an hour's work to remove them. Even Ford recommended their removal in their performance literature.