Scored a good 240 head awhile back. Actually and entire 240 out of an f600. I have been doing a slow, in frame build of the 300 in my 66 f250 4x4. As of now I have an Offy C series, EFI manifolds, Edelbrock carb and a recurved distributor. Pretty lively now. How much spunk is my 300 going to pick up once I install the 240 head? I haven't yet been deep enough into this engine to change the cam yet.

 

You will gain about 1/2 point of compression, up from about the 8.4:1 you now have. That alone will not matter much, but your extra 240 head now gives you a fantastic opportunity to built a head that will leverage the performance gains of all your other go-fast goodies into a really strong runner that will give you a noticeable seat-of-the-knickers improvement. I'd go with the following mods to the head before you install it:

ports smoothed and blended into the valve bowls which are to be opened up for
1.90" stainless intake valves w/ 30* backcut
1.60" stainless exhaust valves
screw-in studs
1.75 Chevy 250 rocker arms
polished combustion chambers
clean-up cut on the deck surface

I use cut down Chevy 1.94 intakes which are available for cheap.

 

Excellent! Thank you for chiming in. The final missing piece to this puzzle is a camshaft. This seems to be a well-beaten dead horse, and opinions are all over the place. Looking for something that will be a noticeable improvement but still have plenty of jam at the lower end of the rev range, as well as still provide good fuel economy.

 

Concentrate on cams intended for "towing" or "RV" applications that generally have about the same duration specs as a stocker cam but with more lift. There's plenty of brands to choose from. I have had good results with Crower. Their specs for the cam we used mirror the factory ones but with an additional .050" of lift or so. If you do decide to go with an aftermarket cam then it is not necessary to add the Chevy rocker arms. I noticed in your original build description that you did not list an aftermarket cam. That is why I recommended the Chev rocker arms.
A bigger cam will amplify your gains from the head even further. GO FOR IT.

 

Are you sure the engine you've got is a 240? I've never seen a F600 with a 240. All the 6cyl. powered F600's I've seen have been 300's. Someone in the past might have swapped the 240 in. You never know on older vehicles. Have you confirmed that it is a 240?

Sounds like you've got a cool project!

 

I had never heard of a 240 in an f600 but upon pulling the head, I was delighted to see bean shaped combustion chambers.

 

But did you measure the engine stroke or check the crankshaft casting # to confirm that it's a 240? Because heads can get changed during the life of the truck. What did the top of the pistons look like? Did they have a dish? Completely flat with no valve reliefs? Or did they have 4 valve reliefs?

 

Thats a good question. Pistons have a dish.

 

The 240 has a stroke of 3.18".
The 300 has a stroke of 3.98".

You could easily check the stroke with a tape measure if the head is off. To get the #1 crank throw to the bottom of the stroke just align cyls # 2, 3, 4, and 5 at the same level in the bores. Cyls 1 and six will be at BDC [or TDC if you do it wrong, in which case you will have a stroke of about .050".]

 

Then I would say there's a 95% chance it's a 300 short block. A 240 piston would have a very shallow dish with 4 valve reliefs ( same as the old 302 V8's ) Depending on the age of the F600, you might have got an even bigger score then a 240 head. I would check the crank casting #. If you have an engine out of the right age F600 then there is a very good chance it's a HD 300 with a steel crank. You probably don't need it for your build, but there are plenty of people out there willing to pay for them. If the crank has a C5TE or C6TE casting # then it's a steel crank. There's a good chance it could also have a " $ " cast into it.

And any idea what the casting # on the head is? If you want to confirm it's definitely a 240 head check the casting # and look for a " A " cast into the head under the valve cover area of the head. Here's a pic that shows where it would be.





It will also have a "A" cast on the one bottom corner by the casting #. And it will have a "A" in the casting # instead of a "T". So it would have something similar to C8AE or D2AE, etc. This pic shows the casting # and the capital "A" on the corner.




This pic shows a comparison between the carbed 300 and the 240 combustion chambers. Just to confirm what you've got.

 

I measured the stroke, and it is indeed a 240 through and through. Shallow round dish in the pistons, bean shaped combustion chambers and an A casting mark.

 

 

A great head to start out with.
hi CR
slotted pushrod holes
stud mounted rocker arms

Watch out for valve seat recession and worn guides. Both correctable.