So I just went to visit the local machinist that did my block and head work just for a B.S. talk and visit to see how they were doing.

I love going there because it make me wanna do more work to my truck anyways, I was wondering if I redo my head or get a spare one from the J/Y which are the valves that you would go with or have used??

Would there be a bigger benefit to it?

 

The Ford 400, which has 50 cubic inch cylinders like the 300, had 2.05" intake valves. The 300 has 1.78" intake valves. So in its stock form the 300 is severely under-valved.

Does it make much difference in the typical 300? Considering the intended usage - chugging along below 3,500 rpm - not really. But if you're planning on getting your foot into the gas and winding it out then bigger valves will let the engine breathe better. If you're going to port the head and get a three angle valve job anyway the cost of the bigger valves is negligible.

SBC valves (1.94"/1.60") are what most folks recommend. SI valves makes 300 specific valves the same size in the correct length for ~$14 a pop. A shop may have some used SBC valves sitting around, or new stock replacement type are ~$4 a piece.

 

I agree with most of what 'Barron' said, except the part about using sbc valves. I used sbc valves. It can be done ... if you use all sbc valve hardware: keepers, retainers. You see, the sbc valves are longer than the Ford valves, so it throws off the geometry of the v/p.rod/rocker. Also, with a longer valve, it changes the tension of the v.spring. Yes, a good builder can set all that up correctly, shimming the v.springs, etc., but do you really want to spend the time and $ to have it done? You'll spend far more having this done than you save on the cost of valves. I thought I had it correctly set up when my v. keepers let go on one valve, and it was a miracle it didn't drop into the c.chamber/engine.

Anyway, if you're going to use the over-size valves, use SI valves made for a ford. By doing that you eliminate a slew of problems. And, be aware, there are two different length ford oem valves, earlier and later models. So, unless you are the original owner of your truck, and know w/o doubt your head is a certain year, get the #'s off the head and check, and know 100% what year your head is, so you get the proper valves.

You'll need hardened seats on the exhaust valves. Get a 3 angle valve job, and a 30* back cut on the intake valves. Don't use larger than the 1.94 & 1.7 valves. I read somewhere, and I'm sure FTF will verify this, that a certain amount of area was needed between the two valves in the chamber to prevent heat and cracking.

Clean up your runners with 110 grit, not polishing, clean the bowls, and polish the chambers, and you'll be amazed. Of course headers, high energy ignition, cam all add and combine to give better result.

 

And just to add what the others have already mentioned.

If you use a longer valve make sure to check your push rod length. You will most likely need a longer set of push rods to compensate for the longer valve stem to get the correct geometry.

According to FTF all 240/300 heads came with hardened seats. And if anyone would know he would. He said all the light duty 240/300's came with flame hardened exhaust valve seats. And all the HD's & propane powered 300's came with hardened exhaust seat inserts.

If I remember correctly Greg aka FTF actually turned down the 1.94" sbc valves to a 1.90" on his engines. Going bigger then a 1.94" in a 240/300 is just a waste of money. And if you have an EFI head it's not really worth the money to swap in larger valves. Due to the horrible valve shrouding that is already there with the stock valves.

 

Man lots of great info guys

Thank you I really appreciate it.