Your G heads have 1 15/16 inch intake valves.  2 inch valves are .062 bigger in diameter, which means one side of the valve will be .031 closer to the chamber wall.  I doubt you would ever know the difference in performance.

John - "The Hoosier Hurricane"

Another update-

So the heads have been at the machinist for a week and they are not happy with the previous work to the extent that the valve seats have been cut so deep they are worried about drilling for new intake seats Incase they hit a water passage. So they have come up with a plan to find some 2inch intake valves (from a scruby) and use the added diameter in the valve to cut a new seat to suit. Alternately they could make 8 custom valves which would cost about $80 each + machine work on top of that- which they said they don’t want to do for my sake.

I did mention that the larger valves could potentially effect the air flow (I think I read the larger valves are closer to the edge of combustion chamber and can “shroud” the valve) so he said he would cut the valve angle for best flow.

Hopefully I receive some good news and can pick the heads up late next week and not pay through the nose.


Thanks, Dennis.

56 F100 - 272 Y Block
NSW, Australia.

On the road to recovery!
What you're thinking of doing would be nice...Y not?

"FREE SAMPLE"

Just chatted to another machine shop 1.5 hours away and I’m dropping the heads off on Friday. The guys said they use the same machines that they use in formula one and can do Anywhere up to 9 angle valve jobs and can cut a valve seat with a tolerance of 1 micron (0.000039). Hopefully I’m on the right track! Plus I’m getting a partial refund from the previous machinist.

This time around, I’m already in deep so I’m thinking I may as well get new intake seats, new valve guide inserts and explore the possibility of getting oversized valves.

Edit- just read that larger valves in the ECZ-G heads does not help and simply cleaning up the bowls will benefit flow more.


Thanks, Dennis.

56 F100 - 272 Y Block
NSW, Australia.

Buy a Neway seat cutter set (used if you can) and do it at home (easy to use but slow) it's not to much money if you only get 2 cutter heads.

No, it's not OK, find someone with a 3 angle cutter (Serdi) and it's a 20 min job , it takes me about 2 hours to do it with stones most people will not take the time to do it right. 

to me those seats look ok,a final check with a marking pen and turning the valve by hand will show the seat valve to head. remember with to days gas they will pound in,with out hardened seat inserts just put a small amount of oil in the gas.  the valves look ok but what does the seat look like, the marking pen or a soft pencil on seat then rotate the dry clean valve and seat in head will show the true storey. hardened seat inserts are difficult as the accuracy of the cut in the head is critical,with no clear sign that the insert is ok(the marker will indicate) . if the insert is not bang on you can grind the valves all you want with poor results.
 i have a old valve refaced as well as seat grinder,it takes a lot of patience to do a good job,if i would charge for my time it would cost you a fortion. the machine shop,at least hear use a cutter foreheads and grinder for valves and demand have guide be on spec


0

Thanks LordGaga,

I found that info online and thats what I’m using as my base line. I’ll see the machinist next week and go from there. I’m keen to drop this engine back in and get the truck running.


Thanks, Dennis.

56 F100 - 272 Y Block
NSW, Australia.

The seat width is very important to flow.

There are almost as many theories on seat width as there are head masters.

 Most of the machinists we spoke with prefer an intake-seat width of 0.040-0.060 inch. Narrower seats generally improve flow but are also less durable. Narrow seats work best on drag-race applications where the engine is freshened often. Harder seat materials (e.g., induction-hardened seats) allow you to run slightly narrower seat widths than in the past while retaining excellent durability. Since exhaust valves operate at extreme temperatures, they require a wider seat to conduct heat away from the valve through the seat. Most shops specify 0.060- to 0.080-inch seat width for the exhaust side.

"FREE SAMPLE"

I measured all the seats and the intake seat width varies from 0.060-0.102 and the exhaust from 0.043-0.060. In hindsight I should have asked all the question first but I have only learnt all this from this experience, as I trusted him to deliver, so I’ll head back to the shop and have him explain the process and what the parameter were that he set out to achieve and why are there such fluctuations.

Thanks LordGaga- Im about sick of it, but it’s been a great learning experience. I’ll ask if he uses a carbide cutter or stone. Part of me thinks it will be ok, but I don’t want to pull the heads off again later down the track so I want everything to be the best possible to ensure longevity.

Thanks Cliff- I will talk to him and see what he can do. Either correct his work or I’ll ask for a partial refund so I can have someone else correct the work.






Thanks, Dennis.

56 F100 - 272 Y Block
NSW, Australia.