hello,
i'm having my 460 F3TE fuelly heads redone at the machine shop, and i'm thinking about installing bigger valves.
The stock size is 2.09" intake and 1.65" exhaust.
Stock 460 non-efi heads are generally 2.19" and 1.76"
Max size that will fit my heads are 2.25" and 1.76"

My GOAL is LOW rpm torque and power, with an occasionally max. 4500rpm.
Cruise highway speed approx. will be 1700RPM.

Any advices on the valve size i should have in these heads?

Thanks.

 

2.19 and 1.76 would help at all cam lifts. If you're porting them, or at least cleaning the bowl up a bit i dont think your velocity would fall off to much. They are high velocity heads anyway.

 

Just for reference stock non EFI valve size is 2.09/1.65 only the CJ/SCJ heads had the 2.19/1.76 valves (that includes the D0VE heads having only 2.09/1.65)

Personally for your stated intent stay with the 2.09 intake and if you REALLY want to change anything increase the exhaust to 1.71 (the exhaust is the restrictive side) That will be plenty for 5500rpms and not kill low end torque.

 

F3 exhaust flows better than D0Ve or D3 castings.
Intake is some 25 cfm short of the other castings
Both Sides need help.

 

big difference between helping with a little bowl blending and cleanup work and putting in bigger vavle sizes.

and the amount of increase of the F3 heads still leaves them a little short in the intake vs exhaust ratio. personally on a motor as described you do NOT want let alone need bigger valves on the intake especially below 4500rpm as the OP said.

 

I dont think a larger intake valve will make the thing fall on its face at lower rpm.
I think you'll still like them over early heads either way.

 

I would just shape what is needed, such as, valve heads and seats and like mentioned before, the valve pockets. If the engine will be generally operated under 4500rpms, the heads should already flow enough, its just a matter of smoothing out that flow, in turn, will allow more flow (in terms of cfm & flow velocity) to happen. Just optimize the flow with minimal work as the heads sit for whichever casting you decide to use.

 

okay,

I decided to go to 2.11/1.71, and gave order for a small port job.
They will adress all ridges, a bit bowl shaping, and gasket match the intake ports with the intake.
They say'd it would give me 80 percent of what's possible with porting, and the last 20 percent would cost incredibly more, so this would be the most bang for the buck.

Also, i have installed flattops (KB138), giving me 10.5:1 including a little shaving on the heads, and zero-decking the block.

I will have stainless valves, and hardened seats installed, with a 3-angle job, and have the tulip back-cut on the valves, pushed by steel comp. magnum roller tip rockers, and matching springs.

Any other options or advises?

Machining shop claimed 450 horses would be in range..

Thanks.

 

Are these flat top pistons with no eyelets or do they have eyelets for valve clearance? Take the sharp edges off the piston as well as in the chamber of the head too. This reduces the hot spots that may come around during engine operation. Since you have the intake valve cut on the backside, you could try if you like, putting a radius on the chamber side of the exhaust valve to ease flow around there a little too. I'd say you have some fancy valves there.

 

they have 3cc total eyelets on them. very small.

fancy? why?

 

The stainless material, thats all. But, if the eyelets have a sharp edge on them radius those an smooth anything else out. I guess you could call this 'combusion chamber surface conditioning' If they (the edges) get too hot from absorbing heat during combustion, they could cause detonation to happen if circumstances are right.

For some insight on conditioning combustion surfaces here is a little article by Larry Widmer to check out.
The Old One - Energy Dynamics