I have a 1969 f-250 running the 360. I've got to pull the heads because i have a bad exhaust valve/seat. My question pertains to oversize valves.

On the front end i've swapped to a performer 390 intake and a 600 cfm 4bbl carb, on the back end i've got long tube headers. I'm using this truck mostly for a weekend hot rod. In the future it will be stroked to a 390, but not any time soon.

Since the heads will be out i will be replacing all valves and springs (to accomodate an RV cam). I am also having the heads port/polished. I would like to throw oversized valves in there as well, but I wanted some of you fellers that have done this to school me a little. What are the largest valves that will be of benefit, and not give me an issue when i stroke this ol girl to a 390?

 

So basically you are going to make the 360 a 390? The performer intake is the same for all FE motors. I also believe the heads are the same as well, if you are going to the expense of having them ported and polished then I would seriously find another cam besides the RV one, you probably won't even know you have an aftermarket bump stick in there. I don't know anything about the valves but whoever is doing your porting should also be a good source for that information?

 

Correct on all fronts sir. Mainly I need the headwork done now before i suck a valve because i have a bad exhaust valve/seat. The intake is already done. I'm having the springs swapped just in case I also have a wiped cam (wont know until the top end is apart). Eventually i will throw a bottom end in her, but while i'm getting the top end taken care of i wanted to get the expert opinion on valve size.

 

I mainly wanted a weekend cruiser and chose a cam that didn't have tons of lift but had loads of duration. It doesn't lope like I thought it would but does sound good......512/512 300 duration

 

Doing the top end and cam on an, apparently, well worn engine and not doing the internals at the same time is going to cost you more in the long run. JMHO.

 

Instead of bumping it to a 390 why not just use a 428 crank and bump it to a 410?

I don't know what valve sizes are possible, but if you want to use an RV cam with a 600 cfm carb you don't need to go to large size valves.

You can buy the Edelbrock heads with 2.090" intake and 1.660" exhaust valves for $800 each...how much are you going to spend to get the work done on your iron heads?

 

Find out what rebuilding and modifying the iron heads will cost and compare to the edelbrocks normally comes out about even $ wise so i'd just get the edelbrocks

 

After many years of working with FE's, my opinion is that you're going to be disappointed with minimal power gains and, most of all, the crappy mileage you're going to realize doing what you're talking about. It's all in how you build your motor. Always build an FE from the bottom UP, not the top DOWN. Think low RPM torque. torque. torque. torque. Keep repeating "torque" to yourself until visions of bowties and the blather of the dweebs who wear them are completely expunged from your mind.

The very first thing you need to do to get power out of your FE and yet also get decent mileage is snitcan the 352 crank and do what another poster suggested: put in a 428 crank with detroit balanced flywheel/flexplate. If you do ANYTHING, do this for better power and BETTER mileage, without all the expense of the oversized valves, cam, carb, manifold, port and polish and all that other Shivvy-lingo stuff. Use the truck 390 low compression pistons that normally sit down low in the 390: with the 428 rods they sit just right in the 390 block to give you a big compression increase to around 9.7 or more, depending on what heads you use.

For a pickup with the aerodynamics of a billboard, you'll do much better increasing the stroke, raising the compression, decreasing the carb to a 2bbl, putting in a 204/214 lift cam, taller gears like a 3:54:1, an overdrive tranny.

Bigger carb, bigger cam, bigger valves, bigger ports but the same old low compression and same old short stroke is a recipe for becoming one of those guys who swears that the Ford FE is a terrible motor, that it should be avoided like the plague because you get no power and can't pass a gas station.

 

That's all good, but the 390 pickup spec piston that sits low in the hole in a pickup 390 is really the 410 Mercury spec piston that gave 10.5 compression when on top of the 3.98 stroke of the 410. (410 being simply a 390 4v car motor with the 428 crank and the shorter piston)

FE Series Engine Specification Chart

Compression is a good thing and good for torque and economy but too much of a good thing makes for a premium fuel pinger/detonator with the timing pulled back so far you lose much of your high compression advantage.

Of course, a lumpy cam can bleed off some of that compression.

 

10.7:1 with the HP390/406 64cc heads, 10:1 with 76cc or larger heads. If you put Eddys on with small chambers, yes, high compression (which works fine with pump gas at my elevation) but with his 360 heads, no problem at all with pump gas.

Go with a lumpy cam for performance, but there goes the mileage back in the toilet. Granted he said he's looking for a weekend hot rod cruiser, but if that's really the point, go with an even longer scat crank and go full tilt build up with Eddys and the performer RPM intake and bigger carb and cam.

Doing a top-down build on a 360 is going to yield at best a mediocre power increase but a huge fuel burn increase. That's just the nature of a short-stroke FE.

 

There are taller pistons out there to raise the sad CR of the 360, they come for the bowtie breed but can be machined to the proper pin diameter , if I hadn't seen it built I would have sworn 390 but eddy heads and a 9.0cr made one heck of a 360. If the bottom is solid polish it up + new bearings and pistons and get the CR up , the heads are where the power is made, but the bottom end needs to be able to take it , if you have it torn down I would go as far as you can towards the 390.