Honest opinion

[JimNolan]

 Guys,
   I just got through putting my 410 block together and I'm ready to install the heads. The Static Compression is going to be 9.25 and the Dynamic Compression is going to be 7.6, I'll be using 87 octane with this setup. After leveling the block I still ended up with .032 deck clearance giving me a .052 quench. The cam is the 268H mild cam with .494 lift.
  I'm sitting here with C1AE-A unmolested 75cc heads with new 2.02/1.56 valves installed. All the surfaces have been refinished and they're ready to go. I will be using the FPA shorty headers and streetmaster intake and 600cfm holley on it.
  My question is this. Should I install the 1.65 exhaust valves in the heads. Is it really going to give me that much more for the trouble of doing it. I've got all kinds of time on this so it's not like I need to put it together tomorrow.    I keep thinking about what the one guy told me. I was applying racing technology to mediocre street power.

[jayb]

I doubt you would even notice a difference just modifying the exhaust valve.  I'd just run the 1.56 valves, or else upgrade both valves (2.09 intake, 1.65 exhaust).  Even if you went bigger on both valves, with your combination I don't think you'd see any major improvement...

[My427stang]

I agree, no significant gain unless your exhaust seats are sunk and you need to make a nicer exhaust seat.

If you have the heads ported, I would go to a larger intake and exhaust, not only for a clean valve seat but also to take advantage of the port work and added flow from an undercut stem of a modern valve.

As far as racing technology applied to mediocre street power.  I think that's a very odd comment

Fixing problems with an intake and exhaust from carb to tailpipe increases efficiency, tight quench and proper cam timing increases efficiency.  Balancing and oil management increases efficiency.  Stable dwell from a modern ignition and proper ignition timing...more efficient.

The real decision is, at what point is the cost greater than the benefit?  There is a lot of room before things get expensive though

Remember, the things new cars do today were cutting edge at one time, and they are far more efficient and powerful for their size than our old FEs were off the showroom floor.  Not to mention, even with our FEs, guys are making more power now with milder cams and more reliability.  Doesn't sound crazy to me

[JimNolan]

427stang,
    I get aggrivated when things don't go as planned. The engine was suppose to have a .040 quench with .010 deck cleanup and it ended up being a .052 quench. The engine is balanced, it's got good parts in it. I can get the 9.6 SCR back by milling the heads .015 so I shouldn't think that would be a problem with intake matchup ( hope not ). The FPA shorty headers are the best that I can do because of fitment problems with my 57 Fairlane A Frame and Steering Box. I'm going to use the Xpypes crossover like I did on the 406 also.
Question:  Will bigger valves and porting impress me with the results I get with what I've got. I can still go with the 670cfm carb like I planned before I got discouraged with the quench.  Keep in mind this car isn't taken out and played with every now and then, it gets over 10K miles put on it each year. 

[My427stang]

I wouldn't sweat the quench at all, .055 - .040 IMHO is decent quench. 

What is bad quench?  Some engines are deep enough you can measure with a ruler, heck my truck 390 was .130 in the hole, .170 when you added the gasket!

If I remember correctly you went with a pretty mild cam because you didn't intend to spin it too high, if DCR is bothering you, crank the cam forward 2 degrees, it'll probably offset what you lost with the deck and maybe even be happier down low.

As far as porting, an old saying we had was "you make power with head work"

I think a good set of viton seals, aftermarket CJ valves and porting would be certainly noticeable, the question is how much do you pay?  Les Schmader in PA is pretty affordable, as is a local guy here in NE, but if your guy charges a lot, it comes down to what you think 25-30 hp is worth.

Make sure you know what you are getting though.  Cleaning up the ports wont do much, cleaning up the guide area and a good transition to a modern valve job will, especially if combined with some work on the ports. 

FWIW I have about 800 bucks in my iron heads on my new 445, new springs, guides, valves, full port flowing 277 cfm.  That is with shipping from Nebraska to PA and back.  It's in a 4x4 with a 270H cam.

Keep in mind an FE also is sensitive to intake choice too, so if you port the heads to flow 280 cfm then cap it with an SP2P, it's a waste, but a good matching intake it gets better and better

Ultimately though, if you are only going to run it part throttle idle to 3500 RPM, I'd might give up the power potential, but if that 10K has you rowing gears now and then, I think you'd be happy if you shopped smartly.

[JimNolan]

427Stang,
    Just got off the phone with my machinest and he said about $500.00 for bowl work, shaving the heads .015, cleaning up the runners and installing bigger valves and viton seals with me paying for parts. 25HP is worth that to me just to not wish I'd done it later. I can't have a missle, I haven't got the wheel wells to handle a missile anyway. But if I can get 25 hp out of it with the cam and parts I've already got and still have a reliable show/go 57 Fairlane, that is worth it to me. Jim

[amdscooter]

If the time and $$$ are a non factor for ya just do it for the piece of mind. That said.. I'm still tuning in my freshened up 390 with the 268H cam (very similar profile to the 270H My427stang just put in his 4x4), it already makes a very respectable amount of torque. Never bothered to have it dyno'd but it pulls real nice. I'm not sure you'd notice or miss an additional 25hp and a few more ftlb at the back tire on that 57.

My2c

[JimNolan]

amdscooter,
    That was what I was thinking. If it doesn't help me that much, what the hell. I've wasted more money than that on stuff I didn't want. The bad thing about my builds are, I'm used to driveability and dependability and I'm afraid to push it to where I might forfit that. That's why I don't have 11 to 1 compression, roller rockers, custom rocker shafts, .700 cam lift and 800 HP. I haven't seen one venture 50 miles from home with success yet. LOL  To be serious, the bigger heads will allow me to increase my power band on up to 5000 from what I've been able to figure out. I don't mind some power being taken off the bottom end since I can't utilize it anyway. Hopefully I'll be able to shift somewhere around 4750 and still have dependability at 1900 rpm cruise. Jim  PS.  Did you ever get a vacuum guage on your 390. I'd think that would be critical for setting the carb idle and timing of a custom cam. When I set my 406 I used the guage to figure out best vacuum, backed the timing down 1" of manifold pressure and then looked at the timing pointer on the crank. And, that was just to see where it ended up.

[amdscooter]

Hi Jim, I had mostly the same items in mind with my build. A bit more giddyup w/o sacrificing reliability or adding a tonne of maintenance. Once I get the tune put on good I'm planning on just driving it. And it's a big negatory on the Vac gauge. I still have not been able to unearth it. I'll probably end up buying another.. and I'm sure shortly after purchase my original will turn up. 

[My427stang]

427Stang,
    Just got off the phone with my machinest and he said about $500.00 for bowl work, shaving the heads .015, cleaning up the runners and installing bigger valves and viton seals with me paying for parts. 25HP is worth that to me just to not wish I'd done it later. I can't have a missle, I haven't got the wheel wells to handle a missile anyway. But if I can get 25 hp out of it with the cam and parts I've already got and still have a reliable show/go 57 Fairlane, that is worth it to me. Jim

I think you'll be happy, anything that makes the motor more balanced and more efficient will make it happier at all RPM.

If you subtract the cut and the viton seals, the actual increase in cost is much less with no downside.

[427Fastback]

I have built half a dozen GT390's (stockers) and always used a CC 268...It is a great little cam...Cory

[hotrodfeguy]

Could always back cut the valves you already have. That makes things improved, and takes a little more advantage of those LR ports you have.

[JimNolan]

The Jury came back,
     With a lot of help from 427stang running numbers for me, I have my cam in now. I'm still waiting for the machinest to get back from Florida to start work on the heads but I'm getting everything else ready. I (we) decided to go with a cam I got from Scott Main out in Colorada. It's a 282/288, .515/.540, 110/104 I didn't use in the 63. It came with the lifters pre-broke-in so I don't have to do that at startup. Between the whiz bang calculators that 427stang has and my DesktopDyno5 software we figure it'll be a pretty good running engine. My calculations are a couple hp less than 427stang but here it is: 379 hp @ 5000 W/ 453 ft.lbs @ 3500.
    The biggest concern I had was since I put so many miles on it in trips would it be feasible for me to have. My old 270 hp 390 at 2000 rpm cruise has approximately 154 hp/401 ft.lbs @ 2000 rpm, it gets 20mpg and has a VE/BMEP of 74.6% / 159.8.  The new motor will have 157 hp/ 411 ft.lbs at 2000rpm with a VE/BMEP of 73.9% / 156.4. I know I won't get 20mpg but I'm very close to having the same efficientcy at 2000rpm as the old motor. We'll see. Thanks Ross.

[My427stang]

No sweat Jim, love to help

That will be a nice street machine with the 5 speed.  For the crowd, Jim needed something that would run well in 5th gear with a TKO/tire combo that put him in the low 2's for final drive ratio.

There are certainly cams that peak much higher, but we looked close at the intended use of the 410.

Although the 282 advertised duration sounds high, the 216/225 @ .050 and early cam timing made it almost indistinguishable from a 268H in torque curve, while the added lift and slightly slower ramps should be real nice for a street motor on any fuel he wants to pour down the tank.

[amdscooter]

Looks like you are going to have one sweet highway ride when you are done there Jim. That 5 speed with 2k final drive should boat down the road nicely. I'm thinking long run I might just pickup a set of 2.75 gears to get my highway rpm's down a bit. As mild as the current 3.00 are they still put me in the 2,700~2,800 range at highway speeds. With fuel here in CA habitually over $4/gal it sure could take some of the fun outta longer roadtrips up to my sisters home 200 miles North. Be sure to post up when you get it running, I'd like to hear what the slight increase in lift and duration (looks like most of the difference is on the exhaust side) sounds like!