OK, here's what the book says. CJ intake and carb = 17 hp. CJ cam = 30 hp. CJ manifolds or headers = 15 hp. CJ heads = 21 hp. Total = 83 hp

 

I found some heads that are C8OE-N that qualifys doesn't it? What are the cobra jet numbers just so I don't get hosed in the process?

 

Those are CJ heads.

 

FT44, just had to go back a page and find this and respond. My work schedule has been nuts a & I didn't get a chance to respond earlier. 400 hp ? is that all you want ? Too easy, even with your C6AE-U heads. The C8OE-N cobrajet heads would also do just fine. But the CJ castings are going to cost you more, 'cause all of the mustang guys want them for restorations or drag racing. A nice cost effective plan would be to have hard seats under the exhausts ( you need this for unleaded anyway....) and open up the bowls and put a 2.15 intake and 1.65 exhaust valving into the heads you already have. Yes, your stock iron intake would work, but it is heavy and it kills power. I would recommend a BlueThunder 427MR intake. It will fit under your hood just fine and breathe a BUNCH better than the stocker. Add some headers and a Crane flat hydralic '801 cam ( 222/232@.050 ) and you'll have a nice 390 that gets you plenty of power. If somebody could desktop dyno a guess on this one, that'd be great. Anyway, I have this cam in a 2wd of mine, currently with an iron CJ intake manifold, and it does just fine with ported C8AE-H heads ( small ports, similar to your C6AE-Us ) in a '71 F100 with a C6 auto trans. And yeah, you can still pull trailers. I do with mine ( full of firewood), and it does fine even with the 3.5 gears in the back. The CJ heads are fine, I would use a set if I had them, they just cost more.

DinosaurFan, on an old 'puter that work threw out.

 

So by putting the larger valves 2.15 intakes and 1.65 in would be a BIG plus??? What would you guess that would cost???

 

The 1.650 exhaust valves are definitely a great investment in terms of power - combined with the porting required to enlarge the bowl underneath. Cost? Don't know...

Maybe Dino can answer that one But I do know, exhaust valve seats, and new valves.

Gotta ask the machine shop what they want to do it ...

 

I just purchased a set of Manily 2.19 intake and 1.75 exhaust for around $350. from Summit... EDL-9754 2.09 intake valves go for around $227. Exhaust EDL-9757 1.66 for $147.39 from Summit. More airflow= more hp.

 

FT44, you could buy valves from Summit, but that would seem to be the most exspensive way to go. If you surf around the net for awhile you can find them from Grady Lowe or Ted Engnbldr. I bought a set of 3/8ths stem 2.09/1.65 valves from Ted awhile back for well under 200$ for the full set of 16. But I can't say I know his or Grady's current pricing. You might also call Barry R at survivalmotorsport, he does lots of FE stuff. You could also have the shop doing the valvejob get them for you.

The valves I'd recommend are one piece stainless valves that were intended to be used in a small block chevy racing engine. I'm not at work now and don't have the catalogs at home, so I can't give you the part numbers, but here is how I found them. The valves in an FE are about 5.45 in length, IIRC, so I searched the diametrical listing in the back of the book to find some 11/32 valves in with the head sizes ( 2.15/1.65 ) and lengths I wanted. Small chevy valves are shorter if they're stock, but the racers commonly use longer ones. I think the ones I found where .500 over stock chevy length. It doesn't matter what engine they were intended for if you stick to using intakes where intakes go and exhausts where exhausts go. I suppose you could use an exhaust in an intake port if you had to, but it just isn't needed. The nice thing about the chevy intended race valves is that they are easy to find not overly exspensive because they make so many of them, lots and lots more than they make of FE valves.

Then you have the 11/32 stems, which weigh a bunch less than the factory 3/8ths stuff. Some of the racecar guys are using 5/16ths and even smaller stems, but I don't think we need to be quite that exotic. So how do we put an 11/32nd stem valve in a 3/8 guide ? After the heads are disassembled and clean, measure the size of the inside of the guide. Quite likely you will find them able to recieve a press in bronze liner. The liner is ball broached into place and then broached and reamed to get the inside size you want, then honed to get the internal finish nice. And presto- you now have an FE head with 11/32nd guides. If the inside of your original guides are too worn to allow the use of the guideliners, you'll have to bore out the guides to .500 and press in new guides. Very do-able, just a little more work.

You'll want to ask the shop if they have a 'bowlhawg' or something similar, to open up the bowls to match the larger valves you want to use. Not every shop wants to do this kind of work, but the places who build engines for performance should be able to handle it easily.

Of course, you'll need new retainers and locks to go with the smaller stems, but you were going to replace those to go with the stronger springs to complement your new larger cam, right ? The stock cam doesn't breathe enough to make good power, so it was going to go anyway, wasn't it ?

If you brought it to the shop I'm with I'm going to GUESStimate you'd be spending something like 500$ on labor, plus buying the valves and and hard seats to put under the exhaust. Still cheaper than Edelbrocks or genuine CJ heads that probably still need a rebuild.

We've used this recipe before and found it effective and not overly costly.
DinosaurFan, on an old 'puter work threw out

 

Yeah i was planning on using a bigger cam, Whats the "bowlhawg" do?

 

How do you measure your valves? Just to see what i already have?

 

FT44, a bowlhawg is this multiple bladed roughly hemispherical cutting tool that one uses to enlarge the pocket under the valve. It also does a nice job of making the bowl nicely concentric around where the valvestem is. If you have the cylinderheads off, you can measure the valves' heads with a calipers. Unless someone has changed something before, your stock sizes are something like 2.03/1.55. DinosaurFan, on an old 'puter work threw out

 

Okay i measured them and came up with the 2.03 and 1.55 But theres only approx. .080 inbetween the two valves. How does that work?

 

It's a cylinder so
1.65 - 1.55 = .1 ./. 2 = .05
2.09 - 2.03 = .06 ./. 2 = .03 .05 + .03 = .080 which I presume is actually for forgiving than whats presented. I do recall the tight fir on Wes's Poor Mans 427 write up.. Google it.. can speak of it here LOL...

 

Okay Dino @ His Dad's, what kind of horsepower gain will i get over stock if i do the larger valves?

 

FT44, what you will gain from the larger valves will depend greatly upon what the rest of your system has.....If you have a stock cast iron intake, and log manifolds the differance will be small. If you have headers, a bigger cam, and a blue thunder ( or similar ) intake, you'll see a much bigger gain. It also depends on how well the bowls are opened up to match the new larger valves. I also like to remove the lump of iron hanging in the roof of ports #3 and #6. After you open up the ports to match the others, there will be a small hole in the roof. Not a problem, but when you install the studs for the rockershafts, you'll need to put some sealant on the ones for those cylinders. You don't have to port the heck out of them but you should at least make sure there aren't any cast iron boogers in the ports.