Worth the cost?

[Mopar4LIF]

Well my 73 340 has been upgraded over time (steel crank, better rods/pistons) but I just got offered a deal and didn't know eather I should take it. I currently have the small valve J heads on it. However my dads buddy is restoring his 70 AAR cuda and he bought a 340 for it as the original block is long since gone/destroyed. The guy he bought it off of gave him in the deal a set of redone X heads. Now they are the stock build, cast valves, standard springs nothing fancy but very clean and can be bolted on he had them redone for the motor and then ran short on money and sold it. Recently I have thought upgrading my cam anyway as I want a little bit more power because honestly I race the hell out of my car on back roads. My cam is an isky hydraulic with the following specs:
Valve Lift - INT .485 EXT .485
Valve Lash Hot - INT .000 EXT .000
ADV Duration - INT 280° EXT 280°
.050 Duration - INT 232° EXT 232°
Lobe Center 108°
Now I figured I might go with a bigger cam like one of the new energy high lifts from comp and get these heads. He is asking $300 for the set. I figure if I upgrade the valve springs, get some ss valves and the cam I am in good shape floating in at around $800. Is this worth my time and money for that extra oomph? Or am I better off spending my money elsewhere? Such as better heads than stock etc... My car is daily driver/stoplight warrior 73 340/727 roadrunner.
I have 3.55's/sure grip out back, ss springs, snubber, mopar drag shocks, 340 with above cam, air gap intake, 4150 with proform main body, crane gold race rockers, a measured 9.7 to 1 comp ratio on the present 68 cc heads, and a TCI 2500 stall. After barely holding off a mustang tonight thsi idea seemed better.

[dwc43]

The 2.02 X head is a great improvemnet over what you have now. He's a little high priced on them though. The stock valves will be fine in them, but if you go with SS valves get them back cut and the heads pocket ported. Don't go too big on your cam, cause your car is heavy and you need the torque to get it off the line. You also need to use a dual pattern cam that has more exhaust lift and duration. IT will help it breath better. An X pipe in your exhaust sytem will get you more torque and some extra hp as well.

[DartGT66]

What is the difference between X and J heads, where does the advance come from? 340 six pack, as well as some 340 four barrells in 1970 had J heads with 2.02" intake valves, are they weaker than their X headed cousins?

[Slingshot383]

Very little difference between X heads and J heads. You can enlarge the seats of your J heads and install the 2.02 and 1.60 valves in them with no problem. If you have a little pocket porting done at the same time as the valve install, they will be a great set of heads for little money.

[rumblefish360]

Well DW, I say if you bring your "X" heads to New York, you'll get more than $300 for them. Maybe $300 bare never mind bolt on and go.

The J's are just a small valve casting of the X head. For the J head, install stainless 2.02 - 1.60 valves with a multi angle valve job and a pocket porting if coin allows. And I really recomend it to let the cam do it's job best.
Springs to match the new cam like DW recomended. Purchase them with the cam to match it all up. (I like split pattern cams alot.)
One point to point at, the X head may have 72cc's. Like my J's are.

Between a pocket ported head and better cam, I can say there is another 50+ HP in there easy.
Click here at the Hughes url on a cam in the same duration at .050 but a bit better I would say.
LOL, click here; http://hughesengines.com/cams/sb_heh.asp#HEH3237AL

(I'd like to know how many cfm that carb is. You'll likely look at a 750 ish + cfm carb for this.)

[Mopar4LIF]

The carb was a 4150 650 double pumper, but the proform center body is rated at 750cfm. I have read articles where it is actually 760cfm when flowed. Thanks for showing me the hughes page, they have some pretty decent cams on there. Any sugestions?

[rumblefish360]

The 3237 is a 232 int. and a 237 exhaust. duration @ .050 and a seriously increased lift while still making use of the stock 1.5 ratio rockers which should be replaced with the MoPar HD units at least.
These cams have a really fast rate of rise. It'll put the other cam on the shelf.
Your heads should be preped to handle the new lift. At .540 int & .548 exh. it's a jump! Bronze valve guides (IMO would be best)

[dwc43]

Originally Posted by rumblefish360

Well DW, I say if you bring your "X" heads to New York, you'll get more than $300 for them. Maybe $300 bare never mind bolt on and go.

Hey, I told you once before, too danged cold up there not to mention the traffic. No thanks. Come down here and I'll show you the real Lynchburg and some cheaper Mopar prices ... LOL!!

Like that other cam choice you gave him though.

[rumblefish360]

Might have to do that one of these days for a Duster/Demon.

[dwc43]

Cheap Duster maybe, but the Demon is a little pricey and harder to find, but they do pop up.

[Tarrbabe]

Mother says the only difference is the intake valve. Have the intake opened up for the 2.02 and install new intake valves, plus 3 or 5 angle vj all around and they are just as good. Worth the money? Depends on where you are.

But you must make sure the valve guides are correct. Loose valve guides cause a lot of lost motion and bind and cost horsepower. Not to mention oil bi-pass.

You really have to decide what you want. For a little more you can have aftermarket heads and more power. If you want to keep that stock looking setup?

Well

[pishta]

If the 650 Proform body is rated at 760, what is the 750 body rated at? at 90 bucks or so, that doesnt seem to be a bad deal to ressurect an old 3310-3. 3 bills is a great deal on bolt on X heads.

[70AARCuda]

I think if you check your holley catalog, you will find that the 650 holley has smaller throttle blades then a 750 holley. There for, the Proform main body will increase the flow of the 650 but it will never be the same as the 750 since the throttle blades are smaller..

The Proform main bodies are nice, I use on a 750 DP and 750 Vacuum Holley.

But dont expect miracles with just a change in carb main bodies...


tony