J Heads on a 1970 Challenger 340? Who can solve a mystery?

[kawahonda]

Ah, thanks. I was off. They are much closer than I thought.

Is it common to have date codes differ on left + right heads?

I just need to know some rough numbers for rebuilding. My current Js vs Xs....He may let these go cheap where it may be worth it.

[1 Wild R/T]

I see allot of $$$ at the machine shop...  If your so concerned with stock date coded X heads why consider an "Air Gap" intake & if your going to run the intake what dump allot of $$$ in a set of heads? 

Your looking at magnafluxing, cleaning process of your machinists choice guides seats valves, springs, retainers, keepers, measure CC's mill as needed....   I can see $5-700 going into those heads pretty quickly.... X heads being as harder to find as they are these days I doubt you'll buy those cores for less than $2-250 so your $700-$950 into having a little X between your spark plugs..... No one is gonna pull a valve cover to see the date codes.....

So your $700-$950 stock looking X heads with an Air Gap on top........ 

A set of 308 castings look more stock than an Air Gap & will out preform the X heads for less $$$   

[kawahonda]

I think what I'm hearing is that there is going to be some serious money required to get the X heads serviceable...and that's not even looking at improving performance, can easily touch $1,000. Keeping in mind that I can sell my J heads to recoup some cost.

Rebuilding my current heads is probably $200-300 max if everything has been/is in working order.

Hell, aluminum performance alum heads are $700ish!

I think aluminum heads break my "look stock and go fast" goal though. I suppose if they are painted...cool....

Why spend more money on the X heads if I'm going to run an Air Gap intake? I would say that heads are not really a "bolt on" thing. I'd rather spend the money to get them right. Intakes can swapped in a few hours, and heads are...a job...at least that's how I think of it. Maybe that's an incorrect way to think of it.

Randy, would like to chat with you more about a mild-build. For now, if I can get rear freeze plug leak resolved by using "genie in a bottle" techniques, then that will prolong a lot of this work and instead will allow me to re-focus on a new rear-end chunk. Knowing me, I always like to plan way far in advance..and try to do everything I can to keep the car on the road as long as possible. So far, so good!

[1 Wild R/T]

I think what I'm hearing is that there is going to be some serious money required to get the X heads serviceable...and that's not even looking at improving performance, can easily touch $1,000.

Rebuilding my current heads is probably $200-300 max if everything has been/is in working order.

Hell, aluminum performance alum heads are $700ish!

ProComps are the low $$ heads, some guys rave about them, some guys rant.....    Personally I'd scratch up the money & look ate the TF 190 thats supposed to be out this month...

[Chryco Psycho]

Well here is my $.02
X& J heads are virtually identical , neither will have hardend seats in them , either can be machined for larger valves so in that respect the small valve heads are more desirable as the seats can be machined to new spec , if they have  large valves already the seats have to be cut deeper hurting flow .
So spending $$ for X heads is a sideways move at best  .
I agree with Wild on 2 points , the later 308 casting if far superior so they are generally cheaper to buy & the machine work is the same so they look stock with better power output .
Better yet get the trick flow head

[GY3R/T]

   When i look at "original" 340 cars/engines i always peek by the spark plug. You've found a set of X heads that fit your engine assembly nicely. It is common to have two differnt date codes of heads on an original engine, although 07099 & 08269 is kinda pushing it. Have the heads magged. if they're cracked he pays, it they're good you pay.      And if you can purchase for 200-250, don't hesitate ! 
   BTW  do you have more pics of the tops of the heads Close-up of valve guide tops? It appears they may have new guides installed. One thing you could do yourself is get a good intake and exhaust valve and after a good cleaning with a bore brush, slide the valves in the guides till it seats. then pull the valves out about 3/4"-1" and see how much play there is. Should be snug. 
Keep that baby stock.   

[1 Wild R/T]

   When i look at "original" 340 cars/engines i always peek by the spark plug. You've found a set of X heads that fit your engine assembly nicely. It is common to have two differnt date codes of heads on an original engine, although 07099 & 08269 is kinda pushing it. Have the heads magged. if they're cracked he pays, it they're good you pay.      And if you can purchase for 200-250, don't hesitate ! 
   BTW  do you have more pics of the tops of the heads Close-up of valve guide tops? It appears they may have new guides installed. One thing you could do yourself is get a good intake and exhaust valve and after a good cleaning with a bore brush, slide the valves in the guides till it seats. then pull the valves out about 3/4"-1" and see how much play there is. Should be snug. 
Keep that baby stock.   

And again I'll point out he wants to run an Air Gap manifold..... Right up on top in plain sight.... The stealth/sleeper/stock element is lost by that one change far more then a little X on the heads..... Hell if you need an X so bad  going the J off & make an X with JB Weld... First I heard of that little gem was some high $$$ Chevy heads they had been on an engine for years, then he pulled them off for machine work.... Went into the tank as something valuable, when they came out most of the JB Weld had melted.... First call was to the customer.... 

[kawahonda]

Correction, I want to run in the 13s, so if that means an orange air gap, then it means an orange air gap. If obtainable with stock intake, then great! I'm just making some assumptions.

Taking something original off (intake) and putting something more original on (x heads) is a wash for originality. It keeps my soul in check.

Still would like to find a good 340 engine builder and discuss my goals so I know what I need.

[RUNCHARGER]

You're taking a lot of the original parts off this car for improvements so I don't see the point in the iron heads dollar wise. I am a results for dollars sort of guy. A few years ago I did up a set of 915's for the 440 in my Road Runner, I had the same amount of money  in the 915's as I would have had in a nice new set of aluminum heads. I'll never do that again. I too see no point in topping off expensive iron heads with an aluminum intake manifold. You would actually get more performance increase using the stock intake manifold on a set of aluminum heads. However it is certainly not my car or my money, but that is what I would do.

[GY3R/T]

   When i look at "original" 340 cars/engines i always peek by the spark plug. You've found a set of X heads that fit your engine assembly nicely. It is common to have two differnt date codes of heads on an original engine, although 07099 & 08269 is kinda pushing it. Have the heads magged. if they're cracked he pays, it they're good you pay.      And if you can purchase for 200-250, don't hesitate ! 
   BTW  do you have more pics of the tops of the heads Close-up of valve guide tops? It appears they may have new guides installed. One thing you could do yourself is get a good intake and exhaust valve and after a good cleaning with a bore brush, slide the valves in the guides till it seats. then pull the valves out about 3/4"-1" and see how much play there is. Should be snug. 
Keep that baby stock.   

And again I'll point out he wants to run an Air Gap manifold..... Right up on top in plain sight.... The stealth/sleeper/stock element is lost by that one change far more then a little X on the heads..... Hell if you need an X so bad  going the J off & make an X with JB Weld... First I heard of that little gem was some high $$$ Chevy heads they had been on an engine for years, then he pulled them off for machine work.... Went into the tank as something valuable, when they came out most of the JB Weld had melted.... First call was to the customer.... 

  That's funny.  And i agree. Does'nt make sense installing X heads if you're running modern aftermarket intake. That's why i said " keep that baby stock " Lots of other ways to make more power keeping it stock looking....   

[kawahonda]

And I keep asking...what is it? Crickets....

440 Carter AVS carb?

What's the secret?

Ya'll know my goals. Help me get there and keep it stock. No problem if we need to exchange a few things.

[Chryco Psycho]

And I keep asking...what is it? Crickets....

What are you asking & getting no answers ?

[GY3R/T]

And I keep asking...what is it? Crickets....

440 Carter AVS carb?

What's the secret?

Ya'll know my goals. Help me get there and keep it stock. No problem if we need to exchange a few things.

If your goal is to run 13s it shouldn't be difficult. Unless you have a tired engine. Bolt on HP is kinda simplistic. I thought you were looking for the correct heads for your A66... Don't know your budget, but if you're looking to rebuild/build your 340, then stroke it. lighten your recipicating assm,
bigger cam, properly jetted carb, AND make it breathe !! Now transfer that power to the asphalt with a good set of tires and the right gears. All looking stock. With that said.... we're talking some coin. But hey, it's just money.... right?   

[RUNCHARGER]

13's and look stock? 3.91 or maybe even 4.30 gears, higher stall torque convertor, mill heads, install better valve springs and a new camshaft, optimize timing curve and jetting. Yes the 440 AVS would help with the other mods I've laid out. I forget but I think you installed 2.5 TTI exhaust correct?

This is a good calculator, a totally stock, new 1970 340 should make 310HP, figure 3800lbs. You need to have the chassis put it down is all. I would also think your 340 might be short a few ponies due to wear. That's why I would mill the heads and install a new camshaft, your old one will be worn too. I would touch up the valve job when you have heads milled, but I wouldn't spend too much on those heads just to get into the 13's, if they were new, stock they would make it as-is.

http://www.wallaceracing.com/et-hp-mph.php

[GY3R/T]

   I'd only mill heads IF they weren't flat. You can control compression ratio with piston choice.
  Higher stall converter  would be good. Valve springs Should/must be matched to cam choice.
  Lighten the car where reasonable....