Heads

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The x’s are good if the price is not crazy. You can get almost the same flow out of any of the other cheaper open chamber LA heads as you can get out of the x’s. Difference being 10-12 CFM at a serious port level. Unless you have to run or are emotionally attached to running a cast iron head. There are better options. Especially if you need to rebuild the cast iron head. It is probably a better idea to save your money up and go aluminum from a respected porter. Not necessarily for the performance, but they would usually have gone through the head and made sure it was ready OOTB when you get it from them.
 
Unless there is a specific goal in mind, and one that’s going to require the heads be pretty “good”, then for the most part any true 340/360 head should be suitable(with the appropriate work) for the typical hot street 340/360 build in the 350-450hp range.

That being said, the effective quench “easy button” is closed chamber heads with flat top or inverted dome pistons at zero deck height.

Depending on local labor rates, it’s pretty easy to spend “new head” money reburbishing old iron heads that would be capable of making similar power.
 
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PRH said:
Unless there is a specific goal in mind, and one that’s going to require the heads be pretty “good”, then for the most part any true 340/360 head should be suitable(with the appropriate work) for the typical hot street 340/360 build in the 350-450hp range.

That being said, the effective quench “easy button” is closed chamber heads with flat top or inverted dome pistons at zero deck height.

Depending on local labor rates, it’s pretty easy to spend “new head” money reburbishing old iron heads that would be capable of making similar power.
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Wow a lot of things to think about I ran a automotive machine shop in the late 70's and have built every big block out there and drag raced with a 427 punched 30 11to1 pistons ZL1 camshaft 513 gear 4 spd and I ran 10.3 in the quarter mile so I still know a lot of things but keep the info coming I am going to run a flat tappet cam shaft with 474 lift . I like all the new info I'm getting you people are great. Thanks John. PS I had a 72 Duster 340 4 spd for 24 years.
 
The story is still the same as it was back when you were in the shop.
Step 1-
Figure out the goals and come up with a good plan

Step 2-
Follow the plan
 
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PRH said:
The story is still the same as it was beck when you were in the shop.
Step 1-
Figure out the goals and come up with a good plan

Step 2-
Follow the plan
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I am I will do the right thing but the only thing I am confused about is the heads, is it posible to have bigger valves in my 340 heads I understand it will be costly but will it be worth it?
 
John Bedore said:
I am I will do the right thing but the only thing I am confused about is the heads, is it posible to have bigger valves in my 340 heads I understand it will be costly but will it be worth it?
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The 2.02 valves can be installed as you know, but unless you have the bowl area opened up under the seat it won't flow much if any better than the 1.88 that is in it. Up to you if it is worth the extra 300 or 400 bucks or so for the new valves and machine work for maybe another 15- 20 hp on the top end.
 
If you have 1.88 heads, and do nothing but machine for 2.02’s and the accompanying “bowl cut”....... there will be very little gain from that.

Is it worth it?
If you’re buying new valves anyway........ it doesn’t add that much more to the overall cost of the heads to have the seats & bowls machined for the bigger valves.
Check with the shop you’ll have doing the work for an estimate.

I forgot an important part of the “step 1”........ which is:
determine your budget, and what things will be included within that budget.
 
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And DONT Deviate from the plan! It’ll only end up costing you more money.
 
John Bedore said:
I am I will do the right thing but the only thing I am confused about is the heads, is it posible to have bigger valves in my 340 heads I understand it will be costly but will it be worth it?
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What do want in the end? What car is it going into, and how do you want to use it? What gas are you going to run? 1.88 intake valve can run very well, You can also step up to 1.92 +.100 with 8 mm stem, or the 1.94 in various stem diameters, as well as 2.02 intake valves. I would be opening up/smoothing the bowls even with the 1.88's Not really a big deal. Your 1973 heads are some of the good ones. I don't feel the need for aluminum heads, as a matter of fact, I'm redoing a set of virgin 2.02 J heads now for my 340 that were on the shelf, but I can do everything myself, except for milling them .020 and .019 on the intake side.
 
Thanks for that thought I lost out on the X heads the guy doesn't want the trouble of shipping even though I offered an extra 100.00 for the heads to get him to ship. The only heads are the ones that have the part #2658920-5 that I'm told were on 273 motors I can buy those for 250.00 but if my 73 heads with a little work will work better I would like to know what you all think. I don't nor want to go aluminium .
 
The 340/360 heads? They’ll run more than just a little better.
 
John Bedore said:
Thanks for that thought I lost out on the X heads the guy doesn't want the trouble of shipping even though I offered an extra 100.00 for the heads to get him to ship. The only heads are the ones that have the part #2658920-5 that I'm told were on 273 motors I can buy those for 250.00 but if my 73 heads with a little work will work better I would like to know what you all think. I don't nor want to go aluminium .
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Use your "73" 340 heads. Mill them flat and get a good competition valve job from someone who knows what he is doing. Get a custom cam.
 
66fs said:
Use your "73" 340 heads. Mill them flat and get a good competition valve job from someone who knows what he is doing. Get a custom cam.
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I am happy that you took time to give me a boost. I am like I said going with 71 340 pistons, stock exhust intake and thermoquad, What would you suggest for a cam and who would make it? I have heard bad things about Comp Cams from Mopar and Ford as I have a 66 Mustang too. I would like to run 355 gears or 391's I done my last 1/4 mile racing 30 years ago. Any help would be great oh one other thing I know you said stay with my 73 340 heads but another set of X heads has come my way with no valves or springs Bare is the word. I can buy for 450 + shipping. What do you think again Thanks ahead of time John.
 
John Bedore said:
I am happy that you took time to give me a boost. I am like I said going with 71 340 pistons, stock exhust intake and thermoquad, What would you suggest for a cam and who would make it? I have heard bad things about Comp Cams from Mopar and Ford as I have a 66 Mustang too. I would like to run 355 gears or 391's I done my last 1/4 mile racing 30 years ago. Any help would be great oh one other thing I know you said stay with my 73 340 heads but another set of X heads has come my way with no valves or springs Bare is the word. I can buy for 450 + shipping. What do you think again Thanks ahead of time John.
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I have been buying custom Racer Brown cams for years. Jim is all MOPAR even if he grinds all makes. I call and talk to Jim and he grinds me a cam. You have to be honest and know what you want your car to do. You also need to tell him the specs for your car and engine. My cars are more handling and highway cruisers. I've never been a drag racer, although a few friends are very serious drag and road racers. I personally don't want cam profiles that are hard on the valve train and require high spring rates. I'd rather spend the extra money on good machining and have the engine last than wring every last hp out of it. My cars are plenty fast for what I want. Anyway, there are other cam companies that can do the same thing, and I would definitely spend the extra money for something specific to what you want. The X heads flow better, and "if" they are in good condition, would be better. Worth the extra $450 + shipping is up to you. Bare is no problem, I'd be replacing valves and springs anyway, unless you have original 340 springs and they work for your cam. The 340 heads in pecking order are X, J, then your 73 heads. All can work very well with what you want to do.
 
Glad you found a set of X heads, I was going to offer you a set of 2.02 J heads reasonable.
 
are 2.02 J's any different than X's?
I always thought the only difference was all X heads were 2.02's and only some J's were?
 
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