340 X head advice

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ir3333 said:
You'll be fine with X heads. You might be happier with a smaller cam on the street unless you have
a high stall converter.
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Another voice of experience. I agree.


When someone has no heads to begin with...I'll open the aftermarket idea...but when they have a set of x heads which are actually decent flowing as is from the factory and are building a fun street motor....no need, all the power they're lookin to make can be made with what they have and about 350-400 bucks in a guide and valve job since he already has new stainless valves.
 
MOPAROFFICIAL said:
For what the op is doing, he should stick with the x heads, he can easily make about 390-400 hp with a cam in his usage range.
I made 392hp with stock xheads and a 284 .528 purple cam, ld340,headers and stock replace kb pistons @9.5 comp
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Oh that can’t be! It’s not better than 10-1 and that lame MP Purple cam will never perform!!!!
:rofl:
 
Oh, speaking of which, same deal here, I’m building a “fun, everyday driver street 340.”

.030 over 340 w/KB flat tops
Stock J heads w/2.02’s and MP springs for the “761” cam, the split duration purple cam advertised @ 268/272-50-110-.440/.455 lift.
TQ intake and electric choke model TQ carb w/trap door air cleaner.
Hooker Super Comp headers (1-3/4) into a H piped dual exhaust @ 2-1/2.

Backed with an auto & 3.55’s, this will be just fine for anywhere at any time to go where ever with pep!
It should be good for 13’s. But I don’t really care.
 
Only concern with the X-heads is that you don't know how many valve jobs have been done on them since 1968. The more valve jobs a head has, the further down they sink the valves. The further the valve seats are "sunk", the worse the flow. I don't have specifics, but it would be possible for a 1.88" 360 head with new, 2.02 valves on fresh,"high" seats to outperform an X-head with multiple valve jobs - all else being equal.

There's always the LA-X or EQ closed chamber head option. Unported, these were over 2 tenths better in the 1/4 mile when compared to 1.88" LA heads with the same prep. (1.88" vs 1.92" and chamber size was about 5cc less on the LA-X.)

Have you talked to Tim Sloan in Sanford, NC? He has a lot of small block experience. He builds a lot of NHRA/IHRA class legal engines as well.
 
Locomotion said:
Only concern with the X-heads is that you don't know how many valve jobs have been done on them since 1968. The more valve jobs a head has, the further down they sink the valves. The further the valve seats are "sunk", the worse the flow. I don't have specifics, but it would be possible for a 1.88" 360 head with new, 2.02 valves on fresh,"high" seats to outperform an X-head with multiple valve jobs - all else being equal.

There's always the LA-X or EQ closed chamber head option. Unported, these were over 2 tenths better in the 1/4 mile when compared to 1.88" LA heads with the same prep. (1.88" vs 1.92" and chamber size was about 5cc less on the LA-X.)

Have you talked to Tim Sloan in Sanford, NC? He has a lot of small block experience. He builds a lot of NHRA/IHRA class legal engines as well.
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No but I'll give him a shout.
 
If you're going to run factory iron and are not concerned about numbers matching, sell the X heads to someone who foolishly thinks they are something special. Then get a set of J heads with 1.88 intakes and install the larger valves. Now you can do a much better bowl job and improve the overall flow from the X heads that are screwed up from the factory.
 
Locomotion said:
Only concern with the X-heads is that you don't know how many valve jobs have been done on them since 1968. The more valve jobs a head has, the further down they sink the valves. The further the valve seats are "sunk", the worse the flow. I don't have specifics, but it would be possible for a 1.88" 360 head with new, 2.02 valves on fresh,"high" seats to outperform an X-head with multiple valve jobs - all else being equal.

There's always the LA-X or EQ closed chamber head option. Unported, these were over 2 tenths better in the 1/4 mile when compared to 1.88" LA heads with the same prep. (1.88" vs 1.92" and chamber size was about 5cc less on the LA-X.)

Have you talked to Tim Sloan in Sanford, NC? He has a lot of small block experience. He builds a lot of NHRA/IHRA class legal engines as well.
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No 1.88 head "2.02'd " with nothing but a 'regular valve job' will outflow a 2.02 x, it will need bowl n ssr work, period.
He should post a pic of the ports, valves out.
 
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skrews said:
^^^ Amen brother.
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That would be worth it if he were doing an all out factory iron head effort.
Here's where opinions, and SOME fact start mucking it up.

Yes go spend on another set of factory iron heads for that "fun street car" and put 800.00 into them. Best of luck!
 
IQ52 said:
If you're going to run factory iron and are not concerned about numbers matching, sell the X heads to someone who foolishly thinks they are something special. Then get a set of J heads with 1.88 intakes and install the larger valves. Now you can do a much better bowl job and improve the overall flow from the X heads that are screwed up from the factory.
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What head isn't screwed up from the factory when it comes to building power...the 906, but it still needs work, they all do.

Have fun with this.
 
MOPAROFFICIAL said:
That would be worth it if he were doing an all out factory iron head effort.
Here's where opinions, and SOME fact start mucking it up.

Yes go spend on another set of factory iron heads for that "fun street car" and put 800.00 into them. Best of luck!
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Sell those "desirable unobtainium" X heads to some numbers match type guy for $400 or what ever they go for these days. Pick up a set of any 360 casting for $50, the profit off the X heads pays for the machine work. Now you're into your heads for next to nothing. FACT!
 
skrews said:
Sell those "desirable unobtainium" X heads to some numbers match type guy for $400 or what ever they go for these days. Pick up a set of any 360 casting for $50, the profit off the X heads pays for the machine work. Now you're into your heads for next to nothing. FACT!
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I'm all over that idea when that's what you have to start and are looking for over 260 cfm. J head is imo the best casting head of the bunch, but my X heads as of this second flow 257cfm by .500 and it took way less than the intro to a port job heads, for damn fking sure.

Sell the heads and buy speed masters then, because for all the ******* trouble you're gonna go through selling and buying and then modifying.... you'd have to be a knothead not to.Finally got to the day and age where people tell you to sell your xheads in order to run a marginally better head.
50 bucks...for j heads, may be 10+ yrs ago.
100 a pair, not mag'd, in cali... is the rate
I have respect for you guys, but really?

Send the op heads and save him from those dreaded x'ers.
 
Good gah-reef! I said, "If you're going to run factory iron............."

I've said it MANY times before........You don't run the factory iron unless you are forced by the rules or your mind tells you, for whatever reason, you just gotta have the factory iron.

I run our ported factory iron because I can show off and make more power than most can with ported aftermarket aluminum. However, when I want to make the most, I'll port the aftermarket iron or aluminum.
 
MOPAROFFICIAL said:
I'm all over that idea when that's what you have to start and are looking for over 260 cfm. J head is imo the best casting head of the bunch, but my X heads as of this second flow 257cfm by .500 and it took way less than the intro to a port job heads, for damn fking sure.

Sell the heads and buy speed masters then, because for all the ******* trouble you're gonna go through selling and buying and then modifying.... you'd have to be a knothead not to.Finally got to the day and age where people tell you to sell your xheads in order to run a marginally better head.
50 bucks...for j heads, may be 10+ yrs ago.
100 a pair, not mag'd, in cali... is the rate
I have respect for you guys, but really?

Send the op heads and save him from those dreaded x'ers.
Click to expand...

Keep in mind though, not everyone has your experience no your prowess with head porting. You see things differently than most because of your unique ability.
 
IQ52 said:
Good gah-reef! I said, "If you're going to run factory iron............."

I've said it MANY times before........You don't run the factory iron unless you are forced by the rules or your mind tells you, for whatever reason, you just gotta have the factory iron.

I run our ported factory iron because I can show off and make more power than most can with ported aftermarket aluminum. However, when I want to make the most, I'll port the aftermarket iron or aluminum.
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I understand what you said, in regards to iron head or not...and between you and I... I'm pretty sure we both, skrewz too, have a few sets of heads to choose from laying around in various configurations..and I'm saying thats kinda impractical to someone else's situation, for lack of a better word. I have both, I'd pick .... of the two... because having the choice on hand dictates naturally choosing the better.
The difference between them at the level of modification spoken of is close to 5 cfm.
If he had J heads 1st, it would be simple, put in 1.94/1.60 Chevy valves shape a nice bowl n turn n have 255cfm ez with very little effort.
I understand, I agree with that approach, but to me it's not life or death.
 
RustyRatRod said:
Keep in mind though, not everyone has your experience no your prowess with head porting. You see things differently than most because of your unique ability.
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The tab crashed as I was typing the same sentiment. Dont ya don't think eluding to someone to dump the x head just to turn around and buy some J heads so they can do said port work on them is a touch impractical... or a reach beyond? There are those that want to learn... good thing too.
As for experience, Jim can do way better than most... thanks though. I guess I'm just a 'make it work' type of person, If i were him I'd find a 250 dollar bowl job on the 894's and go drive around mfrs with a good .525 street roller and some 3.91 gears already.
Last post. I hate it when others do it, so I'm done watching this re run.
 
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MOPAROFFICIAL said:
The tab crashed as I was typing the same sentiment. Dont ya don't think eluding to someone to dump the x head just to turn around and buy some J heads so they can do said port work on them is a touch impractical... or a reach beyond? There are those that want to learn... good thing too.
As for experience, Jim can do way better than most... thanks though. I guess I'm just a 'make it work' type of person, If i were him I'd find a 250 dollar bowl job on the 894's and go drive around mfrs with a good .525 street roller and some 3.91 gears already.
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Maybe for me, no, because I don't have your ability to make "something better" out of the X heads. I don't know. Adding up the cost of guides, seats, valves, springs, all the labor to set the heads up plus port work. What do you honestly think? .....and not everyone can get great prices on machine work and porting. For instance, I can do my own basic valve jobs, as I am sure you can. Not everyone can. I am thinking at least a grand for all the above mentioned work and parts.........with GOOD porting flowed and with flow sheets, maybe more. You think I am not in the ballpark?
 
MOPAROFFICIAL said:
No 1.88 head with nothing but a 'regular valve job' will outflow a 2.02 x, it will need bowl n ssr work, period.
He should post a pic of the ports, valves out.
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Loco said a 1.88 removed in favor of 2.02’s.......

I don’t know anything about the SSR from head to head. But that can be addressed.... LOL
 
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