SB head tech question

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mshred

mshred

The Green Manalishi
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hey guys, originally posted this on moparts with little response, and knowing there are quite a few head gurus on here, im interested to hear your opinions


first off i dont know much about head technology so please bear with me...i dont NEED new heads but id like to try to immerse myself in the options available for me to maybe pick up some used heads on the cheap and learn how to port while also making more power...
I have a mild 340 .30 over that im hoping as it sits right now will run high 12's/low13's...it currently has x heads on it, and i would like to throw a 150 shot of NOS at it...the x heads are unported, intake is not gasket matched, only thing new is valvesprings to keep up with the cam thats in it (comp 280H cam- single pattern 480 lift, 280 duration)...I was thinking of going to some 308 heads in the future since they have the same intake port but better flowing exhaust port than my x heads (which i think would help with the nitrous) or so i have heard...Have also thought about going with magnums as well...Are either of these heads worth any et gain over the x heads i have on it right now? I know that factory magnum heads are prone to cracking, but are 308 heads the same way? if i was to go magnum, i know i would need magnum valvetrain and intake- would i be able to reuse stock magnum valvetrain stuff with the cam i have, or would i have to upgrade? i plan to wind my motor to a max of 6500 (for now) and the car is a 5 speed...I also have 2 sets of J heads sitting at home and have heard recently about alot of praise for them in ported form- do you guys think im better off with these instead? would i be able to reusethe valvesprings from my x heads with the J or 308 heads? like i said, id like to do this really cheap (as in getting lucky from weekly u-pull searches, finding a decent set of heads, cleaning em up and mild port, and stick em on)...thinking it could be a good learning experience, but if this direction is just a waste of time and not much worth it over x heads at all, then ill just stay away...also, if there are any sites with tech info or stock specs on magnum and 308 heads that anyone could share i would really appreciate that as well...just a little about the rest of my combo
340 .30 over 10.5:1 cr, airgap intake, heddman headers, 3 inch exhaust, carb in the 750-850 range, 3.91 gear, stock suspension with the usual traction tricks

Please enlighten me! open to all opinions on this topic!
grin.gif

thanks!
Matthew
 
The Engine Quest heads are magnum replacements.

One thing to consider is the 340 pistons come up above the deck at top dead center so if you switch to closed chamber heads you will have to run a thick head gasket to get adequate piston to head clearance.
 
340sFastback said:
The Engine Quest heads are magnum replacements.

One thing to consider is the 340 pistons come up above the deck at top dead center so if you switch to closed chamber heads you will have to run a thick head gasket to get adequate piston to head clearance.
Click to expand...

they arent factory 340 pistons, though im not sure if they are flat top or not...does this make a difference? also, which of heads that i mentioned are close chamber? just the magnums?
 
If you have x heads on there with 10.5:1 compression the pistons are coming up out of the block at top dead center. They are flat top pistons but they stick up about .018" or so above deck when all the way up. The x heads are open chamber and the magnum and Engine Quest heads are closed chamber. Edelbrock makes both open and closed chamber heads for the LA small block. The open chamber version are called "340" because they allow room for those stock pistons that stick out. The "360" Edelbrock heads are closed chamber and are ideal when trying to build an engine with a quench combustion chamber.

You might want to post this down in the Small Block Tech section of the forum to get more responses.
 
hey man thanks for the info! that makes sense, so i guess magnums are out of this picture then as i dont want to buy new heads, something i can do cheap is what im looking for....can one of the mods move this to the smallblock section? im not sure how and dont want to double post...thanks!
 
Answers contained within the quote;

mshred said:
I have a mild 340 .30 over that im hoping as it sits right now will run high 12's/low13's...

This should be able to be done with a stock 340 and bolt on parts.


it currently has x heads on it, and i would like to throw a 150 shot of NOS at it...

your in!


the x heads are unported, intake is not gasket matched, only thing new is valvesprings to keep up with the cam thats in it (comp 280H cam- single pattern 480 lift, 280 duration)...

Your certainly in!


I was thinking of going to some 308 heads in the future since they have the same intake port but better flowing exhaust port than my x heads (which i think would help with the nitrous) or so i have heard...

The 308's are very good. I see them as a very good street head with the OE valves. Putting 2.02's in would help alot but would defeat the "On the cheap"


Have also thought about going with magnums as well...

This also defeats the on the cheap effort since you'll requie new lifters if not so allready equiped with the AMC style lifters so often surplied and badged as Mopar lifters.


Are either of these heads worth any et gain over the x heads i have on it right now?

Possiby the Magnums in stock as cast form. Not the 308 as cast.


I know that factory magnum heads are prone to cracking, but are 308 heads the same way?

unsure...


if i was to go magnum, i know i would need magnum valvetrain and intake- would i be able to reuse stock magnum valvetrain stuff with the cam i have, or would i have to upgrade?

OE parts would do fine.


i plan to wind my motor to a max of 6500 (for now) and the car is a 5 speed...

Your cam will quite by 6000


I also have 2 sets of J heads sitting at home and have heard recently about alot of praise for them in ported form- do you guys think im better off with these instead?

There to be veiwed as small vlave X heads



would i be able to reusethe valvesprings from my x heads with the J or 308 heads?

Yes, there all the same family of head.



like i said, id like to do this really cheap (as in getting lucky from weekly u-pull searches, finding a decent set of heads, cleaning em up and mild port, and stick em on)...

LOL, me 2! Pratice on 318 heads...



thinking it could be a good learning experience, but if this direction is just a waste of time and not much worth it over x heads at all, then ill just stay away...

The X heads allready have the 2.02 which is an advantage money wise and when in the hands of a pro, they can be a very potent head.


also, if there are any sites with tech info or stock specs on magnum and 308 heads that anyone could share i would really appreciate that as well...just a little about the rest of my combo

Goggle Stan Weiss


340 .30 over 10.5:1 cr, airgap intake, heddman headers, 3 inch exhaust, carb in the 750-850 range, 3.91 gear, stock suspension with the usual traction tricks

As asked earlier, what pistons are in there and how do you know it's a 10.5-1 engine? If it is, then the OE pistons are a positive deck height slug making half the heads listed no good for use. Be sure of what you have before swapping heads.

Please enlighten me! open to all opinions on this topic!

The best thing I can say to do is get every mag and try to copy what they did. Also, theres a few head porters here and I do beileve they can point you in the right direction for some basic to moderate head work. Any iron head, X, J, 308 should be able to be ported to 240 cfm realitively easy (Loosely used term since porting iron heas is not an easy thing) and more extensivlt to 260 cfm. To achieve a 280 cfm head, it will require alot of porting time and expiance. But it is very possible to get there. Above this level, seldom really needed for the street or time you want to run, is possible. But by this time, when you figure it out, you'll have spent tons-o-money and lots of time on a air bench and more likely, have become a excellent hobbiest (Near Pro) at this with a good out look to do it for a living of Pro.
Click to expand...

I hope this helps. Take it easy on the flood of questions. It makes for easier reading and others will tend to answer a quick post rather than a 20 question quiz.
 
hey rumble you pretty much answered the quiz lol...i guess i was just looking for opinions on what may be the best option in the end after home porting...if i can get 250-260 int flow i will be a very happy man! im hoping that once i do this, gasket and port match intake, and throw in cam somwhere in the mid 500ish lift range i can run consistent mid 12's...for now though im sure even the little cam i have could benefit from some better flowing heads...im sure that any of these heads can get me there, just looking for the one that may have the best characteristics with the least work...when you say "your in" do you mean to say that im already going to hit high 12's?

I understand magnums are totally out of the picture, cost wise and not working with my pistons as well...The pistons are Speed pro forged, and it is the pistons rated at 10.5 cr, so not sure what the actual cr is...out of the heads i listed, which are closed and which are open chamber? I wouldnt mind spending some money, but nothing over 500 bucks (mind you ive never looked into the price of new valves)...some on here really toot the horn for J heads, and if all i would need is new valves and they are better in ported form that x's ported, then i think they would be good since i already have a set...and yes i will definatly practice on another set of heads before taking a grinder to the heads i want to use...the stan weiss site has some good info i will take a look at
 
give ya something else to look at...

since the x head and j heads are basically the same head except intake valve size...

how about selling the x heads...since alot of people want them for restoration projects...and investing the money into the J heads...
 
70aarcuda said:
give ya something else to look at...

since the x head and j heads are basically the same head except intake valve size...

how about selling the x heads...since alot of people want them for restoration projects...and investing the money into the J heads...
Click to expand...

thats another reason i kinda didnt want to port them, in case i ever had to sell them i know the resto guys love em untouched...but its not my place to sell them for cash as the heads belong to my dad (and so do the j heads LOL)
 
when you say "your in" do you mean to say that im already going to hit high 12's?
Click to expand...
Yes, it is possible (with a 150 HP on N02,) you'll be looking at suspension to get you goping. The power should be enuff, traction is the issue now.
Stan Weiss (SP?) has a extensive web site and head flows. It's not super comprehenceive (SP!)
 
rumblefish360 said:
Yes, it is possible (with a 150 HP on N02,) you'll be looking at suspension to get you goping. The power should be enuff, traction is the issue now.
Stan Weiss (SP?) has a extensive web site and head flows. It's not super comprehenceive (SP!)
Click to expand...

i know ill hit it with the nitrous no doubt, but im more concerned about hitting that number on the motor...yea his website has a ton of info, but those charts are a little painful to look at
 
Look at it this way, stock 340 is approx. 275 HP w/150 shot of N02 = 425 HP not includeing upgraded parts. You'll run the time.
 
cool! im hoping the bolt ons minus the spray will do it...

back to the main issue at hand now...what heads do you guys think are most worthwhile of my time?
 
ported X heads and more cam will get you in the twelves on motor.
the no2 will give you roughly a second faster at your level of performance.
the 484" cam i have alot of experience with in a 340..
the last one in a scamp (body/weight ect.) went 13.54 fairly easily..
but it took a lot of tune and securing a good 60ft..to only get the car 13.30's
the cam is just done ...right around that point...its only got 230 @50 you need more like
255-260 ..even better being a standard shift...
Maybe put some 1.6 rockers on the cam you have..(i need to calc.@ 1.6 rocker ratio)
you have a stick..id suggest a tad more lift..509".... is hard to beat..
either way.ported or not..thats about right for those heads...
FWIW with a 4 speed ..my dart loved 3.91 gear and 28" tire. 258 duration 490" lift.
I think its worth haveing the heads ported..but by someone with experience.
also
i suggest...finding out what pistons you have for the above mention'd reasons...
AND ANOTHER REASON the no2 needs ring gap...especially if the turn out to be hyperutectic. pistons...
and make sure you dont miss a shift when running the no2.
cheapst
 
Cheapstreet said:
ported X heads and more cam will get you in the twelves on motor.
the no2 will give you roughly a second faster at your level of performance.
the 484" cam i have alot of experience with in a 340..
the last one in a scamp (body/weight ect.) went 13.54 fairly easily..
but it took a lot of tune and securing a good 60ft..to only get the car 13.30's
the cam is just done ...right around that point...its only got 230 @50 you need more like
255-260 ..even better being a standard shift...
Maybe put some 1.6 rockers on the cam you have..(i need to calc.@ 1.6 rocker ratio)
you have a stick..id suggest a tad more lift..509".... is hard to beat..
either way.ported or not..thats about right for those heads...
FWIW with a 4 speed ..my dart loved 3.91 gear and 28" tire. 258 duration 490" lift.
I think its worth haveing the heads ported..but by someone with experience.
also
i suggest...finding out what pistons you have for the above mention'd reasons...
AND ANOTHER REASON the no2 needs ring gap...especially if the turn out to be hyperutectic. pistons...
and make sure you dont miss a shift when running the no2.
cheapst
Click to expand...

I really appreciate your opinion, although it has kinda curbed my enthusiasm for what the car will run lol...would you care to let out any more details about that scamp? there are a couple things i would change about my car, but im going to drive it how it is and enjoy it for now...once i get used to a stickshift v8 car, i plan on doing these ported irons/port atched intake, a cam in the 530ish or higher lift area (is that too big you think?) and throw some of that spray on there...If i can run a consistent mid 12 on the motor and break into the 11's with the planned spray with the current bottom end i will be happy...what was your 4 speed setup and et? id love to get pro ported heads, but in reality i just dont have the money to, plus id really like the experience of it...do you mind sharing what kind of irons are on your 365 and who ported them/ what they flow?

more opinions are welcome guys..thanks so far!
 
Yea, well, cheap would know how to run and he's dead honest about how he feels about it.
He did list that the car (His) ran 13.30's.
Theres your goal.

For now, just put the N02 on it and walk the car out and hit it. No sense spinning it outta the hole for a hundred feet. Get to know the car and have fun. You worry to much about porting the heads and which one to use. Just get your butt out there and do it.
 
rumblefish360 said:
Yea, well, cheap would know how to run and he's dead honest about how he feels about it.
He did list that the car (His) ran 13.30's.
Theres your goal.

For now, just put the N02 on it and walk the car out and hit it. No sense spinning it outta the hole for a hundred feet. Get to know the car and have fun. You worry to much about porting the heads and which one to use. Just get your butt out there and do it.
Click to expand...

well i appreciate straight up advice that isnt sugarcoated...and rumble, when i do the N20 i want to redo my fuel system, so thats not happenening now, and not with my current tranny either...plus give me a break, its winter here and i cant drive her, so i gotta keep my mind in play mode and learn a few things while im at it LOL...the whole reason im asking this now is because i know porting the heads doesnt happen overnight so id like to be able to take my time and have them ready for when i want em and therefore figure out what i need and will use...you sound like my dad lol "why dont you just drive it first and the worry about all this stuff"...all this being said, im still welcome to opinions on this stuff
 
you beat me to the punch..
Definately just get the car out there. and run it ..have fun with it.
I would wait on the no2 though...it can bite you ..and leave you with
a non working car in a hurry..fwiw..

the Scamp i had..was a smallskinney rear tire..which i suppose factors into it..
it was a stock 340 bottom end..original pistons...decked.. .10
with heads cut .10 to straighten them..and port work...(basic ,intake match,,pushrod pinch blend,,bowls cleaned up, guides narrowed, and valve throat/valve job...they flowed around 248 around .550" lift.. (mem ?)
the 484" cam a 2800 converter and 3.91 gear..with a 750 cfm carb.
it went 13.30 with a 9" slick..full exhaust but it was a street car.
memory...it was 1.80ish 60ft..around 100mph..
on steet tires..it would just haze the tire about 10ft or so...very managable. kept it from bogging.. the slicks i would launch with more brake rpm.

after running a few diff 484" set ups i moved to the 490" and a 509" and both were markedly improved..ran well into the 12's...with some pretty simple stuff..just good ported heads..decent cyl pressure..and stable valve train.
low twelves ..in a stick car with some Saturday slicks...shouldn't be a problem..

funny thing is my duster right now has a solid flat tappit .483" cam in it right now..but its got 290 duration..
.and i run a .063 no2 pill in the bigshot plate. (150-175 HP? I am not sure) but it picks up a solid Second in elapse time.
i need more cam.(and will be soon)..but the class i ran ..mandated 483" max lift. thats still in there.
the car runs 6.77 1/8th about 100mph. and 10.69 at 123 mph..a 1.41-ish 60ft. (best et's was with a tiny bit differnt pill set up)
the heads have pretty much the same port work as most of my iron heads have had..except on these i plugged the push rod hole and moved it over/offset rockers..and i moved the pushrod hump out of the way..
they flow..around 268 cfm at 550" but have a better/stable air speed.

fwiw..my car has alot of converter/ 8" 5000, trans.gear 5.13 and 10.5 tire
with alot of drag strip passes and sourcing.. front end/rear end..to get it working...

scamp_73.jpg
 
LOL at the both of ya. You guys R all right.

YEP! Old man winter is there and gettin here, but not down there.
(location location location....LOL)
 
the boy in the pass seat is my son and was about 4 in that picture..... he just turned 13 today.....lol..



fwiw..the 340 dart stick...had a .490" lift solid ft.. in it..
that car was stout...reall nice torque for a 340...it ran 12.70's
but it did have glass bumpers,hood, and no back seat..or carpet.
it had 10" Mt pro-trac's a 391 gear. 800cfm carb..and only an alternator belt..
with no carpet and a street driven/drag car..that trans noise,and turndowns...was just all business...it hyped up the driving experience..
prolly felt faster with all this going on....
was a great memory.. the guy who bought it from me..put a 440 in it and only went 7.01 in the 1/8th..fastest as i recall...
 
hey cheapstreet, i appreciate all the advice! dont be suprised if i ever pm you on this when i can type more (hands in a cast and its starting to hurt)...our setups do sound very very similar...even though i have wider tires tha you, im expecting them to be spin city from what i hear (sportsmans) so not sure ive got much over your setup....the N20 will definatly wait until i learn how to drive this car properly and is tuned to its best on motor....the 150-175 shot is a cheater plate if im not mistaken? the headwork you have had in the past, was it done by you or by a well known shop? man im just a bag of questions lol

and rumble, tell me about it...location! LOL
 
Cheapstreet said:
fwiw..the 340 dart stick...had a .490" lift solid ft.. in it..
that car was stout...reall nice torque for a 340...it ran 12.70's
but it did have glass bumpers,hood, and no back seat..or carpet.
it had 10" Mt pro-trac's a 391 gear. 800cfm carb..and only an alternator belt..
with no carpet and a street driven/drag car..that trans noise,and turndowns...was just all business...it hyped up the driving experience..
prolly felt faster with all this going on....
was a great memory.. the guy who bought it from me..put a 440 in it and only went 7.01 in the 1/8th..fastest as i recall...
Click to expand...

sweet!
 
well?...these current heads were done ...partly by me..and partly by someone who ..i am no longer associated with..and at this point..people arent calling him a professional...So i wont......
this being said...ive done most of what has been done to these as far as porting..or i could do it again...easily...however...i dont have the facility to do machining..(valve seats/moving installed heights ect.)
its not that hard to port....but that being said..there is a learning curve....its sort of like the guy who throws knives for a living.. it looks pretty easy...anyone should be able to do it..in theory..right.?
more is definately not better...in this case....its a finesse..you have to know what NOT to do...mostly..just read up on it..is all i can say..
I have no problem helping....if you have questions...
i dont have the machining capabilities..like some good guys on here have..
but i know ...or understand..alot of it...fwiw...My education is in Engineering.
and i generally have an opinion ....and i really dig into alot of it...have for yrs..
the lack of funds has been my drawback....lol..

since porting these heads is really your question..i would wait on a new cam until.. you port these heads...then
pick a cam that uses the port work/flow chart-map...this will dictate the best cam profile...
for instance if the port is done at 500" you wont need a .530" cam...for example..
cheapst
 
homeported heads on a 10 second car is pretty sweet man! yea, i plan on reading alot of info, watching a few videos or two, having the right equipment and trying on a junk peice first before i do my actual set...and yea, i figured i would need a shop to at least to a valve job or deck the heads (i think thats what they call it)...and yes it definatly makes sense to get them flowed when done and pick a cam from there, i was just predicting a grind that will seem to get me where i want to be more certainly...appreciate all the help man! the pieces of the puzzle are starting to match up in my head now
 
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