X-heads enough for 408 stroker?

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DartmanTampabay

DartmanTampabay

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Been checking threads on SB stroker builds which usually have aluminum heads. I have a bare 69 340 block 30 over and picked up a fresh set of stock 2.02 X-heads a while back cheap.

Planning for a future build down the road. Not sure I really need a 408 but since I will evently have to buy a rotating assy - why not.

Wondering how much work would be needed to flow sufficiently to make a 408 stroker worth it? Not a high build strip motor but a street combo 727 AT w/ 2500-2800 stall and 3.55-3.73.

Inputs please - thanks
 
DartmanTampabay said:
Been checking threads on SB stroker builds which usually have aluminum heads. I have a bare 69 340 block 30 over and picked up a fresh set of stock 2.02 X-heads a while back cheap.

Planning for a future build down the road. Not sure I really need a 408 but since I will evently have to buy a rotating assy - why not.

Wondering how much work would be needed to flow sufficiently to make a 408 stroker worth it? Not a high build strip motor but a street combo 727 AT w/ 2500-2800 stall and 3.55-3.73.

Inputs please - thanks
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They flow decent, though porting them would be best ...as well getting the port volume up for some more rpm if you wanna see say 500 and up type of hp
 
still make a 425 hp motor outa it but should get some rhs /indy x heads then u can turn it up they start where the old ported to max old x heads stopped dont stick a chit load of $ in them but it will make a nice motor yet, then when u can afford it thro down 2 k on some indy's built and u get your 500+ hp small block ready to bust a nut sell off the old 1ns for a dime or a quik 5 if nice yet and get some traction gear was the way i was headed but got detured only about a grand diff to start that way unless you can just buy the short block and bam thro it all together at 1nce otherwise a good start for the top end for now
 
Hi Greg. Your idea is like another one of my dozen or so fantasy builds.....if i ever win the lottery....lol.

Those heads should spec out around 66/68 cc's depending on clean up and would be able to keep the compression in check enough to run a milder split duration cam to run pump gas and help the exhaust flow. My vision is to make serious "big block" torque along with the tighter converter and a 3.23/3.55 gear. Shifting at just over 5k, great street manners and able to easily knock off 12's with the weight of a A body. I can always dream......

P.S. a .030 over 340 w/a 4" arm is 416 cu in.....All the better :D.
 
winstoninwisc said:
still make a 425 hp motor outa it but should get some rhs /indy x heads then u can turn it up they start where the old ported to max old x heads stopped dont stick a chit load of $ in them but it will make a nice motor yet, then when u can afford it thro down 2 k on some indy's built and u get your 500+ hp small block ready to bust a nut sell off the old 1ns for a dime or a quik 5 if nice yet and get some traction gear was the way i was headed but got detured only about a grand diff to start that way unless you can just buy the short block and bam thro it all together at 1nce otherwise a good start for the top end for now
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back away from the mountain dew !!
 

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I don't have the specs offhand yet the 1970 340 I removed from my Signet couple years back ran the 1970 U heads which are the same as X heads and it was dyno-ed at 479 horse power. It also ran any gas from 92 octane up without a problem till others f***ed with the carb, timing and valve adjustments. I sold the heads for 900.
 
With stock x heads your power will fall off quickly after 4500-5000 rpm but it will still have a ton of torque and be fun to drive. Then later you can swap on some better heads and sell those for a couple bucks.
 
A buddy of mine has a 408 in a 69 Dart and it has X heads with no porting, just a good valve job. 280/.474 Mopar purple cam, Air-gap intake, and 3.23 gears. Runs mid 12's and is very mild mannered. Runs out of wind at 5k but with 3.23 gears you don't need a lot of rpm.
 
OldmanRick said:
Hi Greg. Your idea is like another one of my dozen or so fantasy builds.....if i ever win the lottery....lol.

My vision is to make serious "big block" torque along with the tighter converter and a 3.23/3.55 gear. Shifting at just over 5k, great street manners and able to easily knock off 12's with the weight of a A body.
Click to expand...

fishy68 said:
A buddy of mine has a 408 in a 69 Dart and it has X heads with no porting, just a good valve job. 280/.474 Mopar purple cam, Air-gap intake, and 3.23 gears. Runs mid 12's and is very mild mannered. Runs out of wind at 5k but with 3.23 gears you don't need a lot of rpm.
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That's what i'm talkin' about....:D.
 
I'm currently going through the same choices right now for my 408 build. I have some X heads on my running 340 right now (condition unknown). I also have some heads that came off of a 360/300 hp crate motor (need to be redone). I bought a pair of Edelbrock's, but sold them last winter to rebuild my motorcycle. I've looked at RHS Indy heads, and now the Airwolf heads also look promising. So many choices...
 
BrianT said:
I'm currently going through the same choices right now for my 408 build. I have some X heads on my running 340 right now (condition unknown). I also have some heads that came off of a 360/300 hp crate motor (need to be redone). I bought a pair of Edelbrock's, but sold them last winter to rebuild my motorcycle. I've looked at RHS Indy heads, and now the Airwolf heads also look promising. So many choices...
Click to expand...

Exactly my dilemma,I have good X-heads,crate motor heads,and RHS heads.
 
I ran stock X heads on a 372 stroker. It was a stick (street)car with 3.55's.Worked well.
 
I had a 408 with cast crank, Eagle H beams & Diamond Flat tops (12:1). Had a flat tappet cam 260/268 @ 0.50 or about that. Had 2.02/1.625 valves in ported J's. Had a 1.50 60' and ran a 11.21@121 with 3.55 gear in a 3200lb Duster. I think if it had not been laying over on the top end from a bad carb it would have been much quicker. Never got to tune it much after that lost it in Hurricane Katrina. I think if you run those X's you should at least install some 11/32 stem race type valves and at least blend the bowls and gasket match them.
 
Oh and as to why I had a 3.55 gear in that car? I was planning on spraying that motor:)
 
If you compare costs you will find it slightly cheaper to have a performance shop do a "stage II" porting on them, a good valve job, good performance valves, and properly set up. It's easy to reach the performance level of the RPMs that way, but you still have the weight and open chambers. Generally the RHSs are about $200-300 more to get properly done and ready to use, and RPMS are about $200-400 more than the RHS.
 
I'll add it's also pretty easy to make up to 450hp on them with a hydraulic cam.
 
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