what size header should i run on my 340? block
Work done: O-ringed, tubed for roller cam, oil gallies enlarged, bored to 4.07(.030 over) and honed with deck plates by Herb McCandless.

340 steel crank
Prepared by Lunati, stroked .110 to 3.42 stroke and balanced.

340 steel rods
Prepped by Lunati. Hand picked set. All are within .001 of each other in length. Bronze bushed, balanced and lightened.and shot peened.

Heads
340 X heads with 2.02 intake valves and 1.60 exhausts. Double springs for .700 lift cam, Maximum porting on intake and exhaust ports.Ports are 63cc combustion chambers. they flow 260 cfm

Pistons
Venolia lightweight forged pistons. Uses dykes top ring, 1/16 2nd ring and standard tension oil rings. Weight is 510 grams.11.3 comp

Intake
Holley Strip Dominator ported to match heads.the carb is a bigs 950 stage 5

Camshaft
Cam Motion roller 269 275 @ .050 and .631 lift with 1.5 rocker Valves set on .024 .028
RPM range 4500-7500. Cam is degreed in at 104 deg centerline.

Other Parts
High volume Melling oil pump, Comp Cams roller lifters, Crane 1.5 roller rockers(gold), Fluid Balancer, windage tray, Cloyes double roller timing set. SCE copper head gaskets(.060). Tall valve covers for use with roller rockers. Moroso 8 qt deep sump oil pan. Bronze cam gear for use with roller cams.i plan on shifting at 7200.im hoping for low 11s.this is going in a 72 dart with a 727 trans, 4900 stal,8.75 rear with 4.88 gears

1 3/4" supercomps would probably work quite good on that,maybe alitle long primarys. hedman may have something better with alitle shorter primarys but im not sure
hope to see some other replys on this also

all you're shooting for ---
LOW 11 S
what i see is more serious than that??
i see something low 10 s
high 9 s
i guess we'll see ??
ooo header size??
a step header comes to mind
1"7/8 to 2" that'll work great!!
j m o
this is a three bagger

thanks for the help guys

If it were me, I'd go w the headman 1 7/8 semi-fenderwells if you can get a set. I had them on mine when I had a small block in it. They fit nice and made good power.

i have a set of headman semi-fenderwells.if i get this thing into the mid to low 10s i will crap my pants.thanks guys for the help anymore info would be great.