~450hp from stock stroke 340?
The 340 in my Duster was built with the intent of it being between 430-450hp. I haven't had it on the dyno, just a street street car that I daily drive most of the year. Based on power/weight in other stuff I've driven and somewhat similar builds I've seen dyno'd I would wager it's probably more like 420 hp, but that's just a somewhat educated guess. Dyno's are kinda funny anyway, some are definitely more generous than others.
It's a '68 340 with .060" over KB hypereutectic pistons, 9.8:1 compression. Stock 340 rods, resized w/ ARP bolts, OE forged crank, .020"/.020". It has 308 heads, "stage II" ported, 2.02/1.60 valves, that flow 264cfm @.500" and have 65cc chambers. I run Crane ductile adjustable rockers, 1.5 with a Lunati 60404 flat tappet hydraulic cam/lifters/springs, lift .513"/.533", duration 234/242 @ .050" . Also has a Milodon road race pan and pickup, stock windage tray, new main bolts with windage provisions, mellings high volume oil pump w/ milodon pickup, Edelbrock AirGap RPM and a Holley 750 Ultra double pumper
Camcard
Flow bench test on the heads, intake side only
The part I would caution against is going nuts with the engine build to get to a number. If you're concerned about drivability for a street car I don't know that you'll want to do a whole lot more than what I've got, although that will depend on how you're using the car. For a fair weather weekend car only it's great, no issues. For a daily driver that gets stuck in traffic, has to operate in both freezing and 100°+ weather, and has a 60+ mile one way commute I can say it can be a bit much sometimes. Don't get me wrong, I love driving it which is why I drive it all the time. But the car/engine is definitely a lot happier being driven like I "stole it" than it is being lugged along in traffic. And it is not subtle when being driven like it wants to be, it definitely draws attention like that.
The 3.91 gears should be ok with a 5 speed, I know I ran an 833 behind mine for awhile with 3.55's and that was not enough gear for the cam but I was a bit limited because I was also doing freeway driving and needed to be able to maintain a good 75mph long term with how fast the freeways move around here. I run a T56 magnum now with 4.30's and that's a lot easier to start from a stop than the 3.55's were.
I would not suggest increasing the compression all that much from where I'm at, I pulled timing back to be at 34° all in mechanical (I still run vacuum advance too) because all I can get easily is 91 octane so with "summer gas" and high air temps (100°+) I was starting to get some detonation running around in the valley close to sea level. And if it's gonna be a street car you're not gonna want to be running race fuel or additives all the time.
One of these days I should dyno it so giving out my build info is more helpful, but it's more than enough fun for a street car and more than enough power to get you in trouble.
The 340 in my Duster was built with the intent of it being between 430-450hp. I haven't had it on the dyno, just a street street car that I daily drive most of the year. Based on power/weight in other stuff I've driven and somewhat similar builds I've seen dyno'd I would wager it's probably more like 420 hp, but that's just a somewhat educated guess. Dyno's are kinda funny anyway, some are definitely more generous than others.
It's a '68 340 with .060" over KB hypereutectic pistons, 9.8:1 compression. Stock 340 rods, resized w/ ARP bolts, OE forged crank, .020"/.020". It has 308 heads, "stage II" ported, 2.02/1.60 valves, that flow 264cfm @.500" and have 65cc chambers. I run Crane ductile adjustable rockers, 1.5 with a Lunati 60404 flat tappet hydraulic cam/lifters/springs, lift .513"/.533", duration 234/242 @ .050" . Also has a Milodon road race pan and pickup, stock windage tray, new main bolts with windage provisions, mellings high volume oil pump w/ milodon pickup, Edelbrock AirGap RPM and a Holley 750 Ultra double pumper
Camcard
Flow bench test on the heads, intake side only
The part I would caution against is going nuts with the engine build to get to a number. If you're concerned about drivability for a street car I don't know that you'll want to do a whole lot more than what I've got, although that will depend on how you're using the car. For a fair weather weekend car only it's great, no issues. For a daily driver that gets stuck in traffic, has to operate in both freezing and 100°+ weather, and has a 60+ mile one way commute I can say it can be a bit much sometimes. Don't get me wrong, I love driving it which is why I drive it all the time. But the car/engine is definitely a lot happier being driven like I "stole it" than it is being lugged along in traffic. And it is not subtle when being driven like it wants to be, it definitely draws attention like that.
The 3.91 gears should be ok with a 5 speed, I know I ran an 833 behind mine for awhile with 3.55's and that was not enough gear for the cam but I was a bit limited because I was also doing freeway driving and needed to be able to maintain a good 75mph long term with how fast the freeways move around here. I run a T56 magnum now with 4.30's and that's a lot easier to start from a stop than the 3.55's were.
I would not suggest increasing the compression all that much from where I'm at, I pulled timing back to be at 34° all in mechanical (I still run vacuum advance too) because all I can get easily is 91 octane so with "summer gas" and high air temps (100°+) I was starting to get some detonation running around in the valley close to sea level. And if it's gonna be a street car you're not gonna want to be running race fuel or additives all the time.
One of these days I should dyno it so giving out my build info is more helpful, but it's more than enough fun for a street car and more than enough power to get you in trouble.