416 stroker 340 - 400hp and 500 ftlb

[elevenssc]

Thought I'd share my journey down the 416 CID stroker 340 small block rebuild path.  The only thing I got to reuse was the block, oil pan, and oil pickup.

The rebuild was initiated by a nasty vibration at 4000 rpm.  I finally pulled the motor and trans only to discover the crankshaft was usable, and the cylinders needed to be bored .030" over to remove a nasty scratch on #6 from a previous war injury.

Here are the details...

Block = 1970 340 bored .030" over (4.070")

Crank, rods, pistons = Eagle 416 stroker kit. 6.123 I-beam rods, forged Mahle 28cc dished pistons, forged crankshaft with 4" stroke. (cast crank was part of the kit, but it was on permanent back order, so I opted for the forged crank to keep the project moving forward). Recip. Assy was balanced, and block machine work was done by local machine shop.

I custom made some offset mounts for the stock windage tray to accommodate the 4" stroke.

Heads = Indy LA-X.  2.02/1.60 valves. 10 degree retainers and viton seals

Camshaft = Comp Cams Xtreme Energy XE268H (hydraulic flat tappet). Comp cams hydraulic flat tapped lifters, comp cams billet roller timing chain

Stock shaft mount 1.5 rocker arms (stamped steel). Comp cams 7.5" push rods. ( opted for the flat tappet hydraulic cam and stamped steel Rockers to keep the budget from getting out of whack.  May upgrade to roller valve train in the future. )

Headers = TTI 1.625 to 1.75 stepped ceramic coated and thermal barrier headers

ARP main and head bolts

Intake = Edelbrock air gap

Carb = Stock Holley 3310 750 vac secondary

Took the engine to the dyno for break in, and some pulls to get the imporntant numbers.  Best pull of the day was 399.8 hp at 4900 rpm and 500 ftlb at 3200 rpm!  This pull used a 1" 4- hole spacer, 3" K&N air filter using a sure seal top.

I'm using a center force clutch and pressure plate. Currently learning about offset Bellhousing dowels. Going to be getting the motor and trans in the car soon. 

I'm looking forward to putting that 500 ftlb to the pavement! 

Hope this post helps others decide which direction to take their engine build

[elevenssc]

Forgot to mention that I used the stock distributor, Accell 8mm plug wires, and NGK BKR5EGP plugs.  Dyno used a MSD 7 ignition.  Oil pump is a Melling high volume...

[Cudaragtop]

Those are some great numbers!   
Well done.

[crash340]

Thats great info, thanks, did you find out what the vibration actually was in the end??? I have a harmonic vibration at around 1500 rpm, im thinking its in the trans though

[elevenssc]

Thanks Cudaragtop!  I was blown away with the 500ftlb number

Crash340...the crank was drilled for a balance weight that was no longer there. Someone hammered the hole shut and put it back in the motor. Go figure. Also learned that the trans is off center by .010", which didn't help.

[Cudaragtop]

Thanks Cudaragtop!  I was blown away with the 500ftlb number

Crash340...the crank was drilled for a balance weight that was no longer there. Someone hammered the hole shut and put it back in the motor. Go figure. Also learned that the trans is off center by .010", which didn't help.

Need to see some bigger pictures of your car!
I love Black on Black on Black on Black!  My favorite color combo! Did it come that way?  Original 340 car? Hamtrack Plant?
Our cars could be brothers or sisters...  BS27H0B******

- Randy

[crash340]

Interesting, I highly doubt my 340 has ever been apart, my trans is an auto. I have a spare '77 360 and trans to be built up as a stroker with injection, I'm aiming at the 550Hp mark, all forged rotating etc, need to start gather bits but the Aussie $ exchange rate is killing me right now.

[elevenssc]

Cudaragtop...yes, my car is an original triple black car that had a 318 3-spd from the Hamtramck plant.  It was an April 1970 build with 319323 sequence. (BH27G0B). Mine is 1 of 125 318 3-spd convertibles, not as rare as yours, but rare none the less.

My dad bought it in '74...second owner. I remember the day he drove it home. It left a huge impression on me. This is the car that started it all for me.  The original 318 3-spd was replaced in the early 80's with the current 340 4-spd. Dad let me inherit the car early. It was needing some TLC. Since it was not a numbers matching car, I wanted to convert it into a Cuda clone. It's been a blast so far. It gets second looks on the street, which I'm sure you are used to as well.

 I'll get some recent pics posted once I get it back on the road...likely in a month or two...

[Mopar Mitch]

T/Anks for sharing the build info!