Building up my 68 340

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Don't believe everything you read about HP... Without porting the stock heads will get you in the 340-350 range.

Pretty spot on cracked back
Here is something I found.

Duration @ 0.050": 224° / 230°
Max Lift w/ 1.5RR: .477" / .480"
Lobe Separation: 110°
Intake Centerline: 106°
Engine Type: Small Block
Compression: 9.25:1
Heads: Performer RPM
Intake: Edelbrock Performer RPM Air Gap
Carburetor: Holley #3310 Vac. Sec.
Exhaust: 1 5/8" Headers

Max Torque: 413 ft*lbs @ 3800 RPM Max Power: 342 HP @ 5000 RPM
 
Ok so if I wanted to get closer to 375-400 porting the heads would be the next step? Would you port x heads or because they are a valuable head would it be better to sell them and buy different heads?

Rocco, where do you get the compression of 9.25/1.
 
Ok so if I wanted to get closer to 375-400 porting the heads would be the next step?

Would you port x heads or because they are a valuable head would it be better to sell them and buy different heads?

Rocco, where do you get the compression of 9.25/1.

I like aluminum heads. Not that you can't make power with iron heads. Not that you can't make power with factory heads. For many reasons I like aluminum heads.

Head porting would help you make more power. Head porting with a appropriately matched cam would help more. A bigger cam with the stock heads would make more as well.

As far as that compression. That's what the dyno test said it was.
 
Reason I asked about the compression is when I bought the motor I was told it was recently rebuilt (sat for 10 years) and it was 10.5/1 compression.
 
Reason I asked about the compression is when I bought the motor I was told it was recently rebuilt (sat for 10 years) and it was 10.5/1 compression.

In theory yours would make more power but I wouldn't get too hung up on static compression numbers.
 
Stock 340 might say it's 10.5:1 compression. Reality, it is closer to 9.5:1
 
With mild port on the stock heads I was making 413 tq @4300rpm and 398 hp @5700rpm with the xe262 , so yes you can make it with your 340 using the xe 268 . I used Mahle forged 10.5 pistons , they are lighter than the stock , and an Air Gap . Now have the Ede alu heads . There is also suspension and tires to consider if you want good times , you have 3.91 gears so that is a big help .
 
Stock 340 might say it's 10.5:1 compression. Reality, it is closer to 9.5:1

Or it might be 10.3:1 , back in the day some 340 Darts were faster than others from the factory , the machining and assembly back then was not great compared to today , todays pistons and rings are a big improvement over factory parts .
 
Actually gonna be 3.73 gears running a 904. Going for 255 tires. Have not looked at suspension much yet but know I need to. Gonna be a street car with occasional trip to the track
 
Those are good all around gears for street /highway /track .
 
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