Re: 427?
 

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I took a 454 2 bolt main block, put a 6223/3.76 steel crank with 7/16 dimple rods and 427 Keith Black hypereutectic
pistons. Heads were 115cc 6272990 rectangular port with 3933163 intake and 4053/780 vacuum secondary Holley. Compression was 9.975 to 1. Ran on 93 octane and was about 520 HP...... Muncie M20 with 3:73 12 bolt. Tons of fun in my 1968 Nova. https://www.yenko.net/ubbthreads/imag...ins/3gears.gif

The best part about it was it would rev as fast as a small block which is an advantage over a 454 in my opinion. Plus I love rpm's.... https://www.yenko.net/ubbthreads/imag...iggthumpup.gif

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Did you have to use a block girdle or are they splayed mains?

Re: 427?
 

My L72 has static compression of 9.73, and runs on 93 no problem.

Re: 427?
 

Did you have to use a block girdle or are they splayed mains?

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This was a stock 39999289 block with 2 bolt mains. No modifications are needed to do this.

All you are doing is de stroking the motor from a 454 to a 427 when you use a 3.76 396/427 crankshaft. 427 and 454 both have a 4.25 bore. But you have to use 427 pistons with a 3.76 crank. 454 pistons will not work with a 3.76 stroke crank. Just as 427 pistons will not work with a 454 4.00 stroke crankshaft.

If you use a 427 piston that is .030 bigger and a 3.76 stroke it is a 433 cubic inch.

I have a photo of the bottom end of the motor I built. Let me know if you want more pictures.

Hope that helps.

Kurt

Re: 427?
 

I was looking at a comparison chart and have a question and it may be stupid but...were all 427's solid lifter motors?

Re: 427?
 

No,the 427 L-36/390HP & LS-1/335HP were both Hydra lifter engines.

Re: 427?
 

No. Correct me if I am wrong but I believe that oval port (low horsepower) head motors came with hydraulic lifters and rectangular port (high horsepower) motors had solid lifters.

I ran a comp cams solid lifter camshaft with my motor and loved it. I could not afford a roller cam but I still wanted it to rev fast. I called comp cams and gave them all the information that they needed to help me pick the correct application for my motor. I highly suggest doing that unless you are going to build the motor 100% stock. They will need to know compression, intake, carb, power brakes, gears etc...

Re: 427?
 

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No,the 427 L-36/390HP & LS-1/335HP were both Hydra lifter engines.

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What about the L68 400 HP tri-power motor? I believe that is hydraulic camshaft also. But not sure. https://www.yenko.net/ubbthreads/imag...lins/dunno.gif

Re: 427?
 

The 512 block was used for 69 427 and continued into 70 as a 454. however, the 427 was internally balanced and the 454 was externally balanced. Because of that, the crank, balancer and flywheel must be for the correct application.

Re: 427?
 

[ QUOTE ]
The 512 block was used for 69 427 and continued into 70 as a 454. however, the 427 was internally balanced and the 454 was externally balanced. Because of that, the crank, balancer and flywheel must be for the correct application.

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I've seen this before so I thought I would ask. What is the difference between internal and external balancing?

Re: 427?
 

External balance used extra counterweights cast into the back side of the harmonic balancer, and the flywheel. Internal used counterweights on the crank, only.