455 Build

Hello all, I got my hands on a 455 block that checks out with no cracks and is a good rebuild candidate. I would like to make 500 - 600 hp and I have put a list together of some parts. If you would let me know what you think I would appreciate it. (Good combo bad combo, go with this or that, etc.).

455 Block .60 over
Eagle Crank 4.125 Stroke
Eagle Connecting Rods
Federal Mogul Engine Build Kit - Forged Flat pistons.
Edelbrock Performer RPM Cylinder Heads - 72cc
Lunati Bracket Master II Cam and Lifter Kit - Duration 292/292, Lift .490/.490,
Harland Sharp Roller Rockers 1.5 Ratio
Edelbrock Performer RPM
Carb ?
Doug's Headers  
3-inch exhaust

4 speed trans and posi rear end still yet to be determined.

Thanks for your input  

I would go with the Lunati P#60904LK it has a .504/.527 lift and will work well with the edelbrock heads.
I would use the 4.210 stock stroke not a 4.125.  
professional hi-performance engine builder

Horsepower sells engines and torque wins races

I would use a 4.25 stroke with a 6.8 rod and bore it .035. Those heads might give you to much compression to run on the street. Think about 87 cc instead.  

You should have around 11.5:1CR and that is fine on 93octane pump gas with aluminum heads stick with the 6.625 Pontiac rods and not the chevy 6.8 rods.  
professional hi-performance engine builder

Horsepower sells engines and torque wins races

I have access to a set of 6X-8 heads Intake 2.110, Exhaust 1.660, 87 cc. They have been ported, 3 angle valve job, cut and resurfaced, com995-16 springs, com740-16 retainers, com613-16 valve locks, com4851-8 guide plates and arp rocker studs. I can get them for about 200.00 dollars. Money is always an issue, would you recommended these or a set of edelbrock heads? Would I still be able, with the above criteria, to run pump gas with the 6X heads?  

Those 6X heads would have to be very well ported flowing 255cfm with a small runner volume and a solid camshaft to make 500HP. I have built many 455 Pontiac's and there is a big difference in power from what they print in a magazine to what an engine makes on a real dyno that is calibrated correctly. You would also be limited to a compression ratio of 10:1 with iron heads.

Edelbrock heads with mild porting will fetch you 300cfm. Add a solid cam shaft and rocker netting you .600 lift and you will have no problem making 500 - 550hp. The RPM intake is a great choice with some runner porting and cut down the center divider 3/4" of an inch plus a 1" spacer. A 4.25 stroke crank would be much better and you can easily get light weight pistons that will net 11:1 compression with 72cc heads.

You will also have the basics if you want to upgrade to a wilder bracket motor in the future.

I have built this combo before with 11:1, and then years latter the customer upgraded to a roller cam 265 duration @ .050 and .650 net lift. On a very conservative dyno, this combo made 595hp @ 6300rpm and 630ft lbs torque on pump gas. Then we tried a Victor intake and made 610hp but only 570ft lbs. It would take a much larger camshaft, more compression, and peak hp @ 6800rpm to make use of a Victor.

You are on the right path to a killer torque monster that is street friendly.  

If you can afford the edebrock heads then I would recommend getting them you should have no problems reaching the 500HP mark with them and the right combo.  
professional hi-performance engine builder

Horsepower sells engines and torque wins races

If I got those 6X heads and put them on my 67 gto (400, mild Lunati cam, stock ignition, intake, exhaust) would I notice a difference? At this point I have 670 heads, stock, on the 400.

I am going to revise my build and get a complete list to post in a few days.

Thanks for all the input and info.  

The 6X heads would loose power over the 670 heads with the 670 heads you should have around 10:1CR and that is a little too high for pump gas although there are people out there running higher then 9.5:1CR and think there getting a way with it.  
professional hi-performance engine builder

Horsepower sells engines and torque wins races

So the 6X heads are about useless for a 455 rebuild at 500+ hp and the 67 400?  

Yep.  
professional hi-performance engine builder

Horsepower sells engines and torque wins races

Thanks for saving me some money.  

No problem.  
professional hi-performance engine builder

Horsepower sells engines and torque wins races

Guess I should have added that a shorter piston will be needed with the 6.8 rods. I got the Ohio crank rotating assy in my 455 (4.25-6.8-4.185) and love it.