[Cliff R]

Horrible cam choice right to start with for a 455 build and you'd be lucky to see 400hp with that cam at 9.4 to 9.7 to 1 compression and 6X heads with stock flow specs. Right on the dyno the larger XE284 cam and home ported 7K3 heads made 430hp. I didn't build that engine but watch the dyno shop pulling out all the stops to get the big 455 to make the power they were looking for and it never happened. I've custom tuned several 455's brought to the shop using the XE268 cam and it's cousin the XR276HR cam and they were "turds"...IMHO. At least if compared to similar 455 builds I've done here with similar parts but completely different cams in them.

You can make around 440-450hp with unported factory iron heads moving up to a RAIV size cam. I did a build years ago with #46 heads from a 350 engine without any porting at all and made 440hp with a Crower 60919 cam. My first 455 build back in 2000 made 455.4hp using 6X-4 heads cleaned up enough to flow 232cfm. That engine was featured in Popular Hot Rodding and HPP magazine in 2004 (if memory serves me correctly) and was part of the KRE aluminum "D" port head swap and two part articles that followed (dyno testing followed by a private track rental).......Cliff

https://www.motortrend.com/how-to/05...-dyno-results/

https://www.motortrend.com/how-to/05...track-results/

[LT4USMC]

Originally Posted by Cliff R

Horrible cam choice right to start with for a 455 build and you'd be lucky to see 400hp with that cam at 9.4 to 9.7 to 1 compression and 6X heads with stock flow specs. Right on the dyno the larger XE284 cam and home ported 7K3 heads made 430hp. I didn't build that engine but watch the dyno shop pulling out all the stops to get the big 455 to make the power they were looking for and it never happened. I've custom tuned several 455's brought to the shop using the XE268 cam and it's cousin the XR276HR cam and they were "turds"...IMHO. At least if compared to similar 455 builds I've done here with similar parts but completely different cams in them.

You can make around 440-450hp with unported factory iron heads moving up to a RAIV size cam. I did a build years ago with #46 heads from a 350 engine without any porting at all and made 440hp with a Crower 60919 cam. My first 455 build back in 2000 made 455.4hp using 6X-4 heads cleaned up enough to flow 232cfm. That engine was featured in Popular Hot Rodding and HPP magazine in 2004 (if memory serves me correctly) and was part of the KRE aluminum "D" port head swap and two part articles that followed (dyno testing followed by a private track rental).......Cliff

https://www.motortrend.com/how-to/05...-dyno-results/

https://www.motortrend.com/how-to/05...track-results/

Good to see your back around Cliff!

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[PunchT37]

I agree with the above. 550 hp? You have that big engine drinking out of a cocktail straw. The cam is way small and will ping, and you will need ported factory heads or aftermarket heads to get near where you want.

[ta man]

Originally Posted by Cliff R

Horrible cam choice right to start with for a 455 build and you'd be lucky to see 400hp with that cam at 9.4 to 9.7 to 1 compression and 6X heads with stock flow specs. Right on the dyno the larger XE284 cam and home ported 7K3 heads made 430hp. I didn't build that engine but watch the dyno shop pulling out all the stops to get the big 455 to make the power they were looking for and it never happened. I've custom tuned several 455's brought to the shop using the XE268 cam and it's cousin the XR276HR cam and they were "turds"...IMHO. At least if compared to similar 455 builds I've done here with similar parts but completely different cams in them.

You can make around 440-450hp with unported factory iron heads moving up to a RAIV size cam. I did a build years ago with #46 heads from a 350 engine without any porting at all and made 440hp with a Crower 60919 cam. My first 455 build back in 2000 made 455.4hp using 6X-4 heads cleaned up enough to flow 232cfm. That engine was featured in Popular Hot Rodding and HPP magazine in 2004 (if memory serves me correctly) and was part of the KRE aluminum "D" port head swap and two part articles that followed (dyno testing followed by a private track rental).......Cliff

https://www.motortrend.com/how-to/05...-dyno-results/

https://www.motortrend.com/how-to/05...track-results/

For a great street engine the "Jim Hand " build as above just works well. I had a similar engine years ago and it just flat out worked. Plenty of power for the street would be a great 4 speed engine as well. Build your shortblock well so if you wish to upgrade heads and cam later you are good to go.