Upgrade to 273 S (Commando) cam?

[Uglyfsh]

I have a '65 Barracuda 273 auto 180 hp and am considering an upgrade to S (Commando) spec cam and 4bl carb. Will this require upgraded pistons too?
Summit can get a Howard cam that is very close to the Commando specs but not identical. Does anyone know where to get a Commando spec cam (.415/.425 Lift and 248 Duration)?

 

[A56]

Go to "search" and type in Commando cam. Tons of good info

 

[Professor Fate]

The factory Commando package included 10.5:1 pistons.
Are they required for the cam? No, but every little bit helps.
Your bigger issue will be changing to a 4 bbl. '65 and earlier 273s had a different manifold bolt size and angle, so manifolds for '66 and later engines are a no-go, at least not without some reworking. Your bolt-on options are pretty much limited to the '65 factory 4 bbl. manifold and the Edelbrock D4B, maybe a couple other oddballs out there. The factory manifold is also only drilled for the narrow early AFB pattern, requiring an adapter plate for a newer carb- but not an issue with the D4B. Another option would be later 273/318 heads, which would open up all the later LA manifold options. Just don't go too new, as the chamber volume increased in later years and will kill what little compression you already have- plus there may be exhaust manifold fitment issues with '73ish and up heads.

 

[RustyRatRod]

IMO, no not necessarily. If you don't raise the compression, I would advance the cam a little more than what stock is. That won't make up all the difference, but it'll help.

 

[Uglyfsh]

Thanks all!

 

[Cuda Al]

On the 67 Valiant I had I did the full external conversion, 2-bbl flat top pistons stayed along with the cam.
Even the throttle bracket and bit were correct.

Alan

 

[toolmanmike]

I have a '65 Barracuda 273 auto 180 hp and am considering an upgrade to S (Commando) spec cam and 4bl carb. Will this require upgraded pistons too?
Summit can get a Howard cam that is very close to the Commando specs but not identical. Does anyone know where to get a Commando spec cam (.415/.425 Lift and 248 Duration)?

The 4 barrel cam and carb will be a nice addition. The high compression pistons will help as well. Egge and Kanter have the pistons and the Howard's cam or a Isky E4 are close to the original.

 

[Rustyfish]

The factory Commando package included 10.5:1 pistons.
Are they required for the cam? No, but every little bit helps.
Your bigger issue will be changing to a 4 bbl. '65 and earlier 273s had a different manifold bolt size and angle, so manifolds for '66 and later engines are a no-go, at least not without some reworking. Your bolt-on options are pretty much limited to the '65 factory 4 bbl. manifold and the Edelbrock D4B, maybe a couple other oddballs out there. The factory manifold is also only drilled for the narrow early AFB pattern, requiring an adapter plate for a newer carb- but not an issue with the D4B. Another option would be later 273/318 heads, which would open up all the later LA manifold options. Just don't go too new, as the chamber volume increased in later years and will kill what little compression you already have- plus there may be exhaust manifold fitment issues with '73ish and up heads.

Edelbrock 1406 will bolt right up, no problem. I have one on my Charger 273 manifold without any modification.

 

[Rustyfish]

Also, Iske makes an E2 for the same application which in some cases is a better option. Have to call them for the advice.

 

[Professor Fate]

Edelbrock 1406 will bolt right up, no problem. I have one on my Charger 273 manifold without any modification.

True- most Carter/Eddy carbs have both patterns. Guess I was thinking more along the lines of a Holley, which would require the adapter. I believe that's what the factory did on the D/Stock Dart engines.

 

[toolmanmike]

True- most Carter/Eddy carbs have both patterns. Guess I was thinking more along the lines of a Holley, which would require the adapter. I believe that's what the factory did on the D/Stock Dart engines.

The secondary butterflies are too big for a stock manifold if you are using a 600 Edelbrock.