View Full Version : 1957 Power- Pac option

09-13-2020, 05:32 AM
On the 1957 Chevrolet's , the power pac option included ; 4 barrel power pac heads, with bigger valves. 4- barrel intake, and carburetor. 4 barrel oil bath air cleaner,and dual exhaust. Bama can you tell me if the 4 barrel power pac version also used a different cam? How about the carburetor linkage? Is their something else different, besides the gas lines running on the outside of the frame on the 4 barrel car's ? I believe the 2 barrel versions put out 185 HP and the 4 barrel car's 220HP. I have heard that the 2 barrel car's will leave faster, because the 2 barrel carb's have bigger primary's , but when your rolling along at 40 or 50 and you get into it and the secondary's kick in, you know you have a 4 barrel . Also the Dual exhaust , must really make a difference.

09-13-2020, 06:32 AM
I cannot tell you for certain re the cam, but I DO believe the power pak cam was different than the stock cam that came wtih the base engine. I think all you posted is correct. 35 hp difference is significant!

09-13-2020, 02:12 PM
Forgot to mention that the distributor , is also different on the Power Pac 4 barrel version. The distributor has different mechanical weights, so the power band comes on differently than the two barrel version.

09-13-2020, 05:16 PM
PP heads have same 1.72/1.5 valves as stock. PP heads are smaller chamber for more compression.

09-14-2020, 05:01 AM
Thanks', the knowledge is priceless, and disappearing. Dom