1973 351 HO/CJ Build

[wrobinson]

OK guys I just jumped in the deep end of the pool. I just purchased a complete 1973 Mach 1 Q code. I will be retaining the factory heads. My question is what aftermarket dual plane is the best for a mild 351C build? Edelbrock makes two Performer style intakes one for a 4V and another for a 2V. I know the Q code heads are 4V but can the Eddy 4barrel/2V intake be mated to the 4V heads? Reading the 351C forums the biggest debate seems to be that 4V intake volume produces a lack of throttle response and low end torque. On BBC's an old super stock trick was to use an oval port intake on a square port head to accelerate runner velocity while gaining throttle response and more low end torque. The heads will be treated to some 2.09 BBF intake valves along with some pocket porting, and other small performance enhancements.

 

[73pony]

I am running 2v heads but I have heard that the Air Gap runs much better than the performer intakes. It would also help to know what you are running for a trans and rear gears, also are you keeping the stock cam or upgrading that as well.

 

[wrobinson]

The car has a C6 automatic with 3.50 gear ratio.

 

[73pony]

With the 3.50 gear ratio your rpms will be up in the power band of the 4v heads considerably sooner than if you had say 3.00 or 2.75 gears so that will help. My concern with putting a 2v port size intake on 4v heads is it falling flat around 4500 rpms. You can also compensate some of this with a higher stall TC in the trans, allowing you to correctly match the port sizes on the intake manifold and still get that back in the seat feeling we are all looking for.

 

[c9zx]

I've heard good things about RPM Air Gap on stock displacement 351Cs. It will seal to OEM 4v heads The mismatch should increase mixture velocity and may help lessen reversion. Chuck

 

[tony-muscle]

What about the Blue Thunder

1971 M-code Mach 1

 

[wrobinson]

That Blue Thunder intake looks awesome. It looks like a repop Boss 351 or Shelby. Looks are one thing but how does it perform?

What about the Blue Thunder

1971 M-code Mach 1

 

[c9zx]

The Blue Thunder works very well, I have one on my 408C. They are a little expensive and sometime hard to find due to small production runs. It is an evolution of the D1ZX-DA/Shelby intake. Due to smaller runner volume, the Air Gap will likely build a bit more low RPM torque. Chuck

 

[Mikes73]

I can vouch for the air gap, had one one on my old Cleveland and it had power everywhere.