I did some pretty heavy soul searching on the Imperial engine project. My nerdy side had taken over and I got all caught up in making the engine as efficient as possible. Efficient engine means torque. It also means better fuel economy. Big torque also means lively performance and more fun to drive but focusing on that trades off horsepower. Digging back into my fuel and mileage records from the 2012 Power Tour (Dallas to Detroit and back) I saw that I was only getting 12 mpg.

I'd told myself a while back this was likely to be my last old school engine build. The new stuff is just too efficient and easy to get power out of. That's doubly true when you think of these old big blocks with what are essentially small block heads on them. Looking back at my engine builds I realized that I had done some fun stuff but never really built an engine with good parts. They'd always been a hodge podge of used factory bits with cams and other stuff bolted to them.

As for the car, it's only value is the engine. Without a 440/727/8.75 this car is little more than demo derby material. It's an organ donor on wheels.

Only after hours of soul searching and long deep conversation with close friends did the real me resurface.


The Imperial is going back on the road with 543 cubic inches of RB power. It's too late to talk me back from the edge. The money is spent. I'm going back to my happy place which is just a wee bit on the other side of bonkers. I was only fooling myself with all that adult supervision talk.

I ordered a 440 Source 543 kit with 10:1 compression on 88 CC heads. I'll call Comp and discuss a new cam for this build. The old Edelbrock heads that helped the 440 and TT440 will become the bottleneck in the build. Torque will be fierce but there's no way these heads will support over 600 hp naturally aspirated. The heads will likely limit rpm to something around 5500 before they strangle things. That's fine because piston speed will be excessive with the 4.5" stroke.

I'm not going all out. This will still be a relatively mild mannered build compatible with power brakes and a stock-ish converter. However, with the inches I can get away with a bit more cam.

The Headman headers I was looking at are going to be too small so I'll likely have to call TTI for something that fits properly and can handle the flow. There's plenty of room under the car for 3" exhaust.

It will be fun getting back to my maniacal side with something as absurd as an early 70s land yacht. Imagine the look on Mr Mustang's face when this old dinosaur picks on him. It's the Imperial! I'll be ahead of him and behind him at the same time.

I might be able to squeeze out 10 mpg if I behave myself. The OD would still be handy but could lead to bad ideas. The Imp was not designed for high speeds but it would certainly be capable. I'm not always on my best behavior as witnessed by my jaunt to the high side of 160 mph in the half-pint AMG this week.