Ask Away! with Jeff Smith: Picking a Good EFI System for an Old Chevy Inline Six Engine

Hello, I am writing from Cuba. I am rebuilding a 230ci inline Chevy 6 cylinder. I have pistons from a 283 to that are 0.060-inch oversize, a Magnum street cam 61-244-4, and all the parts that are required for the comp cam, also Harland Sharp rollers, a single quad Offenhauser intake manifold and headers, stainless steel valves.

Which electronic fuel injection (EFI) system would you recommend for this engine?

O.S.

This is cool that we are receiving more international tech questions. It sounds like you have assembled a good selection of parts, including the camshaft. We will list the specs in a chart below, but with 218/218 degrees of duration at 0.050, this is a great cam for a mild street engine.

To address your question, with the Offenhauser single four-barrel style intake manifold, a self-learning throttle body fuel injection system is a good choice. Many companies such as FiTech, Holley Sniper, FAST, MSD, and others offer such systems. Personally, I’ve worked with most of these systems and while all worked well, I’ve had the greatest success with Holley’s Sniper system.

In my case, we installed a Holley Sniper on a friend’s 468ci Rat motor in a 1966 El Camino with a slightly longer duration hydraulic roller cam. When performing the conversion, Holley suggests first retaining your traditional mechanical/vacuum advance distributor so you can concentrate on just the fueling side of the system. This allows you to get the engine running with the throttle body EFI first without worrying about what is happening on the ignition side. Once you are happy with the EFI’s performance, then you might consider converting to electronic ignition control using the Sniper software.

This is exactly how we did it on the big block Chevy and we were able to actually improve performance using the Sniper electronic ignition control using an inductive ignition system. We did not feel it necessary to step up to the CD ignition part of the system. The inductive is less expensive and offers all the tuning freedom you will need to optimize throttle response and power.

Don’t Overlook an EFI-Friendly Fuel System

It’s also critical that you build a complete in-tank pump assembly for your application. You didn’t mention the car you are installing this system in, but regardless it is important that the fuel pump be an in-tank unit to produce constant fuel pressure. There are several surge/reservoir tanks that are fed by the mechanical pump and placed under the hood but I’ve always felt these are patchwork solutions. If you want to do it correctly, invest in an in-tank fuel pump and a complete fuel return system back to the tank.

There are several companies like Aeromotive, Holley, and many others who offer either complete replacement tanks with pumps ready to go or conversion kits to convert your existing tank. The Sniper conversion kits are well designed, as are the Aeromotive Phantom kits—both of which I have used with great success.

Proper Break-in is Crucial

Another fair warning is to make sure you properly break-in the flat tappet camshaft. While this should be common knowledge, this demands emphasis since obtaining parts is probably more of a challenge for you in Cuba. The first emphasis will be on measuring valve spring pressure because it’s important that the seat pressure (valve closed) be no more than 90 to 100 pounds and valve open load especially be less than 250 pounds. This gives the stock lifters a chance to establish a proper wear pattern.

The other half of this requirement is selecting a proper break-in oil. In the old days, straight SAE 30 non-detergent oil was one way to accomplish this. Today’s current technology oil has removed much of the zinc and phosphate (called ZDDP) for emissions reasons which has predicated a demand for specific use oils like Driven’s SAE30 Break-In Oil as well as oil from Comp, Summit Racing, and others.

So if you combine running the engine for the first 15 to 20 minutes at 1,500 rpm or higher idle and vary the speed along with using relatively low spring pressures and a good break-in oil, you should be rewarded with a great inline six engine that will run famously for tens of thousands of miles. Spring pressure is important because with a seat pressure of more than 120 pounds and open pressure above 300, this can be enough to hurt a lobe or two. It’s best to run a soft spring during break-in and then change to a stronger spring after the lobes and lifters are fully seated. This is your best chance to achieve a proper flat tappet cam break-in.

COMP 61-244-4 Camshaft Specs