Street Rod Fuel Injection - No Carb Diet Part 2

Going from carburetion to EFI and then down the road

By Brian Brennan

Last month we looked at what it would take to convert your carbureted engine over to electronic fuel injection--in theory. This time we break out the wrenches. Remember we are performing two significant modifications: 1. We are eliminating a carburetor/intake/ignition and installing a new fuel delivery system; and, 2. We are now introducing a computer where none existed.

OK, you have had a month to think about it--are you ready to make the swap? Well, to take some of the fear out of the leap, follow along. Not being one to jump without a net myself, I have enlisted copious amounts of help from the pros. On my way home (that's 1,952 miles) from the Nats in Louisville, my roadster and I paid a visit to COMP Cams in Memphis, Tennessee, where we hooked up with the staff from FAST (Fuel, Air, Spark Technology). The old adage about, "If it works, leave it alone!" is true, but I couldn't resist. I was looking for something that would enhance the roadster's driving characteristics, improve cold and hot starting, and enhance performance. I wanted a roadster that didn't care if it were being driven along Pacific Coast Highway or making the climb over the Rockies, and most of all I didn't want any woes while dealing with the heat of the desert during the summer or getting caught up in the high temps and humidity of the South in August! Did I mention I am not opposed to better fuel economy and lower emissions?

The advantages of electronic fuel injection cannot be overstated. Yes, there was a time when automotive electronics and hot rodding were at odds, but no more. The little "black box" may still be a mystery to most, but the installation and programming should no longer be a cause of panic. It was back in 1957 that Chevrolet introduced the Rochester Ram Jet mechanical fuel injection and, while it appeared on several brands and models of cars over a short period, the most famous was the Corvette from '57 to '65. Today all three versions of the mechanical Rochester are highly desirable, especially to restorers, but the most popular from a performance standpoint was the '63-65 version commonly called the "big box" injector. The earliest fuel injection systems were mechanical and were more complex than carburetors. Consequently, they were expensive and their use was limited.

Ram Jet Fuel Injection Manifold Kit & FAST Electronics
In this particular application, a GM Performance Parts Ram Jet Fuel Injection Manifold Kit (less electronics) is a retro fit to engines (265-400) with iron Vortec (PN 12558060) or aluminum (PN 12464298) cylinder heads. This system requires an aftermarket ECU and wiring harness and that's where FAST comes into play. We started with a FAST XFI ECU (PN 30-1000)--wow, gymnastics for my fingers! The ECU comes with a wideband O2 sensor (all necessary software and instructions). From here we rounded up a FAST main wiring harness (PN 30-1101), an ignition adaptor (PN 30-1302), a fuel injector harness (PN 30-1200), and FAST fuel injectors (PN 30-2408), which are rated at 24 lb/hr.

The GMPP Ram Jet Manifold Kit (PN 12498032) comes with fuel injectors, fuel rails, throttle body, knock sensor, distributor assembly (PN 1104060), ignition coil, fuel pressure regulator, MAP sensor (PN 16194007), as well as an assortment of brackets, sensors, bolts, nuts, and gaskets. The GMPP cast-aluminum intake manifold (PN 12489371) is designed for port fuel injection and comes with two holes in the rear of the plenum that are tapered for a 3/8-inch NPT vacuum fittings. The hole in the rear of the plenum is intended for a brake booster while the hole in the right-hand side of the rear of the plenum is for a fuel pressure regulator (provided). To the system we added throttle cable hardware from Lokar Performance Products, a K&N air filter, Pure Choice braided fuel hose and hardware, and alternator and water inlet relocation hardware from Street & Performance. (When using braided hose be sure to flush all hoses and lines with fuel to keep any fine particles from plugging the injector screens.)

We are going to begin with an assumption, which can be a bad thing! However, if you cannot get the carburetor, intake manifold, mechanical fuel pump, and distributor off your engine, you really shouldn't attempt the following installation. So, let's all agree that we now have a long-block staring us in the eyes that needs a GMPP Ram Jet kit along with the accompanying FAST ECU system installed.

Last month we talked about the areas of concern and what you would address before tackling this project, remember? The gas tank and fuel pump are areas of major concern and should be attentively addressed. In this particular swap we planned ahead and ordered our Tanks Inc. 16-gallon tank with provisions for both an internal pump and a return line for the inevitable fuel injection. The internal pump was selected over an external system for several reasons. not the least of which are quietness and the elimination of heat as a potential cause of pump failure.

The Tanks Inc. internal fuel pump is based on a GM-style (capable of supplying 35 gph with an operating pressure of 43-55 psi) has an internal filter and reservoir tray (prevents fuel starvation when cornering or accelerating). To this an AC Delco GF-481 (or FRAM G-3727) fuel filter with a Street & Performance 16mm to AN-6 fittings and mounting bracket are used. (GMPP also recommends an AC Delco GF-626, 10-micron filter with 3/8-inch fittings.) In this application the bracket is bolted to the mechanical fuel pump block-off plate since this original fuel pump is no longer present. Pure Choice braided lines and fittings are used, and remember fuel lines for most applications should have a 3/8-inch for the supply side and 5/16-inch on the return side. The fuel hose and filter must be fuel-injection rated. (Keep this in mind: A Ron Francis fuel shutoff relay and switch that kills the power to your electric fuel pump serves as an effective theft deterrent system and as an aid in the event of a crash.)According to Mark Campbell of S&P, he receives calls every year in July and August from people experiencing vapor lock, so here are a few tips:
"Vapor lock is the heating of the fuel to a point where it turns to a vapor--logical enough! Internal pumps will help keep exhaust heat away from the pump, lines, and tank. Making a heat shield between these parts and exhaust will also help. High altitude can also be responsible for vapor lock. Another way to prevent vapor lock in the late afternoon is to top off your gas tank with cool fuel. You should keep fuel lines as far away from headers as possible, because with hot air coming off of the radiator and the headers and blowing over the fuel lines, it acts like a heat exchanger. Using an improper fuel filter, such as a billet style designed for carburetors, restricts fuel flow and places added backpressure on the pump. Fuel injection works better than a carburetor because it circulates cold fuel at the injector, a carburetor the fuel "dead heads" and is warmed by the engine heat which takes away horsepower."

INTAKE MANIFOLD INSTALLATION
Installing the Ram Jet intake manifold (PN 88959395) is accomplished in the same fashion as any small-block Chevy manifold--something many of us have done repeatedly during our formative mechanical years. But, let's go over some basics since we are dealing with the "new" Vortec manifold/head combo, which has several inherent changes.

The Ram Jet kit is comprised of new components so there shouldn't be a need to inspect the machined surfaces, but forearmed is forewarned. Make sure to check the manifold's machined surfaces for flatness using a straight edge. If the manifold is warped or the machined sealing surfaces are damaged, it may not seal properly, allowing water and other contaminants to enter the combustion chamber or lubricating system.

Clean the intake manifold thoroughly before placing it on any engine. You will need to clean your cylinder heads of any old gasket material and here are some recommendations from GMPP when prepping gasket surfaces, whether it be the manifold or head surfaces:
Do not use any form of blasting media and/or surface conditioning discs when cleaning the intake manifold.

When cleaning gasket sealing surfaces on new and remanufactured engines and/or cleaning parts, the use of surface conditioning discs that contain abrasives, such as aluminum oxide, may cause premature bearing failure. Now you should be ready to install the new Vortec gaskets (PN 88959395, two). Install the intake manifold side gaskets and the end seals on the block and cylinder heads, placing RTV sealant (3/16-inch bead) at the corners. Install the intake manifold, making sure to tighten the eight bolts (PN 12550027, they are different from other intake bolts) in the proper sequence. Tighten the bolts from the inside out, alternating sides and crisscrossing front to back. You will perform the torque sequence in two passes, with the first pass at 9 lb-ft, and the second pass at 11 lb-ft. Please take note it is 11 lb-ft and not a pound higher! These intake manifold gaskets are designed to seal at low clamp loads; excessive bolt torque may damage the gasket(s). If the intake manifold does not seal properly to the heads, water and other contaminants can enter the combustion chamber causing considerable damage.