How to Megasquirt your 3G Hemi

Fst73 360,

On a fundamental level fuel injecting an LA small block is very similar to injecting a late model Hemi, but since your engine was not originally fuel injected you'll have quite a few more decisions to make. I'd spend a fair amount of time reading the Megamanual (this is the manual for Megasquirt), I'd also read through a number of build articles. They have a bunch at DIYAutotune.com

The reality is that the first few build articles you read are going to sound like a foreign language, but after a while you begin to pick up the language and your understanding will increase.

The key issue with MS is that it is NOT (there are some notable exceptions) a plug and play system. Because it is 1/2 to 1/3 the cost of other stand alone systems and because it can be used on almost ANY engine from a single cylinder engine to a V-12, it has is very adaptable, thus it is complicated. Remember universal parts universally don't fit anything without a lot of work. :)

Here is an example to illustrate:

MS needs to know a number of engine parameters in order to inject the correct amount of fuel into the motor. One of these parameters is the engines speed and position. There are a number of different ways to get this piece of information. On the late model hemi you simply correctly wire the stock crank position sensor and cam position sensor and adjust the setting correctly in the tuning software accordingly. But your motor was never fuel injected, as a result you need to decide which method to use.

1. If you are retrofitting MS onto previously carbureted engine and ONLY want MS to control the fuel, you can use the the positive side of the coil as a trigger. 2. If you want MS to control fuel and spark you need to use either a trigger wheel attached to your crank or an electronic distributor with magnetic pick up. 3. If you want to use MS3 with fully sequential fuel injection you'll need both engine speed and postion sensors, thus you need BOTH a trigger wheel with missing teeth and a camshaft position sensor thus, the computer needs to know when the piston is on the compression stroke.

As you can see from the above example that there are a number of decisions to be made, and the only way to make them is to educate yourself on the various options available along with the costs and benefits of each option.

Good Luck. It may seem daunting, but it really isn't rocket science. There is a bunch of youtube videos that can really help.

Regards,

Joe Dokes