HEI DISTRIBUTOR WITH FORD EFI
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4wd Low
Joined: Dec 2021
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HEI DISTRIBUTOR WITH FORD EFI
I BELIEVE I MAY HAVE FOUND A WAY TO MAKE THE EFI WORK PROPERLY WITH A GM TYPE HEI DISTRIBUTOR, IT SEEMS THAT IF YOU REMOVE YOUR SPOUT CONNECTOR AND POWER YOUR HEI IGNITION COIL WITH THE ORIGINAL FORD IGNITION COIL HARNESS AND SUPPLY THE PIP SIGNAL WIRE WITH TACH SIGNAL FROM THE HEI THAT IT MIGHT GIVE THE ECM THE TACH SIGNAL NEEDED TO FIRE THE INJECTORS AND SUPPLY FUEL, THE ONLY THING I'M NOT SURE OF IS THE NEGATIVE VOLTAGE SUPPLIED BY THE HEI AND WHAT VOLTAGE AND POLARITY IS REQUIRED BY THE EEC-IV FOR THE PIP SIGNAL.
ON A SIDE NOTE, MY TRUCK IS A 1996 F150 4.9 5 SPEED STANDARD TRANS WITH OBD2 AND A MAF SYSTEM, THIS MIGHT WORK EVEN BETTER WITH THE OLDER SPEED DENSITY SYSTEMS AND I BELIEVE THERE COULD BE HUGE POWER GAINS AND AN IMPROVMENT TO THE EFFICIENY OF THE ENGINE BY TAKING CONTROL OF THE TIMING CURVE.
ON A SIDE NOTE, MY TRUCK IS A 1996 F150 4.9 5 SPEED STANDARD TRANS WITH OBD2 AND A MAF SYSTEM, THIS MIGHT WORK EVEN BETTER WITH THE OLDER SPEED DENSITY SYSTEMS AND I BELIEVE THERE COULD BE HUGE POWER GAINS AND AN IMPROVMENT TO THE EFFICIENY OF THE ENGINE BY TAKING CONTROL OF THE TIMING CURVE.
More Turbo
Joined: Nov 2015
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The PIP signal from the stock EFI distributor has one pulse width that is less than the other five pulses to mark #1 cylinder in order to operate the sequential injection on the 1996 4.9.
The HEI distributor will not have the cylinder #1 indicator for sequential operation.
You would lose the knock sensor control which could lead to engine damage.
The EFI head has a fast burn chamber and any attempt to advance the timing would create detonation.
The HEI distributor has way too much mechanical advance timing for the EFI head.
The HEI distributor will not have the cylinder #1 indicator for sequential operation.
You would lose the knock sensor control which could lead to engine damage.
The EFI head has a fast burn chamber and any attempt to advance the timing would create detonation.
The HEI distributor has way too much mechanical advance timing for the EFI head.
More Turbo
Joined: Nov 2015
Posts: 710
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The power is limited by the injector size and fuel tables, not the ignition timing.
Here are a few ways 1987 and newer EFI engine owners have added performance.
Going to a less restrictive exhaust system.
Replacing the stock 1.6 ratio rocker arms with the Scorpion 1.73 ratio roller rocker arms.
The biggest gains in power are a performance cam and cylinder head modifications.
These two changes push past the limits of the stock EFI system and require larger injectors and reprogramming of the stock ECM or replacing the stock ECM with an aftermarket EFI system.
There are several companies that can supply the tools needed to reprogram the stock ECU.
The HEI distributor is a bad idea on a Ford 300 six.
The HEI tach signal is from the negative side of the ignition coil and is what we call a "Dirty Signal" and should not be used to trigger sensitive EFI units.
Here are a few ways 1987 and newer EFI engine owners have added performance.
Going to a less restrictive exhaust system.
Replacing the stock 1.6 ratio rocker arms with the Scorpion 1.73 ratio roller rocker arms.
The biggest gains in power are a performance cam and cylinder head modifications.
These two changes push past the limits of the stock EFI system and require larger injectors and reprogramming of the stock ECM or replacing the stock ECM with an aftermarket EFI system.
There are several companies that can supply the tools needed to reprogram the stock ECU.
The HEI distributor is a bad idea on a Ford 300 six.
The HEI tach signal is from the negative side of the ignition coil and is what we call a "Dirty Signal" and should not be used to trigger sensitive EFI units.
FTE Legend
Joined: Nov 2015
Posts: 30,919
Likes: 4,123
From: Angier, NC
Why do you want to swap in the HEI dist. and then remove everything that is good?
The HEI is a stand alone dist., coil & advance is built in.
You want to swap the coils? and then disable the advance because the EFI computer will take care of that.
BTW if the computer sees anything out of wack it goes into limp mode and everything is locked, reduced timing and rich fuel.
Also because the EFI computer cant be "chipped" like the new stuff, how would you adjust anything?
What is it you are trying to do?
Dave ----
The HEI is a stand alone dist., coil & advance is built in.
You want to swap the coils? and then disable the advance because the EFI computer will take care of that.
BTW if the computer sees anything out of wack it goes into limp mode and everything is locked, reduced timing and rich fuel.
Also because the EFI computer cant be "chipped" like the new stuff, how would you adjust anything?
What is it you are trying to do?
Dave ----
Thread Starter
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4wd Low
Joined: Dec 2021
Posts: 14
Likes: 4
Why do you want to swap in the HEI dist. and then remove everything that is good?
The HEI is a stand alone dist., coil & advance is built in.
You want to swap the coils? and then disable the advance because the EFI computer will take care of that.
BTW if the computer sees anything out of wack it goes into limp mode and everything is locked, reduced timing and rich fuel.
Also because the EFI computer cant be "chipped" like the new stuff, how would you adjust anything?
What is it you are trying to do?
Dave ----
The HEI is a stand alone dist., coil & advance is built in.
You want to swap the coils? and then disable the advance because the EFI computer will take care of that.
BTW if the computer sees anything out of wack it goes into limp mode and everything is locked, reduced timing and rich fuel.
Also because the EFI computer cant be "chipped" like the new stuff, how would you adjust anything?
What is it you are trying to do?
Dave ----
More Turbo
Joined: Nov 2015
Posts: 710
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Which cam are you going to use?
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4wd Low
Joined: Dec 2021
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I was thinking about the comp 268H but I might go bigger, I don't tow a lot and I mostly speed with it so it'd be cool to actually beat someone in a race with it.
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FTE Legend
Joined: Nov 2015
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From: Angier, NC
IIRC you pull the wire and set base and plug wire back in and the computer dose the rest.
So how do you think the HEI that is locked (mechanical & vacuum) be any different?
Computer is still going to control timing, or what am I missing?
With all the changes what have you done to the computer as you cant tune it?
If you have done something to tune it then you could use the TFI dist. and plot the timing curve.
Dave ----
More Turbo
Joined: Nov 2015
Posts: 710
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The reason is, the stock cam also has 268 degrees of advertised duration, but it is retarded 4 degrees with intake lobe center at 114 degrees ATDC to keep the dynamic compression ratio low.
The Comp 268 cam is usually installed advanced with the intake lobe center at 106 degrees ATDC which raises the DCR a lot higher than the stock cam and makes the engine prone to detonation.
if you use the Comp 268 cam install it with the intake lobe center between 110 and 114 degrees ATDC and leave the ignition timing alone.
If you advance the ignition timing it will make the problem worse.
You will need to change the valve springs to the Comp 903 springs and replace the rotator style exhaust valve spring retainers to the intake style retainers.
55-6179 | QualFast High Performance Retainer | Goodson Tools & Supplies
The EFI head uses short 4.750" valves which limits the amount of valve lift.
The Comp 268 cam has relatively low .456" valve lift and is not a problem.
If you go to a larger cam with more valve lift, the valve spring retainers can run into the valve guides and bend pushrods.
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