I'm rebuilding a 4.9L for a '79 project truck, it's a 4x4 manual. The 4.9 will be EFI.

Do I need a wiring harness from a 4x4 manual or does it matter?
Do I need a ECU from a 4x4 manual or does it matter?

Thanks for any advice. Going in blind.

 

Who's EFI system will you be running?
I would not try and run a factory EFI system for a few reasons.
How old is the EFI system you plan to use as some of the parts will be hard to find if you can find them at all.
The information to trouble shoot the factory system if early EFI is also hard to come by and no way will a shop even look at the truck with that type of swap so it is all on you.

Being you have a 79 pre-EFI truck your best bet is to go with a aftermarket EFI like Holley Snipper and a aftermarket intake manifold.
The question is at that point do you go with the 2300 v2 with an adapter from the v4 intake to the v2 carb? Buddy has this setup in his 85 F150 and it runs great.
Others have used the v4 bolted right to the intake and works just as good they say.

What is nice with the Snipper EFI system you can run a larger cam than factory that you cant do with the factory EFI system.
Just information I have seen posted on the web
Dave ----

 

I hear what you're saying and those are good arguments. My reason for wanting to run original EFI was that I want an engine that will last as long as possible (what the 4.9 is known for) while having decent pulling power and decent fuel efficiency.

My reason for resisting the Holley Sniper is that I perceive it as something for high-performance engines / racing / etc. I'm not interested in trying to make extra horsepower. Can I set up a Sniper for max fuel efficiency? If so I'll probably end up going that route.
Is there any other modern alternative to the Holley Sniper that is a programmable option? Or is that the only one?

Edit: what is the benefit of running a larger cam?

 

I forgot the Holley Snipper also makes a EFI that bolts to the factory intake manifold. It is not just for high performance.

We need to look into this a little deeper. A motor is an air pump and the more air in & out the more power you can make.
Now when the factory makes cars & trucks they have to make them to cover a lot of different types of driving / drivers and weather etc. and still be reliable and everything you want but there is more to be had from just about any motor.
It is a known fact the intake and exh manifolds hurt air flow and power. Ford knew this and why the EFI motors got better flowing exh manifolds and would think the EFI intake has to be better also.

They say just swapping the factory intake and exhaust manifolds to aftermarket ones helps power but dose not hurt anything else, well maybe MPG as you are now pumping more air but they say it is not bad and most of the time a little better then the factory carb set up even with aftermarket carb.
If you are going thru all this work if it was me I would go the aftermarket intake and the v2 Snipper and EFI exhaust manifolds. With the Snipper you can get support when needed, who you going to call if the Ford EFI is not working?
Again there is not much out here on the Ford EFI system and even less people who know it now.

BTW my buddy running the v2 snipper is also running EFI exh manifolds for flow and the truck will be used as a cruiser around town. He has a little ove 700 miles on this new motor / EFI and electronic auto trans and loves is.
He did say the MPG is not good yet, about 11 MPG (never on the highway yet) but motor is still breaking in and it has only been driven in town I am sure if out on the high way it will shine.

My set up is factory carb & intake manifold with EFI exh manifolds into factory replacement 94 F150 pipes all the way to the rear. Manual granny 4sp with add on over drive, 2.75 rear gear and 235 / 75R / 15 tires.
I avg 15 MPG combo. 70 MPH highway 40 miles / back roads at 45-55 MPH 40 miles home. I have gotten a best of 17 MPG dont know how and a worst of high 13's.
I have over 28K on the truck in the 5 years it has been back on the road, cab off frame rebuild, and I also pull a 20' enclosed trailer at times.
I also have a AFR (air fuel ratio) gauge and it runs between 14.7 and 16.0 so it is not running rich.
Most people with the 300 six say they get about 15 MPG avg also.

Again I just cant see putting a 40 year old EFI system they has no support or part for on a motor when there is newer out there to use with support to boot. Change the intake and you get more power over the factory EFI too.
Dave ----

ps on the cam it has to do with the air in / out. More valve lift and staying open longer is more air being oved makes more power.
Note a lot of times this can move the power band up in the RPM range and this may hurt when the truck will be used for like pulling a heavy load.
It is always best to talk to the cam people on what is best for you. My motor is all stock other than the EFI exh manifolds.

 

You keep talking about making more power but that's just not what I'm interested in. I 100% take your point that I'm looking at using an obsolete system with no support. That is a concern. I'll just have to keep reading and learning. I've got time, this project will take years. Thanks.

 

You wanted to know about the cam and that is why you would change cams, for more power.

Now unless you run the Holley Snipper that bolts onto the Ford factory log manifold if you change out the log manifold for aftermarket you will get a better flowing intake and it just makes more power.
It dose not shorten the life of the motor any. A fuel pump be it motor driven or electric can fail just like the oil pump, valve guides, etc. When it is time for what ever to fail it will.

I have a 02 Dodge 5.9 with 293K miles and it has had the heads, timing chain and fuel pump since I bought it new with 8 miles on it.
As long as you do service when it is due it makes no difference if you boost the power a little with a intake change with installing a modern EFI system.
Oh the good about the Snipper EFI is it is self-learning, the more you drive the better it gets.

I just wanted to point out what is out there and what happens if you go that way.
As they say it is your truck so build it the way YOU WANT and dont let anyone (me) tell you otherwise.

BTW you did not say what year motor and EFI system you are looking to use? Is it all from a 87> EFI motor and system or a mix of different years? Just would like ot know is all.
Dave ----

 

Haven't found it yet, the engine I bought came without one.

I'm not familiar with this term, but the manifold that came with my engine is the standard EFI manifold, so if I go the Sniper route I'll need a different one.

I appreciate the dialogue! As I said, I'm going in blind so any discovery is helpful.

 

OK a little lesson here.
This is EFI exh manifolds and a factory Y pipe for a 94 4.9 motor.

This is the factory log intake manifold. I dont have a picture of the EFI intake manifold.


Here you are looking at the bottom of the log intake and the EFI exh manifolds. Dont have a good one of on the motor.

This is the factory log exh manifold used up to 86.

Both the log manifolds hurt power, yep I said it again, and why if you have the chance to change them out people do so.
I was not looking to make big power but I needed to change the exh manifold so I traded parts and got EFI exh manifolds as they flow better than the log.
I did not want to go with EFI because I did not have the money and wanted good MPG so I stayed with he carb and log intake manifold.

Here is a link to the replacement EFI for the factory carb that fits the log manifold https://www.holley.com/blog/post/upg...0_carb_to_efi/
If you want to change to a aftermarket intake you can go with the the v2 EFI https://www.holley.com/blog/post/hol...iper_efi_2300/
Just letting you know what options you have over trying to get the factory EFI to work right.

Your EFI exh manifolds, after market intake manifold, adapter to run the Holley 2300 Snipper EFI and call it done.
No messing around with trying to find old Ford EFI parts and then making it all work nice.
Just my .02
Dave ----

 

Yes, thanks, after this thread and some more reading up and consideration, the Holley Sniper seems to be the way to go. That's what I'll be doing, thank you.

 

My point was any change you make to the intake or exhaust on the motor will increases power there is no way around it but will in no way shorten the lift of it, at least in my book.
Like any motor as long as you do normal service when needed it will last a long time. I got a Dodge 360 pushing 292K miles and still runs great.
Good luck and keep us posted
Dave ----

 

Will do, my project thread is here: https://www.ford-trucks.com/forums/1...ercab-4x4.html

 

Am I correct in thinking that the best intake manifold is the Offenhauser C, and that an original upper intake off an old '78 straight six would not be as good? Because I have easy access to one of those if I want it (the old one).

 

I know there are 2 different Offy intakes but I dont know what one is the better as I have not looked into it as I dont plan on going that way any time soon.
They say any aftermarket intake is better then the factory log intake.

When I rebuilt my truck I was looking for MPG and why I stayed with the factory intake & carb with the EFI EXH manifolds.
Dave ----