I have an '86 F-150 302 EFI with 190,000 miles......and theres absolutely nothing wrong with it and it runs fine....and its never had a rebuild.....so i was wondering, if i put a higher lifting cam in it will it mess anything up? My father told me you probably wouldn't want to do it, but i want a rougher idle and a little more horsepower....so i need a second opinion.

 

does anyone have an opinion of what i should do????

 

I looked at playing with my 86 EFI and from what I saw, it wouldn't do a whole lot. The Speed Density system isn't very tolerant of changes. To do it, it looked like I would have to change my system over to a later model MAF setup, then it would do better with CAM, Lifter Mods etc.

FWIW - I do plan on doing it down ther road though my plan is to swap a 351W 5.8L and go to MAF. Either that or do the 429 EFI thing as I wrote in another post though I will have to wait until I get out of California to do that. I doubt I will go that big though as I would like to be able to pass a gas station every once in a while instead of stopping at every one I see. -ggg-

Lee

 

well thanks for the info.....but is hard to change over to a MAF system and how much would it be?

 

If you get most of the parts from a junk yard, it should be cheap and you just put the components where the other ones are now. The major work is for those that don't have any computer stuff.


I would put in a new MAF sensor though since you don't want one that is dirty and has bad data coming from the wire. I have done some of the research already though ot all and it isn't that big of a deal. You can even use some of the same harnesses and just swap a couple wires around.

I have a diagnostic tester and besides the better power, fuel economy and what not, I also want to be able to plug in and get more useful info than the current system we have which just gives the bare bones basics. With EEC-IV, it will tell you EVERYTHING and let you watch the real time signals etc.

I probably won't do it for a while though. I am in the middle of some major suspension work then have to get my rust proof and paint job done so engine/computer swap will be at least a year off.

Lee

 

well thanks alot...

 

The speed density system uses the EEC-IV computer, the MAF was EEC-V. They both will give you realtime information with the right tools. Regardless of MAF or SD you won't be able to use a "lopey" cam, the computer needs a constant vacuum source to read the BARO sensor on the MAF and the MAP on the SD.

 

so there is no way i can have a lopey cam???????

 

It's never a good idea to open up a well seasoned engine and start tinkering, chaos theroy Ive actually beefed up quite a few higher milage engines last one I did was in a vett, it lasted a week before the engine self destructed. So yes your dad was right! If you want to change the cam its time for a rebuild. This way you will start with a fresh engine and gain a whole lot more power.

(semi rant)
Why on earth would you want one? I mean people go all crazy and slap a gear drive in a 145hp engine just so it sounds like it has a blower. Sound means nothing unless your engine has the ***** to back it up! You need to work on other aspects first.
(end)
If you really just wanted a lope to the idle you could retard the timing or pull a plug wire off, thats free.:lol:

 

not unless you run a carb, which will keep you from passing emissions, if you have them in your state or county.

you could swap a MAF fuel injection system from a 5.0L mustang, but they have limits on how lumpy the cam is.

 

i live in tennesse and there are no emissions....and i have a brand new holley 750 sitting around in my garage so i guess i could swap em out but.....someone told me that its a nightmare trying to get the truck runnin when you swith the EFI system to a carb.....any info on that???

 

Well i guess i could just pull a spark plug wire for now....but how much do you think the average cost for a rebuild on my 302 would be?

 

a holley 750 is way too big for a 302. You'll need to get a carb intake, Duraspark 2 distributor, mechanical fuel pump, and probably a couple more things that I am probably forgetting.

 

why cant a 302 run a 750?

 

Well a 750 VS carb can be used on a 302 but its very hard to tune it. The secondaries will have to be converted to a metering block so have rear jets that can be leaned down, the primaries will require very small jets and the pump cam will need to be decreased. A VS carb works off of engine demand if the engine is too small even a WOT you may not see the secondaires crack open more then 1/8in with that big of carb and the jets need to be right on in order to keep the engine from going rich. You would be better off with a 600cfm carb. If you dont know how to tune Holleys (most people dont) I'd suggest an AFB or Edelcrap they are much easyer for the carb beginer to work with although they dont have the advantages a properly tuned Holley will offer.

Now if you did want to ditch the EFI and felt comfortable working with the current high milage engine here are some suggested parts (#) need, (*) suggested.

1.*/# 600 CFM carb.
2.* DII distributor.
3.* 4bbl Intake manifold.
4.*/# aftermarket IGN box.
5.* Coil.
6.* Intake gasket set.
7.* New throttle cable & linkage.
8. ****** A good fuel pressure regulator.

Now some nice components that will give you what you want.

Cam, Lunati #07602, Street Master Series. This will give you the idle and midrange power you want for stoplight to stoplight fun and its a nice cam for passing up slow cars doing 75MPH down the highway

Intake, Weiand #8020, Stealth. This will allow you new induction system all the air it needs and wont effect low end grunt at all.

The carb choice would be, #80457-S Holley, #1406 Edelcrap, or an AFB which I dont remember the part number.

The FPR needs to be a real one to reduce the 30+ PSI of your EFI system down to a useable amount for the carb. I think The Jegs # is 510-12-84 but I dont remember for sure.