Hey guys. I recently bought an 87 f150 with a 302 and c6 from the original owner. I originally bought it for a hunting vehicle, but have decided to restore it since the body is so straight and rust free. I was checking the oil the other day and realized the original owner had not only gotten rid of what I’m guessing was a smog pump or some type of emissions system, but he also has a TON of vaccum lines and wires cut under the hood. The truck runs “alright”, while driving, but has a terrible surge and slight miss at idle, especially when the truck is in park (not under load). Considering I am redoing the truck, I also want to add a couple of performance parts to the 302 under the hood. I know this truck uses speed density and from my understanding, these trucks are hard to get running right even with a slightly more performance oriented cam. And the fact that it doesn’t run exactly the best even being stock, I am wanting to convert the truck over to carb. I was wondering if I could get some advice from you guys regarding on what I need to do this conversion for not only the engine, but also to get the c6 behind it to shift correctly. Thanks in advance.

 

It's illegal, regardless of local inspections. Everywhere. And it's counterproductive, expensive, and NOT conducive to reliability, economy, or even performance. There are MANY reasons no one sells carb vehicles any more, and why they're not desirable. If you want the truck to run well, just fix it - it's MUCH easier than hacking it up & then trying to make it run OK. No, these early EFIs are not difficult or expensive to maintain, unless you start trying to re-engineer them. If you're not an automotive engineer, just keep it running the way Ford designed it to, and you'll enjoy owning it more.

There are only about 8 vacuum lines on that engine, shown in this diagram:


(phone app link)

Silicone vacuum tubing is only ~$1/ft, even in original colors:


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Even the secondary air (smog) system is easy & affordable to maintain:


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Wires are not hard to repair, if you're patient & methodical. The ones shown in this & the NEXT few pics were cut with a sawzall by thieves:


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If you're not comfortable soldering, they can be crimped:


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No matter what you choose, this is a wise investment:


(phone app link)

 

Illegal to drive a carbureted vehicle? Don’t think so. Lol. This truck is not going to be a daily driver. Don’t care how it starts in the cold because it’s “cold” for about a whole month in southeast Georgia. Carbs are much easier to work on and no computer re-writing when it comes to performance. Speed density motors do NOT respond well to performance add ons anyhow. Not going to put that much money in sensors and emissions systems to have the truck run worse than it does now. I’m sure there’s a REASON he took it off in the first place. Thanks for the “help” though.

 

Well, my neighbor just carb`d his `93 XLT, & it seems to run fine. He does not have to worry about inspection because he got antique tags/title for the truck. I don`t know all that he changed, but I do know he bought an Edlebrock carb & intake & a new distributor.

 

No, your first post didn't ask about how to drive a carb vehicle. Remember? So that's not what I was talking about, either.Irrelevant. If you ever plan to drive it, it will drive better the way Ford built it. The closer you get it to the way Ford builds them today, the better it will drive.That's not what "cold starting" means.No, they're not, but they do NEED more work.No re-writing period - these computers can't be flashed.Newsflash: NO engine responds well to backyard (beercan) engineering.So you're going to put MORE money into a carb?It certainly will, if you continue with your plan.Oh, well then just trust him - you can be sure he knew what was best. After all: he unloaded his problems onto you, and got some money out of you to boot!

 

To the OP - Here are my thoughts that will hopefully steer you into the right direction should you have a thought to stick with the EFI.

1) The vacuum hoses aren't all that complicated. You'll need about 20 feet of vacuum hose and two vacuum Y's or T's. Take your time and look at the diagram and piece it all together. It is relatively simple. You can re-route the vacuum hoses around the front of the engine (either over the top of or under the throttle body - depends on what works best for you) as opposed to how the thin, brittle factory vacuum hoses are routed around the back of the engine. I suggest replacing all of the vacuum hoses, to eliminate the possibility of a cracked vacuum hose causing driveability issues.

2) Make sure the vacuum tree on the upper intake is clean. Crud can get caught up in it and block the flow of vacuum to your MAP sensor. That could cause a surge. If necessary, remove it and clean it thoroughly.

3) Regarding the EGR system, this is where lots of folks tend to have problems. Depending on how the vehicle was maintained, there is a possibility that the passage for the EGR could be stopped up down in the intake. If you have to remove the intake, do what is necessary to clear that passage out from both sides of the intake. If you have EGR valve or EGR sensor problems, only a Motorcraft EGR position sensor will work with an OEM EGR valve. If you go with an aftermarket EGR valve, then an aftermarket EGR position sensor or Motorcraft EGR position sensor will work with the EGR valve (yes, I did the experimentation to figure out why aftermarket EGR position sensors didn't work with OEM valves). Also, the EGR tube from the intake that connects to the EGR valve could have a crack in it that causes a hard to track surge. If you have to remove it, spray WD40 or some sort of penetrating oil on it to loosen it if it's rusted on. The EGR tube is worth investigating.

4) Invest in a code reader. Will save you lots of trouble and steer you in the right direction.
and the cable for the above reader

5) As for aftermarket cams, you'll need an IAC bypass valve so that it doesn't surge. The 'surge' happens because there is not enough airflow at idle to meet the requirements of the new cam. That is what the IAC bypass plate cures. Also, you'll need an SD friendly cam so that it makes enough vacuum to keep the MAP sensor happy.

6) PCV Valve - Make sure this is a Motorcraft only part. Aftermarket PCVs do not work on these trucks. This could lead to idle and performance problems as well.

7) IAC valve - Make sure this is clean along with ensuring the throttle body is clean.

I don't know a whole lot of details about your truck (from reading your first post), but it doesn't take a whole lot to get the EFI running properly.

Hope this helps.

 

To the OP:
Getting these trucks back to running as new isn't difficult. Vacuum lines, spark plug wires, IAC, and EGR parts seem to be the most common failure items. Start with these, none are difficult. A search of this website using Google will provide all the information that you need.

A Haynes manual can help. A set of Helms Manuals will be infinitely better. Readily found on Ebay. The price is worth every penny if you plan to keep this truck for long.

The cost to convert to carb will likely cost more than replacing the missing sensors, wires, and vacuum lines. You'll need a good carb, an intake, a distributor, and either a low pressure fuel pump or a regulator to lower the fuel pressure at the carb.

A visit to a local junkyard would provide all of the hard parts that you are missing and the sensors for a fraction of the cost of the conversion. Take a lot of pictures to help you get it back together correctly.

Either way that you go you will have some money and time involved in getting this truck back to its best. Get it back to running good prior to any modifications regardless of which fuel path is used.

For a good write up of how to get a little better performance from your speed density Ford truck check out the thread link below:
https://www.f150forum.com/f10/bit-in...l-302s-276512/


Good luck with your truck,
Jonathan

 

Thanks guys.

 

Wipe the tears from your eyes, and take a closer look... I didn't bash or down YOU - I bashed & downed CARBURETORS. You're not a carburetor, are you? I always discourage people from making the few of these trucks left on the road ILLEGAL on the road, and I always will.Again: you're mistaken. Perhaps more than most, I understand making your vehicle your own. I've certainly done that to ALL of mine. But you came here to get HELP, right? That's what I've given you - it just wasn't what you wanted to hear, but that doesn't make it wrong. And it certainly doesn't make it a personal attack. I've seen & done quite a few things with vehicles (these trucks in particular) over the years, and I'm trying to save you a few of the headaches I've endured (and seen others endure).No. EFIs are substantially more-powerful than carb engines of the same design & displacement. Even these old MAF EFIs. Particularly if you ALSO consider the cost & effort of getting that power out of the carb engine, and or its durability compared to the EFI version. EFI will always win in the long run, and quite often in the short run.

 

Would you happen to have a link to the IAC bypass?