Hacks and tips for carbureting the 98-2001 Explorer v8, with HEI and separate TCU

[corerftech]

Backstory broad strokes:

Carbureted my 01 Exp 5.0 with a squirt TCU, asking why will be futile.

Hack #1: Purge Valve Modification

Only a few caveats exist for the conversion and I know them all.... one is the purge valve for the vapor canister.
In an attempt to make things behave like the EFI but run a carburetor, I dont want fuel smell, I dont want vapor accumulation under the car and certainly not under the hood where Ill smell it as well. I also want to actively be purging the canister at least as well as a 1972 Ford truck would have in 1972. The factory of course uses a 12v solenoid purge valve that gets a signal from PCM, that opens a needle valve which lets manifold vacuum pull a large diaphram with a twin seal out of the way, thereby connecting the vapor can line to the manifold vac port/PCV system under the appropriate conditions.

I am cheap. Initially I was going to use a GM vacuum switched purge valve as a contemporary analog device. Thats another $40-50 so screw that!
Last night I decided that the purge valve was pssing me off and making me think to hard to find a way to bypass it. You may say, "thats easy". No it is not. Bundy connectors are used for both in and out. Two differing diameter Bundys, 1/2 inch and 3/8. The 1/2 inch is a "nylon" hose extension from a steel line as far as I can see and is the input. The output is just FI hose with Bundy to barbs, that part is easy. I found parts ot help but again, another $25.00. You mess up a nylon hose under your Air Conditioner compressor and you rapidly become an angry person.

So I removed the entire bracket with purge valve and found it was quite easy to disassemble. I will post some stills of the modified device later tonight.

Essentially it is a clamshell. Take the electric half off to expose a large return spring, a diaphram with 3 separate seal surfaces and a plate with two orifices. The diaphram has a major diameter outer seal that seals the clamshell. The inner diameter is for sealing the INPUT channel cast into the plate. The center of the diaphram has a TIT that is like a pencil point, and it PLUGS the OUT to manifold orifice. At rest the diaphram simultaneously blocks the CHANNEL, the ORIFICE and maintains a seal on the clamshell. When vacuum is applied from an accessory tap by the solenoid, the diaphram is sucked away from the platter, opening both channel and orifice linking them.

The hack is to both maintain the clamshell seal integrity but loose the dual seal integrity permanently. Once opened, I removed the return spring as there will never be high vacuum applied to the system. Second, I added two BUMPS to the platter surface causing the dual seal to see a lump rather than a smooth surface to seal against. Lastly the center of the diaphram is aluminum and I hammered a small dome into it so that it could not seal the old TIT/Orifice even with the silicone TITcut off. Under test even with tit removed, the flat center of the aluminum did effective seal about 90% the orifice.

Essentially the diaphram is now unable to seal except the perimeter of the clamshell. You can suck/blow with very little restriction. I effectively married the two ports making a butt connector out of a purge valve. I get to use the factory hoses in total, the valves outlet will feed the air cleaner base plate port with the 3/8 OEM hose which happens to be the correct length to get there.


Thats the hack. It is a rare situation I believe I created but Ill bet someone else on some other later model RBV(ish) car may desire to link the purge line to the carburetor region of the engine cheaply on their converted EFI to carbonator system. Could be done on any car with a purge valve, at least from Ford. I have seen quite a few purge valves from Fords and they all seem to be built similar.

If you were wondering why I did not just power the solenoid, I dont believe the device is rated or designed for continuous duty. It would smoke later on and stick closed.

Hack #2: Coolant temp sensor (gauge) location for the Edelbrock Performer 289 manifold with HEI distributor combo

The 289 manifold will accept the EFI T-stat housing. The manifold T-stat port opening is significantly further forward than the EFI manifold. Therefore the Water Pump shot molded bypass hose cant be used. Making matters worse, the HEI distributor is so large in diameter (large cap/coil version) that the normal location for a gauge transducer is covered and too close to distributor to fit. Interestingly the OEM stat housing has a cast recess that has not been drilled or tapped, for a coolant sensor. Even worse, the thread pitch of your "reused" efi sensor is 16x1.5mm pitch, not 1/2 NPT like the manifold wants. What to do???

Plug the driver side 1/2 inch port in manifold.
Either buy a Drill/tap kit for 16x1.5mm and thread the OEM stat housing or buy a Dorman replacement. The Dorman is JUNK, aluminum and will have more casting slag, chips, burrs and crap than the floor of a foundry. But it has the 16mm port already D/T and has a plug in it. Remachine the housing with a file to remove what they left in China, remove the plug, install the sensor. It will clear the HEI housing by 1/16 to 1/8 depending on how you clock the sensor and that is with the single wire OEM connector attached. Excellent position as well.

Hack #3: Performer 289 distributor relief cut

There is a boss that is cast into the manifold and it will interfere with the HEI distributor cap CLAMPS and a uninterrupted rotation of the distributor for timing. Before manifold is installed, deck that boss where it can be seen to interfere with the base plate of the HEI. On mine, I got 1/16 inch relief from the boss with a few minutes and a file.

Hack #4: HEI dist orientation

At 15 degrees BTDC on your installed crank timing tape that was indicated by a piston stop before you installed it........
Point the rotor button at the area between cyl #1 and 2 as you install the dizzy. This will place the vac advance can approx 4 o'clock as seen from front of car. This will both clear the A/C lines, alternator wire, PS pump stuff, etc (re: the vac advance can nipple), will place it in a short but sweet relationship to the carb manifold vac nipple (edelbrock carb) and also allow you to route all HEI harness wires cleanly to the C115 harness connecor on firewall.
The #1 plug position on dizy shall be at 7 o'clock with the HEI wire connectors at 6 o'clock. 13726548 and your done. As well you can reuse ALL the spark plug wire management clips for a relativey clean, free wire management.
Lastly, you will also gain even more clearance from the CAST BOSS on the manifold mentioned earlier.

Hack #5: Water pump bypass line

No hack, just a crappy situation. The Stat housing is SOOOOOOO far forward that unless you make a 5/8 hard pipe, you can't get the two nipples, housing and pump, to connect. So no hack.... pulg both sides and live with it.

Really the hack is to drill and tap the housing port for a plug. A Dorman replacement would be necessary. Remove the expoxied 3/4 inch hose nipple, then D/T carefully but not so deep as to alter the housing gasket surface. It was too risky for my timeline to do so. If I screwed up I would have had to tap the OEM housing for 16mm temp sensor, and my old housing was done for its service life. I did not take the risk but it is clearly doable. one migh also have success simply doing as Dorman did, but with a solid smooth sided plug, epoxy the port. Make a steel plug, not quite interference fit, maybe .001-.002 loose and then use appropriate epoxy. If the plug is short enough, you could then PEEN the front edge to secure the plug as well as seal and glue.

Hack #5: A/C lines (the big fat hard one transverse to engine!)

Hack is to remove the bracket that secures it to the alternator (leave it on the A/C line, remove from alternator.
Then you and a friend (I did it by myself and it was all I had in me), bend the hell out of it. I am a 30 plus year veteran electrical contractor, so I used my special 'Trician powers to bend it just right. Support with one hand and pull like hell straight up. This will relieve the Vac Advance can for access and rotation as the dizzy and the A/C interfere badly. Dont be gentle or careful, it needs to move a LONG ways up and will then pose an interference for the upper rad hose. All is well, keep bending it up, it has plently of give and room below the hood.

You will need to lengthen the hose bracket to alternator with a metal strap. That will be obvious how to do. You dont want that hose to flop around as it will produce a leak later at the filter/drier coupling.

Hack 6: Where to install the Microsquirt TCU?

Remove your glovebox by squeezing the sides, it will flop down to the floor. There will be a defroster hose and some orange insulation. Driectly behind that is the old PCM firewall pocket. Run the TCU harness from the left side of the glovebox, behind the defroster hose and it will thread right into the PCM pocket. The TCU will live to the left of the glove box behind the A/C controls, plenty of room and your serial port access could not be easier for tuning. The PCM pocket will be sealed by the original cover, drilled for a gland to maintain water/air tight. Harness emerges less than 12 inches from the C115 firewall harness connector where it will marry with both the instrument panel, the trans harness, the ignition as needed. A 3 foot TCU harness is plently long with some to spare.

Hack 7: A messed up EGR boss on the passenger exhaust manifold

Luck me, someone had fixed the EGR a long time ago. Really fixed it. I had to find a simple way to plug the EGR boss. I tried to buy something, not happening. It is a unicorn. So, 3/4 inch NPT drill and tap, while in car. Kleenex stuffed both directions in the EGR boss to stop chips from moving to bad places. Liberal cutting fluid. Appropriate drill (its cast iron and butter soft to machine), drill as deep as you can! There are steps in the boss and those will be an impass for the tap to cut.
tap it (thats a big tap so expect lots of in/out/chip removal and slow progress by hand), vacuum it (Kleenex then exists naturally with chips, if not, set it on fire with torch). Amazon 3/4 inch NPT stainless plug. Use an impact to install it and send it with 200 lb/ft. When the Milwaulkee impact stops, its done. No leaks.

Hack 8: Spark plug wire heat protection

Due to HEI, needed custom wires. Good luck reproducing cheaply the Motorcraft aluminum heat shields. And they will not transfer to other wires.
I intended to terminate the OE cables to retain the factory boots/shields, the wires are simply too short for the dizzy install.

Moroso $39-49 Amazon kit, generic 8mm, with 45/135 boots. Includes HEI ends.
A plug wire crimper (proper, Titan brand or similar)
Take the old ford aluminum shields apart. Take the straight tube section, remove from boot and shorten the back side with tin snips. You want the spring to stay in, you need it. Install that on the plug end of the wire, it wont stay by itself very well (yet). You will need to alter the tube so that the end you cut cant cut into the boot, bend a radius into half of it. Sharp edges and spark plug wires are not a good thing.

Amazon, $12.00, 2500'F fiberglass heat sleeves for LS engines, and also use the old Ford aluminized sleeves as well. The more wire shielded in length the better.
Install the plug wire end with the shortened metal sleeve on the desired plug. Slide the amazon sleeve (and or OE sleeve) down to the boot and then thread the sleeve onto the aluminum tube so that they become one. That reporduces as best possible the 145 degree solid aluminum heat shield as found on a factory wire set.
Of course you only need to do this at a few plugs, the balance just get an Amazon sleeve.
Cut and crimp perfect length wires to your dizzy.

Hack 9: Remove the old air filter box.

Not a hack, it was just phun and made me happy.

Hack #10, Fuel pump

A hack or maybe just a rework, depending on your desire.
I replaced the fuel pump 2 years ago, in tank EFI. It died again and in concert with the PCM coil drivers. Bye Bye in tank pump.

I installed a low cost, easily serviced frame mounted carb pump and needed to mod the tank pickup to make that work.
A 3/8 stainless tube (Amazon, from another project) of about 12 inches replaced all the parts in the tank hanging on the pump hanger. It is a siphon straw about 1/4 inch from bottom of the tank. there is no return line on the 2001 chassis so easy for me.

Along with pump, the OE line was reused.
Buy a Ford QD to barb adaptor. This will couple a 3/8 fuel hose to the EFI stainless fuel line. That will feed your carb adjustable fuel pressure regulator and done.

Hack #11, timing tape

Use spark plug piston stop to generate the marks, split the difference precisely with a tape from under the car. Once you have teh split marks, manually turn the engine over so that you have access to the business side of the damper laying on your back. Use white paint pen very fine for the split marks. Sand the damper to bright metal prior to attempt. Mark TDC center, use small file to notch the edge of damper. If you trust the white paint pen, when you spray clear it will wash off. MAKE A NOTCH! Spray CLEAR rust oleum on the damper wherever your MSD/Holley timing tape will be. A light coat. Let get tacky but not dry. Apply timing tape carefully. Wait 10 mins. Respray the entire tape/damper affected areas with clear again.
Walk away for 24-36 hours. Timing tape should be semi-permeant like maybe 10 years permanent. The notch will guide a reinstall if it does fail to stay at some point.



I think that is all for now, I will post more when Air Condtioning is reactivated as it requires some intervention for absolute factory control features.
Pics forthcoming to help make sense.

For the TCU and harness changes, the 2000 Helms Elec manual is your friend. I may create a schematic PDF for the conversion that will save some folks some time. I have many, many hours of turning pages and creating offset sheets between devices to ensure my first start was perfect and everything works as it should with no wiring errors.

 

[alwaysFlOoReD]

Awesome write up.

 

[corerftech]

I am working on the TPS hack: using the OE throttle body TPS which uses a flat slot shaft for actuation. I am cheap and don’t want to spend the dough on the Hughes or US Shift kit. Most hacks use a GM TPS with the metal tab, a small wire linkage and a mount bracket of stamped sheet metal.

The Edelbrock AVS carbs (manual choke), have a primary shaft bell crank with a small 3mm(ish) hole on passenger side. Has a very small radius from the shaft centerline so it is a short stroke from closed to WOT but it is avail. I have tried to find a TPS with some kind of cable or heim joint or better lever and it doesn’t exist or it’s China garbage.
I was going to attempt to machine a shaft, bushing, stop collars, etc and that is a waste of time and energy.
The FoMoCo CTS TPS, JB weld putty and a flat ended shaft. Add a simple bell crank looking lever to the shaft and tack weld (tig) or any other fixing method of attaching. JB the shaft into the recess of the TPS. Wait and hour- voila. A TPS with a permanent shaft and bell crank.
Mounting will be from carb base studs (I think) or overhung like the Hughes kit from the carb top plate screws. Lastly- Amazon 4x4 toy car strut rod kit. I guess you get 6 to a pack from 1.6 to 3.2 inch for these super RC off road trucks. $15.00 gets you 12x. 3mm Heim/ball joint ends, on aluminum hex shafts (turnbuckles!)

It is a perfect little linkage and 3mm hardware at each end to connect carb bell crank to the TPS bell crank is just right.
The Ford TPS rotation direction is the same as the passenger side primary bellcrank.
Again, I’ll post a pic or two. I would be at peace with a repeatable $50 deployment of a Carb TPS. That’s a fair price, $190-230 is robbery. I was hoping to use MAP sensor for load detection but all I have read about the TCU is it really doesn’t shift well/reliably/precisely with MAP, but is perfect with TPS. MAP is infinitely easier though.

 

[superj]

nice find on those little rc car parts to use.

 

[bobbywalter]

so.....back in the 90,s i used to piggyback the van ecm to run a 4r70 or e4od with a carb. its not perfect but worked okish.


i do similar with my diesel and the 4l80 in my ranger now.

what i did was ran a throttle body off of a vic or whatever mounted in a project box we used to get from radio shack back in the day with its own cable on the throttle pedal. then ran the pcm coolant, map, idm and throttle body and some other signals(manual vss) to it and the trans outputs out. and either a gm or ford analog cruise control.

 

[DaveTS]

Wow, that’s quite the project! You've done some impressive work with those hacks, especially in finding creative solutions for fitting modern components like the carburetor and HEI distributor into the setup. It’s clear you’ve put a lot of thought into keeping things functional and tidy while working with what’s available.

I’m particularly interested in how your purge valve modification worked out—using factory hoses and simplifying the system to avoid vapor buildup sounds like a clever solution. The other hacks, like the coolant temp sensor fitment and HEI orientation, show your thorough approach to overcoming compatibility challenges.

Looking forward to seeing the pictures and any additional details on the air conditioning and TCU setup. Thanks for sharing—this will definitely help others trying to tackle similar EFI-to-carb conversions or using an HEI with tight clearance. Keep us updated!

 

[corerftech]

In my haste to assemble and rainproof the car, I installed the purge valve complete before pics. So my less than professional artwork must suffice

Pic of the complete valve.
Drawing shows the base of the valve which is removed from the whole assembly with a couple of small flat screwdrivers, easily. Perimeter plastic latches get stretched a bit and it pops apart.

This will expose the base with the tubing connections and the diaphragm. Coil spring presses on diaphragm and seals the concentric inner and outer seals when solenoid not active/and or vacuum not present. The little tit in the middle of diaphragm is removed with a screwdriver gouge easily. The aluminum dome is then dented toward the spring to raise its clearance from the central port opening. Or alternately you could shave down the port tower an 1/8 inch. The dent is less work.

the epoxy putty high spots are placed approx in line with the inner diaphragm seal surface. These should be very minimal, 1/16 inch to 3/32. This will allow the outer diaphragm seal to seal the entire device when you snap the top back on but the inner will have an obstacle in a few places. The diaphragm is flexible and will distort to the new shape. The dented dome will permit gases to flow from the central pipe to the outer pipe channel.
Remove the spring completely and toss.
Once assembled, blow or suck both directions on the two ports to ensure you have a complete bypass that has satisfactory flow. If too little for your liking, open and add more blobs of putty or- taller.
Let the epoxy have time to surface harden so the device doesn’t get stuck to the diaphragm with incited epoxy.

There are probably 9 ways to skin this so this was fast and took 10 mins, had stuff on hand. Simply ensure you have violated both the tower seal and the inner concentric seal permanent, whatever way you choose to go. Violating one or the other will leave you with no flow.

Had to wait on a job for 30 mins today and figured my scratch paper and boredom could be useful.

 

[corerftech]

Bobby,

You never cease to land quality data.

I had considered cutting up my 5.0 TB to a minimalist point but I am selling (a little investment recoup) the entire Explorer top end and I mean the whole thing including harness) and figured the TB with balance of parts was worth more as a group than the cost of the TPS hack and incomplete top end.

But—— a Honda TPS or similar (little ity bitty thing) bastardized and mounted with a throttle cable is a slap in that face for me. You added a box as mentioned, I say screw the box. I’ll mount a TB somewhere, anywhere.
Thank you Sir for yet again quality inspiration!
I’ll add- I have not given two shits about a PCM in my 50 plus years, so until recently I have not considered what might be possible with a factory PCM hack to allow trans only control.
Now that the squirt has been deployed, I have had to delve deep into operation. You again inspired more thought into hacking the Ford PCM with external resources (maybe 1997 and earlier to avoid some other pitfalls) to permit standalone operation. Although—- the Microsquirt is awful cheap in the grand scheme and is likely the best alternative. More food for thought Sir.

 

[corerftech]

Hack#21
Turn carb 180 degrees with primary to rear.

I have had a less than perfect throttle cable deployment since the car was started last weekend. It’s a 900 foot cable with cruise control parallel cable. I ordered an Amazon China junk cable kit, 24 inch. Examined the kit and returned it.
Staring at the engine bay, I decided to simply turn carb back to front. I was also forced to change the valve covers to some marketplace junk with breathers and pcv port. I contemplated modifying the stock ones and for the $15 I paid for nice lightly used stamped steel covers that included a 1.25 breather filter and grommets, that was the move.
In placing the pcv cover on passenger side (pcv to rear) this allowed a short and sweet vac line to the reversed carb. That also put the breather diagonal at driver side.
With the carb 180 flip, it will be more difficult to set idle, fast idle, mixture screw in total. But the throttle and Cruise cables can smoothly and lazily be routed from firewall direct to the linkage and snap right on. This move puts both in roughly the OE position.
Using the OE steel cable bracket (has pinch outs for both throttle and cruise endpieces) and welding to the Amazon Chinajunk universal carb throttle cable kit, there is a perfect union of OE fitment and “cheaper than I can fab from scratch” Amzonian China crap.
Lastly it places the fuel line from the FPR mounted to power brake booster, in short/sweet/protected line with the edelbrock fuel rail with gauge facing driver side of engine bay. Now while adjusting FPR you can see 10 inches away the gauge face.
This all involved a reroute of all plug wires and liberated some harnesss issues from back to front of engine.

Lastly, it better places the vac port shared by the vac accumulator tank for interior, advance can and MAP sensor for TCU— all inches from the devices with excellent routing.

Absolutely idel in this case to flip the carb. PCV port at rear, everything!

pics forthcoming.

 

[ummduh]

#1 I just took the seal out of the gas cap and plugged the vents in the tank. I never smell the fuel

#6 I put it under the cupholder. Made a small plate to mount it to the mount that used to hold the SRS module (I removed the airbags). Cup holders go right over the top of it.