This question is for Lou (Dart270) or anyone else using the MegaSquirt system.

I think I’m getting close to trying an EFI system. My 65 Barracuda is currently not running because of a set of rusted out headers I bought way back in the 1980s. This year, I discovered that the accelerator pump of my 625 AFB has stopped working so it is nearly impossible for me to start the car. The AFB used to be on a racecar and the previous owner removed the entire choke mechanism so even when the carb was still good, the car was a bear to start in cold weather. This year I want to get it running and I will be installing a pair of Dutra Duals.

However, I am trying to decide what I should do for a fuel system. The simplest option is to replace the AFB with a 500 CFM Edelbrock PN1403. I like the idea of using fuel injection and when I was researching this last year, I found that Rance Baxter was the only one I could find who could offer a complete MPFI package for a slant 6. I was thinking that if I went that route, I could get the Rance EFI to modify the Offy intake manifold, fabricate the fuel rail and hold downs, and ship it back to me for US$450. For US$3150, I could get a complete Accel DFI MPFI conversion (except for the fuel lines). This is probably a good price for a complete DFI system but is still is a bit too much for me. I am planning to stay away from the system Bob DiBiase wrote about just because junkyard ‘85 and earlier Buick 3.8L cars are so hard to find around here.

I was following the discussions about others’ experiences with EFI and noticed that a lot of people are starting to use the MegaSquirt system. From what I can tell, the same control unit can run in TBI and MPFI modes. I am now thinking that I might start off with TBI and upgrade to MPFI later on. However, if MPFI is still reasonably affordable, I might just spend the money to go all the way.

Is there anyone out there who runs either TBI or MPFI? I’d like to hear your experiences in making the MegaSquirt conversion. What components are you using to make your system work?

Hi Frank,

I am gathering the parts for a megasquirt install right now. I am planning on a MPFI right from the start, with an aluminum manifold(easy drilling and modification, don't care too much about the porosity issues).

Don't let the manifold and fuel rail hardware scare you off from this approach. Here are a few links that might help you out
http://snow.prohosting.com/~johngift/intakefab.html
http://www.rossmachineracing.com/extrusion.html

Lots of how-tos at this page!
http://www.sdsefi.com/tech.html


Hope this helps. Good Luck!

Greg

Although Im a month away from doing this on my slant I have TBIed some of my other vehicles. I use the factory GM/Rochester 220 throttle bodies, puters(PCM) and sensors. The keys are:
(1)get the whole wire harness including the diagnostic port. There are actually few wires that need to be spliced and these are easy to figure out. The bulk of the wiring goes to the CPU.
(2) Get a chip burned that reflects the new vehicle the system has been installed to.

My slant system is being donated by a Chev Astro Van with 4.3. This system is virtually identical to the ones in my 73 Suburban and my 91 Buick Roadmaster. the differences are in the injector sizes and chips. Example: I just replaced (last week) the 305 in the Roadmaster with a cammed 350 with EGR,air pump and Cat delete. The stock chip hardly worked. I temporarily replaced it with a stock 89 Suburban 3/4 ton 350 AIR delete chip. It runs great but has no convertor lockup. My chip dude should have the new chip here next week.
My 73 Suburban is a torque monster with a split duration cam , headers, 3" exhaust, EGR delete, cold air package, heatriser blockoff, adjustable fuel pressure,and 4x4 conversion. It pulls a 24ft trailer. A new chip makes it start, and idle like a pussy. It took me about 4 hours to TBI the truck. The hard part is the fuel lines and fuel pump/sender.
All the Rochester 220 systems use the same CPU. The chips and injector sizes are the only differences. TBI 454 uses a largerTB but the same CPU. The injectors can be used in a 350 TB. 305 and 350 use the same injectors and CPU but the CPU supplies a longer injector pulse for the 350. The chip is the deal. The IAC setup on the 220 will work fine stock with any cam up to about 268 advertised duration.
The megasquirt seems attractive but the GM CPU is so flexible I dont see the point.
By the way the chip dude is at www.pcmforless.com.
Take a 12"x12" x .125 or .250 piece of aluminum with a TB gasket and a 4bbl carb gasket to any machine shop and they can make a TB adapter to bolt to your manifold. Im using a Super6 aluminum intake for mine..the adapter is a no-brainer. I plan to use the GM Electronic Spark control with a Lean Burn slant distributer (which I still need to find)
The oxygen sensor and a digital volt meter can be used to tune fuel pressure for power.

_________________
Yeah....Im the one who destroyed this rare, vintage automobile.....

Thanks for the advice, Sandy. I haven't thought of using a complete OEM system because I thought I wouldn't be able to reprogram the chip.

Some questions:
* What do you have to tell the chip dude to give him enough information to properly configure the chip?
* How much does he charge for a new chip?
* How does the ignition system tie-in with the fuel system?
* Is it possible to use a stock mopar distributor with the TBI computer?
* Do the throttle body barrels line up with the super six manifold barrels?
* What are the differences between the 4.3 TB and the 305/350 TB?[/list]

The chip dude has a whole form you need to fill out. You can always create a "faux" profile to represent your vehicle. Example: 97 Astro Van lightened to 3000 lbs , Comp Cams 252, headers , 5spd , 3.23 gears 24" tall tires = my Valiant. The new chip is $99.
The CPU controls injector pulse width and ignition advance (and EGR, AIR etc) I plan to use a Lean Burn dist with the GM TBI ignition module,,,2 wires.
The throttle body bores line up with the Super6 manifold but the bolt pattern is different (no big deal)
I dont have my 4.3 setup home yet (sea of breakup mud in wrecking yard) to see if the TB is the same as the 350 one I have. I suspect it is smaller from my quick look. The cool part about the Rochester 220 is how short it is,,. a big deal on my Valiant where the hood is so low I have to use a small aircleaner on my Super6. A cable throttle will hook right up to the Rochester. Kickdown should be easy. (mine is a 5 spd.)
Last week I paid $100cdn for a complete TBI setup out of a 350 SUB for our mudbogger. We are looking for driveability in the bogger so it starts and runs like our work truck (same cam and headers and heads more compression)
These systems are like a carb at idle and full throttle(fixed metering) but run on the oxygen sensor for part throttle. By choosing the right size of throttle body and fuel pressure you get good starting and idle and full throttle. It takes an hour and no money to convert a 220 to adjustable fuel pressure. On the mudbogger we need a chip that says : 1800 lbs, 350, 268 cam, no EGR, no AIR, no cat, no airconditioning , 5.50 axle ratio , 33" tires.
If putting the fuel pump in the tank isn t appealing you can get external pumps from Summit for about $120us. Dont forget the filter! You need a fuel return line to the tank. You need a code reader from Canadian tire. You need to weld an oxygen bung into your headers or drill and tap your manifold.
You can use a Corvette LT4 knock sensor to overcome the spark retard/solid lifter issue.(or slide the sensor in a piece of heater hose and hang it in a safe place)
With a Super six decal on the aircleaner 90% of the folks looking wont know its not a carb.
Good luck

_________________
Yeah....Im the one who destroyed this rare, vintage automobile.....

Great stuff, Sandy! I take it no tough-to-mount sensors are needed (cam position, crank position, etc.), just MAP, O2, etc. My experience with GM TBI vehicles has been less than terrific ('91 LO5 9C1 1BN) but if set up properly it's probably better than a carb. What's been your experience as far as mileage, emissions and driveability?

Frank and all,

I have covered the components of my MS TBI conversion on my '64, mosly on ss.com. I suggest searching "megasquirt" and related terms here and on ss.com.

In a nutshell, I used a Holley 2bbl 670CFM ProJection system and just replaced their computer with the MS ECU and added a narrow band O2 sensor and a GM air temp sensor (as specified on MS site, for '88 Celebrity 2.5L, for example). The MS was a BIG upgrade over the Holley computer and the tunability is awesome. The software is easy to download and use.

In the next 2-4 months, I'll be installing MP-EFI on my '68 Dart controlled by the MS. I expect it to be a step up from the TBI. It will be batch fired and so won't have a cam/crank sensor except for the tach signal.

One drawback is that it does not include ignition timing control as many of the $1000+ ECUs do, but hey, it's $200...

MP-EFI parts/work summary:

- Clifford 4V intake w/ bosses cast in ($200)
- Holley/Accel fuel rail (this and manifold drilled on a drill press w/jig) ($40)
- Fuel pressure gauge ($20)
- MSD in-line EFI fuel pump ($80)
- New 24lb Delphi injectors ($85 off Ebay)
- '98-up low mileage Mustang 4.6L TB with TPS ($27 off Ebay)
- Homemade adapter plate to mount TB
- MS ECU kit and accessories ($200)
- Temp sensors ($30 w/ wiring)
- O2 sensor and bung ($45)
- Modify sending unit for return line and run return line

Did I forget anything?

Happy building,

Lou

_________________
Home of Slant6-powered fun machines since 1988

I had a look for ss.com and found that http://www.ss.com/ is a web page for software solutions. Would you post the full web address for the site your are thinking of for us?

BTW, were you running the Holley 2bbl TBI on a Clifford intake? As far as TBI units go, how well did the Holley TBI unit work? Would you know if it works as well as the OEM TBI units?

On the MegaSquirt web site, you wrote about having problems with 1.2 ohm injectors without resistors. Were these injectors in the Holley TBI or were they in something else?

Frank, that is www.slantsix.com

_________________
Charrlie_S
65 Valiant 100 2dr post 170 turbo
66 Valiant Signet 170 nitrous
64 Valiant Signet
64 Valiant 4dr 170
64 Valiant 4dr 225

Dan:

My experience with a TBI swap on a SBC in my 73 Suburban 4x4 1 ton work truck are as follows:

Gas mileage went from 10mpg to 13.5mpg
Torque increase was significant across the RPM range (at least 30ft/lbs over the whole range...more off idle )

We have no emmissions testing here.

The biggest thing is driveability, especially in winter. (no heated intake air, no heatriser crossover, no block heater, no problem) Just reach in and hit the key.

The sensor swap is very easy... we put the O2 sensor in the header collecter,,,next time I would move it closer to the exhaust valve. I dont use air inlet temp, EGR, AIR. I did use ESC and IAC and TPS. The puter was chipped. www.pcmforless (Alvin the chip monk)

The reason I gave stats on this TBI swap is that I have over 150,000 miles on this swap (2 motors) since 1997. 1st motor had a Comp 252 cam, 2nd a split duration truck cam 262/268. we went to the 2nd cam to lose some low end torque to reduce driveline breakage in off road low range and to increase upper rpm power for towing our 24ft trailer(no OD)

_________________
Yeah....Im the one who destroyed this rare, vintage automobile.....

Terrific info. I may try this!

Sometime when I have time and money to burn (HAH!) I might even toy around with the idea of doing a similar controller swap on my '89 D100, currently equipped with factory TBI hardware driven by factory TBI software. These trucks are notorious for poor MPG and middling driveability; wonder if a different controller system would work better.

As far as emissions go, though you have no testing, if your mileage went from 10 to 13.5, your emissions have got to be lower.

Thanks again,

DS

The Holley TBI is basically the same as the V8 TBI used on many Dodge and Chevy V8s in the 80s-early 90s, EXCEPT that it has an adjustable fuel pressure regulator and it uses large 85lb/hr injectors. Yes, they are 1.2 Ohms and need some ballast so as not to fry the MS drivers. I would not use it on a stock Slant as it is too big - my motor is pretty built. There are smaller (400 CFM or so) TBIs out there that would be perfect.

I forgot to mention the Accel adjustable FP regulator in my MP-EFI list above ($80). That brings the grand total to about $800.

Sorry, I always just use ss.com or ss.org for shorthand.

Lou

_________________
Home of Slant6-powered fun machines since 1988

OK I think Im figgerin this out. Lou has a Holley TBI setup that measures up considerably different from the Holley TBI I have here from a 87 3.9 Dakota. The Dakota TB has the same bolt pattern as a BBD.
On occasion I have seen posts from people who have swapped out the injectors on their Holley TBI and replaced them with ones from Rochester TB. This apparently requires no modification. Some even use the BIG injectors used on 454SS trucks. Dont get excited ,,,,these are too big for even a modded 5.7 SBC. Dan talks about a Holley TB from his Dodge truck that has the oblong bolt pattern that sounds the same as a Rochester220. Lous 360 van has the same. .....
Im betting the Rochester 220 and the PU Holley TBI throttle bodies are the same except for the injectors. Lous has an adjustable fuel pressure regulator as does the Rochester. The Rochesters fuel regulater although adjustable is "fixed" like idle limiter screws. A simple mod is all thats required to make them adjustable.
From experience I know the GM ecus and sensor systems are far superior to the Chryco electronics. The Megasquirt setup sounds even better.
For my money I will probably use a 4.3 litre Rochester220 and attendant sensors with the factory ECU to start. The megasquirt and some resistors is an easy upgrade to end up with a cheap and easy TBI slant.
I dont feel tempted by that bolt on Holley TB at all........

_________________
Yeah....Im the one who destroyed this rare, vintage automobile.....

I've been working on adapters to mount Rochester 220 TBI's on slant six engines. I have one for the Chrysler 2bbl intake and one for the Offenhauser 4bbl intake.

The adapter for the 2bbl intake is a two-piece design and is made from 1/2" bottom plate and a 3/8" top plate. My price is C$143 or about US$110.

The adapter for the 4bbl intake mounts the TB's throttle shafts parallel to the engine because of the cut-out on the intake base for the exhaust manifold mounting bolt. My price for this part is C$85 or about US$65.

I don't have pictures yet but you can find a few more details at:
Mopar A-Body Products

Frank
Raso Enterprises

The offy and clifford manifold use the same pattern right? So your adapter should fit the clifford as well?

I'd like to see your adapter Frank.

In my setup, I used the holley 4 barrel adapter to throttle body 220 adapter from howell, but drilled out the holes for the clifford intake. This worked out well, becasue then I used the existing protruding holley 4 barrel part of the adapter to hold down the lokar cable mount. You can see it here: http://www.slantsix.org/forum/viewtopic ... sc&start=0

Frank, does your adapter have provisions for the lokar bracket? Although, if your mounting the throttle body in another orientation the bracket may not work because it would hit the manifold.

The only issue is, due to the divit on the flange I bearly get about 1/16" of sealing surface on that part.