MSefi.com read only forum (Jan.15,2018)

Hello all.

Been lurking around, studying Megasquirt for about 7 years now. Already a gearhead, I've taken a few basic electronics classes, gotten ever more comfortable spinning wrenches on my vehicles, and now I'm finally feeling like I'm ready to tackle this project. Not sure if this should go here or the fuel/intake section, but here goes.

The vehicle in question is a 1962 4wd Willys Utility Wagon, purchased new by my Godfather in '62. A mechanic and engineer by trade, he immediately set out to optimize it for it's primary purpose: go-anywhere safari wagon for the recreational exploration of the Moab, UT area and all points of the desert southwest. Ride height air-adjustable suspension, gear splitter for the trans, PTO winch, improved instrumentation were all added long before it was fashionable to do so. Within 2 years, he grew tired of the anemic Willys I-6 and installed a 1964 Chevrolet 283 V-8.

Now the Jeep is mine, and in the spirit of improvement, I intend to 'Squirt the old girl. Improvement of mileage and off-road driveability are the primary goals. Any additional power realized would be fun but secondary. I know I'm gonna go for the MS2; eventually with EDIS-8, but maybe HEI in the meantime.

Now the easy way out for me would be a regular TBI. But with mileage being a goal, the fuel distribution limitations of the typical TBI system made me feel like I could do better. Fine, I thought. TPI is the obvious choice. But the majority of TPI units produced and likely to be found used will not bolt onto my antiquated block - different angles where heads and intakes meet up being an issue. Then I discovered the "Injection System From In Between That Time Forgot": Cross-Fire!!

Found on 'Vettes and F-cars from 1983 until the TPIs were ready for the road, the Cross-Fires used 2 separately mounted 1 barrel throttle bodies on a wide plenum/manifold very much in the style of the old Offy Cross-Ram manifolds. While obviously not as precise as a port injection set up, I figure it will still give the cylinders a better crack at an even fuel distribution... even if some of it drops out - what's a little wall-wetting between friends? And it'll bolt right up. It looks like it won't be much harder to hook up than a single TBI. Still only 1 fuel supply, 1 return, and all the sensors are typical GM.

Price is always a consideration, and I got a phenomenal deal on a very complete take-off set-up, with original wiring harness and everything. Pretty pleased with myself.

A secondary consideration here was that I'm kind of... bored, I guess?... with opening the hood of a Jeep and seeing a TPI looking up at me. It's not the '90s, and I'm not trying to build a super-Jeep. My Jeep doesn't look like some kind trail-monster. I wanted something a little different, something fun, something that maybe looks a little more classic or vintage. And if that takes a little bit of extra effort on my part, I'm good with that. Prefer it, maybe.

Ordered up a relay board and stim board, and soldered them up last weekend to get warmed up. Next will be the MS itself. So does anybody have any experience with one of these systems? Any "gotchas" I should be looking out for? Any general advice? One concern: each throttle-body has it's own IAC motor. Nothing I've read on here or the Megamanual gives me any clues as to how MS would deal with that. Having one of them go bad or out of sync was a problem that was commonly misunderstood to be an issue with the balance-screw between the units - this caused a lot of the hurt and discontent that still leaves a bad taste to this day. Do I just use one of the IACs? Block 'em both off and run a hose from the manifold to a single, remote-mounted valve ala modern Jeep I-6? Any thoughts, folks?

-Tom Z

I know there have been a couple dual TBI installations before. It might be easiest just to use a single IAC, though you can connect two of them in parallel with OK results.

v_e,

I have run the cross-fire efi throttle bodies (on the original Corvette 350, and I also used the cross-fire throttle bodies as the basis for a dual side draft system on my Honda Prelude). Electrical they are the same as a 2bbl GM throttle body injection system.

I needed to use 18-20% PWM, with a 0.7-0.8 msec PWM time threshold and opening time.

I used just one of the throttle body's stepper IAC - it worked fine. I had no issues with the throttle being in sync. I think that because there is a plenum (unlike a IR setup) this isn't much of a concern.

The cross-fire manifold is very restrictive - it used only the top 1/2 of the port in the head. There's no easy way to enlarge it either - there are passages under the runners. But for torque under 4500 rpm on a reasonable sized motor (350 cid or less - a 283 would be perfect), it should be just right (not so good on my 'built' 406, though). The Tuner Port Injection (TPI) manifold is a little better, and looks cool, but is still a relatively low rpm manifold (though you can get larger runners and bases to make it flow better). Either should give good gas mileage in stock form. In my case, I ended up going with a Holley single plane manifold, port injectors, and 4bbl throttle body to feed my engine, which will wind to over 7000 rpm.

Lance.

Lance and Matt,

Thanks for the feedback, guys! Sounds like using just the one IAC is the easy way. And in my application, if that little 283 is running anywhere past 4500 rpm it probably means I'm upside down next to the Lion's Back in Moab, with my foot wedged against the accelerator. Everything I've read about it online, I figured this set-up would be just right on my engine. Plus, scuttlebutt I've read suggests that this manifold is good for torque off the bottom end, which is right where I can use it. I find myself getting more excited the further along I go. I look forward to eventually posting under the "Success Stories" header!

-Tom Z

What with life happening and whatnot, this project has languished in various stages of incubation. But I'm starting to get it back on track. I've mounted my relay board under the hood and wired up IAT, CLT sensors, run a hose to the MAP sensor, and wired up the MS2 to the vehicle's electrical system. I noticed that my tach signal, which I get right from the negative terminal of the coil, gets a lot of spikes in the signal at higher RPMs. Don't know if this is being picked up inductively from a spark plug cable, or if it's some artifact of the probably-'60s-vintage capacitive discharge ignition my Godfather installed back in the day. Not overly concerned, as I'm most likely going to go EDIS-8 on this, or possibly HEI. SO that's it so far. Just wanted to wire it up in a passive role and watch it go. Finally got a new job that allows me to indulge my hobbies, financially. So this month I hope to plumb up the high pressure fuel system, install an O2 sensor, and make it happen for real. There are a few other little things I will need to do under the hood in support of all this; namely install new valve covers with breather and oil fill, as the '64 283 handles all that through a tube that goes through the intake manifold currently, and that will go away once the Cross-Fire manifold is installed. Also, I found a place that makes a reasonable looking aluminum radiator just for these Jeeps, which is good as the old one is just... old. And weepy. Said radiator will be treated to the biggest electrical fan I can fit on there, and a nice variable speed Flex-a-lite controller. Also, gonna have to ditch the generator in favor of an alternator to handle all this electrical demand.