I Need Some EFI Advice

[DT1]

I Recently purchased and installed a new (Jegs) stock 190Hp Gen 1 350 engine in my truck. Right now I'm running the stock Rochester Quadrajet and a Delco HEI distributor. The truck runs really well but I would like to change the fuel delivery to EFI. This is where I need some advice. I did a little research and came back more confused than ever. I would like to hear from those that are running EFI on a stock set up. What type did you use and did you have to change things like fuel pump Etc. I'm not looking for more HP, just a good, reliable system that will self tune at varying altitudes.
Thanks

[davepl]

OK, just did this, so here's a brain dump of what's hard and what's easy.

First off the fuel system is the only "hard" part. If you can do that part, you're set.

You need an EFI fuel system which is a supply side that goes to a regulator, normally up at the motor, and feeds excess unused fuel back to the tank. Keeps the lines cool, lots of benefits. Just more work to plumb up.

Many people chose to use a GM filter-regulator. It's what it sounds like, a filter with the regulator built in. You mount it half way, or by the tank. You run your 100psi pump to it, the return comes back from the regulator, and 58psi regulator flow goes forward from there.

Since you have a Q-jet you might have a spreadbore intake (where the back barrels are wider). If it's not set up for a Holley as well you'll need an adapter plate.

I went with the Holle Sniper EFI and recommend it.

It takes the place of your 4-barrel carb. You run battery, ignition, and a yellow wire to the coil ground, and you're done wiring.

I was not looking for HP but boy did I find some down low in terms of driveability! The Holley is TOO sensitive and I can help you with that if it is on yours too (but my motor makes 600lb-ft, a little different I imagine).

Keep the HEI if it works well now. You can, if you want to, set the Holley up to be driven by a magnetic pickup and then run a coil driver module or ignition box and so on and let the Holley control the timing, but I didn't think the benefits (more stable idle) were worth the work and complexity. I doubt it would be in your case either, so just go "coil minus". That means that you simply run one wire to the coil - terminal and the distributor does the timing like it did before.

You need to run PTFE (teflon) braided hose at a minimum, not the old rubber AN stuff, as modern fuel isn't compatible anymore and it will weep through.

Your biggest challenge, or at least mine was, will be found in making, bending, and flaring the hard lines. I had to go all the way back to the tank on a sedan, but our truck tanks are much closer.

Don't cut or weld on a tank that's ever had fuel in it. I bought a brand new tank for this reason. I've done it in the past after rinsing the tank and having it full of water while I was cutting on it, but don't recommend it.

I am pleased to report that I now have what is like a fully modern, running and driving EFI motor in the middle of an old truck :-)

I prefer in-tank pumps because they're quieter and easier to feed. If your pump is external make sure that it is below the fuel level or you will, eventually, one day, be left at the side of the road when it can't prime itself against gravity.

I went with the Tanks Inc pump module but someone must make something for out trucks. You can hang a pump on the frame and be OK becasue our tanks are high up in the cab, which makes it easier.

I'm also told that you can run your return line to the filler neck, which avoids having to drill into the tank itself, but have never done it. The factory pickup and sending unit may also have some room for adding the return bung.

[MARKDTN]

Following is information on TPI swap in a 68-82 Corvette, however much of it is applicable to a 67-72 truck. The big difference is the fuel tank. If you don't mind the tank behind the seat, you can use a stock tank and the Ford external pump. The truck I did was a short bed and he wanted the tank out of the cab. I looked into a 87 truck TBI tank and I think it had clearance issues with the rear suspension (might work on a long bed). I used an '86 S10 Blazer tank from a 2.8TBI vehicle. I even used the fuel lines from this Blazer up to the engine compartment with some re-bending, but they worked pretty well. This put the filler rear and right. He swapped to a stepside bed from a 88-99 pickup and had the body shop swap the filler around. It did require a bit of frame cutting and boxing, but it was all behind the axle mounts. I just swapped the TBI pump to a TPI pump from an IROC Camaro. The TBI tanks work nicely because they use barbs on the hose instead of screwed fittings. Be sure to swap to FI hose and FI clamps, there is a difference and it is important. On the truck, he wanted headers. I despise headers, on my own truck I would use stock manifolds and weld a bung into the exhaust for the oxygen sensor. I mounted the ECM behind the glove box which took up a lot of room. If I ever did another, I would buy a C4 Corvette weatherproof ECM and mount it in the engine compartment instead. This requires a more expensive harness and ECM, but it would help in the cab. On the swap I did, I used C4 Corvette serpentine accessories, which forces you into electric fans because the aluminum water pump cannot stand up to mounting a fan. If you go this route and have A/C, it will require a custom hose. Also, you will want to upgrade to a CS144 alternator, the CS130 is not very reliable. A better (less expensive) alternative is probably 88-95 TBI truck accessories, which would allow a pump mounted fan. This was written over 10 years ago, so finding good used low-mileage TPI engines is probably not possible now, and the prices are not correct anymore. Just look at the technical info below and ignore those details.
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You have a unit
First you have to determine whether you want mass air flow or speed density. The C3 is more conducive to speed-density due to space issues. Mass-air flow is easier to make engine changes without PROM changes. If you are technically proficient enough to make a Camaro harness work they can be bought for $100 or less. I have been told that you can also use a 3.1 Corsica or Cavailier harness with a little work, it uses the same 7730 Speed-Density ECM. Aftermarket harnesses range from about $300 for Painless to $500 for Howell to $700 for Street and Performance. Howell makes a great harness, but for a Tuned Port they do not make one that will control the converter lockup on a 200R4/700R4/4L60 transmission. If you are running a manual or non-overdrive-automatic transmission I highly recommend them. I have heard great things about Street and Performance harness, but do not have first hand experience with them. I also have a Fuel Injection Specialties (FIS) harness and it is OK. The ECM can be had used for $10-50. A good external fuel pump will cost at least $100. I use an 88 Ford Truck external pump, $114 from CarQuest, made in Texas by Airtech (also available at O'Reileys). If you have a 78-82 you can use your fuel tank with an 82 sending unit and a TPI pump. 68-77 can also use a modified tank or Rock Valley makes a tank for these cars with a baffle and a GM internal fuel pump. Stock 82 tanks do not have a baffle contrary to popular belief. An aftermarket PROM with VATS and Emissions codes removed will be $100-200 depending on source and complexity. You will have to add an oxygen sensor to your exhaust, $20 for the sensor, $5 for the weld-in bung, and say $25 for an exhaust shop to weld it in if you can’t. Some harnesses use VSS and some do not. An auxiliary VSS sensor is around $75. I recommend using VSS to get better drivability. To install a TPI I say figure at least $800 plus the TPI unit and whatever repairs are necessary to bring it up to useable status. I have TPI/700R4 in my 69 Corvette (Howell harness) and an 83 Pickup (FIS harness) and I love it. Starts good, great torque, good fuel mileage, easy to swap onto stock engines (although both of mine are complete engines out of 90/91 ‘Vettes).

Differences in years
All Corvette TPI intake manifolds work with the older (through 86) iron heads and the factory aluminum heads through 91. F-body TPI intakes use the upright center bolts on 87-92 and thus fit all 87-95 iron heads (non LT1). Either can be swapped to fit the other with some drilling. F-body has the fuel lines come out on the drivers side and has a central port for EGR. Corvette has fuel lines that come out on the passenger side and has an external port for EGR. Corvette fuel rails fit F-body intakes and vise-versa. The runners are all the same through the years, but the LH runner has a hole for a 9th injector in the 85-88 runners. This can be plugged off if you get a nice LH runner and don’t want the 9th injector or decide to run speed-density. The plenums all physically interchange, but 90-92 have an extra vacuum port for the MAP sensor used with the speed-density computers and wiring. 89 is an odd year, it is mass-air flow but without the 9th injector. 89 up throttle bodies can be used on all years, but a 85-88 throttle body requires a ½” hole be drilled in the front of a 89-92 Plenum for idle air. 89-92 Throttle bodies have a more desirable cable attachment. The cable attaches around a circular linkage which has a smoother actuation than the straight linkage on the 85-88. The Corvettes have an aluminum plenum extension over the distributor, the F-body extensions are plastic. The Corvettes use an HEI coil-in-cap distributor for 85-91 (Delco 1103680). 85-86 F-body also used a big-cap distributor. 87-92 F-Body used a small cap distributor with an external coil (Delco 1103479). This same distributor is used in the 87-95 5.0/5.7/7.4 TBI injected trucks and pre-LT1 B-body. The F-body intake gets it's exhaust for EGR from the center passages in the heads like most SB Chevys. A Corvette intake gets it's EGR exhaust from the RH exhaust manifold/header through a flex-tube to an opening near the distributor-no center passages in the intake. If you are required to keep EGR and you have a Corvette intake, I recommend getting the C4 exhaust manifolds. They are like mini-headers, and have a 2 1/2" outlet. I have them on my 69 and like them.

As far as a throttle cable to use, on my 83 truck I used a TPI F-Body cable and it was OK, but I had to coil it up into a loop in the engine compartment because the housing was so long. I also TPI'd a 72 Chevy truck and used a 90 350 TBI truck cable for it. It was 1/2" short outside if anything, but I was pretty pleased with it all told-I didn't have to shorten it. In all vehicles I've done you need a die grinder to square the firewall hole off a bit. All vehicles I've done used the late throttle-body.

I would look into a TPI. They start immediately in winter, have great vacuum, and will get great mileage. I can open the headlights and the wiper door at the same time with no hesitation at all-solid wooomp. With 3.70 gears (and a 700R4 overdrive) I get 18mpg city and 22+ highway. With 3.55 or 3.36 it would be even better. You can probably find a used Corvette TPI engine for $1000 and with an $800 harness/computer/fuel pump you would be set. With the Vette TPI you would have aluminum heads that would remove weight. Even with an F-body iron-head TPI 350 it will be less weight than a stock intake. It will bolt up to everything in your car, use stock accessories, use your transmission, and the visual appeal is awesome. Don't be afraid of fuel injection, it really works.

As far as websites see:
www.corvettefaq.com for conversions or more TPI info at www.fuelinjection.com also www.jagsthatrun.com for misc hard to find conversion parts and info.

[CharlieBrown]

I did the holley Sniper on my 72....still have the tank in the cab....real easy install.

Only problem was the wrong sim card was shipped with mine..after being online with holley they worked me through reprogramming the sim card.

have 600 miles and so far I love it.

[davepl]

I was going to say some of Mark's post was out of date, but then it probably wasn't when he wrote it in 2004 :-)

https://www.corvetteforum.com/forums...or-advice.html

So suffice to say I don't think TPI or a MAF are the hot ticket today. For the price of a good carb I'd throw a Holley Sniper on it and be done!

If you want to get fancy, though, I've got a complete Dominator setup with MPFI and 100# injectors for sale!

[Ekliptix]

I did the Holley sniper EFI with the optional fuel system on my 402 and would recommend it so far. I documented the whole thing using the stock fuel tank. I have 0 miles on it since I cracked the intake manifold from over tightening.

http://67-72chevytrucks.com/vboard/s...d.php?t=755926

[JMC1965]

I did the FiTech EFI...works great, runs great. I've read good things about the Holley sniper system. Not. sure ones better than the other.

I do like the reliability so far.

[FRCvette]

I also did the Holley Sniper with stock tank still in cab. I used Edelbrock fuel sump as return. I have a couple thousand miles on my set up with no problems.

[davepl]

Apparently, the MSD systems can be run returnless. They actually manage to control the fuel pressure by doing PWM (pulse width modulation, or turning off and on very fast) on the pump.

Although they caution this is not ideal and you can still get vapor lock and other issues, it's a nice theory and idea!

Hopefully someone can do fuel injection that just takes 12V and the low side fuel supply at 6psi and make it work from there!

[72Cheyenne454]

Originally Posted by FRCvette

I also did the Holley Sniper with stock tank still in cab. I used Edelbrock fuel sump as return. I have a couple thousand miles on my set up with no problems.

Can you post pics of the Edelbrock fuel sump. I'd like to see how and where you mounted it.

Thanks,
Miles

[Tuff Gong]

I have a stock 1970 C10 long bed with 350. Bought a Fitech EFI and need fuel delivery help. Do I use the g-sumo regulated or single pump? I don't understand the difference and is there a cheaper way to do this that doesn't require a return line. If I install a return line, do I have to worry about metal shavings in my tank?
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[Old_Gold]

The FiTech does not need a high pressure return, so if you have a vent line back to your tank, you can use that. I use the mechanical fuel pump to feed an Edelbrock fuel sump (with a built in electric pump) to get the pressure up as required for the EFI.
Hope that helps!

Jim

[Accelo]

I like modern fuel injection. Nothing is better than reaching through the window and starting the motor ,using the key only, and have it idling perfectly with the idle coming down as it warms up.
You will love it.

[body bolt]

Originally Posted by Old_Gold

The FiTech does not need a high pressure return, so if you have a vent line back to your tank, you can use that. I use the mechanical fuel pump to feed an Edelbrock fuel sump (with a built in electric pump) to get the pressure up as required for the EFI.
Hope that helps!

Jim

This is my plan as well. I don't want to send fuel into the cab under pressure.

[Tuff Gong]

Thank you. I will install it this way and let you know how it goes and performs