EFI conversion on l31 swap

[Frankenchevy]

Hello. Let me start by saying I’m not a mechanic. I’ve worked on small engines on motorcycles and air cooled vws. Other than that, just maintenance items on various vehicles. Let me also say, all in, I’m trying to keep this project around $4000 bearing in mind the longblock manifold, electronic ignition, EFI, serpentine setup and fuel tank/pump mods. Been kicking around what do with my truck for quite sometime now. Went back and forth on a Cummins swap, but decided to just buy a 1st gen cummins.


I finally settled on l31r vortec longblock from Chevy with a self learning efi system. I’m mostly focused on reliability and fuel economy. Don’t need a bunch of hp, just usable torque.


As the truck sits, it is a 327 with a t400 behind it. That little revver has to push my heavy 3/4 ton, t400, and 14-bolt & Dana 60 king pin front. It isn’t an ideal pairing. The fuel is supplied by dual saddle tanks, only one of which I use regularly. For now I’m sticking with that transmission until I can figure out something sweet like a 6l80e down the road.


My three questions are:


1. What is the best route on the fuel supply? Who makes the cheapest reliable solution to the efi fuel pump? I’ve seen quite a few inline ones that get okay feedback, but I can’t mount it lower than the k20s stock tanks, it would be to prone to getting damaged by a stick or rock. I want to get ethanol compatible on pump, tank and lines. I was thinking an oem 87 tank, but not sure of an ethanol proof fuel pump to go inside the tank.


2. Which EFI? I am leaning towards the newest version of the Holley sniper efi @$800-1100 depending on if you get their fuel supply setup. I like the feedback on their customer support. I know the more expensive units have the ability to control electronic trannies, but they are double the money and I can wait. Besides, most say they control 4l60e or 80e, not much about other trannies. By the time I get around to that, maybe stand alone tranny controllers will be cheaper..


3. Probably the most straight forward question. I’d like a link to an affordable flex plate for a one piece rear main 350 to a t400 trans.


My main concern is reliable pressure and something that can handle our horrible e15 fuel. This fuel is what has mudded up my current carbureted setup as the truck sees very occasional use. The amount of moisture our newer fuel out here sucks up is incredible!


Since these EFI systems have been out for a long while now and are getting more popular, I figured I’d rely on the most up to date knowledge from this forum, rather than the 5 year old posts google returns.

 

[twinturbo427]

1) the more modern galvanized tanks are E15 compatible, as are the zinc coated to some extent. You would then use the hanger assembly that matches the tank and the outlets you need.

2) Sniper seems to be getting good reviews. I have no hands-on experience with that brand but can tell you the current generation of DIY fuel injection is light years ahead of the 1st gen from 2010-ish era. The efi you choose will dictate the required pump which can be installed on the new hanger for your new tank.

3) the stock 168 tooth flexplate is usualy supplied "dual drilled" now to fit a variety of torque converters in various applications. If you have the 6 bolt torque converter, you need the flexplate from a 350/th400 combo in a 87-91 dually or cab and chassis. Think heavy duty applications for the source.

With the right cam, torque converter, and gearing, there is nothing that 327 can't do. You need a well matched combination fit for the mission at hand (and budget!)

Now post some pictures in the Introduction thread. or else..... lol

 

[1987 GMC Jimmy]

1. I would really do the '87 OEM fuel setup with the appropriate sending units. For the pump, I'd see what Walbro had that could supply the necessary pressure. Next in line would be a later model Delco/Delphi. As far as I know, ethanol is bad because it leaves residues that pure gasoline doesn't, it makes fuel degrade faster, and it's hydrophilic so it catalyzes rust formation when left to sit. Carbs hate it more than anything especially when they sit with it. They have a lot of small parts that were not designed with crappy fuels in mind and only now are we seeing aftermarket parts that are more resilient towards it. Fuel injection will fare better every time, even a wet manifold setup like TBI or aftermarket EFI. The only thing that you shouldn't do is let it sit for any protracted period of time. If it has to sit for whatever reason, time to get some ethanol free.

2. If it were me, I'd go with the FiTech Go EFI. You're looking at the same price ($795) for their entry level unit, which is rated for 400hp. I don't know what you're looking to get out of the new motor, but 400 is just right for me. They have an internal regulator like a TBI so no need to screw with an external one. Plus, I've only heard good things about them. Their pressure requirements are 58 psi, I believe, so that's what you need to look for when shopping for a pump. If you need it immediately, I wouldn't worry about transmission control. I think you've got the right old school transmission for your setup. If you wanted something more modern, I'd only go with a 4L80E anyways.

3. I'm not sure on this one.

 

[bluex]

2. If it were me, I'd go with the FiTech Go EFI. You're looking at the same price ($795) for their entry level unit, which is rated for 400hp. I don't know what you're looking to get out of the new motor, but 400 is just right for me. They have an internal regulator like a TBI so no need to screw with an external one. Plus, I've only heard good things about them. Their pressure requirements are 58 psi, I believe, so that's what you need to look for when shopping for a pump. If you need it immediately, I wouldn't worry about transmission control. I think you've got the right old school transmission for your setup. If you wanted something more modern, I'd only go with a 4L80E anyways.

That Fitech unit doesn't have the ability to control timing. Imo doing fuel only is taking a half step as your leaving a lot of potential on the table. Similar to putting a carb on an LS swap lol. Just my opinion though.

 

[bluex]

I purchased the sniper unit right before christmas an I hope to start on the install next week. Here is what I'm doing.

Fuel system is an 87 tank and sending unit. In using a stock pump for a 1996 C1500 with a 5.7 the a.c. Delco pump is #EP381. All these carb replacement systems require 60 psi so you can basically follow what people have done for an LS swap. I don't know what you need to change to keep the dual tanks though.

As for which unit I went with the sniper. I wanted timing control an between the two I felt more confident with the available support from Holley. It cannot control a transmission but it can control electric fans, it has launch control, nitrous control an some extra outputs that you can setup however you want.

If you get the Holley lookup Efi System Pro, they sell for the same price as everyone else but they offer their own Holley trained tech support. I've heard wait times for support from Holley themselves can involve a considerable wait time and you have to work through tech levels sometimes to reach the right people that have the answers. Chris is top level trained so you dont have to go through all that either.

On the flexplate couldn't you order one for a 2500/3500 truck that had a 4L80E? Are those converters the same pattern as a TH400?

 

[Jrgunn5150]

1. What is the best route on the fuel supply? Who makes the cheapest reliable solution to the efi fuel pump? I’ve seen quite a few inline ones that get okay feedback, but I can’t mount it lower than the k20s stock tanks, it would be to prone to getting damaged by a stick or rock. I want to get ethanol compatible on pump, tank and lines. I was thinking an oem 87 tank, but not sure of an ethanol proof fuel pump to go inside the tank.


2. Which EFI? I am leaning towards the newest version of the Holley sniper efi @$800-1100 depending on if you get their fuel supply setup. I like the feedback on their customer support. I know the more expensive units have the ability to control electronic trannies, but they are double the money and I can wait. Besides, most say they control 4l60e or 80e, not much about other trannies. By the time I get around to that, maybe stand alone tranny controllers will be cheaper..


3. Probably the most straight forward question. I’d like a link to an affordable flex plate for a one piece rear main 350 to a t400 trans.


My main concern is reliable pressure and something that can handle our horrible e15 fuel. This fuel is what has mudded up my current carbureted setup as the truck sees very occasional use. The amount of moisture our newer fuel out here sucks up is incredible!


Since these EFI systems have been out for a long while now and are getting more popular, I figured I’d rely on the most up to date knowledge from this forum, rather than the 5 year old posts google returns.

1. I'd just get the Spectre 1987 replacement tank and sending unit with a Delphi EP381 pump. It's E85 rated.

2. The Fitech kit is pretty straightforward and easy to setup and tune, the Holley is very comparable for a little more.

3. To link a flexplate, I'd need to know your converter diameter. TH350 and TH400 converters interchange BTW, as do flexplates, but the converter and flexplate need to match each other. Or use a dual pattern one.

 

[Frankenchevy]

That Fitech unit doesn't have the ability to control timing. Imo doing fuel only is taking a half step as your leaving a lot of potential on the table. Similar to putting a carb on an LS swap lol. Just my opinion though.

What distributor will you be using?

 

[Frankenchevy]

1. I'd just get the Spectre 1987 replacement tank and sending unit with a Delphi EP381 pump. It's E85 rated.

2. The Fitech kit is pretty straightforward and easy to setup and tune, the Holley is very comparable for a little more.

3. To link a flexplate, I'd need to know your converter diameter. TH350 and TH400 converters interchange BTW, as do flexplates, but the converter and flexplate need to match each other. Or use a dual pattern one.

I saw some of the cheaper replacement tanks. Good to know that combo is e85 ready.

I won’t know what diameter converter until I pull the current motor I guess...

 

[bluex]

What distributor will you be using?

I got the Holley dual sync. I've seen a lot of rfi issues from trying to use a magnetic triggered one (like an msd) and when the dual sync was on sale it wasn't that much more than an msd anyhow.

 

[4WDKC]

the l31 vortec and carb intake to work with fitek would be my choice for this option, but why not just do a LS swap? With an after market harness its just like an aftermarket efi install.

 

[Jrgunn5150]

the l31 vortec and carb intake to work with fitek would be my choice for this option, but why not just do a LS swap? With an after market harness its just like an aftermarket efi install.

That's why I swapped, by the time I bought heads, a cam, a roller valvetrain, some kind of OD trans.... I was past the cost of a swap, but to each his own. I'm secretly a little bummed my engine isn't going to look cool lol.

 

[bluex]

the l31 vortec and carb intake to work with fitek would be my choice for this option, but why not just do a LS swap? With an after market harness its just like an aftermarket efi install.

This is a very valid point here. Unless you just want a new long block an LS will be about the same place price wise after you buy all this stuff...

 

[4WDKC]

That's why I swapped, by the time I bought heads, a cam, a roller valvetrain, some kind of OD trans.... I was past the cost of a swap, but to each his own. I'm secretly a little bummed my engine isn't going to look cool lol.

Put a carb intake and dummy carb?

Also heads/ flat tappet cam swap cost me what I would have spent to buy an 5.3 and 4l60, maybe 6.0 if you shop around.

 

[Jrgunn5150]

Put a carb intake and dummy carb?

I considered it, instead I've decided to put a turbo on it and blow fireballs out of the hood.

 

[4WDKC]

I considered it, instead I've decided to put a turbo on it and blow fireballs out of the hood.

One of these?

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