Wow MFI convertion GREAT!

[jay8454]

Disconnect the battery first.

I did the MFI conversion in my Vortech 5.7.
Made MPG better than before, also runs better.
I took some pic's and referenced some of them so to help who ever may need it, as it sure did help me.

Fuel rail or simply put line, and where the Injector spider is located.


Plug for the MFI a little tough to unplug with out cracking something.


Removed the plug finally without cracking something and went for the fuel line next (fuel rail).


I chipped the old spider body a little prying it down through the plenum (cover), but it could still be used for a rebuild.
A screw driver works fine to pry the spider from the plenum. ( Being careful)
There are numbers on the spider body (new and old) for the corresponding cylinder on the engine where the injector(s) goes, it's relatively easy to match the new injectors. I wouldn't over bend the tubes be EXTRA careful not to kink tubes ether.
When I took the old injectors out I noticed that 4 of 8 were burnt badly.


This pic shows the numbers where marked on spider, also when you insert the new injectors into there ports they have to not show any of the white plastic they kinda click a little when you insert them.



I cleaned where the plenum gasket seals and used a little RTV black to Beed around the rubber seal on the plenum I let the RTV dry a little to help make a tighter seal. I did try to clean up the area as good as I could under the plenum, made sure that I cleaned the ports where the injectors go really good. When I put the plenum back on I made sure to not over tighten the nuts. I used a small 1/4" ratchet, like people say "you could crack the plenum if you over tighten these nuts". I hand tightened them down and than use the ratchet and went around almost a 1/4 turn two times around maybe a little less. (kinda like doing a trans pan)



When I stated the engine it turned quite a bit because naturally the fuel went back to the tank.
When it ran I test drove it for a about five miles and the first 1/2 mile it smoked blue smoke. Yes I know why, the slight cleaning I did under the plenum.

I am glad that I haven't had to replace any O2 censers yet, sometimes it's a must if you let the thing go for as long as I did, about a year.

Fixed 12/26/08

[Bob B]

What goes in place of the spider block? Or do you also replace the plenum?
Bob B

[tempfixit]

Is this a AC Delco conversion kit or aftermarket? Cost? ANything else needed besides spider?

What year vehicle?

Great pics and thanks for posting these pics. Post will help many Do Yourself People.

[jay8454]

Originally Posted by Bob B

What goes in place of the spider block? Or do you also replace the plenum?
Bob B

I didn't have a manual for a Vortech engine, just a manual for Chev/GMC 5.7 1989 to 1997 so I don't know what the block is maybe what your talking about is the metal bracket that the spider pops in and out of or even the black plastic cover (plenum) that holds or houses the spider top side (The thing that you take off to get down to the spider). I just changed out the spider and noting else. The plenum was fine, I just put a Beed of black RTV (Permatex) sealer following around the rubber seal of the plenum. to make sure it was air tight. I took some more pic's to explain farther.

Kept the old one no crackers. /\ pic up side


See the spider pushes up into the plenum and the plenum seals down on the spider the new spider you get a new 'O' ring lube a little to help ease getting the new spider and plenum together./\ pic up side

Leave the butterfly (or thing that looks like a carburetor attached./\ pic up side

[jay8454]

Originally Posted by tempfixit

Is this a AC Delco conversion kit or aftermarket? Cost? ANything else needed besides spider?

What year vehicle?

Great pics and thanks for posting these pics. Post will help many Do Yourself People.

The year is 1997 5.7 Vortech engine (350) 186,000 Miles wow!

The name of the part is Nieoff, #8701989 (Nieoff part # 63886) I got it at Checker auto parts here in Las Vegas for $360.00 after tax. I have Googled it and seen it for $288.00 but they want you to send the old one back to get that price and I could wait.
I purchased 2 cans of carb spray and 2 cans of brake parts cleaner and some BLACK RTV (Permatex). Carb spray is worthless buy 4 cans of brake parts cleaner. That is the only things extra I got. Just be careful pulling wires there all very brittle. Be careful not to wrench down hard the plenum (cover) you don't want to crack it, some people use a torque wrench I think like 8 to 10 pounds per square inch (psi). I just did hand tight and than went around in a circle till they were almost 1/4 turn. I didn't have a torque wrench, it's kind of a feel thing (common sense).

Delco conversion?, well... in CA, these 4.3 and 5.7 engines years 1995 to 2001 were all recalled to replaced the old SFI with the new MFI for free. Something to do with EPA.

It just replaces the injection from the body of the spider, to the tips of the legs of the spider also a more quality injector. You can tell the deference when you match the old one up with the new one. It's such a simple thing and makes it run so much better.

The symptoms I was having were:
Hard Starting
Poor fuel economy
Rough Idle
Truck runs fine when cold and terrible when warm
Truck will start just fine when cold and not when warm
Getting a fuel smell inside the car
Loss of power in acceleration
Check engine light
And ghost codes too.

Yea this is the greatest place I have found for help, the people here helped me so it's only fit that I give back the best way that I can. Thanks to the Blazer guys thread too.

[jay8454]

P.S. you may have to replace the 'O' ring around the power brake booster where the PBB and plenum connect it's a bugger to push back together, use some BLACK RTV and let it dry over night.

When the truck started I heard an air noise coming from there.