TBI Conversion Refresher

Gearing up to do a TBI conversion on my 86 K20 (350/700r4/NP208). It’s not my first time, but it’s been a minute since I’ve done one and could use a little refresher on a couple of things.

1. VSS: Last conversion I did was on an 84 GMc w/ a 700r4. I used the VSS from JTR to control TC lockup and eliminate any potential for drivability issues. That truck was 2wd. My new rig is 4WD. Is the VSS from JTR still good to go? Anything different on 4WD vs 2WD as far as the conversion goes?

2. Knock sensor/EGR delete: I read somewhere that the knock sensor is not required if you delete EGR. Apparently the KS only operates in conjunction with the EGR system? Any truth to that? Not sure if it’s kosher…last conversion I had no EGR valve, but I still ran a knock sensor.

3. Harness: I’m going to pull the trigger on a harness after the holidays. The last harness I bought was from Fuel Injection Connection, which I was really happy with. Just checking to see if FIC was still good to go. If not, any other recommended harness builders out there?

4. Fuel lines: I heard a tip somewhere that there was a company out there making flexible SS braided lines with the correct fittings for the supply and return on the TB, but I can’t seem to find that info anywhere. I thought I saved it on my phone, but I guess I didn’t. Anybody know anything about that?

Quote:

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Originally Posted by JCampbell

Gearing up to do a TBI conversion on my 86 K20 (350/700r4/NP208). It’s not my first time, but it’s been a minute since I’ve done one and could use a little refresher on a couple of things.

1. VSS: Last conversion I did was on an 84 GMc w/ a 700r4. I used the VSS from JTR to control TC lockup and eliminate any potential for drivability issues. That truck was 2wd. My new rig is 4WD. Is the VSS from JTR still good to go? Anything different on 4WD vs 2WD as far as the conversion goes?

2. Knock sensor/EGR delete: I read somewhere that the knock sensor is not required if you delete EGR. Apparently the KS only operates in conjunction with the EGR system? Any truth to that? Not sure if it’s kosher…last conversion I had no EGR valve, but I still ran a knock sensor.

3. Harness: I’m going to pull the trigger on a harness after the holidays. The last harness I bought was from Fuel Injection Connection, which I was really happy with. Just checking to see if FIC was still good to go. If not, any other recommended harness builders out there?

4. Fuel lines: I heard a tip somewhere that there was a company out there making flexible SS braided lines with the correct fittings for the supply and return on the TB, but I can’t seem to find that info anywhere. I thought I saved it on my phone, but I guess I didn’t. Anybody know anything about that?

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If that truck had cruise control from the factory it will have a 2000 ppm VSS already in the instrument cluster. I used the stock VSS in my 1983 G20 van for both my TBI and TPI setup.

As for the Knock sensor. Deleting the EGR does not eliminate the knock sensor function or the need for it. I would add a knock sensor because it is cheap insurance against detonation. If you are deleting the EGR valve, make sure that you have the EGR disabled in the chip.

I am not to sure why you don't find an '87 truck (86 actually came with TBI but 4.3L only) and take fuel lines, tanks, engine harness, dash harness, etc. Bolt in, done. TBI or "saginaw" flares can be made with the mastercool kit. They work on stainless tube, i bent up stainless engine lines many moons ago for my TBI caprice. you could make the stainless tbi flares then take them a hose place that does stainleaa braided hose and get them crimped.

I think I remember that about the factory VSS now. In fact, I think I have a cluster out of a 90 Suburban with the VSS module in it. My 86 does not have factory CC. I'll need to check to see if the guage clusters are a direct swap for those two years.

That's what I thought about the knock sensor. Funny thing is, I saw that on Affordable Fuel Injection's site. I misremembered about it having to do with EGR (it doesn't), but they still don't reccomend a KS when you go to order your harness. I thought it didn't sound right.

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