LS1 swapping a '91 RS. Engine is from a 2002 Corvette and came with an accelerator pedal, but does not fit current mounting. Do I need to change pedals? If so, ideas regardring retrofit? Thx.

 

Change the TB to a cable style

 

Are you saying to keep the original throttle cable and accelerator pedal?

 

You would use your stock 3rd gen pedal, a 4th gen throttle cable or an aftermarket like Lokar with the DBC throttle body

 

Changed DBW to DBC throttle body with Lokar cable and original pedal. Question on vacuum hose connections. Original DBW TB had THREE hose connections...new DBC TB has one. Can someone refer me to a post with pictures and instructions on how to handle? Thank you!

 

Don't even bother hooking up the coolant hoses to the throttle body. All you need is a connection for the steam vent T. I've been running this piece for years, it moves the steam vent hose connection from the throttle body to the upper rad hose.
​​​​​​https://jagsthatrun.com/products/fix...v8-engine-swap

Edit: Oh, yea the vacuum hoses. I think the top one goes to the valve cover with no pcv just the vent, and the bottom one goes to the valve cover with the pcv valve. Not sure about a 3rd one, I just thought you were referring to the coolant ports at the bottom.

 

Thank you. Take a look at these two pix. First one is original OEM DBW TB and second is aftermarket DBC TB. You will see the first one has THREE vacuum (?) ports and the second has only one. I am figuring the top one on both (indicated with red arrow) goes to the valve cover (no PCV). It is the bottom two on the OEM that is concerning since the new TB does not have either. The bottom right port appears to connect to the manifold via a rigid "rail" and no clue on the bottom left. Any ideas for an LS1? Thank you!


Original OEM DBW TB

Aftermarket DBC TB

 

Yea the two bottom ports are for coolant. The factory setup flows hot coolant through the throttle body so moving those hoses gains a little power. I forget where the left side connects from, but the right side goes to the steam vent tube on the engine below the front of the intake. You can simply just leave those ports open, no need to connect them to anything. The red line in the pic below shows the old steam vent connection. If you want to eliminate coolant flow through the throttle body just run it from the engine to that T connection in between the upper radiator hose like the blue line shows. The top port does go to the passenger side valve cover. So yea if you want to hook it up this way you need to pickup a piece for the upper hose like I linked above.

 

Thank you again. Pro's/Con's of NOT running coolant thru TB? Also you said..."If you want to eliminate coolant flow through the throttle body just run it* from the engine** to that T connection in between the upper radiator hose like the blue line shows" *Run what? **And from the engine where?

 

It's a potential leak point, for one. Two, it heats the incoming air charge.

You only "need" it if you live in a cold climate, in which case there is a SLIGHT risk of the throttle plate developing ice and sticking open.

Think about it this way: If it's really that important, WHY DID GM STOP USING THIS DESIGN?
Why do many other successful engines NOT use a heated throttle body?

Oh, and you take that steam line (the blue one) and route that to the radiator, or other sealed coolant source.

 

Makes sense. Does someone have a pic of that T-connection to the engine? And where on the engine is this connecting? ...To the (now open) steam vent tube?

 

Yes. The now open steam vent tube is itself a T. You connect that to a high point in your cooling system. The piece from Jags that Run is relatively cheap and easy to use for this purpose. Others have put a fitting in the top of their water pump and plumbed it there.

 

Thank you again...sorry for all the questions...this is not my first engine swap, but is my first LS swap. Can you ("3.1EyeCandy") clarify what you mean by this: "The piece from Jags that Run is relatively cheap and easy to use for this purpose."? Is that a part you are suggesting I order? If so, have the link to that part? Would you happen to have a pic (even if from the internet) that will help me visualize what you are referring to when you say "put a fitting in the top of their water pump and plumbed it there"? Or a picture of what "Dixiebandit69" suggested: "take that steam line (the blue one) and route that to the radiator, or other sealed coolant source."? Lastly, I ran into an issue properly mounting the engine to the Umi K-member brackets due to the location of the A/C compressor. In your experience, does that have to be moved or at least removed to mount the engine? Thank you all!

 

He linked it above


Have you read the swap guide?
https://www.thirdgen.org/forums/ltx-...third-gen.html

 

Here is a picture of where I've connected it on my LS1 swap. I just had a tube with a T welded up, but that piece from Jags that Run accomplishes the same thing. As Scooter said, the swap guide has a great wealth of information inside it, and I definitely wouldn't have been able to complete my swap without it.

 

Thanks Scooter & PG29...any insight on my last questions as it relates to the AC compressor?
(Lastly, I ran into an issue properly mounting the engine to the Umi K-member brackets due to the location of the A/C compressor. In your experience, does that have to be moved or at least removed to mount the engine?)

 

From what I can tell umi’s crossmember doesn’t allow for use with low mount a/c. They have a link to this setup on their crossmember page. http://www.kwikperf.com/

I had to go with a bmr crossmember myself just for the low mount a/c.

 

Correct.

If you run the UMI k member and the factory brackets, you will have to relocate the AC. I bought all of the Kwik bracketry and it still didnt clear. I went with the Holley mid mount system. Even if you didnt run the factory braces it still wont clear. The BMR unit also doesnt "fully clear" like they say it does. It requires heat and a BFH.

 

Thank you all. Ok, onto the wiring. I am using a Painless wiring harness which is pretty much plug and play. I realized that it is missing two connectors: (1) Oil Pressure Sensor (located in rear of manifold) & (2) Vapor Canister Vent valve (located below passenger side fuel rail). Is it suggested to remove and use these two plug/wires from the original LS1 harness? Is either or both needed?

Also, with the LS1 swap into the 1991 RS bay, what replaces the connections on the passenger side firewall where the three relays were as well as the other "old" harness connections (i.e.: C100/C207)?

 

What do you mean, what replaces them? Nothing, those should be part of the Painless (all i read says it should be called Painful) harness

 

The LS harness I have is missing two connectors: (1) Oil Pressure Sensor (located in rear of manifold) & (2) Vapor Canister Vent valve (located below passenger side fuel rail). Is it suggested to remove and use these two plug/wires from the original LS1 harness? Or are either or both not even needed?

As for the question above, I have the C207 harness which I am guessing is the lighting, etc. However the old 3rd gen RS harness w/C100 connector is gone. Do I need a replacement for that C100 plug or the three relays that were near it (all on the passenger side firewall)?

Thank you.

 

The relays were for the fans and fuel pump.
If you don't have the C100 you need to replace it to make the car run. That had the power wires for the whole car, starter wire and the wires for the tach and oil pressure gauge plus the airbag ground at the very least.
I make LS swap C100 harneses to use for "stand alone" LS harnesses

 

Here is what I have and have installed. Only two wires missing that the origianl LS1 harness had was (1) Oil Pressure Sensor & (2) Vapor Canister Vent valve.

https://www.jegs.com/i/Painless-Perf...60508/10002/-1

I do still have the original "light harness" which I guess is the C207? I also have the battery cables/starter wires from the LS1. Just as a reminder, this is a 2002 LS1 from a C5 Vette with a 4L60E going into a '91 RS.

That all said, what exactly do I need from a wiring perspective?

 

Did you read the swap guide?

 

Now looking for guidance (with pix) on best way to attach the Lokar cable to the 3rd gen pedal. Original cable had TWO small clevises (or cable end stops) on the pedal end. I know one is the cable stop with the small black plastic housing, but what is the other for? Anyhow, can someone share their process for attaching a new cable to a stock 3rd gen pedal? Can you buy those tiny clevises/end stops? Other ideas? Thank you!