5.3 ls with th350 questions

[bd blk 12v]

Hello guys i just purchased a 5.3 ls taht im going to swap into a 47 chevy ad truck. I dont have a transmission and am looking at what to buy. The truck was a 4x4 that i got the engine from. Im just wanting a nice cool cruiser. The 47 has a 10 bolt rear end. Im not sure on ratio. Would a th350 be an ok choice and maybe a 3.42 ratio? Would it be better to have an auto with overdrive and spend the extra money? I have access to a th350 pretty cheap and plan on a cam swap possibly on the engine. Thanks

[BR3W CITY]

Overdrives will always be preferred for fuel mileage, and they allow you to run a steeper rear end. O/d with a 3;73 or higher is pretty popular around these parts.

The th350 will still work, but then something closer to a 3;23 will keep it manageable on the freeway.

[Willie Makeit]

I have a TH350 behind my 5.3, running 3.08 gears and it does fine. Keep in mind it's no wannabe pro mod car, but I wasn't building a race car when I went the LS route.

I think a 3.42 would be a good choice. A guy I met just last weekend is running 3.42 behind a mild 5.3 and he said he is turning appox 2600 rpm at 55-60 mph. My 3.08's are turning my 5.3 at approx 2100-2200 rpm at 55-60.

[robgmaddux]

I am finishing up a ls swap in my 72 k20 and I am curious. What did you do for vacuum for the module and the detent cable? Mine is dbc.

[dec010974]

if you are referring to the vacuum used to help the tranny shift, the attach a some tubing from transmission's modulator and run that tubing to on of the ports on the intake manifold. the port at the top, in the middle of the manifold would be perfect. I've seen others use the port on the passenger side of the manifold tha has the protection tabs. they would open it up, and use it.

[Willie Makeit]

Originally Posted by robgmaddux

I am finishing up a ls swap in my 72 k20 and I am curious. What did you do for vacuum for the module and the detent cable? Mine is dbc.

used the vacuum port on the back of the LS1 intake for the power brakes and modulator valve.

mine too is drive by cable and a friend help me calculate the arc needed to gain the correct straight-line pull needed to engage the kick down. we then drilled a hole in the butterfly pulley and welded a post that allows the kick down cable to attach.

[Jstock85]

Originally Posted by Willie Makeit

used the vacuum port on the back of the LS1 intake for the power brakes and modulator valve.

mine too is drive by cable and a friend help me calculate the arc needed to gain the correct straight-line pull needed to engage the kick down. we then drilled a hole in the butterfly pulley and welded a post that allows the kick down cable to attach.

Willie! I know its been a while but i have scoured the internet in search of hooking up a th350 to LS. If you happen to still own the ride your speaking about in this thread can you PLEASE describe in more detail and share some pics on how you hooked up the detent cable and the vacuum lines??? Any help is greatly appreciated!!!

[Willie Makeit]

Originally Posted by Jstock85

Willie! I know its been a while but i have scoured the internet in search of hooking up a th350 to LS. If you happen to still own the ride your speaking about in this thread can you PLEASE describe in more detail and share some pics on how you hooked up the detent cable and the vacuum lines??? Any help is greatly appreciated!!!

I've moved on from the LS1 intake to an LSA supercharger, 4L80 and drive by wire.

Here is a pic of the original setup. Used a Lokar throttle cable and bracket for the accelerator and the stock LS1 throttle bracket (trimmed to fit) for the TH350 kick-down cable. Not the greatest of pics. sorry

I will look around the shop tonight and see if the drive by cable TB is still laying around. If so, I will take some pics.

[Willie Makeit]

as promised. drilled a hole. machined a "stud" & tack welded from behind.

located 180° from the original cruise control linkage

[Jstock85]

That's what I'm looking for! Say Willie if that TB is just "laying around " since you have "moved on" from that style will you be willing to parts ways with that TB?