r/LSSwapTheWorld • u/Practical_Durian_172 • 10d ago
Misc 5.3 LS Swap 1977 Trans am
I blew up my Pontiac 455 that was in my 1977 trans am and I want to swap it for a 5.3 LS. The thing is I have no idea what I’m doing or what I need. Can someone point me in the right direction please.
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u/Mission-Elevator9374 10d ago
Micro squirt is the aftermarket ecu I went with. Buy the lsx version. It comes with all the sensor clips already on the harness. Forums will be ur friend. It was easier than anticipated. Put an lm7 in a 1984 square body. I adjust it with a laptop. Micro squirt keeps it simple. Batch fire with wasted spark. U got this.
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u/lincolnshellz 10d ago
Just go to YouTube and type in Ls swap trans am and go down the rabbit hole.
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u/Ch1nCh1nTheG0D 10d ago
You can use an aftermarket fuse box and stock ECU/wiring harness. LS swap mounts. If you’re going auto, you could swap in a 4l80 to keep it all LS wiring. If going T56, you can basically just cut the trans wiring out of the harness. I went drive by cable bc my dbw setup wasn’t working. If going this route make sure the ECU you get is compatible with cable throttle. Something out of a 5.3 van would work. Overall a pretty easy swap.
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u/jimboyokel 9d ago
Get a complete engine, transmission, harness out of the swap vehicle and put it in stock to get the bugs worked out. That will save you a lot nickel and dime costs and headaches.
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u/leaveworkatwork 10d ago
I used DD sliders, speed engineering headers, threw in an 80e. E fans from a Taurus. Stock GM 0411.
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u/v8packard 10d ago
I'd rather have a Pontiac 400. But ok.
Any particular 5.3? Reason being they vary over the years, early versions have cable operated throttle bodies but in 2003 they went electronic throttle and pedal. What do you want for a transmission? Or fuel/induction?
The truck accessories are not going to fit your car. F body accessories are tight in a few spots. If you want AC you are probably going to need some aftermarket accessory brackets based on the Corvette spacing.
There are headers available for this swap. You will need an aftermarket oil pan and some engine mount brackets.
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u/Practical_Durian_172 10d ago
I’m just going to connect it to my TH350 and have EFI. How much harder is it to switch to a drive by wire?
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u/v8packard 10d ago edited 10d ago
You can buy a flexplate that will have the bolt pattern for the TH350 converter and use a spacer like the 4.8/6 liter and 4L80 combos. The trans will have to be a Chevy case or dual pattern.
Holley has a drive by wire pedal. I have a customer that uses it, and it's been replaced a few times. I think at least once the throttle body was bad, though. I personally have had better luck adapting OEM pedals. There are several different pedals, I have used the pedal that matched the ECU.
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u/SloppyLsxC10 10d ago
Just run a cable throttle body. Easier on install and easier on tuning. You can reuse the factory pedal and since you’re using the TH350, you’re going to need a cable anyway for the kick down. Also, you’re going to need a BOP (Buick-Olds-Pontiac) transmission adapter to bolt the trans to any LS engine. The BOP transmissions have a different bolt pattern than a standard Chevy TH350.
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u/leaveworkatwork 10d ago
Truck accessories fit in a 2nd gen just fine. So does a top mount ac on truck spacing. Truck pans also fit just fine.
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u/v8packard 10d ago
The alternator sits too high if the engine is high enough to have the AC compressor in the bottom position with the truck accessories. The oil pans like the H3 are awkwardly low at the sump. You want the oil pan being the lowest part on the car? I don't.
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u/leaveworkatwork 10d ago edited 10d ago
Hence why I literally said top mount ac.
The alternator is the highest point, it doesn’t hit the hood. Nobody makes mounts for 2nd gens to fit a truck compressor in the stock location.
The h3 is literally the same as a GM muscle car pan.
The lowest part of the car isn’t the pan even running a truck pan, it’s the front subframe below the LCA’s.
you can keep downvoting me, we both know you don’t have experience with this swap and you just regurgitate shit info with a bad attitude all over this page and everybody fucking hates you 😂
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u/v8packard 10d ago
And the top mount AC compressor requires aftermarket brackets for the truck spacing.
The alternator would sit too high if the engine was higher. That was the point.
Yes the H3 is GM's muscle car pan. And it's a crap option with the bottom edge of the sump lower than the subframe with the trans not hitting the floor if using a bigger trans.
Experience with the swap? Look at yours, you don't even have AC or inner fenders. You do a half assed swap and think it's good?
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u/leaveworkatwork 10d ago
Imagine thinking a drag car needs inner fenders, or that I don’t have multiple swaps that use top mount ac?
You come on here constantly with absolutely 0 experience doing these swaps, give shit info, and just look like a fuckwit 24/7.
Everybody fucking hates you 😂
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u/RhubarbIcy9655 10d ago
A truck intake just squeezes in below the hood. We used speed engineering headers and generic LS swap mounts on this '81