Is the swap worth it? Input would be greatly appreciated.

**slow4thgen** · 06-02-2016, 01:01 AM

So here is the rundown of things. I recently purchased an 84 silverado as a beater daily. It has a 350 and a th350 in it. Turns out the motor is using oil, needs rings. I was looking to build another 350 for it. Well here is the kicker... I have a freshly built lt1 that i never installed into anything. was planning on building an fbody, but funds got tight so i couldnt afford the car/trans setup. The motor is completely fresh. I put a CC503 cam, springs etc in it. All it needs is rockers and its done. I had a parts car so I have accessories, wiring harness and pcm. Id want to use the same trans that is in the truck and im not sure exactly how that would work with it being a th350. not sure what to do about accessories and would really like to keep power steering. itd run better and be a hell of a lot more fuel efficient. would want to keep it efi. how much money do you guys have wrapped up in similar swaps and what are the biggest challenges that you faced? i have this motor just sitting there, wrapped up in the garage and i think itd be an awesome swap, i just need to see if it is feasible or not. I am not a fabricator by any means, so id need it to go together as easily as possible.

**gmpowered** · 06-02-2016, 01:55 PM

If it was me, I'd buy a 5.7 junkyard vortec swap the manifolds with the carb and be done. Itd run similar to an lt1.
Short on cash a swap is not a good thing.
If it was a project truck where time money wasn't an issue go for it.

**Catmaigne** · 06-02-2016, 04:33 PM

Do you use the truck for hauling/towing?

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**Ccreddell** · 06-02-2016, 05:47 PM

Get a hold of Tinbender59 on GM truck central. He can walk you through the swap and tell you what it will cost you. Its actually pretty simple and quite a bit more efficient than a regular 350.

**slow4thgen** · 06-03-2016, 12:19 AM

I dont use it for anything heavy. Maybe an engine or a trans here and there, but no major hauling or towing. Is gm truck central a forum? i know things will pretty much bolt in without much issue, i guess im more so worried about the pcm. not sure how the trans would work and also worried about the security system in the pcm not picking up signal and what not. is that something that can be removed in the tune? the motor and pcm is all set up for a 95. the efficiency is ideal. id love to do this, but it has to be something i can do in a weekend.

**Ccreddell** · 06-03-2016, 10:04 AM

Most of your questions have been worked through by others (Like Tinbender), but a real quick rundown of your questions; GMTC is a forum. PCM isnt really a problem-there are harnesses and hookup instructions all over the place. Yes, the security (and, most likely a few other things) can be turned off in the tune. You can probably do the swap in a weekend, but the details (like electric fans) may take you a bit longer. You may (may) be able to drive it but you'll be fine tuning it for a while.

**superspirit** · 06-03-2016, 05:49 PM

It's worth the time and effort. I put an LT1 in an S10 blazer. as for wiring I can give you links on how to make a stand alone harness out of the factory F-body harness. The biggest headache would be notching the frame for the A/C compressor, but it's not all that hard. you can PM me if you want the links or have any other questions.

**Ccreddell** · 06-06-2016, 01:24 PM

Over the weekend, I decided to swap in an LT1. Short story' Im running vortec heads on my stock 90 5.7, so I already am running an adapter under my TB to a 4V manifold. Im losing the rings and going through copious amounts of oil. I also happen to have an LT1 sitting at the machine shop, that Ive ignored for a while. It'll be .040 over when its done. But, what has been keeping me from going ahead with it up until now was the fact that Im running an EBL system in my computer so I didnt want to throw that away to run the LT1 on a 0411. So, over the weekend, I had an epiphany; if I run the dual plane intake made for the LT1 (which, according to Chevy is worth 30 ft. lbs. over the stock intake) and run my same distributor and adapter/TBI, I'll get all the advantages of the LT1 (aluminum heads, reverse cooling, 10.5"1 compression), and still be able to run it with the ECM I already have. I'm already running electric fans, so Im OK there also.

**superspirit** · 06-07-2016, 12:17 PM

That would be correct. However all the fuel economy of the LT1 comes from the LT1 fuel injection system, I wouldn't go that route personally but what youre thinking will work.

**Ccreddell** · 06-07-2016, 03:45 PM

Ive gotten as high as 24mpg at cruise in my 5.7 over 300 miles at 70-75 mph (and I didnt have my lean cruise enabled at the time). And its still going to be fuel injected. I know its not as sophisticated as the LT1 system, but I kinda figured it would be offset a bit by the extra 30 ft.lbs. in the manifold, and I'd have the peace of mind of not running an Opti......