Do I rebuild my SBC or swap for an LS3?

[DoubleDingo]

Yep, the carb'ed vortecs do run crappy in the cold, I can attest to that. It's cooling down here at night, and I am noticing more rough idle and hesitation when driving the truck in the mornings. Come wintertime I'll have to drive it after about 10:00-12:00. But man, with a nice torquey 300hp/327 camshaft and the vortec heads, the engine sure does pull like crazy.

 

[77 K20]

No not cold start, cold weather runabilty. The suspicion is not being able to keep the intake warm enough to keep the fuel suspended. So in cold weather rough idle and hesitation I think is the main problem. If @77 K20 see this maybe he'd come in and tell you about his experience.

Warning: Long. It was a long fight for 2 years? Learned a lot. Hated the truck and engine for a long time. Still kinda do...

I thought my HT383 crate engine with vortec heads was going to be the perfect engine for me based on all the reading and research I did. Turns out everything I read was from people in the southern part (warm) of the US.

The vortec heads removed the heat plenum that went across the intake manifold under the carb/tbi. This was because the vortec heads were designed to run with a multi port fuel injection. With multi port you want the intake manifold as cold as possible because cold air = more power.

I installed the engine in the summer with a q-jet carb. Ran great! Then winter hit. Would start right up, then run for about 30 seconds then start sputtering a bit. With a little throttle it would sputter then clear up again. My drive to work was a few hundred yards thru a residential area, then a left turn onto a highway. 65 mph (3,000 RPM) for about 8 miles. Then a stoplight. It would always sputter and choke a bit upon pulling out into the highway (hated that). Would run good going down the highway. Then at the stoplight would start sputtering again. (Intake manifold was unable to heat up with cold air at 3,000 RPM constantly being sucked in). After maybe 30 minutes if I was doing stop and go driving it would then run good.

I thought it was the carb- as the GM performance manifold didn't have a provision for a thermo-choke riser thing (sorry, can't think of the right name). Played around with an electric choke kit and a manual choke. Gave up and moved to an Edlebrock EFI throttlebody. Now I had cold weather issues along with "heat soak" in summer that caused my idle to surge. Once again- crappy support from Edelbrock. No help.

Finally heard about the cold weather issues. Additional research showed the GM performance manifold has a very smooth "floor" to the intake under the carb/TBI. This is good for power, but not good for cold weather. Air with fuel suspended in it doesn't like sharp 90 degree changes. Fuel will want to drop out of suspension. Most intakes then have a waffle pattern or some speed bump patterns on them to help fuel droplets break free and get back into the airstream. I ditched the expensive GM performance manifold for an Edelbrock 7116 manifold. This had special fittings so you can get the old heat plenum back under the carb/TBI. They said you could plumb coolant or exhaust to it. I couldn't think of a good way to run exhaust without melting everything- so chose to do coolant. Besides- with vortec heads you are supposed to run a coolant bypass (around the thermostat) to keep temperatures stable. (I tried to not use a bypass before this manifold and water temps would fluctuate greatly every 20 seconds or so on the highway). So it would still sputter on a cold start but maybe 5 minutes in things were much better. Just a little heat and the waffle pattern did the trick!

Then I started losing coolant. Replaced intake manifold gaskets. No help. Bought a graduated cylinder to measure how much coolant I had to add. Found out it was the number of trips and not the mileage that caused coolant to disappear. Meaning I could take 7 short trips of 10 miles round trip would be the same as if two of those trips was 160 miles. Finally found out that after the engine was run and it was shut off that coolant would then slowly seep up thru the manifold itself (porous casting) and then PUDDLE under the carb/TBI. The waffle pattern would hold little puddles of coolant. I called Edelbrock and emailed them. They had NEVER HEARD OF THIS before even with my pictures. They took no responsibility. Like an idiot I figured I was just unlucky enough to get a poorly made "fluke". So I ordered ANOTHER one. Installed it. SAME #@$%$%# thing. I also found out that burning coolant on each start up is bad for my O2 sensor. O2 sensor couldn't handle all the coolant deposits on it and left me stranded a few miles from my house. (TBI went into full rich mode and flooded out the engine so it couldn't run).

At this point I was ready to set the whole thing on fire. Probably spent $7,000 now on this engine? Parked it and bought another daily driver. Didn't have the $$ to "waste" getting maybe the Edelbrock pro-flo multi port fuel injection. Finally out of despair I installed something like a 6 psi radiator cap and dumped in a tube of Alumi-seal (aluminum powder) into the radiator. And I have run like that now for 6 years?

One last thing I learned- this engine has a lot of vacuum to it. When you take air and draw it down into a vacuum the air temp gets colder. I had found it had issues with sputtering a bit with temps even around 40 and below. The colder it was, the worse it was. At 0 degrees or below it would just constantly stall out.

 

[Kurnacopia]

I built a stroked 350 (383) with all eagle products...internally balanced. I picked the block and had a machine shop do all the balancing and machining of the block. I had a special stroker oil pan put on and a set of aluminum brodix heads... I am into this engine about 6K. What you will find is that when you start building you start getting into "plan creep." You want stronger, better, quality. It seems to spread pretty quickly as well.

I agree with Vbb199. Get a quality crate engine, pull all your old parts off and throw that guy back in. Unless you are into picking every dang detail, a crate will be your best bet.

Best of luck to you!!

 

[85K304SPD]

Rebuild it. It has worked good all these years, so stick with it. Make sure that you don't try to build a half race car motor and expect it to run good and get decent mileage. Plan out your combination and improve it wherever you can without taking away from drivability. Maybe add a good dual plane alum. intake and dual exhaust, and a slight camshaft upgrade to match it. Not too much though. Make sure it runs on cheap pump gas, not with octane booster or super unleaded. Keep it simple. That's my opinion.

 

[SirRobyn0]

Warning: Long. It was a long fight for 2 years? Learned a lot. Hated the truck and engine for a long time. Still kinda do...

I thought my HT383 crate engine with vortec heads was going to be the perfect engine for me based on all the reading and research I did. Turns out everything I read was from people in the southern part (warm) of the US.

The vortec heads removed the heat plenum that went across the intake manifold under the carb/tbi. This was because the vortec heads were designed to run with a multi port fuel injection. With multi port you want the intake manifold as cold as possible because cold air = more power.

I installed the engine in the summer with a q-jet carb. Ran great! Then winter hit. Would start right up, then run for about 30 seconds then start sputtering a bit. With a little throttle it would sputter then clear up again. My drive to work was a few hundred yards thru a residential area, then a left turn onto a highway. 65 mph (3,000 RPM) for about 8 miles. Then a stoplight. It would always sputter and choke a bit upon pulling out into the highway (hated that). Would run good going down the highway. Then at the stoplight would start sputtering again. (Intake manifold was unable to heat up with cold air at 3,000 RPM constantly being sucked in). After maybe 30 minutes if I was doing stop and go driving it would then run good.

I thought it was the carb- as the GM performance manifold didn't have a provision for a thermo-choke riser thing (sorry, can't think of the right name). Played around with an electric choke kit and a manual choke. Gave up and moved to an Edlebrock EFI throttlebody. Now I had cold weather issues along with "heat soak" in summer that caused my idle to surge. Once again- crappy support from Edelbrock. No help.

Finally heard about the cold weather issues. Additional research showed the GM performance manifold has a very smooth "floor" to the intake under the carb/TBI. This is good for power, but not good for cold weather. Air with fuel suspended in it doesn't like sharp 90 degree changes. Fuel will want to drop out of suspension. Most intakes then have a waffle pattern or some speed bump patterns on them to help fuel droplets break free and get back into the airstream. I ditched the expensive GM performance manifold for an Edelbrock 7116 manifold. This had special fittings so you can get the old heat plenum back under the carb/TBI. They said you could plumb coolant or exhaust to it. I couldn't think of a good way to run exhaust without melting everything- so chose to do coolant. Besides- with vortec heads you are supposed to run a coolant bypass (around the thermostat) to keep temperatures stable. (I tried to not use a bypass before this manifold and water temps would fluctuate greatly every 20 seconds or so on the highway). So it would still sputter on a cold start but maybe 5 minutes in things were much better. Just a little heat and the waffle pattern did the trick!

Then I started losing coolant. Replaced intake manifold gaskets. No help. Bought a graduated cylinder to measure how much coolant I had to add. Found out it was the number of trips and not the mileage that caused coolant to disappear. Meaning I could take 7 short trips of 10 miles round trip would be the same as if two of those trips was 160 miles. Finally found out that after the engine was run and it was shut off that coolant would then slowly seep up thru the manifold itself (porous casting) and then PUDDLE under the carb/TBI. The waffle pattern would hold little puddles of coolant. I called Edelbrock and emailed them. They had NEVER HEARD OF THIS before even with my pictures. They took no responsibility. Like an idiot I figured I was just unlucky enough to get a poorly made "fluke". So I ordered ANOTHER one. Installed it. SAME #@$%$%# thing. I also found out that burning coolant on each start up is bad for my O2 sensor. O2 sensor couldn't handle all the coolant deposits on it and left me stranded a few miles from my house. (TBI went into full rich mode and flooded out the engine so it couldn't run).

At this point I was ready to set the whole thing on fire. Probably spent $7,000 now on this engine? Parked it and bought another daily driver. Didn't have the $$ to "waste" getting maybe the Edelbrock pro-flo multi port fuel injection. Finally out of despair I installed something like a 6 psi radiator cap and dumped in a tube of Alumi-seal (aluminum powder) into the radiator. And I have run like that now for 6 years?

One last thing I learned- this engine has a lot of vacuum to it. When you take air and draw it down into a vacuum the air temp gets colder. I had found it had issues with sputtering a bit with temps even around 40 and below. The colder it was, the worse it was. At 0 degrees or below it would just constantly stall out.

This, your story and then seeing other guys complaining about it why I ditched the idea. I might be able to get away with it 90% of the time where I live, but I've hate to be dealing with those issues while towing my trailer over the pass or something like that.

 

[OneShot]

Warning: Long. It was a long fight for 2 years? Learned a lot. Hated the truck and engine for a long time. Still kinda do...

I thought my HT383 crate engine with vortec heads was going to be the perfect engine for me based on all the reading and research I did. Turns out everything I read was from people in the southern part (warm) of the US.

The vortec heads removed the heat plenum that went across the intake manifold under the carb/tbi. This was because the vortec heads were designed to run with a multi port fuel injection. With multi port you want the intake manifold as cold as possible because cold air = more power.

I installed the engine in the summer with a q-jet carb. Ran great! Then winter hit. Would start right up, then run for about 30 seconds then start sputtering a bit. With a little throttle it would sputter then clear up again. My drive to work was a few hundred yards thru a residential area, then a left turn onto a highway. 65 mph (3,000 RPM) for about 8 miles. Then a stoplight. It would always sputter and choke a bit upon pulling out into the highway (hated that). Would run good going down the highway. Then at the stoplight would start sputtering again. (Intake manifold was unable to heat up with cold air at 3,000 RPM constantly being sucked in). After maybe 30 minutes if I was doing stop and go driving it would then run good.

I thought it was the carb- as the GM performance manifold didn't have a provision for a thermo-choke riser thing (sorry, can't think of the right name). Played around with an electric choke kit and a manual choke. Gave up and moved to an Edlebrock EFI throttlebody. Now I had cold weather issues along with "heat soak" in summer that caused my idle to surge. Once again- crappy support from Edelbrock. No help.

Finally heard about the cold weather issues. Additional research showed the GM performance manifold has a very smooth "floor" to the intake under the carb/TBI. This is good for power, but not good for cold weather. Air with fuel suspended in it doesn't like sharp 90 degree changes. Fuel will want to drop out of suspension. Most intakes then have a waffle pattern or some speed bump patterns on them to help fuel droplets break free and get back into the airstream. I ditched the expensive GM performance manifold for an Edelbrock 7116 manifold. This had special fittings so you can get the old heat plenum back under the carb/TBI. They said you could plumb coolant or exhaust to it. I couldn't think of a good way to run exhaust without melting everything- so chose to do coolant. Besides- with vortec heads you are supposed to run a coolant bypass (around the thermostat) to keep temperatures stable. (I tried to not use a bypass before this manifold and water temps would fluctuate greatly every 20 seconds or so on the highway). So it would still sputter on a cold start but maybe 5 minutes in things were much better. Just a little heat and the waffle pattern did the trick!

Then I started losing coolant. Replaced intake manifold gaskets. No help. Bought a graduated cylinder to measure how much coolant I had to add. Found out it was the number of trips and not the mileage that caused coolant to disappear. Meaning I could take 7 short trips of 10 miles round trip would be the same as if two of those trips was 160 miles. Finally found out that after the engine was run and it was shut off that coolant would then slowly seep up thru the manifold itself (porous casting) and then PUDDLE under the carb/TBI. The waffle pattern would hold little puddles of coolant. I called Edelbrock and emailed them. They had NEVER HEARD OF THIS before even with my pictures. They took no responsibility. Like an idiot I figured I was just unlucky enough to get a poorly made "fluke". So I ordered ANOTHER one. Installed it. SAME #@$%$%# thing. I also found out that burning coolant on each start up is bad for my O2 sensor. O2 sensor couldn't handle all the coolant deposits on it and left me stranded a few miles from my house. (TBI went into full rich mode and flooded out the engine so it couldn't run).

At this point I was ready to set the whole thing on fire. Probably spent $7,000 now on this engine? Parked it and bought another daily driver. Didn't have the $$ to "waste" getting maybe the Edelbrock pro-flo multi port fuel injection. Finally out of despair I installed something like a 6 psi radiator cap and dumped in a tube of Alumi-seal (aluminum powder) into the radiator. And I have run like that now for 6 years?

One last thing I learned- this engine has a lot of vacuum to it. When you take air and draw it down into a vacuum the air temp gets colder. I had found it had issues with sputtering a bit with temps even around 40 and below. The colder it was, the worse it was. At 0 degrees or below it would just constantly stall out.

First let me say, that all of you have been extremely helpful and I'm very grateful for your input. I'm a member of some other car forums where people aren't nearly as kind or helpful. You guys rock. I think I'll stick with the SBC. The question now is exactly how to go about doing it (crate, rebuild, junk interim motor, etc).

Unrelated to the original topic, but the above is EXACTLY what happened to me when I swapped my cast intake manifold for an aluminum Edelbrock performer intake that didn't have the heat pipe! I didn't think anything of it really - swapped the intake - and now it runs crappy in cold air and the idle speed is all over the place. I figured I had a vacuum leak (I checked religiously - I don't) but this totally describes my problem. So thanks, I'll be going back to an intake with a heat pipe because I want to stick with the carb.

Also a good description of the cold weather runability of the Vortecs... I'll try and look for some 461 heads and call it good. Cold weather runability is important to me.

Rebuild it. It has worked good all these years, so stick with it. Make sure that you don't try to build a half race car motor and expect it to run good and get decent mileage. Plan out your combination and improve it wherever you can without taking away from drivability. Maybe add a good dual plane alum. intake and dual exhaust, and a slight camshaft upgrade to match it. Not too much though. Make sure it runs on cheap pump gas, not with octane booster or super unleaded. Keep it simple. That's my opinion.

At this point I'm thinking I'll live with my current setup (sans intake manifold) for the time being and in the spring, I'll yank the engine and mic the cylinders. If they're round I'll just hone em, install new bottom end bearings, new rings, add 461 heads and an RV cam, put it all back together, and run it. I think that's a pretty good "stock plus" combo that will run well but doesn't attempt to be a race car engine.

I do need an intake manifold now though. Open to suggestions. And if anybody wants a chromed Edelbrock performer intake for a TBI setup, let me know.

 

[AyWoSch Motors]

First let me say, that all of you have been extremely helpful and I'm very grateful for your input. I'm a member of some other car forums where people aren't nearly as kind or helpful. You guys rock. I think I'll stick with the SBC. The question now is exactly how to go about doing it (crate, rebuild, junk interim motor, etc).

Unrelated to the original topic, but the above is EXACTLY what happened to me when I swapped my cast intake manifold for an aluminum Edelbrock performer intake that didn't have the heat pipe! I didn't think anything of it really - swapped the intake - and now it runs crappy in cold air and the idle speed is all over the place. I figured I had a vacuum leak (I checked religiously - I don't) but this totally describes my problem. So thanks, I'll be going back to an intake with a heat pipe because I want to stick with the carb.

Also a good description of the cold weather runability of the Vortecs... I'll try and look for some 461 heads and call it good. Cold weather runability is important to me.



At this point I'm thinking I'll live with my current setup (sans intake manifold) for the time being and in the spring, I'll yank the engine and mic the cylinders. If they're round I'll just hone em, install new bottom end bearings, new rings, add 461 heads and an RV cam, put it all back together, and run it. I think that's a pretty good "stock plus" combo that will run well but doesn't attempt to be a race car engine.

I do need an intake manifold now though. Open to suggestions. And if anybody wants a chromed Edelbrock performer intake for a TBI setup, let me know.

Good choice sir, just what I'd do.

I'd be interested in the intake.
Does it have the middle bolts at a different angle for TBI heads?

 

[andybflo]

LS.

Especially if you leave it alone for a while (Ethanol issues with plugging carbs, seal failures from sitting, etc.)

My C10 is a truck. I haul things, buy building supplies, and generally run the vehicle as it was designed to be run. I put in a used 5.3 from a wrecked truck. Mild cam. Headers. Tune. With 3.42s and a 4L60e, it runs perfectly. Air blows cold. Cruise works. Starts in Buffalo winters and summers perfectly. Doesn't leak or burn a drop. Makes way more power than the 350 I pulled (not tired, always the plan), it's lighter, and easy to work on. PIs lus, gets 20mpg on the highway (with tonneau cover), tows like a champ, and has great low throttle driveability.

I own several cars with Gen1 SBs. A flathead. A bored and stroked 409 (481ci.) There's a solid place in the world for dinosaur tech, but there's also a reason it's been retired and surpassed. If you wanna use the vehicle, go LS. You want something to show? Old stuff.

There's a solid reason GM doesn't install them anymore. Swap it.

 

[peats]

I would look for a good running used 350, maybe even buy a rusted out running truck or car and swap the engine. Machine shop turn around times are crazy and rebuild parts can be questionable. you can always sell or scrap the carcass.

 

[69project]

You need to determine why you want an LS swap in the first place. If it's for mileage, then the trans you have needs to go. You either need to put a minimum of a 4-speed auto or a 5-speed overdrive to take advantage of its efficiency. A old school 4 speed manual will result in similar dismal fuel efficiency, which is why I always scratch my head when I see peope stick a muncie behind an LS in a muscle car. The premise of an LS swap, to me, is similar or increased power ALONG with increased fuel efficiency. I own a 2009 Pontiac G8 GXP and it will knock down 22-24 mp with a 415hp LS3 but I have 6 speed manual behind it with double over drive. If you are looking for towing power, stroking the SBC, installing a BBC, or even installing a small under hood blower like a Wieand 144 will get you what you need. If you are installing it just because and your budget supports that, then go for it. With an LS install you have to consider, the fuel systems, accessories, gauges, cooling system and ability to tune among other things. It definitely won't be a weekend project.

https://www.holley.com/products/ls_power/ls_swap_systems/ Holley now sells a "one stop shop" LS swaps but I don't see anything for a square body 4x4 so you might have to cobble something together. I was pricing this out for my Camaro and also for a GEN III Hemi swap into an A-body MOPAR and you are looking at about 8-10k if you need all the pieces and want everything to fit together without having to piece it together. Then you need the LS engine/trans. I am quite sure if you are handy with a welder and scrounging parts you can make this a more cost-efficient endeavor.

 

[GO-N-BRK_84]

I unfortunately find myself in a similar situation, I recently pulled my 400 SBC to prepare for the Porterbuilt dropmember I have on order, figured it would be a great chance to rebuild my 400, it ran great, didn't smoke just leaks oil everywhere. Was planning a 450-500 hp build but find myself with the opportunity to drop an LQ9 with 4L80E in instead....I'm torn, see benefits in both builds and have to decide soon because it will affect some of the Porterbuilt kit.

 

[Hunter79764]

My $.03 (due to inflation) is to LS swap, but ignore half the stuff you think you know about LS swaps. You do'nt need a 100k motor or to rebuild it unless it's over 300k and you don't know the history. If you can see it run and there aren't signs of abuse (caked oil, silicone coming out of the water pump gaskets, etc.), you will be fine for many years. In my family we've had at least 6 5.3's along with a 4.8, 2 6.0's, and 2 6.2's. None of them have had major issues except one of the 6.2's with a failed AFM lifter at 200k, all of them have run to 200k+ unless wrecked, and a couple have been over 250k when sold, still running fine. One did consume some coolant, probably a cracked head, after 150k. I put a half gallon in every 6 months or so and continued on.

Yes, you will need a fuel system, but it can be simple or it can be expensive. For what you need, the "best way" would be a full set of TBI tanks, lines, etc., swap to the higher pressure pump, and run a return style regulator on a 5.3/6.0. Cheapest way is an external pump and a Corvette regulator with a short return line and a returnless rail on the engine, maybe new nylon line if your existing line isn't up to the task. Take your pick.
2wd is a known quantity on the mounts etc, and mating it to your existing trans has been done before as well. With the right mounts, you don't need a new trans crossmember or driveshaft, and your speedo cable still runs fine. If you are willing to sacrifice a tiny bit of tuning flexibility, the VSS is not strictly needed, or you can spend a few dollars on a pass through cable VSS or an external VSS.

You don't NEED the Holley style kit, you don't NEED braided fuel line, you don't NEED a rebuild and headers (it'll have 300 hp from a stock 5.3, once upon a time a 300 hp 327 was Corvette territory), a cam is nice, springs are fairly easy, but you should have no reason to pull the heads on it. Unless you have a really good machine shop and a lot of recent experience with parts combinations etc, the LS is the better current platform for stock components. All the SBC guys that really knew what they were doing at the aftermarket sources are retiring, same for machine shops. Unless you KNOW it, you are going to be at the mercy of a 20 year old kid reading parts catalogs just like you are, but he's never had a carburetor on anything but a disposable lawnmower. I'm not judging him, I haven't DD'd a carb vehicle either, it just hasn't been part of life for a few years for most people. I much prefer to trust GM engineering and run relatively stock stuff that was computer designed to be easy to work on and last a quarter million miles and hours of WOT redline testing. Along with that, you get a great water pump design that can be swapped in half an hour, a 160A alternator, good power steering, and if you want it, a much better AC system and electric fans with factory style control. I like old stuff, but for something to use consistently, I'd go modern engine in the classic truck for the best of both worlds.

 

[Albrigap]

I had a busted ring land on #5 cylinder and a cold start knock.
I rebuilt the 350 in the 90 Suburban 4x2.
That was work in itself.
An LS swap means you change everything.
You can add a lot of $ to the costs.
LS = more work and more $ but better driveability.
350 = Quicker, cheaper and easier but poorer mileage and driveability.
It's your time and checkbook.
So it is your call.

 

[andybflo]

You don't NEED the Holley style kit, you don't NEED braided fuel line, you don't NEED a rebuild and headers (it'll have 300 hp from a stock 5.3, once upon a time a 300 hp 327 was Corvette territory), a cam is nice, springs are fairly easy, but you should have no reason to pull the heads on it. Unless you have a really good machine shop and a lot of recent experience with parts combinations etc, the LS is the better current platform for stock components. All the SBC guys that really knew what they were doing at the aftermarket sources are retiring, same for machine shops. Unless you KNOW it, you are going to be at the mercy of a 20 year old kid reading parts catalogs just like you are, but he's never had a carburetor on anything but a disposable lawnmower. I'm not judging him, I haven't DD'd a carb vehicle either, it just hasn't been part of life for a few years for most people. I much prefer to trust GM engineering and run relatively stock stuff that was computer designed to be easy to work on and last a quarter million miles and hours of WOT redline testing. Along with that, you get a great water pump design that can be swapped in half an hour, a 160A alternator, good power steering, and if you want it, a much better AC system and electric fans with factory style control. I like old stuff, but for something to use consistently, I'd go modern engine in the classic truck for the best of both worlds.

^^ This.

These motors are in junkyards everywhere. Pull a 5.3, and yank the harness/PCM with it from a truck or van.

If you're looking for off-the-shelf, go to Napa/AutoZone/O'Reilly's stuff to swap things in go to Tejas Steel's website, they have a great LS Swap guide using OE Style components, and they sell inexpensive motor/tranny swap parts for 4WD and 2WD squares (I have their fan shroud, it's gorgeous.) My brackets/mounts are Dirty Dingo stuff. You can do a single tank swap (mine is dual, it was a little messier, lots of profanity and skinned knuckles, but still mostly GM OE parts) with GM tanks, GM pumps, and steel line to the firewall. I bought 6AN quick-connects into an AN jumper at the 5.3's fuel rail for convenience/flex. Stick with GM or OE replacement parts and the swap will cost about the same as rebuilding your SBC correctly.

I have a SEMA registered business, and have been a member for years; I build, locate (especially weird Euro stuff) and restore cars for other people as a side hustle. You don't need high end parts to do this; my only non-OE splurge was the Holley oil pan. It's really a nice piece (302-1) for swaps, I've used dozens and they always seal and clear crossmembers. But you don't need it, the GM pans will clear. All those high-end swap kits like Holley is debuting may look pretty in the box, but you'll never see my transmission crossmember or motor mounts once they're installed. The DD's look great and work flawlessly.

The swap was cake. Start to finish I had probably three or four total days into removing the old 5.7/700R4, stripping the firewall bare, and installing the LS to a running motor. Double that for getting things the like AC/HVAC back in and working, cleaning up wiring, hacking unused wires from the '86 harness, re-running the Choke light as my MIL, diagnosing a cooked PCM, etc. Plus, I sold the engine/tranny on Craigslist for $900. There's your harness/tune/misc part money on the LS.

I guess it depends on your mission; you want to daily this or drive it on the weekends? I wanted a vehicle capable of driving to wherever I wanted to go, whenever I wanted to get there. I know my way around a QJet or 4150. I didn't want to be thinking about a stuck float on the highway, while towing a car. I don't want to swap valvecover gaskets every couple of years. Think about rear main seal leaks. Think about ethanol boil on a hot day. I just want it to work.

One of the guys who helps in the shop has a '01 Tahoe. 262k. 5.3. It has a really slight rod knock on a cold morning at startup (common on early LSs, it means it has another 100k on her), and we'll need to do a knock-sensor swap on it in the next few weeks. No smoke, no leaks, it's grimy, but I'd drive it cross country tomorrow. The truck is going, the motor isn't. You aren't getting a Gen1 to 260k without at least 2 rebuilds. Maybe ever with wall thickness.

And someone above brought up a good point; I have a solid local machine shop, not everyone does. A good valve job (guides/seats), tank, mag, bore, hone, and line-bore/hone is well into four figures for me locally. That gets you a solid LS that won't need any of that for as long as you plan to drive it.

 

[Frankenchevy]

When taking the entire computer/harness from a donor, do you just cut the wires off at the firewall or are there other components inside the donor besides a dbw pedal?