620 buick 3.8 swap

[sethris]

hey guys, ive been looking for hours, but i know there was a post about a kit you could buy to swap out the l16 to a buick 3.8 v6. does anyone know about it? ive decided to go that route instead of the ka motor. thanks

[bob72gts]

As the owner of a 3.8 Buick powered 620 I advise you to reconsider. My truck was built with a hooker headers kit which included multi-piece headers, Fiberglass firewall modification, a cut down front crossmember, and engine mounts. It has a stock 4bbl. intake with a Carter AFB and it sucks to work on this truck.

 

When I bought the truck the Buick was already in it. It was missing the carb and had not run in years. I bolted on a carb and tried starting it, but it just would not run. I pulled the engine and trans out(the only way you can work on this truck is to pull the combo out), and I found out why it would not run. 2 burned pistons and a cracked block :( Well, the guy I got it from did say the previous owner was squeezing it.

 

I started collecting 3.8 parts. I wound up with 6 long blocks and I still did not have one that I considered buildable. On a trip to the junkyard I found an 84-5 Regal with a pretty fresh engine in it. The heads were obviously fresh, everything else looked clean and it had a set of .040" pistons in it. :D I took it home and started taking it apart. My plan was to clean, paint, re-seal, and put a mild cam in it. Then I found out why it was in the boneyard. The fresh engine that I had just bought had a rod knock and needed a crankshaft. :angry:

 

What I have learned about 3.8 Buicks is that there are 2 common causes of death, over-heating and rod knocks. The over-heating is easy enough to deal with. Maintain your cooling system, install a quality temp guage, and don't be dumb. The rod knocks on the other hand seem to be due to an oiling system design problem. In doing engine "autopsies" on my engines and talking with other people it is always rod #1. :blink:

 

I got a freshly turned crank from a local machine shop and I installed a High-volume Melling oil pump kit. I have not had any more oiling problems, but I have only driven it about 5k miles in 12 years.

 

So the new engine went into the truck, got her fired up and broke in the cam. Throttle response was crisp and the torque when you gave it a rev would flex the truck like no N/A 4 banger L series ever could. :D Now it was time for the first test drive. Backed it out of the garage and headed up the street. The TH350 tranny was completely blown up. Squeezed right? :( Back into the garage to pull the tranny, did I mention you have to pull engine and trans if you want to work on it. :angry: Ok, the new engine and the new trans are now back into the truck and I drive it around town for about a week before the starter goes out. Because of the way the Hooker Headers are built, you can't get the starter out with the right side header on. Unfortunately the headers go in before the engine and trans. :( Time to pull the engine and trans AGAIN. :angry:

 

Now that it is all together and working there are some other things you need to know.

 

1. With the high volume oil pump kit you can't get the oil filter off without pulling the idler arm bracket off of the frame.

2. A Buick V6 with a TH350, a stock Datsun rear end, and 245/50/16 rear tires is not highway friendly. I am now running a 295/50/16 and it will run 70s

3. A stock sized radiator will not keep it cool in the southwest USA

4. Hooker only makes the headers now. The rest of the parts are no longer available.

5. It sucks to work on :D

6. It is not as quick as I thought it would be. To be fair it is over carbed and I need to install the Edelbrock intake that is in my shed.

 

If you still want to do it here are some tips.

 

1. The high volume oil pump is mandatory, and use a remote filter

2. I used a V6 1981 Chevy Monte Carlo cross flow radiator and an electric fan. It fits between the inner fenders, you just need to trim the bumper brackets down some and notch the bottom channel of the radiator. Use the hoses for the same car. They fit great and you can get them at any autoparts store, universal hoses suck.

3. If you are going to run a TH350 with the stock rear end housing get a set of 3.90s for it.

4. GM did make an overdrive to use with that engine, but I dont think it will fit because of interference with the crossmember where the torsion bar adjusters are at. If you plan to run coil-overs then this does not matter.

5. If you don't already have a 3.8 get the 4.1 V6. I believe the 84' Park Avenue had it among others. This car would also have the auto overdrive if you decide to go this way.

6. Go with a 1 piece drive shaft. The 620 center support bearing rubber bushing really isn't up to it.

 

I know TL DR

[sethris]

wow, thats a streak of luck! i appreciate the help.

honestly i dont know what to do. the 1.6 is just too weak. i put a 5 speed out of a fairlady z, and had the driveshaft shortened, but im still not satisfied. i have a 2001 frontier that i was going to do a conversion with, but it looks like that is a ton of work too.

thanks again!

[Spades]

well...here is my take on the subject.

 

The 4.3l v6 is amazing if you can get it to fit...it is a 350 with two less cylinders. plenty of power, tons of torque, and many go fast and stock replacement parts...if a 4.3l won't fit, I would still take the 3.8l v6.

 

GM v6's get a bad rap mostly because of the people who buy them...like most American cars. Sure, you can take an old Nissan or most Toyotas and never change the coolant, oil, ect...and they will most likely outlast a GM product...however, when maintained properly, I see the 3.8 motors go to AT LEAST 100k when heavily abused, and often see them go to 250k miles when abused. The problem is you are looking in a junkyard for your core motor...BAD idea for these motors. The redneck or grandma driving that 80's V6 powered GM will just keep bandaiding that car until something serious breaks, and if it is in a scrapyard, it is usually because the motor or trans or both are bad.

 

If you want to do this swap, do yourself a favor, read as much as you can on the internet about these swaps, and don't go cheap. Do not go buy a non running core motor for $200 at the wrecking yard, go find a still running car for $500 that you can drive and will know what is wrong with it BEFORE you buy it...chances are you will run across a older car with a trashed interior and body, but still mechanically decent, but is leaking like crazy and needs more TLC than the interior and body will warrant.

 

I will never again buy a non running motor on someones word, been burned by that, and trusting people and trying to go cheap as possible will just cost you more money in the end...I learned that the hard way.

 

Put a motor in that you like, do research before you try to swap or buy an engine, and don't trust ANYONE.

 

p.s. the reason 3.8l's have oiling and cooling issues is because people go 10k miles on penzoil with a cheap oil filter and change the coolant every 15 years(if at all). we see about 2 or 3 GM v6 powered cars a day where I work, and if they change the coolant at least every 10 years and the oil every 5k miles, you would be surprised how far they can go...it isn't that uncommon to have some late 70s or early 80s pile of American crap that lasts 300k+ miles with poor maintenance. While most Japanese cars have a one up on American stuff from the 80s, when properly cared for a engine like a 3.8 would not be a bad choice.

[datzenmike]

The 3.8 was very successful and over 25 million have been built. I looked at the GM V6 swap a while back. Even had a running 4.1 from a FWD Cadillac. Had the equivalent of the 720 electro-carb but was a 4bbl Quadrojet. Needed an ECU and O2 sensor. Had that but could see that it was a terrible fit in the 620 said fuckitall. Gave it all away to an old boy who has an early '60s Skylark odd fire V6. He was very happy.

[nismo dr]

This one was at the Blue Lake show last weekend. Don't know anything about it, but it looks sexy as hell.

 

 

 

[bob72gts]

I agree that the best way to do it is to buy a complete running car, but it is not always possible to do a complete car. I never bolt a boneyard motor in without a complete teardown and inspection first. If you can find one with clean fluids and you plan on doing rings, bearings, and gaskets anyway, go for it

 

On a related note I recently bought a 91 Camaro RS with the 3.1 V6 The 2.8/3.1/3.4 engine family is a 60 degree V and is a much better fit into a small rear drive car or truck. The bellhousing pattern is also smaller than the 3.8/4.1 and 4.3/SBC/BBC which should minimize trans tunnel hacking.

 

My 3.1 is rated at 140hp and the later 3.4s made 160hp. You can also build a pretty decent runner out of a 2.8. A buddy of mine has a Jeep Cherokee with the 2.8 and 5 speed. Originally I thought it was going to be a total turd, but I was wrong. It has an Edelbrock torquer intake with a 390 Holley, a mild cam, and a set of headers. I do not know if the 2.8 intake will fit the 3.1/3.4 they may have a taller deck I have never checked. WARNING avoid the pre 85' 2.8s at all costs, they have smaller journals and are known to break cranks.

 

It is easy to sell the parts from a 3rd or 4th generation Camaro/Firebird so you wind up with a free engine swap.

[sethris]

thats a sweet 620! but yeah ive got to think of something. im not much of a fabricater, so, thats my delima.

there was a site that sold a kit for a 3.8. came with motormounts, headers, and maybe the hoses, already to go. now i cant find it! my old laptop crapped, and all my fav sites got gone :angry:

[DRIVEN]

I think most people here would probably advise you to just step up to an L20b since you say your fab skills are limited. If that weren't the case, I would suggest skipping the '70s/'80s vintage stuff and go straight for the Series II. I lifted this from wiki:

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Introduced in 1995, the Series II is quite a different engine. Although the stroke for the 3.8 L engine remained at 3.4 in (86 mm), and the bore remained at 3.8 in (97 mm), the engine architecture was vastly changed. The deck height is shorter than the Series I, reducing weight and total engine package size. This required that the piston connecting rods be shortened 1 in (25 mm), and the crankshaft was also redesigned. A new intake manifold improved breathing while a redesigned cylinder head featured larger valves and a higher compression ratio. The result was 205 hp (153 kW) and 230 lb·ft (312 N·m), better fuel economy, and 26 lb (12 kg) lighter overall weight (to 392 lb (178 kg)). This 3800 weighs only 22 lb (10.0 kg) more than the all-aluminum High Feature V6 that currently dominates GM's six-cylinder applications, despite being an all cast-iron design. This is the only Series version of the Buick V6 to have longitudinal RWD versions built, and these versions were only used in the F-body Chevrolet Camaro and Pontiac Firebird, and in the Holden Commodore, Caprice, and Ute.

 

The new intake manifold greatly improved airflow. To meet emissions standards, an EGR tube was placed in the intake manifold to reduce combustion temperatures. This increases fuel mileage by a substantial margin.

 

The 3800 Series II was on the Ward's 10 Best Engines list for 1995 through 1997.

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I think this engine along with a 4L60E transmission would be a great driver in a 620. I know that in the Firebird/Camaro they were capable of better than 30mpg and, in my experience, were extremely durable and reliable. The factory supercharger from some of the performance trimmed FWD cars can also be fitted to get you close to the 300HP mark.

[justin 620]

Already been covered right here.

[sethris]

yep saw that one back when i was doing my initial searching, but then i found a kit that didnt need any real fab work.

 

seems like the site had something to do with gm's and so forth, not really a datsun site.

 

but there was no messing with the firewall, cutting mounts, or headers, etc. but i saved it on my favs, and then when i got home from overseas, my comp crashed and i lost all my sites. oh well bummer