58mark

iTrader: (3)

I might be picking up a 86 trans am this weekend with a LG4. Not familiar with that engine at all, other than it has a decent amount of torque considering the HP is pretty pathetic.

I also hear it has TWO fuel pumps! how insane is that?

Tell me what you know about it, good and bad, and that will help me make up my mind if I want to get involved with one.

What kind of Highway MPG can I expect out of one?

MoJoe

iTrader: (5)

I am guessing on the dual FPs: A low pressure pusher in the tank, and a traditional mechanical on the engine.
It has a computer controlled quadrajet.
It is a 305ci. Whether it has enough power, with or without hot rodding, is up to your opinion.

I had one years ago. The stock cam wheezed out ~4300rpm. Add some Edelbrock shorties, 3" Y and cat, and it wheezed up to 4600. Add a Crane Compucam and free heads (don't remember the specs for either) and promptly floated the valve pulling up to 5700rpm.
With 5 speed manual, somewhere along the way, I took 2 teeth off the ring gear. I replaced the 3.42s with 3.73s and it was a better city, stoplight grand-prix car.

In that way, it is easier to mod that EFI. Mileage, cold start, temperament probably isn't as good as EFI, especially with modern LS technology.
If I had to guess, before the 3.73s, highway (back then = 55mph) might hit 22mpg. 3,73s likely took it down to 18.

Daily Driver going 50-100 miles a day, get a Camry if you want mileage. Part time, fun car, occasional road trip... yeah, it can be a low cost option.

58mark

iTrader: (3)

22 is better than I get in my v6 right now...

It will be my wife's car. She has always wanted a Trans am, so a carry ain't gonna cut it

Thanks

nhgator

My 85 lg4 Trans Am is what it is,fun to drive,handles decent,gets mediocre fuel mileage if you don't get into the 4 barrell every chance you get.
Could it use more power? hell yes,someday when the 305 dies,but the cool factor is 10 times of any Camry,cars just don't look that cool anymore.

Damon

85-86 LG4s were the "good guy" LG4s. Aside from a weenie cam, a strangulated exhaust system and a weaker spark curve in the chip, they were basically identical to same-year L69 HO 305 motors. Lots of upgrade potential (starting ALWAYS with a complete manifold-to-tailpipe exhaust).

When you get it, before you do anything else, give it a good tune-up. Plugs, wires, cap, rotor AND COIL. A fresh O2 sensor is a good idea, too.

Then bump the timing up from the stock 0* BTDC setting to 6* BTDC (using proper factory procedure for setting base timing- very important).

It'll at least be mildly entertaining to drive like that for a while. They're pretty snappy if you don't try to take them over 4000.

Then you do the exhaust- shortie headers, 3" all the way from the y-pipe, to the cat and cat-back. You probably throw a 14x3 drop-base open element on it while you're at it, because it's a cheap upgrade.

Then you agonize over whether it's worth changing the cam in the motor and eventually decide it's WAY more bang for the buck to replace the whole motor with a mild 350 like the GM Targetmaster "universal replacement" 350 rated around 250HP (or 260, depending on who you believe).

You're good for a couple years like that. One day you wake up and decide "I want to run 11s instead of 13.9s/14.0s". At which point you empty your wallet, stop daily-driving the car and get seriously bit by the hotrod bug.

58mark

iTrader: (3)

I would probably do headers and exhaust first so it would carry over to a replacement 350 someday.

chazman

iTrader: (4)

^^^^^^^^^^

What he said.

AssaulT/A

I've got the LG4 and everyone has hit the nail pretty much right on the head. The only thing I would add is that with the T5, the lowest factory gears in the rear, and driving like a grandmother, I got 30 mpg once on the freeway, averaging 80. Food for thought.

58mark

iTrader: (3)

I'm getting to the age where I hope to take some cross country trips with my wife, and getting decent mpg is more important to me than 300 hp. I'm disappointed that my v6 is getting such crappy mpg on the highway (20) but it was never designed to sustain 80 mpg like we have here in Texas, so it really labors

I'll post pics of the car if and when I get it.

58mark

iTrader: (3)

Aw hell. I'll share it now. What do you think?

MY87LT

iTrader: (2)

Looks pretty straight. Btw, not all the LG4's came with two fuel pumps. A well tuned LG4 mileage varies with driving styles. Back in the day, average mileage was 16 city/24 highway. With a lead foot, forget it. LOL.

AssaulT/A

Looks clean to me! If the price is right, I'd bite.

sofakingdom

iTrader: (1)

It's eeeeezier to fix a weenie engine in a REALLY NICE car, than to fix a wasted POS car with a mountain motor stuffed off in it.

The LG4 is arguably the worst of the V8s; its only competition for that distinction is the L03. But, that's ALOT easier to fix, than a rust bucket, a used-up POS, a hack-job conversion from somebody that used dykes WAY too much, and all those other "difficult" situations. Out of all possible shortcomings that a car might have, the motor is the least trouble to set right.

If it's a nice car, at a price you're willing to pay, go for it.

58mark

iTrader: (3)

I doubt this engine bay is hacked up. You usually don't see a car look that original on the outside if the drive train is modded to hell

I hope it's in original condition, and we can drive it as is for a while until we decide what to do next

MY87LT

iTrader: (2)

Well I wouldn't call the LG4 the worst engine. Some say the 1975-1976 262 cu.in. V-8 that came in Vega's, Nova's and some other cars were the worst can't really say that about them since I have no real experience with those engines.

But with an LG4, they are very forgiving. Agreed, if you want ***** out performance, then get another engine. But just for cruising and some road trips, its a perfectly fine engine. Like sofakingdom mentioned, a lot of times, engines on our cars can be totally ruined by previous owners.

Fast355

iTrader: (2)

I had an 1983 G20 van with the 165 hp 305 4bbl, 700r4 and 3.08s. When i got it and started driving it in high school it was a 10 mpg DOG with 180k. I cut the clogged factory pellet cat out and put a high flow on. The vans had larger manifolds and Y-pipes than the L69 cars (2.25 to 3") and a single in, dual out factory muffler with dual tailpipes. I tuned it up and rebuilt the carb. Still didn't run well and one day it just died in the HS parking lot. It was summer and wanting to be a mechanic at the time I dug deeper into it, found a broken nylon timing gear and while I had it open I put in a 204/214 rv cam and lifters in it. The factory cam had lost alot of lift and the chain was wasted from stretch before the gear gave out. After tweaking the carb and recurving the distributor it was pretty peppy and would run 80-90 mph in od down the highway pretty easily. It would get 18 mpg most trips with a high of 20 on one long highway trip. I pulled 23 out of the same engine with TBI and lean cruise. I think an aerodynamic car like a F-car setup the same way could do 25-30 mpg on a long trip. The engine gave up at 275K after spinning #1 rod bearing from oil starvation.

86LG4Bird

iTrader: (1)

More concurrence here. If the car is nice, buy it. As was said above already, the LG4 can be a snappy driver with just an exhaust upgrade and the bump in initial timing. Better yet, an L69 chip. Properly maintained, it should easily get mid 20's highway mileage. I've gotten in the 26's with the stock engine AND with the engine currently in the car, with 3.73 gears.
And, if the mod bug bites harder later on, you will thank yourself for buying a CCC car rather than a TPI or TBI car. You can stuff more engine under the CCC carb and it will handle it just fine; no programming skills required. See my sig.

rusty vango

lg4s are the universally hated motor on here. if all you want is a street car they do fine. you CAN get some serious smiles out of it. and if you choose to rebuild it you can get a reliable 300 HP . every body and their granny are gonna tell you the " LS " or "threefiddy" crap. however ,since its gonna be your wifes car. I would concentrate on reliability. nothing worse than having her call you from the side of the road. happy wife=happy life

58mark

iTrader: (3)

There has been some awesome advice on this thread, but these words are probably the smartest thing said. I hope the seller will agree to my offer I fell the car is worth and what I can afford

yaj15

iTrader: (3)

This is a good thread. It really highlights the point "build the car for the goals you have in mind". If it was me I would replace the 305 with a 350 at some point and do some minor transmission and suspension mods. My goals for the car would be a fast street car that is hopped up a little more than stock but not to crazy.

Someone else may get that car and want to strip it down, put a roll cage in it, put a big block in it, and make it in to a drag racing car.

Someone else may want to go all out on modifying the suspension and brakes to compete in autocross style events.

Some people want a car that 100% show-room factory stock.

Nothing wrong with any of these options. At the end of the day it's your vehicle and you have the right to do with it what you want. Just make sure whatever you do, your modifications (if any) match what you are trying to do with your car.

At any rate (and I know this goes with out saying) LG4 or whatever else, make sure the car and all the components are in good mechanical condition and operate properly. I know you don't want to have an unreliable car - ha ha most of us don't have a NASCAR pit crew truck following us with all the tools and components we would need to do an engine overhaul on the spot.

Even someone with an LS7 powered C6 Z06 won't feel so super in their car if the shocks are shot, lifters have failed, clutch is worn out, or there is an ignition problem.

I remember when I first got in to thirdgens I test drove a lot of different cars with different engines - IROC's, Z28's, RS's with the LO3, LB9, L98, and LG4 motors. It became real clear to me the difference between a car that was kept in good running condition and one that needed some work to get back in to shape.

The LG4 may not be a land rocket in stock form but a few LG4 powered car's I drove would have destroyed a couple of TPI cars I tested that had not been taken care of by previous owners.

chazman

iTrader: (4)

I agree. A great running LG4 is a more pleasant drive than a bad running TPI.

chazman

iTrader: (4)

Also, if you don't want to go with headers in the future, L69/LB9/L98 exhaust manifolds with a 3" exhaust will really wake it up while retaining a stock look.

58mark

iTrader: (3)

So stock L98 manifolds aren't bad? Good to know, thanks. Where I live, sometimes it's hard to get cars with headers to pass inspection, especially if you have to remove anything emission related to put them on.

Fast355

iTrader: (2)

Never have had an issue myself. Just get headers with air tubes and matching Y-pipe for a highflow cat and you are golden. The biggest power gain I made on my smallblock builds have been headers. Even my 1997 Express conversion van and 2014 Nissan Titan have headers. Even the LT1s with a far better exhaust manifold design than the 3rd gens gain noticeably from headers.

58mark

iTrader: (3)

My only experience with even thinking of getting headers was for my v6, which has to dump the AIR pump to put the headers on. Even though my car is 25 years old, they still do a visual inspection to make sure the items that are supposed to be there are still there

Not sure if they would actually fail me or not, but I've never taken that chance

chazman

iTrader: (4)

Here is all you need to know about 3rd gen exhaust manifolds from a 2003 post:

Do the exhaust, bump the timing, get a better breathing air cleaner, and you'll be good to go.

Fast355

iTrader: (2)

Have the same here as I am also in DFW but never kept me from doing stuff like swapping my 83 G20 first to TBI then to TPI then to vortec heads and OBD2. My 2006 Ram had a Hemi swapped in it. My Express lacks an EGR valve, headers, highflow cats and has a marine intake but passes the OBD2 test with flying colors. As for a visual its practically impossible to know if the EGR is there but I bolted the valve to a plate I bolted to the thermostat housing to give the appearance it was in the oem place. The supply tube has been removed and its off in the pcm programming. The last time my G20 was on the rollers with TPI, vortecs, a cam, headers and high flow metallic core 200 cell count cats it blew practically zeros. No smog pump, airlines or egr valves allowed.

86LG4Bird

iTrader: (1)

Not bad at all. See sig below.
No argument that headers are always worth some power, especially at higher rpms and when running more than a stock cam, but the stock L98 exhaust can support some decent power. I have removed the old cat from mine.

58mark

iTrader: (3)

OK, I have a friend parting out a 91 camaro with a nice exhaust system in it. Here's the specs, tell me if there's any reason I shouldnt jump on this for a good price

non a.i.r. hedman shorties with the hedman y pipe.
A magnaflow cat and a hooker aero chamber dual outlet muffler.

he think's it's a 2 3/4" system

Also I was thinking of this air cleaner, but I'm not sure if I need a drop or non drop base.
this link shows a photo of a drop base, but the description is for a non drop
http://www.jegs.com/i/JEGS-Performan...rentProductId=

what do you think? I want to get as much of this worked out before I see the car on Sunday, that way I know what I'm in for

rusty vango

you may run into non compliance issues.does your state check for emissions? if so those headers are a no go. AND it would be loud as he#@ too. if emissions aren't a problem then yeah go for it!! but expect to pi$$ off your nabors!

58mark

iTrader: (3)

The would be aged out of an sniffer tests, but there's "supposed" to be a visual test, that's not often done

The car that the exhaust is coming off of is at the 1:48 point of this video

rusty vango

well, your luck may be better than mine!! I would be the one guy they inspected!

58mark

iTrader: (3)

that's what I worry about

I could take most the the exhaust and use the l98 manifold and y pipe, or get different, legal, headers

rusty vango

you could ,although headers are the best single improvement you can make to gain HP and MPGs. they are a PITA. sometimes you have to use shorter spark plugs.get artful to keep from burning plug wires.starter heat wrap/shielding. copper header gaskets are the ones to use ,and there are header bolt kits I have seen that wont come loose. bottom line is ,,if you don't mind the BS that goes with having them . they are a lot of bang for your buck

yaj15

iTrader: (3)

Check out these links for results of modding the LG4. This website as a lot of magazine articles about thirdgens as well.

https://thirdgenfbody.wordpress.com/...aft-july-1987/

https://thirdgenfbody.wordpress.com/...phr-june-1987/

58mark

iTrader: (3)

Thanks, I had found those links in a search, but it's noce to have them here

Car was not as nice in person as in the photos (photos used were years old)

made an offer, seller made a counter offer ($500 more than my offer) and I left, telling the seller that I was leaving town, and after 10 days if they haven't had a better offer, let me know


Craigslist sellers are starting to get on my last nerve. One of the FIRST things I asked her was if the AC worked. She said yes. Well, what do you know... we get there, and then damn thing doesn't even have a belt on the compressor.

rusty vango

plus one on craigslist. you get to meet the bottom of society selling and buying .lyers,hacks and thieves. but I have dug up some nuggets too. like a IROC hood with louvers for $75!!! AND rust/dent free.no less.

58mark

iTrader: (3)

got the car! (seller took our offer we made when we found the car was in less than ideal shape) That Lg4 has a lot more punch than I thought it would. really nice torque for something with less than impressive HP ratings I'm a FAN!

https://www.thirdgen.org/forums/memb...ml#post5799208

1982Z28Modified

The LG4 takes a lot of kicking on this site. Here's what I know. Put a free flowing exhaust on it, a better intake and decent carb (no q-junk) and you will have a very drivable car. I went further and removed the air pump, egr, cat, computer, new MSD distributor, did a serp conversion. Now it runs like a raped ape. Next upgrade, a 700R4 to get some MPG's on the way to work.

dmccain

iTrader: (2)

Had an Lg4 in a Formula in HS. First we put 3in exhaust,cut out cat,and a Holly DP and an intake on it. Later came headers,gears and a cam swap. It was a pretty solid runner it broke into the 14s. When i got it it ran like 15.7 I liked the lil engine.