five7kid

iTrader: (14)

There was only one engine called "HO" in 3rd gens - the L69 (VIN code "G") from '83-'86. There seems to be a lot of confusion over what made it "HO", so here are some basics.

At least in 3rd gens, LG4 (VIN code "H") and L69 used the same head castings, 416 from 1982-1986, and 081 for 1987 LG4's and '87-up LB9's (VIN code "F"). The '85 & '86 LB9 also used the 416 casting. The chamber size (at least as far as the factory is concerned) is determined by the casting. Therefore, LG4, L69 and LB9 will all have the same size chambers.

The '82-'84 3rd gen LG4's had lower compression because they had dished pistons in them, which, when combined with the 58cc chamber 416 heads, produced 8.5:1 compression ratio. The L69's and '85-'86 LG4's & LB9's had flat top pistons with 4 valve reliefs that, when combined with the 58cc chamber 416 heads, produced 9.5:1 compression ratio. '87-up used a slight dish piston with 4 valve reliefs that reduced compression to 9.3:1. The factory typically used steel shim head gaskets, although they have also used composition in later years. And, for the record, 3rd gen LG4's, L69's, and LB9's all used 1.84" intake and 1.50" exhaust valves.

The L69 had a better cam, larger exhaust manifolds and exhaust all the way back, different PROM tuning, knock sensor ('85-up all 305's have knock sensor), different carb calibration, dual snorkel air cleaner for Camaro, cowl induction for Firebird, and electric radiator fan ('86-up all 305's have electric radiator fan).

If you want to improve the performance of an LG4, you do the following: Replace all of the exhaust with headers, y-pipe with 2-1/2" downpipes to 3" at the cat, 3" cat, and 3" cat back to 3" inlet muffler (single 3" outlet or 2 x 2-1/2" outlets is your choice). Replace the cam with something with a little duration and lift (the Crane 2050 worked well in mine). Replace the valve springs with something that can handle the lift of the cam. Upgrade the ignition coil and module with aftermarket pieces. Replace the single-snorkel air cleaner with a dual snorkel unit, either a factory type (Camaros), or fabricated one (see the tech articles on the Board home page, or Link to Home Made Dual Snorkel Post for the latter). If you want, further improvements can be obtained by having the heads reworked for 1.94" intake valves, and cleaning up the port bowl area (do a search for porting, you'll find out what is required). Pinning the rocker studs or having the heads machined for screw-in studs is a very good idea with an upgraded cam & springs. If you want, you can put an aftermarket performance intake on it such as the Weiand Action+ or GMPP q-jet intake manifold. Most of this will also help an L69 or LB9.

If you have an LO3 TBI or LU5 cross-fire - well, those are special cases and you're on your own...



jk, check out the TBI forum "Important/Useful" stickies.

Nate86

LOL @ "If you have an LO3 TBI or LU5 cross-fire - well, those are special cases and you're on your own... "

Thanks for taking the time to write this up. Hopefully this will reduce the amount of "How do I make my LG4 faster?" threads. I will certainly be using it as a reference to any of the said questions.

Just thought I'd make it even easier for everyone by adding a few links to the stuff you mentioned. Enjoy.

Tech Articles
-----------------------------------

Performance CC Quadrajet tuning - https://www.thirdgen.org/newdesign/tech/quadrajet.shtml
Quadrajet secondary metering rods reference - https://www.thirdgen.org/newdesign/tech/rods.shtml
Dual snorkel air cleaner fabrication guide - https://www.thirdgen.org/newdesign/t...lsnorkel.shtml


Important/Useful Threads
-----------------------------------

Head Porting & Polishing - https://www.thirdgen.org/techbb2/sho...hreadid=117410
Exhaust FAQ - https://www.thirdgen.org/techbb2/sho...hreadid=152269
Header information - https://www.thirdgen.org/techbb2/sho...hreadid=204967
A.I.R. information - https://www.thirdgen.org/techbb2/sho...hreadid=213310
LG4 Cam recommendations:
https://www.thirdgen.org/techbb2/sho...hlight=LG4+Cam
https://www.thirdgen.org/techbb2/sho...hlight=LG4+Cam
https://www.thirdgen.org/techbb2/sho...hlight=LG4+Cam

Other Stuff
-----------------------------------

In-depth LG4 performance writeup (by five7kid) - https://www.thirdgen.org/techbb2/sho...hreadid=227857
Some backpressure information (yes, it is a bad thing) - https://www.thirdgen.org/techbb2/sho...t=backpressure
Technical data and power ratings for thirdgen f-bodies - https://www.thirdgen.org/newdesign/tech/techdb.shtml
Vacuum diagram for most LG4/L69 engines - https://www.thirdgen.org/techbb2/sho...hreadid=257699
V-belt to serpentine conversion:
1. https://www.thirdgen.org/techbb2/sho...ight=vbelt+fan
2. http://sethirdgen.org/serpentine.htm
Mechanical to electric fan writeup (very technical) - https://www.thirdgen.org/techbb2/sho...hreadid=248873
Tuneup information (written on the V6 board but applies to almost every thirdgen engine) - https://www.thirdgen.org/techbb2/sho...hreadid=162251

Hope that helps!

five7kid

iTrader: (14)

Thanks for posting all those links!

I could have added a few other things, like:

All US-delivered carb'd V8 3rd gens were computer controlled (along with the distributor).

All US-delivered carb'd V8 3rd gens had an aluminum intake manifold - and they were the same part whether LG4 or L69 (except the '87 LG4, which had the center two mount bolts on each side at a different angle than the rest - '86-earlier were all the same angle).

LG4's originally delivered to Canada typically were not computer controlled (I believe they finally were in the later years - but don't hold me to that) and had a cast iron intake manifold. However, their L69's were computer controlled and had the aluminum intake.

Mr.Wolf

iTrader: (1)

i hv carbed 305 whats the cam measurements u suggest?

five7kid

iTrader: (14)

If you retain the computer controls, you should consider a computer-compatible cam. Comp, Crane, Lunati, all carry cams that meet that description. The Crane 2050 cam I referenced is such a cam. It requires a good exhaust and higher stall torque converter (if auto tranny).

Lucid

iTrader: (4)

Did the LB9 camaros have different exhaust manifolds than the L69 camaros?
I had heard once that the L69 camaros had better exhaust manifolds and i ran across one at the junk yard, i should have pulled them off but i ran out of time ! (my dad has the LG4 car and i have an LB9).

five7kid

iTrader: (14)

LB9 and L69 are different, but fairly equal performance-wise.

The L69 has the EFE valve while the LB9 does not. The L69 EFE valve is bigger than the LG4 valve, so you can't put the L69 manifolds on with the LG4 valve.

R1UK

Pardon my ignorance but where should the G be in the Vin code?
ie: mine starts 1G2AW so does that make it an HO?
The reason i ask is it had an HO transfer on the back of the car which was obviously aftermarket.

five7kid

iTrader: (14)

8th character of the VIN.

R1UK

Thanks again, mines an LG4 then and seems people buy and fit any old stickers.



Now where did i put those 600ci Supercharged stickers............

aku

are there any aftermarked snorkel kits sold? or just factory/custom ones?

five7kid

iTrader: (14)

Ramair. Goggle it.

Project84TA

am i correct in thinking that L69s had 650 Q-jets. if so what did the LG4s have? i always thought the carbs were diffrent.
Engine Specs

i'm basing my info on this site, seems to be a very reliable site with good information.

Project84TA

sorry about the long obnoxious post, i dont know what happend there, just coppied the link and pasted it in my post. it wasn't that big when i copied it

five7kid

iTrader: (14)

The carbs are basically the same but tuned differently. The LG4 had a cast-in "tab" that kept the AV from opening fully (on some LG4's, not all - mine wasn't). The primary jets and secondary rods/hanger were typically different L69 to LG4.

Both carbs have the same capability, basically.

(BTW, don't try to copy a page into a post. Go ahead and copy the URL and put it in your post. Not-so-good things happen when you try to copy content into a post.)

Project84TA

ok, that makes sence, so basically what you find in the "tuning Q-jets" tech article is the only diffrence from the Lg4 carb to the L69. and you're saying that some LG4s have 650s??

five7kid

iTrader: (14)

They flow, or have the capability of flowing, in the 750 to 800 CFM range.

5 Spd Formula

mines a 88 h.o? we talkin bout High Output?

five7kid

iTrader: (14)

Officially, "H.O." designations were only from 1983 to 1986 model years, and were only on cars with the L69 carb'd engines VIN code G. If you have an '88, it isn't "H.O.". Some people refer to the LB9 as the "H.O." engine, but technically, it isn't.

5 Spd Formula

ooo thats weird my hood says5.0 h.o and those are the orig stickers.. i will look at my build sheet i bought it off my dads cousin who bought it new in 88 its only got 55 thousand on it

but im assuming ur right maybes its just one of those weird things

5 Spd Formula

yeppp sure enough MY BADDD was thinkin of somehting else

Z28er

so what your saying is: do these mods to your car and it will just be as good as a L69?

five7kid

iTrader: (14)

That's right.

The L69 cars did have the AC line routed slightly differently to stay out of the way of the passenger side snorkel, but I haven't had any problems with the LG4 line & L69 snorkel.

freestylin

the 8th letter in my vin is a E what kind of engine is this does anyone know

camarosource

iTrader: (1)

Enter your VIN : http://www.camarosource.ca/php/camar...year=2002&tm=1

five7kid

iTrader: (14)

(Edit: try this again)E = LO3 305 TBI.

freestylin

i entered in the vin online and it says its a v8 305 tbi i just wanted to know ifit was ho or lb9 or what it is its a firebird btw

freestylin

okay i got it its a LO3 anyone got any info on these engines

five7kid

iTrader: (14)

https://www.thirdgen.org/1988-pontiac-firebird

LO3 = 170 horse base V8. Lo-po, designed for some semblance of power while maintaining good standing with the government's CAFE (corporate average fuel economy) requirements, "at least I can say it's a V8".

coolram62

iTrader: (2)

Just to add,for those of us on our own...LOL,the LU5 CFI motors used the same 9.5 compression as the L69.And the stock cam specs fit in between those of the LG4 (.234/.257),LU5 (.257/.269) and the L69 (.269/.276).The LU5 (250 ft/lb@2800 RPM)produced similar torque at a lower RPM than the L69 (249 ft/lb@3200 RPM).The L69 (190 HP@4800 RPM) had the horsepower edge over the LU5 (175@4200 RPM) but again at a higher RPM.
The L69's big advantage was the exhaust system.That along with the electric fan,available 5 speed and deeper rear gears (3.73 vs 3.23 LU5 w/G92) all added up.And yes the CFI can be tempramental.But it can be made to perform.

classiciron

Hi,are you sure 82 didn't have a HO engine option? I have an 82 Z28 that has HO in the VIN numbers. Which I assumed met it was a high output motor.
Dennis

camarosource

iTrader: (1)

What is your VIN #?

classiciron

1G1AP87HOCN107527

Here is my VIN number

classiciron

I guess it has the LG4 Engine, my mistake.

D BERRY

iTrader: (2)

Brand new to the ThirdGen board, having just bought my first Camaro. As luck would have it, I got a 89 RS with the LO3 engine, twenty more horsepower than my old Neon. What are the major differences between the LO3 and the LG4 engines, which appear to be rated the same horsepower wise, other than the induction. Would I be better off in the long run changing engines??

Dave Berry

five7kid

iTrader: (14)

The LO3 used a roller lifter cam, electronic throttle body injection, and "swirl port" heads. Great for fuel economy, pretty much maxed out the way the factory made it. The "best" LG4 had 165 HP, 145-155 much more common. So, the LO3 and its 170 HP was a little better, and emissions and fuel economy were improved over the LG4.

If trying to improve an LO3, add "replace heads" to the above list. Then, do what was said in the original post, check out the TBI forum.

D BERRY

iTrader: (2)

Thanks, I'll check out the TBI forum!

hgffrank

I am getting an 83 T/A with LG4 so I'd just like to say thank you to all involved with this thread for the great information. its weird though cause my T/A also has the HO decals. I dont know why someone would put an HO decal on a fake HO car? Kinda stupic in my opinion. Thats something I expect from ricers. Now if the engines and all are switched to the HO equipment then I could understand it. lets just hope mine has been converted properly, or else teh decals will be removed.

Ozz1967

iTrader: (4)

I attempted to decode my vin # on this web site but it comes back as "Not a valid 17 digit vin number"...

Carfax finds it, but two other web sites that I went to couldn't.

Any ideas?

---EDIT---

Found it here

http://www.fbodydomain.com/VIN/VIN.asp#1982

Mine is definitely an 84 Trans Am, L69 car. What threw me was the 4th digit was an "A", not "F" for Fbody like some say. Apparantly the "A" stands for manual restraint system.

69-er

Just for the record, in 83, the 8th character for an L69 was a "7". I think I read somewhere that it changed to a "G" in 84. My 83 L69 has a "7".

Larry

HasseO

So, what rods/hanger did the L69 use? I think Ill use them when modifying my lg4 carb, since Ive done a lot of other mods..And Im retaining the ccc so I need something compatible

Lucid

iTrader: (4)

You would also want to get an L69 ECM or just the L69 chip. If you can find a verified source for a monte carlo SS like an 88 model year, it has a better ECM and will work mighty fine. The difference is the spark advance programmed in the chip.

Kelby Jones

my vin is 1g1fp87f6f1489339

Kelby Jones

im wondering what it is

five7kid

iTrader: (14)

Originally it was an LB9, TPI 305.

Anybody's guess what it is now.

Guest

I see some errors here. The '82 LU5 was 8.6:1, the '83 was 9.5:1.
The LG4 cam was 178/194, .233/.257", the LU5 cam was 195/202, .260/.273", 112@108, and the L69/LB9 cam was 201/206, .269/.276, 114.5@115

five7kid

iTrader: (14)

This is our source:
https://www.thirdgen.org/1982-chevy-camaro

What's yours?

screaminformula

great, informative post...but i'm gonna disagree about one thing. the L69 was NOT the only "official" H.O. engine. my buddy's 86 Trans Am that is all stock with the LB9 TPI 305 has stickers on the sides that say "5.0 Liter H.O.". and, in my thinking, if GM put "H.O." on the car...then it was about as official as you can get.

Guest

Old GM service manuals.

five7kid

iTrader: (14)

Was he the original owner?