Hey guys, I was just wondering what significant differences there is between the base 305 and the high-output 305 (I dont know the abbreviation) besides the horsepower lol. Thanks

 

I believe the HO is L69 if not, then it's LB9. The other base 305 you're probably referring to is the LG4. The LO3, TBI was also the next base 305.The main difference is the cam I think.

------------------
"Putting any amount of money into a RICE BURNER is like wiping your a$$ with a turd. "
'86 IROC
T-TOPS, TINTED WINDOWS, BRAKE LIGHT BLACKOUTS
GM GOODWRENCH 350
EDELBROCK TES HEADERS
3" Hooker CatBack w/Aero Chamber muffler
EDELBROCK 600CFM CARB.
KN AIRFILTER
ACCEL HEI DISTRIBUTOR
160* Stat, just switched to 180* b/c of winter coming and going to college in the mts.
3:73 Posi
Rebuilt 700R4
B&M Megashifter, 5" Autometer Tach w/shift lite

 

The LG4 has dishpistons so its got lower compression also.

------------------
I was going faster than I'd ever gone before but then I fell off.

 

the 305 HO engine (L69) was available from 1984-1986. only about 75 were made in 86. the mail differences between the L69 and the LG4 were the L69 had a bigger carb with special rods and hangers. it also came with a larger camshaft as well as a dual snorkel intake system and slightly larger exhaust pies. this gave it a 25 hp advantage over the LG4.

------------------
1986 IROC-Z
305 LG4 w/ TH700-R4
Edelbrock TES headers & Y-pipe
3in Edelbrock cat-back
K&N air filter
Direct wired fan

 

The L69 was first used in 83 (I have one) and continued until 86. The largest number of them was made in 84.

In 83 the LG4 was rated at 145 HP, the L69 at 190 HP. Torque was much higher for the L69 and both HP and torque peaks occurred at a higher RPM.

The block, heads, and intake were the same; just about everything else was different. The LG4 got the "peanut" cam, the L69 got the one that was later used in the better (5-speed) TPI 305s. The L69 got the dual snorkel intake in the Camaro. It had electric fan as opposed to the old-style clutch fan the LG4 got. The L69 exhaust manifolds were larger, with 2¼" outlets instead of 2"; the Y-pipe was larger; it had the huge oval cat, 2¾" I-pipe, and 2¼" tailpipes, all much larger than the LG4. Carb calibration is different. The earlier LG4s didn't have a knock sensor, but the L69 did; this allowed a more aggressive timing curve, since the ECM could back it off if necessary based on knocks, where the LG4 just had a safe, lazy curve. The LG4 had dished pistons for about a 8.5:1 CR; the L69 had flat-tops, which gave it about 9.3:1.

The LG4 got a few improvements as time went on. I believe the last year it was offered, it had about 160 or 165 HP. By that time they had switched it to flat-top pistons and electric fan, and added a knock sensor.

L69 cars came stock with 3.73 gears, at least in 83. Some but not all had posi and discs: mine didn't. (It does now.) The cars, both Chevy and Pontiac, carried the "5.0 Liter HO" badges both interior and exterior.

A Chevy L69 5-speed car ran the ¼ in very low 15s off the showroom, 15.2 or 15.3. It was very easy to get them into the 14s. The LG4 5-speed was about a second slower and the auto added a few more tenths on top of that.

For 2 motors that look as similar as they do, it's amazing how much different they run. It really shows where the weak points of the LG4 are: exhaust and cam above all else are the limits in that motor.

------------------
"So many Mustangs, so little time..."
ICON Motorsports

 

I have the LG4 in my 86 Trans Am, ran awesome after I swapped to an Edelbrock 1406 carb.
Ran a best of 14.94@91.67mph, 133K miles on motor, everything stock except carb and distributor.

Car is now a TPI 305.
Before,

Now,


------------------

WS6 Trans Am.

View My Ride @ thirdgen.org

 

I liked it better before.... Seriously, they're both pretty sharp, but why TPI? Daily driver? With a Crane 2050 Cam, doesn't it like the upper RPM range? How do you like the B&M Ripper? Thinking about getting one. Sorry, lots of questions...

------------------
-1983 L69 Camaro Z28 305 H.O. (Bored .030 over,Teflon oil seals,Melling H.V. oil pump,Hyperetic pistons,chrome-moly rings,T-tops, 3:73 Open rear, BW T-5, Rebuilt E4ME 4 Barrel, Duel Snorkle Air Cleaner w/K&N Filter , Rhino Clutch, Crane 2040 Compu-cam, LS1 valve springs, porting, PST front end kit. Now for paint, interior, etc...etc.... Also:
2000 S10 4.3L 4WD LS
1995 Ford Thunderchicken, 4.6 V-8