I know that the 305 is like the red-headed step child of chevy V-8's, and very often deservedly so. I've driven 305's that are completely gutless and worthless. However, in my '84 z28, the 305 HO is not too shabby. It's much quicker than I expected it to be.

So exactly how much difference is there between the run of the mill 305 and the HO?

Thanks again.

 

Ok 305 & 305 HO. Differences are few. 305 HO has the 350 camshaft, higher compression ratio (don't know specifics) and i believe slightly higher flowing heads. That is the difference. The cars with these had several other modifications to support this platform. All 305 HO F-bodys have the dual-snorkel cold air intake. Exhaust still has the dumpy 305 manifold, exhaust pipe increased to 3" from cat-back. The catalytic converter also was a 4 bolt (instead of slip on). GM identified these cars with the Engine Vin code of "G"

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--Steve S--
1984 Trans Am 305 LG4, 5 speed Auto
RPO codes point to Recaro version
Daily Driver, Flowmaster 80 Series

 

LG4 (base 4-barrel) had 145 HP; L69 (HO) had 190. Those are factory ratings for what they are worth.

Heads and intake are identical; heads on both are 416 casting. LG4 had dish pistons, L69 had flat-tops for higher compression. LG4 manifolds and Y-pipe are 2", L69 2¼"; plus the larger cat and big oval pipes. L69 cars came from the factory with 3.73 rear gears, LG4 ones got 3.23s at best. L69 got the dual snorkel air cleaner. Some years or cars (not sure of details) got a fiberglass hood; mine at least did.

The HO was a pretty good motor for its day. It was faster than the 350 Cross-fire Vettes of those years, and hung pretty well with the TPI cars until the S-D 350s came out. The only bad thing is that the heads are nearly maxed out in the factory cofiguration, so there's not as much room for improvement as in some other motors. That's a typical 305 situation.

The Edelbrock TES is a good setup for them, and you can put somewhat more cam in them. Still, a 5-speed one runs abotu a 15 flat, which is not bad for a 305 off the showroom floor.

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

 

I've got a set of 85 HO heads on my 89 305, while my original heads are being reworked. Only differance between the two is HO Heads have a 58cc Chamber with 1.84, 1.50 Int Ex, were as the 89 heads have 64cc chambers with 1.85, 1.50 valves. Not much noticible power gains, but it seems to pull a little better than before with the 9.5 comp up from 9.3

89 RS Conv

Drove first one like i stole it, had to buy another.

 

I have a stock LG4 TA with 3.27 posi. And the heads are different from the 305 to the 305HO and have more flow capability. And the size of the exhaust doesn't really matter if you are going to swap. I am swapping one this summer. Monte Carlo SS had smaller exhaust pipes than the HO f-bodies. It just gives you slightly more power and torque if you go with the bigger pipes.

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1985 TransAm BLK/GLD Stock
1985 TransAm BLK/BLK
305HO (soon as it is put in) 5-speed, 3.27 posi, WS6, power everthing.
http://www.geocities.com/bullfrawgs

 

Your L03 didn't have 64cc heads, it's around 58 cc's

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1989 Pontiac Firebird Formula LO3 Auto
-180 degree stat
-Hooker Cat-Back
*****Possible summer '01 mods*****
Open Element, Auburn Posi, Keyless Entry, wonder Bar off the IROC, 4th gen seats, T/A tail lights

1985 Camaro IROC-Z LB9 Auto
http://www.geocities.com/krt80/

 

is that Recaro (conteur) seat option mentioned above rare? My 84 L69 has this option and i have never seen another set.

By the way my 305 L69 with many mods will run with a new Z28 so HAHA to all the 305 naysayers, they can be made to run fast for cheap. One must pay attention to detail when building and modifying stock parts

 

There were 1321 Recaro T/A's made in 1984.
There were also about 1500 15th Anniversary Edition T/A's made with recaro seats. What RPO code do you see for it, Y84?

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1982 Recaro Trans Am LU5/WS6/Y84, lowest mileage '82 T/A yet! - http://indiemonkey.com/82recaro
1985 basic Firebird, LB8/F41/GU6/DE1, '82 T/A wheels, CB, 128k - Get JPG picture here