Can someone tell me the difference between a 305HO and a normal 305? I would really like to knw.

 

the HOs got better cams, slightly better heads, exhausts and air inductions which made the 30-40HP difference.

 

Heads are the same as an LG4. 416s.

Connecting rods are better, too.

 

Okay Sitting bull, My question is: Are the 416 that much better than the l03 heads.. I am going to have to have a valve job done, and I know that there isn't much for the L03, I am on a very tight budget, going with an LT1 cam an edellbrock performer intake, headers and 3" catback, march underdrive pulleys..

Would the 416's flow anybetter with this setup.
Thanks Scoty

 

Yes, they are that much better.

The L03 heads are among the very worst production heads for performance that have ever been produced by GM. They have this giant "ramp" to make the intake charge swirl (which is why they're called "swirl-port"); that ramp thing is just this massive blob of casting stuck off into the intake port, as an obstruction. It may help the motor out at below 3000 RPM; but above that it's a power killer.

Although you actually need 081 castings, to keep your existing valve covers and intake bolt arrangement; same basic head, late-model bolt-up.

 

If the lg4 heads are so much better were did the 20hp come from? The lo3 has 20hp more than a lg4. Could it be the roller cam setup and the fuel injection? Ive heard the lg4 heads can be milled alot. I can get a set of them for free but I think I would end up with to much compression. My motor has 9.6:1 with lo5 heads. Im not sure of they are shaved or not but something must be different,

 

The last year of the LG4 and the 1st year of the L03 had about the same HP.... the difference between the early LG4s and later, was the comprssion ratio; they went to flat-top pistons like the L69 had.

 

which engines did the 081 come out on. If I can find a decent set of heads that will work better than the swirl ports, I will get them..I just have to watch what I spend right now.

 

081s are 87-92 centerbolt 305 TPI heads

 

HO's also got electric radiator fan, knock sensor, and more aggressive PROM spark curve. '85-'87 LG4's got the electric fan and knock sensor (along with flat-top pistons).

 

The 081s came on 7 LG4s, 87 L69s in Monte Carlos, and 305 TPIs through 92.

 

The 416 heads are fundamentally the same as L98 heads, but the intake valve is only 1.84" versus the 1.94" on the L98.

Spend a few dollars on having the intakes widened to 1.94" and then take the time to port and polish what remains of the 416s (or 081s--same heads just different bolt pattern) and you will have a set of small block heads that rival Vortecs. It is almost ENTIRELY a matter of time. Not much money at all.

Follow the link at the end of my sig.

 

l69 (h.o.) had better exaust, higher compression pistons, same heads, dual snorkels on camaros only, better cam, different rods and hangers on the qjet, higher volume oil pump and put out 190hp at 4800rpms (highest rpm peak power in any v8 thirdgen) and 240ft/lbs at 3000rpm, redline at 6k, tach warn at 5.5k. Lo3's had more power (edit: than the lg4) because of partially the f.i. but mainly also it was a roller motor and had higher compression, the 87 lg4 had about the same power as the 88 Lo3 because in 87 the lg4 finally got higher compression and a roller cam

 

Thanks for the info guys. I am going to start looking for a set of 081 heads this week.

 

Even post that you want a set on the Classified board. Folks have them kicking around in the garage and will often just give them to you for the cost of shipping. A set from a junkyard should only cost $30 or $40. 601 castings work well, too, though they are the pre-87 style perimeter valve cover bolt setup like the 416s.

 

Thanks i just wanted to know because my budy and i are just about ready to put my 305HO in my 86 Firebird but we had to configure a lot of wiring because of the 2.8L that was originally in there. We put an Edelbrock Performer intake on it, new valve seals, new rod bearing, new double roller timing chain, new water pump, and headers. And a new 3" all the way back will be put on there right after everything is just right. Can anybody tell me what i might be running for HP's with all these upgrades from the original 190Hp?

 

I'd say around 240 or 250 hp. Heads and a cam would put you around 300.

 

thnx

 

Sorry i forgot we put a Crane Cam in it too my bad.

 

hey guys

what heads could be on my 88 lo3? the production date is 9/87

interesting?

where can i find the casting # on the heads. it's a sport coupe also

 

I think all TBI's got the swirl port heads.

 

if it is a tbi car then they are the swirl ports.

 

Sport coupes didn't come with the HO motor. Here's a pic of the badge that came on Z28s with that motor; there's a very similar one for Trans Ams (not regular Firebirds since it wasn't available). So, not to be a jerk to you, but you don't have a Firebird sport coupe HO, unless somebody has put a L69 motor in it since it was built. If your car didn't come with the badges, then it didn't come with the HO motor either.

As said before, the block, heads, and intake are the same between the LG4 (base 4-barrel) and the L69 (HO); the differences were compression for the first couple of years, exhaust all the way from the heads to the street, cam, carb, electric fan vs. clutch fan in the earlier years, the HO cars got 3.73 gears, and computer calibration.

 

On the TBI thing:

You're right, all the TBI motors got the swirl port heads. Casting # 193 IIRC.

9/87 would be a very typical production date for the 88 model year. 88 cars hit the dealers the first week of September 87; 88 model year production would have begun in June of 87. A motor built in 9/87 was probably installed into a car in about December 87, and probably arrived at a dealer in about Jan 88. Altogether pretty ordinary.

I would expect you to get around 250-260 HP out of the combo you describe for your 305 HO, if it is in fact a HO.

I shouldn't post stuff before my first cup of coffee. I overlook things.

 

Well I had bought a 83 Trans Am with the 305HO in it and thats what i worked on and am putting it in my 86 Sport Coupe right now so thats why i was wondering what kind of HP and Torque i will have with my 3.73 Posi Dics Brake rearend(which also came out of the 83) and my 305HO that i put new valve seals in, new crane cam, new edelbrock performer intake, new rod bearing, new double roller timing chain, carb kit for my Quadrajet, and Headers. So ya I was just wondering if anybody could throw out some numbers for me?

 

Gotcha...

I'll give you a ballpark figure. My car, 305 HO car (duh), 305 flat-top short block, nicely worked 186 double-hump heads (I know, but I had them laying around), XR264HR cam with 1.6 roller rockers, Edelbrock TES, every single piece of emissions and computer stuff hooked up and operating from when I lived in California; stock air cleaner, stock carb, stock intake, stock exhaust except a new cat and a Dynomax muffler, stock fan, ..... did I say stock enough times? ...., 214 RWHP and 282 RW ft lbs.

 

So this was for a Fuel Injected 305HO? And do you know what the Torque specs might be?

 

Forget the Fuel Injected part there read it wrong. And what do you mean by all the Computer stuff?

 

I mean EGR, AIR, EFE, all sensors and valves, basically every single emissions-related part. The entire stock carb and computer and all the stuff that goes with it is on there and operating.

How stock can something possibly look?

But that should give you a good idea of what does and doesn't cost HP... the stock carb and intake, for instance, aren't a restriction.

 

Ya see i don't have to worry about emissions in Alberta so a lot of what you have there wont be on my motor.

 

Do you have Disc brakes on your car?

 

RB83L69--I'm shocked!!!

Your aircleaner needs painting ... you should be ashamed of yourself

 

 

BTW RB.....Is that some kind of heater control valve that is sitting behind your ALT bracket???

I don't have one of those. Am I supposed to have one?

 

The car didn't come with the heater control valve. I had needed some part of the A/C control system at one time, and I ended up with the control head and harness out of a 90 or so car.... it has the provisions for shutting off coolant flow to the heater when not needed, so I hooked it up.

Yeah, my breather needs paint; whenever I find a new HO sticker for it, maybe I'll do that.... kind of low on the priority list though.

Yes, I have a rear with PBRs in the car now. Stock gears of course. It came with aluminum drums.

 

hey guys

I was at work and done some research on 305 heads. here are some casting #'s that i have found.

78-86- 416, 450

80-85- ho/efi 601

86-94 187, 081


out of these heads what ere the best for making power.

also on the swirl port heads can that ramp in the intake runner be
ground out to make it smooth or will it make the metal to thin around the push rod.

what is the best valve size combo for these engines

1.94/150 or 1.94/ 160 ?

 

BTW RB... My Air Cleaner looked about as bad as yours. I just masked over the decal and carefully exacto knifed around the decal, sanded and painted..

I'm on a quest to "save the dual snorkles" lol.