Hello All,

Thank you for allowing me to join. Purchased this 85 Trans Am a month ago. VIN number tells me the engine is a LG4 305. However on the side of the car it calls out 5.0 HO. Is there such a thing? As stated, its new to me and I'm having fun driving it. Just looking for some clarification...kind of my curiosity. Not 100% sure long term what I will do with it outside of enjoy it.

Thanks!

 

Hi BG Hawks, Welcome to TGO and congrats on buying such a nice looking Trans Am !

I'm sure someone will be along who knows the engine codes, if not, asking in the "History/Originality" section may turn up the answer.

 

My Camaro has SPID sticker in center counsel bottom of lid. It has a vin number that matches vin. It has the L69 code that is for the 5.0 HO engine. My vin also has G in it which is for the HO.

 

The 8th digit of the VIN would be H for the LG4 305 or G for the L69 305HO.

Both motors were available in 85’, however the L69 was only available with a 5-speed manual in 85’.

If your VIN is H, then someone put the 5.0 HO decals on there at some point.

 

Thanks all. My thought someone stuck the HO decal on it...still having fun driving!!

 

The HO motor (my car is a 83 one, a Z28) was "rated" at 190 HP, while the LG4 (regular 305) had a 145 HP "rating". Factory "ratings" aren't particularly reliable, in terms of take it to the dyno and that's what you'll get; but that'll give you a pretty good idea. In reality the HOP motor would do closer to 205 - 210 if you fed it REALLY GOOD premium, because its timing curve was so much more aggressive (i.e. more nearly correct and less emissions dominated). The HO would have still had about 25% more power even on regular gas. Which of course is YYYYUUUUUUUUUJJJJJJJJE: it's like the difference between a 300 CID motor and a 375 CID one, with all else equal. When the 82 Camaro came out, and I first saw a pace car, I damn near FILLED THE CUP driving down the road. I was floored. Then I went and drove one... it SUCKED. I had a 79 Z28 4-spd at the time, and though the 82 car was altogether better as a car, the motor was underwhelming. Then the L69's anticipated introduction was announced; I COULD NOT WAIT to get my hands on one. It did not disappoint. It would HUMILIATE my 79 in every way. In fact one of the in-stock cars at local stealerships I was looking at, at the same time, was a Recaro T/A; but it only had the LG4. Beautiful car: black/gold like yours, except with the tan interior. Totally nice except for the motor. I kept looking.

One thing you will learn IN SPADES as you deal with old cars like these: STICKERZZZZZZZ!!!!! are much cheeeeper than parts.

 

Had determined the stickers were for show but wanted to run it passed the experts. Thanks!

 

Back when these cars were everywhere, lots of people thought their 305 4bbl was a 305HO, but most were LG4's. This got even worse when repaints started to happen and the decal kits came with the HO decals.

 

Got it. Someday the repaint will come and the decals go away.

 

Looks like a nice car anyway. Nothing wrong with an LG4. It’s a solid, reliable motor and it does respond well to intake/exhaust/tuning if you so desire.

 

Would fuel economy suffer from this?

 

Better flowing air intake and exhaust and bumping the ignition timing will not hurt and will probably help gas mileage. However, bumping up ignition timing will require 91 or higher octane fuel.

 

Not necessarily, in a 8.5:1 (AT BEST) 85 LG4. That's a pretty regular-friendly platform no matter how much timing you give it.

 

85’ and later LG4’s were 9.5:1, same as the L69 & LB9.

 

I guess I would be filling up with 95 anyway since over here in The Netherlands that's the only gass without ethanol. We have 92 also but that's 10% ethanol.