hey..this isn't really a tech question but i need some people to help me figure this out...i have an 85 trans am 305 5 speed, the vin number says it's an LG4, but it's running low to mid 15's completely stock, except exhaust, i know that's not fast but that's right around what L69's run correct? and the motor feels much stronger than a few of my friends with Lg4's, one of them has an 86 ta Lg4 and the valves float at around 4400 rpm...and it's very slow! i can take it past 5000 easy. there were 2 owners before me and the last owner says nothing at all was done to the car, it's totally stock! another thing is the car has 4 wheel disc's..i know they were an option on ta's but i thought it wasn't on an Lg4 car..it does say "performance suspension" on the dash too, does that have to mean the car is a WS6?? it does have the larger sway bars, but 15 inch rims. so it bascially has everything that a Ws6 car as with the exception of the 16 inch rims. also i forget the rpm, but in 5th, the rpms match up with 3.73's, the lg4 came with 3.23's, and the L69 with 3.73's. i'm really confused...is there anyway GM just totally screwed up the car, the rpo codes, vin, ect...if anyone could help me figure this mess out i'd appreciate it thanks a lot!

 

what is the 8th letter in the vin??? if its an H then its the lg4... if its a G then its a L69... other than that you should do some research on the rpo codes for the car (usually located in the center console)... that will give you most of your answers... I think there is an rpo decoder on this board (I had to figure mine out the hard way)...

zroc

 

no that's what i mean, the vin says the car is an LG4, with non of the options i've stated above. my question is, is there anyway possible that GM just totally screwed it up, maybe they gave the car the wrong RPO codes, or was there a shortage in LG4 parts in 85? just asking if anyone knows...thanks

 

Or perhaps the owner before you did some work to it.

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89 iroc-z 305 tbi
k&n filtercharger, open element air filter. nuffin' else

 

You said in 5th the rpm's match that of 3:73's, with a stick you should be in 4th to match rpm's.

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'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
3:73 Posi
Rebuilt 700R4
B&M Megashifter, 5" Autometer Tach w/shift lite

 

yah 4th gear is a 1;1 ratio. check your rpm then. assuming that you have the correct vin #. as far as the engine is concerned all someone had to do was swap in a L69 cam. the heads and compression are the same between the 2 engines. i think the L69 had a different intake manifold than the LG4 too. if you really do have 3.73s, disc brakes. you should have the fat sway bars and beefy springs of a ws6 too. it doesn't suprise me that you have 15 in rims. 85 z28s did. keep in mind that teh base engine for the TA was the LG4. there are alot of LG4 IROC cars too. so it may have the hotrod suspension and the sucky LG4.

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86 IROC-Z
305 TPI
700R4 W/ shift kit
3.23 gears
T-Tops
maroon with gold stickers and rims/ black interior
43,000 miles
flowmaster exhaust, edelbrock headers, gutted airbox, converter, and MAF, K&N filters.

soon to come are 3.73 gears and subframe connecters.

[This message has been edited by FlameRedMetallic (edited September 17, 2001).]

[This message has been edited by FlameRedMetallic (edited September 17, 2001).]