Ok I am working on my 1986 Trans Am and am having some trouble. The engine numbers match the VIN which should make it a LG4, but it does not run like any 305 i have ever had. The car is capable of running down the road at 80mph while only turning 1750rpm and will hit 160mph at 3800rpm. I don't know if it was modified before i bought it but it doesn't appear to have been. Can someone plz give me an idea of how this thing is doing what it does??

 

Are your speedo and tacho reading correct?

 

How do you get 160mph when the highest guage available was 145mph?

And where does one get to go that fast?

 

Yes my tach and speedo work fine. I have had it that fast in PA and along I-81 through VA. Also I am using aftermarket tach and speedo, and cops radar nailed me for a $3,800 fine and loss my liscence for 4yrs

 

well just cause car will go fast does NOT mean it is powerful. But not to debunk you, the power needed to travel at that speed you probably don't have anyway. Also, what transmission are you running, what tire size and gear. Assuming that you have whatever transmission in overdrive with a ratio close to .63 (in a T5) which is kinda tall and roughly a 26 inch tall tire, you would need something like a 2.73 gear to make it hit 160mph turning roughly that rpm.

Now, using the same numbers and according to your signature you have a 700r4 in it. A typical 700r4 will not run wide open in overdrive, so you will probably were in third which is one to one ratio, which means you were only going 110, which is way more likely and your speedo is off.
You could hit 160 in overdrive with an auto, wide open, with 2.73 gears, but not likely with that motor. It is possible that someone swaped your motor, or did some mods, but you said the number on motor are correct to car. so with the 165hp or whatever lg4, no way, you would need a long straight downhill road with a tailwind, and someone pushing...110mph is way more likely. I believe you would run out of hp before running out of gear.

I have pushed my car to 150 or 155, and it was a push, and I have built car, and way more than double your hp and multiple chasis mods to support car at high speed.

your speedo is off or your telling fish tales.

 

I had my 2000 SS at 150mph in 5th gear and more left in it on the turnpike here in Pa, I know an lg4 305 would def not do that. It was a very stupid move and i will not do that again.

 

The transmission is a 700R4. The tires are 250/45R16s. The gearing in rearend is unknown because the numbers on the axle tube are gone. So short of tearing the rear apart which i don't want to do since it is not having trouble i am not sure how to figure out the gearing. I also fail to see the need for the 750-800cfm carb on top of a 305, seems like an awful lot of carb for such an engine. And yes i have checked the numbers on the carb so i know what it is without a doubt.

 

Doesn't your profile indicate that it, as well as your truck, has a 350? So??

 

Jack car up , out of gear.
Put chalk mark on driveshaft and wheel ;count how many times the wheel has to go around to get one turn of the driveshaft.
That will give you ballpark rear end gearing

 

Thirdgen88, I have 2 1986 T/As or, should say had 2. A storm last winter brought down the building the 350 powered T/A was in. Unfortunately the car was totaled, I may try and rebuild it but i doubt it. The one I am currently working on is stock as far as I know. I had bought it originally to restore and show but now I need it for an everyday driver. I have checked the rear and it appears to be somewhere in the 2.7 range so I am guessing 2.73 as that is the closest gear set to my count that came factory.

 

$3800 fine.....so you got a felony??? a misdamenor is limited to a max of 1 year jail and 1,000 dollar fine, anything higher is a felony conviction. A regular infraction carries a fine usually under 500 dollars....so what did they charge you with??

 

He's full of ****, let it go.

 

Hey six, this is EXACTLY the reason why I stopped visiting other forums. Too many neon light/muffler tip/gangsta wannabe's.............

I guess if they nailed him on SEVERAL charges, it could have added up to 3800...or he might be referring to his lawyer fees...either way...how do you loose your driving privileges for 4 years? The worst Ive heard of is 1 year....and trust me, I deal with this kind of stuff daily......

Regardless....Im not gonna rip ona guy I dont know because heaven knows Id love to do that kind of speed. The simple fact of the matter is that a LG4 will NOT do 160....and a older 350 is stretching to make that kind of speed......Im thinking Nemisis had 1 of 2 things happen....

1) a cop screwed him and wrote him a ticket for 160. (Not likely, as anything over 100 mph involves reckless driving charges, towing, citations, court appearances and generally way too much work for a cop

or 2...

2) Nemisis got a bunch of ticket for lots of little **** and is 'assuming' his 160 speed based on conversation with the cop.......IE cop says "Son, you were doing like 160, heres all yer tickets....yee haw......"....

 

I have a friend who lost his liscence for ten years, but I can promise that involved drugs and proabably some serious misconduct. He just got it back last year.


There was a guy who got a ticket for over 200 MPH last year on a bike based on how quickly the chopper clocked his passing one mile marker then the next, it was nothing to get that reduced or expunged because of the uncertainty involved.

What I simply dont buy is the 160 at 3800, cop LT1's top out at about 150-160 and thats with the 60E running in OD and the engine reving well past 4G.