83 Caprice Top speed limiter

[bhw33191]

So is this what the ECM controls? If so i'm really interested in trying to modify it if thats possible? I hear people commonly do this so whats required? Can't i change the spark timing and things like that? (as primitive as the computer is in this thing?) I'm an adept computer guy and i know the ECM on this car isnt that complex so i figured i'd ask about it.

[j cAT]

Originally Posted by bhw33191

So is this what the ECM controls? If so i'm really interested in trying to modify it if thats possible? I hear people commonly do this so whats required? Can't i change the spark timing and things like that? (as primitive as the computer is in this thing?) I'm an adept computer guy and i know the ECM on this car isnt that complex so i figured i'd ask about it.

your speedometer goes up to 85MPH correct ?
this I believe is the programed speed limit..I'm not sure you can replace the EPROM on this with the instructions to go higher...

this vehicle should not be going above 85MPH anyway...not designed or with the proper componets to handle above this speed..

the distributor can be adjusted but why ? if you advance or retard the timing even 1 to 2 degrees it will run poorly..

If you want to work on things like what your mentioning here , get a pre 1975 vehicle ...lots of regular maintenence engine adjustments which I surely do not miss doing..


hows the 350 cu coming along ?

[bhw33191]

Originally Posted by j cAT

your speedometer goes up to 85MPH correct ?
this I believe is the programed speed limit..I'm not sure you can replace the EPROM on this with the instructions to go higher...

this vehicle should not be going above 85MPH anyway...not designed or with the proper componets to handle above this speed..

the distributor can be adjusted but why ? if you advance or retard the timing even 1 to 2 degrees it will run poorly..

If you want to work on things like what your mentioning here , get a pre 1975 vehicle ...lots of regular maintenence engine adjustments which I surely do not miss doing..


hows the 350 cu coming along ?

Yeah times better spent on my 350. I'm still in the process of cleaning it up but it looks like a great motor. Just waiting for some good weather to scrub the engine down outside (after i cover all the delicates of course). But after that its ready to go in.

Only thing is i dont know what to do about the exhaust manifolds. I figure while i'm swapping this thing in i'll get dual exhaust put on it, but i dont know if i should upgrade the stock manifolds to something else?

[j cAT]

Originally Posted by bhw33191

Yeah times better spent on my 350. I'm still in the process of cleaning it up but it looks like a great motor. Just waiting for some good weather to scrub the engine down outside (after i cover all the delicates of course). But after that its ready to go in.

Only thing is i dont know what to do about the exhaust manifolds. I figure while i'm swapping this thing in i'll get dual exhaust put on it, but i dont know if i should upgrade the stock manifolds to something else?

I would go to lou's custom exhaust and see what he says...this is in reading RT28...they do alot of these...headers ?

with what ever you do with the exhaust make sure they don't weld it together as ONE piece...if you need to drop tranny or whatever you are screwed...they like the one piece ..

[silicon212]

Originally Posted by bhw33191

So is this what the ECM controls? If so i'm really interested in trying to modify it if thats possible? I hear people commonly do this so whats required? Can't i change the spark timing and things like that? (as primitive as the computer is in this thing?) I'm an adept computer guy and i know the ECM on this car isnt that complex so i figured i'd ask about it.

There is no top speed limiting in these cars.

[96capricemgr]

http://www.tunercat.com/index.html
He has a LOT of the GM stuff covered. Take a look around.

That is what I use to tune my car, tho according to the dimwitt jcat I have probably just screwed everything up doing so.

I would be surprised if an 83 had a speed limiter though. I had boxies before the current pair of a 94 wagon and the 96 sedan, never played with them much though, just transportation.

[j cAT]

Originally Posted by 96capricemgr

http://www.tunercat.com/index.html
He has a LOT of the GM stuff covered. Take a look around.

That is what I use to tune my car, tho according to the dimwitt jcat I have probably just screwed everything up doing so.

I would be surprised if an 83 had a speed limiter though. I had boxies before the current pair of a 94 wagon and the 96 sedan, never played with them much though, just transportation.

you are not very good with these early 80's vehicles .
yes they had speed limiters ...now I believe they cannot be tuned /adjusted..I guess if you send out the computer to be altered anything is possible...

with your vehicles thats your business what you do to them ...

your drive train is only as good as the weakest link...

[caffeineaholic]

Whether or not they have a speed limiter (governor?) I know that my '85 Caprice goes over 85 -- perhaps to 100mph maybe? (never put it on a dyno) Just my

[Blue Bowtie]

Your 1983 CARBURETED engine does not have a fuel cutoff MPH parameter which does anything. The ECM has no control over fuel delivery to the carburetor, and only operates the MC solenoid and affects the ignition advance. Later (about 1984) ECMs controlling CFI, TBI, TPI, and SFI engines used speed limiters to cut off injector pulses anywhere from 98 MPH on some truck to 118 MPH on a lot of passenger cars to 254 MPH on others. Some trucks were limited to 94 MPH for safety, and most passenger cars were limited depending upon the speed rating of the tires originally shipped with the vehicle. Since several cars had "Z" rated tires from the factory, the fuel cutoff parameter was usually set to the maximum value of 254. Obviously, none of them could attain anything near that speed and were considered "drag limited" vehicles due to aerodynamic pressure.

You can load up a free editor such as TunerPro, load the correct mask (TDF) file, then read the binary (BIN) file for your vehicle to see if I am misleading you.

[silicon212]

Originally Posted by j cAT

you are not very good with these early 80's vehicles .
yes they had speed limiters ...now I believe they cannot be tuned /adjusted..I guess if you send out the computer to be altered anything is possible...

with your vehicles thats your business what you do to them ...

your drive train is only as good as the weakest link...

You can't speed govern a car with a carburetor.

[96capricemgr]

Originally Posted by j cAT

you are not very good with these early 80's vehicles .
yes they had speed limiters ...now I believe they cannot be tuned /adjusted..I guess if you send out the computer to be altered anything is possible...

with your vehicles thats your business what you do to them ...

your drive train is only as good as the weakest link...

Stock drivetrains are usually pretty tough and speed wont hurt them torque can but not speed.

The 90s cars the driveshaft had a critical speed that worked out to like 158mph on the Impala SS so the car was governed to 154mph. Even if the 80s driveshaft was a smaller diameter it couldn't be much and it is roughly the same length so critical speed would not be that much lower and would still be above what the vehicle could attain. Meaning the drivetrain would have no meaningful weakness in this discussion.

Heck the 90s cars one guy was running 9s at over 140mph at 4500lbs before he had driveshaft troubles. I think he was a little nutty for pushing it that far but it is interesting to see just what lowly "stock" parts can handle and it is a LOT more than most people want to give them credit for.

Yes I understand I am talking 90s stuff but these cars actually share a surprising amount.

I owned a 84 and 85 Caprice when I bought my 96 10 years ago and before that had a 82 Delta 88 so I HAVE been around the boxies a little bit.