so i have a 1984 chevy k20 with a 350 cid eng and a 700r4 trans. the problem is that it wont rev passed 2200 rpm when in 2nd 3rd and 4th gear it will rev to 6000 in 1st and neutral/park i cant seem to find the problem… there is no computer or ecu and its a bone stock 350 carb crate motor please if you can help that would be great
I just have one question…why on earth would you rev an engine to 6 grand in 1st gear or neutral? My reference material indicates an ECC (Engine Control Computer) for your truck. The ECC may have a “rev limiting” function when it’s over revved so you may be causing the problem yourself.
All vehicles from about 1981 up have an engine management computer. Are you saying that the one on your truck has been removed and the engine replaced by one that does not use computer controls?
Have you checked the fuel flow volume? I think this is a one ton vehicle and don’t know if they were subject to the car requirements in 1984.
Check the accelerator pump in the carburetor.
The fuel system in your truck was never designed to use ethanol blended gasoline. The ethanol can damage rubber components in the carburetor. And one of those rubber components is the accelerator pump.
So the engine will rev when little or no power is demanded from it. But as the truck shifts up thru the gears and more power is required from the engine, if the accelerator pump doesn’t introduce enough gas into the engine, the RPM’s are only going to go so high.
Tester
When you step on the accelerator does the engine hesitate and stumble or does it come up to 2200 rpm quickly and smoothly and then top out at 2200 rpm?
when it gets to 2200 rpm it wont go passed it, its like a wall its not like hitting a rev limiter where it kicks back or strains to go pass it like an electric motor set to 2200 rpm in 2nd 3rd and 4th gear… 1st gear will go to the rev limiter
If you continue to rev the engine to 6000 rpm in neutral and 1st…you won’t need to worry about it for long. You’ll destroy the engine and you’ll be looking for a new vehicle.
As far as the other gears, I think you need a mechanic capable of performing a few tests on the fuel delivery system.
Yosemite
I go along with the theory of a fuel delivery problem.
When an engine revs free without a load and tops out way early when under load, it’s a good sign that it cannot get enough fuel to keep it’s power up beyond the revs that it poops out at. An engine under load needs a lot more fuel than an engine revving freely.
It’s also possible that it can’t breath freely due to a valve issue (timing or whatever) or a restriction in the intake system or the exhaust system. This apparently being a modified vehicle, you need to figure out the needs of the new motor in these areas: fuel needs and breathing needs. The engine might be a “bone stock” configuration, but of the fuel delivery and exhaust were designed for a different motor, well, you need to look at these issues.
By the way, although I mentioned a valve issue, I’m inclined to dismiss it because that would normally cause problems without load too, but the reality is that an engine under load has to move more volume, so it’s something to keep in mind.
Still no info on carburetion, how much if any of the emission stuff is still in place, and whether or not the ECM is still trying to do something or if it’s buried in a landfill somewhere.
There’s a number of theories from a clogged converter to an errant vacuum line incorrectly routed and possibly causing a carburetor flap to close when the pedal is nailed, etc, etc, etc.