jotto

Hi all.

Took the Vette out for a blast over the weekend and she didnt seem to have any get up and go at the higher end. At first I thought I was trying to push too hard too early thinking the secondaries were locked out due to low engine temps but even towards the end of the run, she didnt have any high end get up and go.

Car is an 81 4sp manual. Crate engine, HEI tach and standard Q-jet. CCC not connected.

I wont have access to the car for a couple of weeks due to work but want to work through it in a methodical manner when I do get to her so am looking for some input.

Pretty sure the timing is correct and curve is good. 36 degrees all in by about 2800rpm IIRC.
Have a new set of plug wires fitted. Have a set of plugs ready to fit.

Engine starts very easily even after standing for several weeks and runs very smoothly. Need to double check idle speed as tach is registering around 1000rpm when warm but not sure how accurate it is. Will pick up my digital multi meter/tach to check. Throttle response is great when getting in to her gently, just falls flat at higher rpm/speed. Planting the loud pedal she picks up fine and doesnt hesitate but again,just falls flat on her face.

My thoughts are possibly secondaries not opening correctly or fuel starvation. New fuel filter was fitted a few months ago and old one was clean. Not sure if the 81 has a sock in the tank?

If it was the accelerator pump, I would expect a hesitation and then for it to pick up. I have no hesitation as such but it just doesnt pick up.

I have a camera that has a flexible neck that I could rig up to see if the secondaries are opening and will be picking it up on my way home.

What do you guys think I should be checking?
After the basics, will check valve lash etc and hope the cam isnt going south. ( good excuse for a rebuild! )

mr303

From what you describe it sounds like the secondary metering side is at fault. Timing, accelerator pump, idle mix would show as rough running or miss fires during light and heavy acceleration, which you say is good. Fuel starvation could be an issue after a period of heavy acceleration, does it run OK at a fast cruise speed?

jotto

Thanks for the input. Secondaries or fuel starvation is what I am leaning towards.

Surfer69

I remember having a bad coil do that to me. Took a while to figure out. My 0.02

jotto

Something to think about. The distributor was new and has less than 1000 miles on it. Hoping it wouldnt have gone bad that quickly! lol.

BKbroiler

The most likely problem here is that the secondaries are not opening, as others have said. Make sure your choke disengages completely allowing them to open.