'77 vacuum test

[Rupesy]

I performed a vacuum test from one of the fitting on the manifold below the carb. I got a minimum of 15 psi, but the gauge was fluttering non-stop between 15 and 18 psi. Is that normal?

All the other times I have done a vacuum test on all my other cars, it seems to be fairly constant.

The engine is missing a little bit at idle and I have to keep the idle at around 1100-1500. I have been working through many issues and decided to see what the vacuum looked like. I still don't think it should flutter like that.

New coil, points, plugs, plug wires, distributor bearings. I did rebuild the carb. No amount of twisting or turning of anything that can be adjusted smooths it out.

I did spray starter fluid all around the carb and manifold it doesn't appear that there are any leaks.

Any thoughts on the vacuum?

[Dombrockt]

Should tell you what you need to know:

http://classicinlines.com/vacuum.asp

[Rupesy]

Thanks.....and yuk!

[majicwrench]

Vacuum not measured in PSI, but we get the idea. Rapidly fluctuating/fluttering vacuum is bad new, usually engine mechanical. That said, a vacuum gauge is the last thing I use to fix cars that are not running correctly.
Compression test in order.

Good luck,
Keith

[Rupesy]

Sorry, had psi on the brain. Should be In. Hg.

I did a compression test a couple weeks ago:

#1 - 125
#2 - 135
#3 - 135
#4 - 120

those are psi! LOL