Fast twitching vacuum reading on my engine... - 460 Ford Forum
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post #1 of 4 (permalink) Old 05-15-2019, 11:08 PM Thread Starter
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Fast twitching vacuum reading on my engine...

Hi,

I have a '69 429, with a stock block, heads and internals. This is the K-code (2bbl 10.5:1) engine. I am running the Weiand stealth intake, with a MSD Atomic throttle body. I have a fast twitching vacuum reading (twitching from 18 to 18-3/4) This is happening at idle and at higher rpm. A compression test showed 175-185lbs at cranking across all cylinders.

When I got the car I had two bent push rods and one of the valves were frozen shut. I had to soak that for a couple of days to get it running freely.

Video of the vacuum gauge/test. https://youtu.be/4PzHeXErJ78

Any thoughts/ideas?

Thanks,

Mark

Last edited by D-train; 05-15-2019 at 11:18 PM.
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post #2 of 4 (permalink) Old 05-16-2019, 08:27 AM
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Looks good to me.
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post #3 of 4 (permalink) Old 05-16-2019, 01:04 PM
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Cool

Reading should be rock steady however given the age and condition you could have weak valve springs / sticky valve(s) or a valve that is not seating completely. Not the end of the world.


Take a look here:


https://www.gregsengine.com/using-a-vacuum-gauge.html



SJ
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post #4 of 4 (permalink) Old 05-17-2019, 11:24 PM Thread Starter
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I was thinking weak valve springs ( I thought that I put that in the initial post, but apparently not) I was going to run a leakdown test and see if I am getting anything past the valves. I wanted to get thru this summer season with a cleaner exhaust... If I replace the springs, can I go with the Melling VS840's ? ...or the Sealed Power VS703's?

Thanks!

Mark
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