Take a look at this video and fire away at your comments. I have never seen one do this before as far as a very small fluctuation between two very close inches of mercury (19 and 20). The vibration is gone from before the carb rebuild, but I wonder what gives? 4 of the 8 plugs I removed were fuel/carbon fouled, the other 4 were just fine. Cylinder #5 does show a much lower exhaust temperature at the manifold exit than all of the other exhaust ports. (used an infrared thermometer) But I don't know if that is because #5 is so close to the radiator cooling fan or what.

https://vimeo.com/331574496

and here is a link to another video I made concerning exhaust temperatures:
https://vimeo.com/331576377
<iframe src="https://player.vimeo.com/video/331576377" width="640" height="360" frameborder="0" allow="autoplay; fullscreen" allowfullscreen></iframe>
<p><a href="https://vimeo.com/331576377">1955 Ford Fairlane 292 Ford Exhaust Port Temperature Readings</a> from <a href="https://vimeo.com/user66981451">Daniel Jessup</a> on <a href="https://vimeo.com">Vimeo</a>.</p>




Daniel Jessup

Lancaster, California

aka "The Hot Rod Reverend"
check out the 1955 Ford Fairlane build at www.hotrodreverend.com

I would suspect that the flutter in the vac gage is caused by an intake valve bouncing or leaking back into the manifold.

Frank/Rebop

Bristol, In ( by Elkhart) 

Hi, Daniel, try a valve adjustment, this was the problem for me in the past, watch for a worn spot on the face of the rocker (dip from the valve stem).




! HE IS RISEN ! 

My Vote is for leaking Valve or Valve Adjustment. It looks like the same regular repeating Pattern caused by One Cylinder.

  

you guys are leading me in the right direction... I checked secondchance garage and they had a nice adobe flash display of different vacuum gauge scenarios. The scenario they showed that came very close to matching my reading was indeed indicating a valve not closing all the way. Almost a valve overlap it said. Which would make sense. When I removed the spark plug from #5, it was the worst, almost 3 times worse, than all of the others. It is the one in the video where the tip had just about "welded" to the electrode. Cylinder 5 was also the one that had the least amount of heat when compared to all other cylinders exhaust temps.

Next time I am in the garage I will take the valve cover off and check #5 intake and see where we are at. I did adjust the valves before I put the engine back in the car, so who knows? I may have adjusted #5 intake too tight... If it is not #5 then I will do a compression check on all cylinders. Last time I did this I was at 155 for all 8, with very little variance from that number. That was some time ago however.

I will let you know how it turns out. Thanks for the advice guys. 

Daniel Jessup

Lancaster, California

aka "The Hot Rod Reverend"
check out the 1955 Ford Fairlane build at www.hotrodreverend.com

Look at the tech article by Walt Knuckles. http://www.y-blocksforever.com/tech/html/valvelash.html 
He explains a way of adjusting the valves without a feeler gauge. This allows for wear on the valve stem and rockers and gets a truer setting. 


Y's guys rule!
Looking for McCullouch VS57 brackets and parts. Also looking for 28 Chrysler series 72 parts. And early Hemi parts.

MoonShadow, 292 w/McCulloch, 28 Chrysler Roadster, 354 Hemi)
Manchester, New Hampshire

I have used His System several Times. Pretty Accurate.

  

And you guys were spot on! When has this forum ever failed me? 

#5 valve lash on the intake was only .010 and the exhaust valve was OPEN at TDC just a hair. Duh. 

Video to show results on the vacuum gauge!
https://vimeo.com/331877284

thanks again fellas!!!

Daniel Jessup

Lancaster, California

aka "The Hot Rod Reverend"
check out the 1955 Ford Fairlane build at www.hotrodreverend.com