compression??

[Legendcar78 NJ]

So i checked my compression on my 1219 conversion engine,  i checked it while it was cold with no carbs on the engine. My numbers were 155, 160, 125, and 175, my concern is the low cylinder number 3. Now i no the engine wasnt warm when i checked and is suppose to be, do you guys think my cylinder 3 will come up when warm. id warm up my engine and check but my carbs are out being rebuilt. Im sure im just being overly worried but just want some oppions. I used a matco guage. Also the engine only has one race on it since rebuild and dyno. Thanks in advance

[Legends57x]

I just went thru the same exact scenario on my sealed 1250 engine last week and checked it both cold with no carbs and then hot with carbs, throttle wide open.  You can add approximately 10-15 PSI to your cold readings to get approx. hot compression readings.  One thing I would highly recommend would be to check your valve lash first, especially on low cylinder.  Remember .004-.006" intake lash and .006-.008" exhaust lash.  The cylinder the compression is low on could have a tight valve causing the low reading.

Good luck!  

[amp racing]

any time I have a question with low compression I do a cylinder leak test...

[Legendcar78 NJ]

Ya thats what i was thinking valve adjustment, i also performed leak down test with cylinder 3 at tdc on compression stroke and dint hear any air leaking so im pretty sure it could be vlave adjustment needed or just cause its cold, or even my guage idk. Thanks for the replys!

[Gimpster]

Hearing leak down ?? Might be surprised if you use the proper leak down gauge set and procedure..

[Legendcar78 NJ]

Ya you put air to the cylinder when its at tdc on the compression stroke so you no all your valves are closed, if you see guage going down , or hear air leaking through exhaust you no its an exhaust valve, if you hear air from intake its obviosly an intake valve giving you the issue.  Im pretty sure thats correct , i may be wrong.

[Legends57x]

BTW - Keep us posted on what you find.

[amp racing]

roll the cams til all the valves are closed..10 percent is my limit of concern....

joe

[Legendcar78 NJ]

 My carbs should be in next week sometime, so im gonna warm engine up and then try another compression test. Thanks for the replys il keep you guys posted! really hoping everything is fine being engine was just rebuilt 1 race ago