| benchracer1 |
Thu Sep 25, 2014 8:33 pm |
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| Just stuck a pair of of freshly fly cut heads on a 1600 dp. I put 80 psi of air and got a few bubbles between the head and cylinder. 8mm studs sequence tightened to 18 labs. Do those tend to seal up? Does anybody have any tricks to seal those? I've never checked this on a build before. Kinda wish I didn't check it. Probably would have never known. Maybe loosen and retorque? |
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| bugguy1967 |
Thu Sep 25, 2014 9:23 pm |
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| Pull the head off and put a straight edge across the two cylinders. See if they're even first. Also check both mating surfaces. |
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| HRVW |
Thu Sep 25, 2014 10:50 pm |
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:idea: As an engine builder I would slap the heads on making a noise when they hit the cyls. This was w/o any push tubes.
Would also make sure the cyl fins was NOT hitting the head due to excessive material being cut when the flycutting/valve job was done. Does happen depending on who rebuilds the heads or what machine shop did the job.
My supplier always gave me good heads for my engines.
After you torque the heads to the 18 ft/lbs turn the engine over by hand using a wrench on the pully bolt and with the other hand stick a finger or thumb over the spk plug hole and hear a loud POP...compression should be okay now.
Install the rocker arms and adjust the valves. |
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| benchracer1 |
Fri Sep 26, 2014 6:24 am |
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| plenty of space between heads and fins. Its just one out of 4 leaking. kinda seems like the minute it warms up it would probably take care of itself. I may pull that head and give it a quick lap with an old cylinder and valve lapping compound |
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| HRVW |
Mon Sep 29, 2014 12:17 pm |
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:idea: One thing that many do not recognize is the seating of the cyls on the case. Every so often one seat might have a wear of cyl pounding that will allow some clearance (daylite) if you will between the head and the cyl allowing a slight wiff of air escape and then thinking that heat expansion will seal....not even close.
What I had done in the past was use those 1600cc paper gskts for a sealer in a stock engine (2-3) would work and thus eliminate that air ? leaking.
Just a thought. |
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| benchracer1 |
Thu Oct 02, 2014 5:23 am |
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| lapped the head with an old barrel and valve grinding compound. leak persisted. finally pulled the cylinder and surfaced the top of the barrel on a surface plate. that took care of it. what a pain in the asss |
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