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Air loss through the barrel when installing M3 powerblock kit

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Enkey

Enkey

Member
Jun 14, 2015
854
46
Illes Balears, Spain
Hi
I have installed a powerblock on an M3.The M3 kit is reduced in the number of parts that compose it. I have to mount a new Valvehouse, Impact, Power Plenum part number fx 20671 in which the valve seat is included with a used part which is the valve part number fx 20275. The problem that causes me that combination of used part with new part is a small air leak, my intention is to rectify the valve and seat with the same technique that is used in the valves of the engines but before I would like to know your opinion or your experiences.
Regards
Enkey
 
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Work slow with mild abrasives and low pressure if mating the two surfaces together via lapping. I use toothpaste and work it by hand personally, some use a drill. I also lightly burnish by hand rather than drill as well, its more tedious and time consuming but if the surfaces are machined square enough, you really shouldn't need power tools to mate them together.
 
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Stubbers said:
Work slow with mild abrasives and low pressure if mating the two surfaces together via lapping. I use toothpaste and work it by hand personally, some use a drill. I also lightly burnish by hand rather than drill as well, its more tedious and time consuming but if the surfaces are machined square enough, you really shouldn't need power tools to mate them together.
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Hi Stubbers
I didn't know that toothpaste was a mild abrasive.
Thanks for the information.
 
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Lapping is most definitely a common way to deal with a leaking poppet / valve seat. Mild or aggressive abrasive as needed depending on the severity of the flaw. Color the mating surfaces with a black Sharpie or dye, then spin the surfaces together for a short time, and wipe it clean and view the surfaces with the aid of magnification. The low spot(s) will still have the marker. Continue lapping until all the marking is removed and you have a smooth, continuous ring of contact.
 
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N1neWivesSniper said:
I wonder if you have the old 20275, they increased the size of the poppet to help with these leaks, I bet I could tell if you have a picture.
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Hi
I finally disassembled my M3 and found the mystery of the air leak.

IMG_20230412_105515.jpg
IMG_20230412_074527.jpg
IMG_20230412_164021.jpg
IMG_20230412_161023.jpg
IMG_20230412_161608.jpg

Do any of you know the difference between these powerblock kits?
Fx 20845 and Fx 20825
Thanks
Regards
 
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N1neWivesSniper said:
The kit looks right, they started putting removable valve seats back into the plenum house and increased the poppet size.. Your kit looks like the updated parts.
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IMG_20230412_203434.jpg

If I buy a powerblock M3 kit and they have modified the valve seat size it should come with the valve corresponding to that modified seat.
These are my thoughts, Now I have two problems
 
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Hi guys

Fx has modified the valve seats on the M3 powerblock to be removable and larger diameter Fx 20671-1 and the valve is also larger diamerter Fx20860.
The valve fx 20860 is not included in the kit for M3, must be purchased separately
If you bought the new powerblock kit for M3 and you have an air leak through the barrel you need to buy the new valve as well.
Regards
Enkey
REMOVABLE VALVEHOUSE M3 FX20671-1
 
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