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screw in welsh plugs holden 6 block


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#1 turboman

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Posted 04 May 2016 - 04:34 PM

was wondering if you can get screw in welsh plugs in the size to suit a holden 6 block



#2 _Agent 34_

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Posted 04 May 2016 - 05:38 PM

Not to my knowledge ,

 

 

BUT i have seen a system where by the welsh plugs have been machined up out of flat plate aluminium and a " o ring put between the to mating surfaces. Then a nut on one side and a bolt running through the centre . pulling the two faces together then pushes out the O ring and seals against the block.

 

lot of mucking around - it has been done on a race engine - holden 6. 

 

G



#3 _Muzzy_

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Posted 04 May 2016 - 06:10 PM

I have replaced the front oil gallery welsh plug with 3/8BSP, never heard of water welsh plugs being tapped out,

#4 LC-GTR-1969

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Posted 04 May 2016 - 06:29 PM

No reason it could not be done but why? They are not that hard to get to seal properly as long as the mating surfaces havent been gouged with a flat blade when removing the plug.



#5 turboman

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Posted 04 May 2016 - 09:45 PM

cause if you run big boost/power and knowing how standard block moves around,,would save the standard welsh plugs popping out. and putting water under the wheels and putting car into the wall.



#6 _Bomber Watson_

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Posted 04 May 2016 - 09:52 PM

I dont believe that has ever happened.....



#7 RallyRed

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Posted 04 May 2016 - 10:02 PM

This is interestng.. but probably could fit into that area that lots of other stuff also fits into.. its a solution to a problem. But what is the problem?
Having said that..I do agree that sqeezing a pressed metal cup into a cast iron block..is a cheap and nasty solution. But hey....millions of engines later, gotta say it works. The pressure applied to them is only = to the radiator cap pressure? Corrosion the real issue.

#8 rodomo

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Posted 04 May 2016 - 10:08 PM

202's are known to crack through the welch plug holes under the manifold but I fail to see how screw in plugs would prevent this? :dontknow:



#9 _datpsi_

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Posted 04 May 2016 - 10:11 PM

A lot of nc guys run a strap down the side of the block just in case.. have tapped my front and rear ones as mentioned above.

#10 turboman

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Posted 04 May 2016 - 10:38 PM

same reason why they put screw in welsh plugs in clevo/chev blocks,to add strength to block.



#11 turboman

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Posted 04 May 2016 - 10:41 PM

and yes this does happen to holden 6 blocks as in popping welsh plugs out,im talking with turbo/blwn combos with big boost/power 500-600hp



#12 ozyozyozy

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Posted 04 May 2016 - 10:54 PM

It is not uncommon mod.
In severe applications the plugs can fall out.
I looked into this for a 308, ran into some issues.
Used to be able to buy a kit to do it, not anymore.
The screw in plugs are available but the correct size might be an issue and the tap for something that size is stupid expensive.
Otherwise a machinst with a cnc should be able to cut a thread but once again cost.

#13 N/A-PWR

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Posted 05 May 2016 - 12:07 AM

my motor's have only cracked between the welsh plugs vertically,

 

 but found this in the wiki:-

 

Quote - 'In some high-performance engines the core plugs are large diameter cast metal threaded' - end quote

https://en.wikipedia.../wiki/Core_plug



#14 _Agent 34_

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Posted 05 May 2016 - 05:24 PM

A lot of nc guys run a strap down the side of the block just in case.. have tapped my front and rear ones as mentioned above.

 

Dan any more details on the welsh plugs and where you got them done ?

cost photos etc



#15 _datpsi_

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Posted 05 May 2016 - 11:14 PM

Can't remember the size grant buy just drilled and tapped either npt or bsp thread, allen head grub screws. You will need to slightly file the cam retaining plate for clearance. Then down side of the block we drilled and tapped small thread and ran a strap covering all the plugs.. will try find pic next week one this weekends finished up

#16 _duggan208_

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Posted 05 May 2016 - 11:58 PM

I've wondered that if you had taped solid welsh plugs might add some strength to the block especially were they like to crack. Maybe even machine the block and bolt on a steel brace over the welsh plugs.

Regards






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