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Richard71

Cyl Head Mods

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I don't have a standard untouched cylinder head to compare with, so can anyone confirm if the combustions chambers in the attached pic have been re-shaped?

post-6267-0-79981100-1511719431_thumb.jpg

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its been modded, as the plug side ridges ev gon awol

Note, unless its been shaved, it,ll ne down on CR as opposed to an OE,n

 

Only realistic way to check is t,burette the chambers to find oot

just hoo much CCs are needed t,fill them up

 

 

 

M

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Thanks for the replies, it's the "re-shaped" combustion chambers I'm interested in, I know it's been skimmed, ported & polished, what in addition to GT6M's observation has been done to theses chambers that can be seen with the naked eye?



Richard.


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+2 Has been modded. What do the ports look like, has the casting roughness gone as per the tops of the combustion chambers? What do the valve seats look like?

 

Bruce.

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Richard

 

Side-by-side comparison with a 219019 casting. This one is skimmed and measured at just over 9:1 (the crease in the combustion chamber touches the face approx 2/3 across the water way - red line). Shape looks pretty similar, though.

 

Paul

 

post-12218-0-73699300-1511727386_thumb.jpg

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Having a good look at that pic, like 400X zoom,

it looks like the margin es gon between the seats.

 

Compare area between seats on the 2 pics Paul bunged up

on his, ye can see heed matterial,

on your, it cannae be seen

 

And, cant see any evidence of an insert

Which means that valve had pocketed, and been cut back,

hence having to bung in a bigger valve

 

Has all chambers got same valves, and been cut the same

cutting ex valves too wide { Not too deep, 2 totally diff things, depth an width }

 

this could well lead to a burnt / cracked area between the 2,

as the seats are open, and ex gasses flow across the ..dip / cut oot bit, on overlap

 

a common affliction in my findings

 

M

Edited by GT6M

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Having a good look at that pic, like 400X zoom,

it looks like the margin es gon between the seats.

 

Compare area between seats on the 2 pics Paul bunged up

on his, ye can see heed matterial,

on your, it cannae be seen

 

And, cant see any evidence of an insert

Which means that valve had pocketed, and been cut back,

hence having to bung in a bigger valve

 

Has all chambers got same valves, and been cut the same

cutting ex valves too wide { Not too deep, 2 totally diff things, depth an width }

 

this could well lead to a burnt / cracked area between the 2,

as the seats are open, and ex gasses flow across the ..dip / cut oot bit, on overlap

 

a common affliction in my findings

 

M

 

They're all the same as per attached pic. I'd have to remove a set of valves to clarify your point, but I doubt there'll be an issue.

post-6267-0-38069000-1511882986_thumb.jpg

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Might just be the effect of 3 angled seat cut? 219016 head pictured further up seems to have been modded with the larger exhaust valve fitted? Normally they have a smaller exhaust valve

 

Nick

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