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+--- Thread: Valves and valve seats - Some questions for the experienced (/showthread.php?tid=1737)
Valves and valve seats - Some questions for the experienced - Steve Bryant - 16-09-2018
Please bear with me as I am not familiar with what does and doesn't work on Austin Seven side valve engine valves and seats for better reliability and incremental improvement in breathing and running.
I am not modifying the block in any way apart from cleaning up ports and fitting new guides, springs and valves.
I have cut new 45 degree seats and am going to cut 30 and 60 degree clearance angles to produce a valve seat width of about .050" to .060" (also suggested by others).
In the book by David Vizard "Tuning BL's A Series Engine" he suggests cleaning up valves and seats as per these drawings as shown in his book:
I'm wondering if these suggestions (particularly the valves) would provide any benefit to my A7 block given as it isn't an A series head? Or am I misguided in my thinking that this will improve flow and breathing - even if it is minimal ?
What are your thoughts ?
Cheers,
Stephen
RE: Valves and valve seats - Some questions for the experienced - Stuart Giles - 16-09-2018
Can't see any issues with the inlet valve mods. But...as the exhaust valve seat cooling on the A series heads is much better than that on the standard 7 block, I would use a seat nearer .090 wide on the exhaust valve seat if it's a road going motor and you're using the standard exhaust valves.
While you're cleaning up the ports, blending/removing the near razor sharp meeting where the valve throat meets the top of the port -i.e. what tuners call "the short side radius" would be well worthwhile in terms of gas flow as it is usually the biggest restriction to flow in inlet ports on almost any older motor.
RE: Valves and valve seats - Some questions for the experienced - Bob Culver - 16-09-2018
Read through recent post Necessity is Mother of Invention.
Go easy with the steep seat cutter especailly.
Some moderns introduced slight relief of the inlet head underside as a production mod.
RE: Valves and valve seats - Some questions for the experienced - Austin in the Shed - 16-09-2018
If its apart fit a set of reprofiled cam followers,3/4".They will give you as much as the valve mods.