GolfGTIforum.co.uk
Model specific boards => Golf mk2 => Topic started by: gazareth on 25 August 2013, 15:13
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hey guys. does anyone know if there is any gains to be had by fitting the agg 7mm valves into the pb cylinder head?
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anyone??? :undecided:
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Waste of time
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smaller stem size will increase port area avalible to flow
some minor gain, worth it probaly not, used to just machene back the stem a bit.
valve head itself is the problem when it comes to airflow
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I don't suppose it would be worth stripping down just to convert it. but if it was needing guides done anyway it would be same amount off work to change to 7mm stems. and both types of guides cost the same.
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looked at the price of valves yet ?
the cheepest, quickest and singel biggest power gain you will get from that cylinder head is to have the valves and seats tri cut. end off
all the flow problems are where the air has to turn the corner then get between the valve seat and valve head, i would proably be modifying the sd valves rather than replaceing them but more likly to be changes to the back of te valve rather than stem to start with
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I have a set of low mileage 7mm valves already. also have the springs/collets and retainers which need to be changed to. yeah I might just get some head work priced up. got 2 spare heads anyway so car wont be disabled for any length of time.
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well if thevalves are there it would be rude not to, still get them and the seats tri cut it would be rude not to
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very true. only problem is the 7mm inlet valves are .5mm longer than the 8mm pb 1s so when the seats are cut it could be pretty close to binding up the hydraulic tappets. I will have to do some careful measuring first or just get the valve tip ground down a touch.
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very true. only problem is the 7mm inlet valves are .5mm longer than the 8mm pb 1s so when the seats are cut it could be pretty close to binding up the hydraulic tappets. I will have to do some careful measuring first or just get the valve tip ground down a touch.
Careful they are not case hardened could leave the tops a bit soft if you take too much off. Suggest you get them all done on a cylindrical grinder to the same length over the set +0 - 0.005 on the correct items
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yeah they would have to be ground very accurately. otherwise the part of the tappet that sits directly on the valve could wear out quickly or even jam if the tops of valve stems were not perfectly horizontal. but they might be ok as they are because the agg and pb head seem to be exactly the same dimensions/use the same tappets and have the same cam base circle.