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Location:
Kita-Ku, Sapporo, Japan
Registered:
January 2003
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Re: 4K engine mods what to go for ?
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Sat, 13 November 2004 22:53
 
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[quote title=KiwiKe70wagon wrote on Sun, 14 November 2004 07:34]p.s. sounds stupid but whats a welsh plug !? 
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sounds like you know of the bigports then  the 3K bigports have 30mm intake ports, vs 27mm (or 25mm!!) for standard ones.
the exhaust ports are near identical between K to 4K heads tho.
regardles of ports, the stock manifolds all seem to go down to about 25mm in the runners, so they can definitely be a restriction.
a picture of the carbs would be good to identify them, same for extractors.
for cam, take off rocker cover, rotate motor until one of the valves is full open and an adjacent one is fully closed, then measure the height difference at the top of the valve spring retainer (just below where the rockers act on the valves).. also check when both valves have same height when fully closed..
this is the valve lift. stock is around 8.5-9mm. highly modded is 11mm and greater!!
as for duration, it's a bit harder.. you need a degree wheel (google for tania free degre wheel) and then attach to your carnk pulley and rotate motor and measure angles at which the valves open and close.
YES. 3K head, original rocker gear, and should be ok... if you get a bigport or early 3K head, then there are issues. they have no valve stem seal, and instead have an o-ring above the spring retainer.. so they have a taller retainer and a double groove on the valve stem.. restricting the amount of lift you can run.. BUT you can swap in the 4K valves too. if you have much higher than stock lift i recommend getting the rocker shaft towers machned down by the increase in lift (over standard.. ie 11mm lift = 2.5mm machining)
if it's a 4K, the engine code is on drivers side, at the bacjk, just below the head (ie top of block), but if it's a 4K.. it's a 4K
also look on the head for the numbers "24010". thats a 3K bigport head.
welsh/welch plug is a metal disc that seals a round hole in a head or block.. it's kinda like a cup i guess..
google for an image.
if your 4K head has had porting work, then it is likely better than a stock 3K head.. if it has been shaved, it may have 10:1 compression anyway. the larger intake ports of bigport are only an advantage in minimising porting time, and also allowing larger ports to be used... 30mm intakes i think are a little overkill for mid-range.. still need to compare to stock suzuki swift ports...
Cya, Stewart
ps, get some pics
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