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ProWeld 2, 3 & 4 Valve Heads

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     It's often been said that the Crank-Shaft is the heart of an engine and the Cam-Shaft is the Brains.....Well with regards to the Cylinder-Heads.....the Valve Guides are the Heart of the Heads.  We do something at Pro-Weld that is very different from any other Performance Cylinder-Head Shop.....We replace every Valve Guide and Valve Seal  from the start.  No extra charge here or there, and we don't wait till the customer purchases a higher Stage Head to do it.  WHY???  Why..,  is it that we feel this is such an important step??  The GUIDE is the Heart of the Head, without it,  the head will fail to due it's job, and you will not be happy nor get any Performance. 
     As Performance Cylinder Head Standards go, the Valve Guide should be replaced every time, and right away....Because every other Performance Up-Grade that follows is indexed off that Valve Guide.  So, if you were to leave in the old guides, then start the re-building process, you would be building everything from that point forward on a falsehood.   Kind of like putting new Pistons in and leaving the old rings alone....It just doesn't make sense, not to me or you!
     We use the best Bronze Valve Guides made....Why? Why not.?  Shouldn't the main part, the heart of the Cylinder-Head,  be made of the best materials, and of the best design.??  Of-coarse they should...and that is why we only use K-Line Bronze Valve Guide Liners.  We take no short-cuts, so you don't have to worry.
     This is a section from the K-Line web site, hopefully it further sheds more light on this subject.

Continued advancements in the tooling and installation process means that we can produce premium quality valve guide repairs, and upgrades, in the most efficient manner.
  • Superior Quality

Since the early 1970's K-Line has run numerous dynamometer tests in conjunction with major production engine builders and O.E.M.'s. Repeatedly the Guide-Liners and has out performed cast iron guides and has become the approved method for rebuilding. In fact, these tests have found the Guide-Liners to be up to three times more durable than cast iron. Further more, the minimisation of both guide lubrication and guide to stem clearances have failed to induce either a seizure or cause metal transfer. 

Ford, G.M., Caterpillar, Cummins, White Engines, Detroit Diesel-Allison and others have tested the product and confirmed K-Line's Guide-Liner system as an approved product for use in rebuilding their engines.

Fitting diagram
Fitting and Fettling Liner Shown in Red

  • Increased Efficiency

Our best result was with one customer who, after 50,000 on his BSA A10, still had 2 and a half thou or less clearances valve to guide. Less than they would have been when they left the factory. Standard replacement such as those Norman Hyde sells, guides run at clearances of 2 to 3 thou. Same as the the tolerances on the new 1999 model Harley-Davidson and others. The standards of early original factory parts can sometimes even be as bad as the parts they are replacing, so it is worth checking that your parts supplier knows what they are selling you.

Closer Tolerances Valve to Guide
Offer a Number of Benefits to the Owners of Classic, Vintage, High Mileage or Racing Vehicles
  • As the rocker action on the tip of the valve places lateral forces against the guide and wears it into an oval, it also forces the head, or rim, of the valve to cut into the newly cut cylinder head seats. Reducing tolerances minimises this making for a longest lasting head,
  • They also allows for a greater transfer of heat from the valve to guide and away into the head and stops oil and air being sucked down the side of the guide. With unleaded petrol running at far higher temperatures, in hot climates or in racing conditions, this is good news,
  • Improved fuel economy and cooler running,
  • Quieter running, increased responsiveness, some racers claim that their engines now tick over for the first time. Greater vacuum created in the inlet port in engines improves all round general performance to the point of requiring re-calibration of the carburettors.
Anyone and Everyone can Benefit from K-Liners.
  • More Performance

At low to mid range cam lift there is a huge vacuum in the inlet port as the engine tries to pull the volume of mixture in the inlet port through a tiny gap between valve and seat, a flow that is improved by a 3 or 5 angle cut. On high revving modern engines, 10,000rpm or more, this is also true of the exhaust port where exhaust gases are escaping along the pipe draw by the gases of the last stroke. 

The engine under these circumstances is trying to draw air from any available source, including down the side of guide with its inevitable oil mist included. Narrowing the gap reduces this and requires the engine to take gases from where it should be taking them; through the carburettor or out of the chamber. 

To avoid petrol wash, where too much petrol is drawn through the engine washing away all the lubricant and causing premature wear, it is necessary to lean out the mixture by always reducing the slide size and sometimes the needle jet.
  • Unmatched Durability

With K-Line Guide-Liners fitted, matched to quality new or refaced valves and freshly cut seats, we guarantee owners to return 2 to 3 times the mileage one would expect. One racing head we set up, a championship leader, did 3 seasons without need a head job and still was still in better shape that it would have been straight from the factory at the end of it season. Nothing more than a light lapping with Solvol Autosol was necessary to send it out for its fourth year racing.

More recent tests have shown that K-Line's Bronze-Bullet Interrupted Spiral phosphor-bronze Guide-Liners exhibited 41% less wear than smooth wall liners, as used by other tuning shops, under harsh durability testing environments even at similar tolerances. K-Line manufacture and stock the only complete selection of Guide-Liners and Guide-Liner installation tooling in the World.

Due to our many years of successful adoption of this technology, any problems in wear following the fitment of K-Liners or Nucleus Sports Elite Valves can be traced to the lack of carburettor adjustment. The penultimate combination would be to have Nucleus Power Guides fitted with K-Line Guide-Liners. Bespoke fit, incredible heat transfer and many other individual benefits for differing models.


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Pro Weld

5937 Ethan Drive

Burlington, KY 41005