Cylinder Head Work

• Seat Cutting / Valve Job
• Replacement  valve seat inserts
• Replacement valve guides
• Valve refacing
• Valve spring testing 
• Should I grind / lap my valves 

 

Read all the way through the head work page as important information is dotted everywhere. it's never one part of your engine that makes power!

Seat Cutting

IA Motorsport has a 'Serdi 3' seat and guide machine in house. As with everything performance related if you don't measure you are just guessing, so everything is measured and checked even on new performance parts, as they aren't always as good as you think they should be!

Looking for something other than the generic 30°45°60° on both inlet and exhaust ? These angles actually suit very few performance engines and you have most likely lost flow over the stock manufacture leaving Horsepower on the table!  For instance in 1989 Nissan gave its performance road engines different seat angles for inlet and exhaust with 5 angles on the exhaust to get close to a radius and 4 on the inlet. Times have moved on but many machine shops are stuck in the dark ages!

IA Motorsport has a number of seat forming tips 1-5 Angle along with 2 angles and a radius, plus a number of seat widths, these should work with most performance applications. If you need something else or bespoke for testing purposes no problem custom seat tips are available. 

You could easily see up to a 15 cfm flow drop with a badly cut valve seat and depending on engine specification that could be 15hp!

We vacuum test each port for a good seal and leak down. 

Concentricity: Industries all have tolerances and the general rule for high performance seats is 0.001" (1 thou) of run out per inch of diameter (remember a human hair is around 0.003) and although 0.002 will seal correctly all tolerances stack and there is also a valve!   At IA Motorsport with the supporting parts 0.001 or under is usually achievable.  If you don't measure it you are guessing! check out IA Motorsport on Instagram or YouTube.  

Don't forget your valve back cut, read on!

Seat Inserts

If your seats are worn beyond a recut, damaged or simply need swapping out for a more exotic material to deal with the excessive heat of your performance engine IA Motorsport can remove and replace your current seats. 

Valve Guides

The guide is the foundation of your valve job, everything must be as concentric as possible to the guide. Its starts with the correct choice of material for the usage. These days the go to performance material is Manganese Bronze they allow excellent heat transfer and lubricity. 

Valve guide install height is incredibly important and failures can happen if not installed to the correct depth. Where possible and to remove this error, stopper style is prefered. 

The Valve guide removes roughly 40% of the valves dissipating heat so the correct clearances are critical. Here a Diamond Hone is used to leave the correct cross hatch finish while also keeping the guide straight, true and on size!

Valve Refacing 

IA Motorsport has a Serdi Valve Refacer that uses centerless grinding at its heart allowing a straight valve to have almost zero run out, numbers at 0.01mm or 0.0004" (4 tenths of a thou) are commonplace.The Serdi Valve Refacer also has a digital angle readout and speed adjustment for different size valves. The machine can cater for valves from 13mm all the way up to 112mm.

IA Motorsport can reface your old valves to give them a new lease of life if they have it in them! The size of the valve margin is important here and grinding a valve to have little margin will only serve to overheat the valve and cause further issues.

New Valves? Doesn't mean they are good valves! Valve concentricity from the performance aftermarket is in question as its been seen that 0.04mm isn't out of the question.    

Some exotic valves cannot be refaced due to coatings like that found on titanium. In this case valves are only to be replaced.   

Please see our Instagram or YouTube to see how a brand new set of performance valves performed when we carried out a concentricity test, you will be amazed to see 0.04mm or 0.0016" of run out. 

Valve Spring Testing  

IA Motorsport has a New! Rimac Spring tester rated to 500lb for better accuracy on the smaller springs we see here in the U.K.

This tester is also equipped with a digital dial test indicator for accuracy when needing to know seat and open pressures. 

Calibration of the tester is carried out periodically using a calibration spring.

Seat pressures are worked out using a spring height micrometer following the correct procedure. Using a vernier calliper will give you an idea but isn't the most accurate tool for the job. IA Motorsport has all the tools to do the job right. 

Grinding Valves 

Grinding valves isn't necessary or recommended, in fact it's the wrong thing to do for performance valve seats. 

The use of 240 or 400 grit grinding paste will destroy a good valve job with deep gauging of the seat while imbedding particles in the metal faces of both the seat and valve. It can also leave concave and convex shapes on the sealing surface.   

Lapping is not grinding, using 1200 grit lapping paste is not the same as grinding. Lapping a valve to see high spots and chater markets etc is something done in house to see the condition of the seat being cut.

We vacuum test each port for a good seal. It's not the perfect way of testing but it's one of the ways.  Every test has its upsides and downsides.

If you want to see and check your valve seat then prussian blue (engineers blue) is perfect, don't apply to much and definitely don't rotate the valve this defeats the purpose. if you rotate the valve then the highest spot on both the seat and valve will just create a perfect circle every time.

If you just want to see where the seat is sitting on the valve and how wide it is then good old marker pen on the valve and give it a spin on the seat.    

Remember ! Grinding is needed and high performance valves with exotic coatings can't be ground or lapped, you'll cut through the coating. It's not necessary if the job is done right!