when doing 1mm engnbldr o/s valves, I am researching what kind of machine work needs to be done at the same time. I called a machinist and had a conversation that I didn't really understand. I got a list of services, and prices. pls teach me if these are reasonable, and necessary, and WHY they are necessary. thanks for helping me understand this. I am going to paste the text of our conversation below, I was typing as he spoke
=-===================
-----------------------------------------------
Definitely have it resurfaced-
also porting in the cylinder heads-
are valve springs upgraded?
You have to port, you are not gaining anything if you don’t port.
Without porting. All you are doing is changing the valve size, meaningless without porting.
some price estimates-
Resurfacing= $85
-valve job, I have to do it.
Valve grind 325 for the pair,
o/s valves, $200 to open up the seats (just the seat)
-bowl and shortsize radius, not too big but keep low end. Porting for $250 for cylinder head.
-adjusting the valves

you should try to get a leakdown test first...
-------------------

 

porting means making the intake/exhaust passages bigger in the head to increase airflow. The valve grind is a specific angle ground for the valve to seat and seal properly.

Not a clue on prices, call other machine shops and ask for quotes.

 

Oversized valves can increase overall flow capability, but on a 22R head the port is the restriction, not the valve. Larger valves will help some though by increasing the valve "curtain" area and helping flow at lower lifts and slightly increasing cylinder filling.

At a minimum you will need to machine the valve seats to fit the larger valves. with an ordinary valve job with standard sized valves the seats are reconditioned by grinding them to the correct seat angle and inside and outside seat diameter. Also a good valve job smooths the flow past the valve decreasing turbulence and increasing flow even more. Unfortunately most valve jobs do not include attention to detail in this area.

To increase the diameter of the seat requires additional machining to open up the seat to fit the valve. Obviously this will cost more.

In order to really benefit from larger valves porting is necessary. However just making them larger is an invitation for disaster.

As was mentioned, the bowl and short side radius are critical to flow. However on the stock head there is really no material in the area of the short side radius on the exhaust side to shape. Now the intake port can be made to flow about 20%-25% more by just paying attention to the bowl, short side radius, and unshrouding the valve some in the combustion chamber.

To do all this will require a skilled technician to spend time working on it, and time is money.

Do some research to educate yourself on these matters and shop prices.

 

save your money for that 3.4 swap you wanted!!!!!!!!!!!!!!!!!