and i want to but over size valve seatscan i do it in a 1991 chevy chenynne k2500
I am assuming that you are referring to a small block chevy or similar engine. Valve seats occasionally crack where the two exhaust valves sit side-by-side. This is the only part where the two exhaust valves are next to each other; the others are separated. This causes high heat in this area and can fatigue and crack. You will need to replace valve seats on the heads which involves boring out the existing seats and installing new ones. You will then need to have new valve angles ground in so that the valves seal properly. While you are doing this I recommend putting in new valve guides, or in a worst case scenario bronze liners (this prevents the start up smoke). To do a set of heads properly you are probably in the neighborhood of $1500 plus and that does not include the removal and reinstallation. If you can I'd recommend a set of World Products SR Torquer heads, you will save money and increase performance. There are also a number of other good aftermarket cylinder heads out there, so the only limit is how much you want to spend. Good luck.
just age mostly and any Machine shop is where to take it an d talk with them
Jasons $1500 quote is way over priced. Valve seats crack due to heat and age. Its a common prob with chevy heads really. Price at a machine shop to replace the seats and do a valve job will be about $400 If your wanting to go larger on the valves, then you will need new valves ($75-150) Now why do you want larger valves in a stock head? Most chevy heads has 1.84 or 1.94 intake and 1.50 exhaust valves. I had 1.94/1.50's on my 355 making 505 HP, and running mid 11's 1/4 mile in a camaro. I have now stepped up to 2.02/1.60 It might be cheaper and better for you to buy an aftermarket set of heads with the larger valves if thats what you want. Aftermarket heads range from about $600 to 1200 a pair. I bought a new bare set of alum brodix IK 200cc heads for under $700, then bought all parts I needed to build them with for about $175
