Hello All,
I am planning on doing the high compression mod to my p79 head and there are a few thing that I would like to get cleared up before I do it. I read a couple posts and site that people say to use the 75-78 280z valves but none of them match up on the size. One says that they are .08" longer while another says .1" which is it? I want to get the shims too but the motorsport ones are .03" and are not stack-able and was wondering where I can get the .08" or .1" shims, as well as washers for the springs? What about lash pads? Stock .15"? And last but not least would the valve clearances be left the same as stock with .007" and .009" for cold? I did search the forums and didn't find the answers to my questions and I think it would be helpful to have a full write up on the process and places to get the parts in one thread and I am willing to document it with a some help from the more knowledgeable.
Thank you all,
Bogdan

 

Basically the route i went was shave the head .080 this equaled 44-43 cc per camber. i then bought the Schneider spring kit from MSA. mine were old and my cam is .460 lift, right at the end of stock spring spec. I kept the stock valves and i cut new 3 angle surfaces and new seat angles. So now we have the issue of how do i shim the cam? where do i get the shims? well you can buy them from Derek at hybridz from like 100$? or make your own by hand for 30$ and 2 hrs. Then I bought large lashpads my cam recommended .180 (stock being .160) + the .080 that was shaved= .260. the Schneider spring kit cam with retainers that are deep enough to handle the .260 lashpad. the stock retainers are too shallow. With a felpro 1mm gasket and a .5mm over bore I have a 10.3:1 compression ratio. and 190 psi in each cylinder. I have not broke in the new rings yet and once broke in i except 210psi. meh build thread: https://www.zdriver.com/forums/280zx...x-build-39579/

 

Ok, Do you have Dereks email or contact info I cant find it on hybridz, I dont have the tools to make my own shims

 

longer valves is also a good way to go, get them from a n47 type head, they are longer and don't require the super tall lash pad. not necessary but it helps. you will have to get the correct springs to match if you do this. your machine shop will be able to advise the correct springs and test seat pressures for you. lash pads need to be checked for wipe pattern anyway to ensure they are the correct fit. every cam grind is slightly different and nothing should be assumed. just do a member search for derek on hybrids and you will find him.

 

You can trust shady he help me through my mod. Hes the bees knees.. if they have bees in Canada

 

Hey guys sorry it I didnt give any updates on the project. I've been busy and just got around to it. I got the head off and ran into a problem the 77 280z intake valves are way too small in diameter to fit. Which leads me to the question can the 77 280z valves fit at all or was the information on Datsun P79 cylinder head mods incorrect?

 

Never mind rockauto shipped me the wrong part they gave me 7 exhaust and 5 intake and i only opened the exhaust one without looking the the numbers but the box

 

Well how's the mod going!?