300zx twin turboed heads????

[jred]

Got a set of these customer brought in a set of 1mm oversize in/ex valves ferrera valves asked if we could do them,, I checked the seats and found that I could move the valve seat contact out and still have seats left..

The problem is that ferrera wants a valve spring installed height of 35.5 and 80lbs,,and to achieve this I have to sink the valves about .070 thou..

Right now the valves are sitting proud above the chamber floor about .035 and I will have to sink the valves about .040 below the chamber floor , and this seems wrong to me ..

I called ferrera and talked to a tech and got no hope at all from them.. other than that's what is wanted for installed height..

Unfortunately the heads came in with no valves and a pile of parts so i not able to measure the valve stem installed height and just make the new ones read the same..
And of course I have stalled doing this and the customer is starting to question me why the heads aren't done,, any help on this please????

[user-23911]

Give them back to the customer?
As is.

[Cubic_Cleveland]

Got a set of these customer brought in a set of 1mm oversize in/ex valves ferrera valves asked if we could do them,, I checked the seats and found that I could move the valve seat contact out and still have seats left..

The problem is that ferrera wants a valve spring installed height of 35.5 and 80lbs,,and to achieve this I have to sink the valves about .070 thou..

Right now the valves are sitting proud above the chamber floor about .035 and I will have to sink the valves about .040 below the chamber floor , and this seems wrong to me ..

I called ferrera and talked to a tech and got no hope at all from them.. other than that's what is wanted for installed height..

Unfortunately the heads came in with no valves and a pile of parts so i not able to measure the valve stem installed height and just make the new ones read the same..
And of course I have stalled doing this and the customer is starting to question me why the heads aren't done,, any help on this please????

I would think sinking the valve that far might mean you can't reduce the tip height enough for correct lifter preload. Also on the ferrea website ( http://www.ferrea.com/Nissan-Valve-Springs/p34376 )it mentions using their retainers and spring seats. Did the customer supply these??

[jed]

Do not sink the valves that much.
Get another set of valves that will accommodate factory installed heights.

[mag2555]

Do not use those valves, sinking them will fully offset the gain in flow that could be had from a bigger valve !

If there are specific springs and retainers that make these work at the proper installed height then have the customer provide them , or give the heads back to him!
Also just because this is a open chamber does not mean that the bigger valves will flow more, many times this conversion only ends up increasing the motors compression unless the rework/ valve job goes down in the valve bowl deep enough to open up the Throat area also!

[jred]

I do have the springs and retainers for this valve kit and mitchell on demand is not very helpful as they only give valve spring free length 1.697 and 102 lbs at 1.043.. guess i order some stock valves to make sure the keeper groove is in the same place and the valves are the same lenght????

[Keith Morganstein]

Stock valves would help you make some measurements for sure. You still have to find where the tip height ends up...once you get the seat out to where you need. Its not always so predictable when going to oversize valves until you cut the seats. (At least for me) I always end up proceeding carefully until I know. After that I can be confident where my retainer height will be.

Maybe someone on here with access to prosis ( or factory manual) can find the valve tip height. Thats going to be a limiting factor of course. The engines have hydraulic lash adjustment, but idk how much tolarance there is, prob not much.

As far as sinking the valves, I have no idea how well or not it works in those heads. I suppose if the customer wants it, you just have to be sure it works mechanically, not performance wise.

[jred]

so i do have a pair of core heads on a long block core in my storage if all else fails i guess i can pull them and measure the tip height on the stock valves.. Keith I have gone slowly and have cut the seats just barely have the 30 degree showing on the top of the seats and is/was preceding with caution ... also the customer does not have the new cams yet so i don't know if they are regrinds or new and don't know the base circle size yet,,

I was/am just trying to get all my ducks in a row..
and have to make a cutter to cut the guild boss for the inner spring and made a spacer to measure the spring height as you can't get anything in there with the retainer in the way to measure the retainer/spring height..

[benno318]

i did a set of these probably 4-5 years ago, i kept the std valve size but had the same issue with you - it was all bought disassembled in pieces!! the bloody cam caps were not marked or numbered in any way on these heads!! yes, a few hours there playing "try and see" to get all caps in their correct place... who does that sort of thing???!!!

did what i call a mild port job and with some japanese JUN cams the customer supplied (still hydraulic) i am told it makes 620hp at the wheels on E85.