HD/ Performance 1.9TD Cyl. Head. Valves,springs,guides,etc.

[Tony2ltr]

There is a higher pressure differential on each side of the valve with boost.  The higher pressure on the backside of the valve will hold it open longer than wanted causing valve float, just like high rpms will.  A higher spring force will make the valve (and follower) follow the cam profile, rather than jumping off, just like would happen with a cam with a steep ramp.  Giving extra boost to a stock set of valve springs is just like having a weak or broken spring.

-Tony

[gldgti]

on the question of boost affecting valve float:

there is no question that the increased pressure gradient across the valve head will have some effect, detailed nicely in an earlier post, on the float point of your valves.

however, 30lbs of force (about 130N) is probably not a large percentage of the overall spring rate of the valve spring(s).

stiffer valve springs will negate any potential problems with valve float, the stiffer aftermarket gasser ones will work just fine. the issues you may have with this relate to excessive wear of cam lobes and shims. this may or may not be an issue. there are also more mechanical losses incurred within the valve train by using stiffer valve springs, which will at least in some small way, affect power output at all revs.

so, if your not going to use your engine at high revs, stiffer valve springs are not going to be much of an advantage, if any.

lightening the valve train, with titanium/lightened steel retainers, etc, is also a waste of money.

with regard to combustion chamber volumes: it is very important to get them equal. the engine will last so much longer of you do.

[Tony2ltr]

Even a brand new set of valve springs can have variances that can seriously affect valve timing and thereby, compression ratios, cylinder pressures, etc. in each cylinder.
Every set of springs that is used, be them new or used, should be tested for open and close force at installed height and max cam lift.  Spring rates can be adjusted by adding shims, and swapping tighter inner springs onto looser outers, swapping tighter spring sets onto longer valve stems (there should not be too much of a difference if your machine shop has done their work right).  Shimming valve spring is a very important step in head assembly, you would be surprised at how much variance there is between valve sets. Just buying a set of springs and throwing them in is a big mistake if you are concerned about performance or engine longevity.  So you have to set valve spring forces anyhow, why not take an extra couple of minutes to make sure you are not going to wipe a cam lobe out, make sure your valves will close when you want them to, and relative to each other under boost, and at high rpms?

-Tony

[subsonic]

Good info.  Pays to check and recheck.  

SO this would be kind of like doing a balance job on the head.
Does it do any good to weigh your valve train components?
I have a high speed digital scale that I use for reloading that is accurate to:
0.1grains / .006479grams / .000228oz

It will handle weights up to:
1500grains / 97.1985grams / 3.42857oz

just wondering.

Still looking for the part number and sizes for the 1.9IDI intake and exhaust valves.

I am looking for the ones with the smaller stem diameter.

Anyone have a good link / source for these?   I was at some web site and the wanted like $45.00 US per exhaust valve. kind of steep.

Thanks, Jim

[subsonic]

Why are the newer valves so much more than the older ones?  I found a online place and the intakes for the old style were about 18 bucks, newer thinner dia ones were like 45 bucks each!  Why the big price difference?

[foxracer1]

Cause you want them.  :lol:  Thats how everything i want is.

[Tony2ltr]

Well as far as weighing the components, why not? I guess the big Q is, where do you remove material from on the heaviest valves to match the lightest one?  Ideally, you want a big box of the small stem valves that you can weight them all and make a matching set. Probably not practical overall.

Tony