Upgrading valve springs

[Bazda]

I had 1 valve bend as the piston came up, gave it a wack and knocked off its collets, and about 5 other valves where the shims had come off caused by valve float.

I think matt dunn had done the same thing with his car as well. Also a 20v.

SInce I put in stronger springs I've had no issues for 2 years now.

[Mr Revhead]

how about we all remember that ppl have different opinions

if you stick the technical reasons behind your opinion and explain those, as well as reading and THINKING about what other ppl are saying then maybe we can have a good discussion that will help a lot of ppl learn something.

if needs be count to ten

I can see where MAGN1T is coming from. and also FIVEBOB has a point.
if your spring is exerting 30psi on the valve seat, and you have 20psi pushing against the valve then yeah.... suddenly the effort required to move that valve is a lot less. its effectively making your 30psi spring a 10psi spring (figures pulled out of my arse) as for pressure dropping when the valve opens, there will be a pressure fluctuation but there isnt going to be a huge drop in pressure, unless you run out of boost!


i for one have not heard of many 20v turbos failing for this reason. Im fairly sure Matts one didnt have that problem, no doubt he will clear that up soon.

there are many 20v turbos out there with stock springs and no problems, and there are many with aftermarket springs.

im thinking the issue with stock ones maybe age, gone a bit soft and lost some tension. or not being set up right when rebuilt.
certainly if your building something thats going to rev, have some wild cams or have a ton of boost thrown at it you need to at the very least check the springs and seat pressures etc.
theres obviously a point were stock ones dont cut it anymore.

[rollaholic]

theres obviously a point were stock ones dont cut it anymore.

i think this pretty much sums up the whole thread!

[fivebob]

if your spring is exerting 30psi on the valve seat, and you have 20psi pushing against the valve then yeah.... suddenly the effort required to move that valve is a lot less. its effectively making your 30psi spring a 10psi spring (figures pulled out of my ar*e) as for pressure dropping when the valve opens, there will be a pressure fluctuation but there isnt going to be a huge drop in pressure, unless you run out of boost!

That's one explanation of what might be happening. Also remember that valves reach there maximum extremity when the flow is greatest, and by definition there are more air molecules hitting the valve per unit of time at that point, so more force is being applied to the valve

However what I was really meaning is the forces involved in overcoming the inertia of the valve at rest are reduced. That energy has to go somewhere, so some(most?) of it goes into increasing the valve acceleration. This gives the valve greater momentum, therefore it has a greater potential to loft and either hit a piston or spit a shim.

If that explanation of what I believe is happening isn't clear enough then I'm afarid I'm at a loss as how to clarify it any further.

[matt dunn]

I had 1 valve bend as the piston came up, gave it a wack and knocked off its collets, and about 5 other valves where the shims had come off caused by valve float.

I think matt dunn had done the same thing with his car as well. Also a 20v.

i for one have not heard of many 20v turbos failing for this reason. Im fairly sure Matts one didnt have that problem, no doubt he will clear that up soon.

there are many 20v turbos out there with stock springs and no problems, and there are many with aftermarket springs.

I did had problems with shims and collets on the 1600 race engine,
but that was nothing to do with valve springs, and all to do with incorrect valve clearances.

The guy who built my 1800 20V engine check my valve springs,
but we did not fit aftermarket ones, and the standard ones are still in there now.
I will be thinking about doing valve springs possibly in the future if I
want to run more than 20psi,
but would need to do some research on them as I have heard of two engines,
and seen one personally, self destruct because of an aftermarket spring failure causing dropped valves. They were both 16V 4age's though.

so dont always think that aftermarket is better, just because it is aftermarket,
in fact the only non genuine toyota part in my whole engine is the conrods.

[TRD_ZERO]

[
I have heard of two engines,
and seen one personally, self destruct because of an aftermarket spring failure causing dropped valves. They were both 16V 4age's though.

so dont always think that aftermarket is better, just because it is aftermarket,

Damit i didnt wanna hear that.

[Bazda]

I had 1 valve bend as the piston came up, gave it a wack and knocked off its collets, and about 5 other valves where the shims had come off caused by valve float.

I think matt dunn had done the same thing with his car as well. Also a 20v.

i for one have not heard of many 20v turbos failing for this reason. Im fairly sure Matts one didnt have that problem, no doubt he will clear that up soon.

there are many 20v turbos out there with stock springs and no problems, and there are many with aftermarket springs.

I did had problems with shims and collets on the 1600 race engine,
but that was nothing to do with valve springs, and all to do with incorrect valve clearances.

The guy who built my 1800 20V engine check my valve springs,
but we did not fit aftermarket ones, and the standard ones are still in there now.
I will be thinking about doing valve springs possibly in the future if I
want to run more than 20psi,
but would need to do some research on them as I have heard of two engines,
and seen one personally, self destruct because of an aftermarket spring failure causing dropped valves. They were both 16V 4age's though.

so dont always think that aftermarket is better, just because it is aftermarket,
in fact the only non genuine toyota part in my whole engine is the conrods.

16v uses shim over bucket. Usually causes a problem .

[tsoob]

lets solve this like real men do and have a punch up