Stiffer Valve springs? mizumo gasket kits?

[renfen]

Gday
im rebuilding a 1uz to put in my ra28 celica with acl race beaings and cometic head gaskets and head studs etc and will eventually have FI setup, have searched and everyones saying the valve springs are weak and while i have the heads apart is it worth getting this valve springs?
http://www.lextreme.com/Tundra-Valve-Springs.html
If i did get them does that mean i need to do anything about shims?

Also has anyone had any experience with Mizumo gasket sets and timing belt/water pump sets that are on ebay?

Cheers
Dan

 

[ash]

Gday
im rebuilding a 1uz to put in my ra28 celica with acl race beaings and cometic head gaskets and head studs etc and will eventually have FI setup, have searched and everyones saying the valve springs are weak and while i have the heads apart is it worth getting this valve springs?
http://www.lextreme.com/Tundra-Valve-Springs.html
If i did get them does that mean i need to do anything about shims?

Also has anyone had any experience with Mizumo gasket sets and timing belt/water pump sets that are on ebay?

Cheers
Dan

Dan, the shims will only have to be changed , if the installed height of valve changes, or camshaft changed ( base circle that is different to the original )

cheers

 

[XR8tt]

I used 2J Valves which are slightly longer and Brian Crower 2J springs..
Shimmed up from memory to 120Lb seat and just under 200Lb over the nose..
I had to shim the springs to get CORRECT installed height / spring tension..
There are valve springs on EBay made by Valve springs Aust.
It depends what specs your cam is when it comes to shim over or under..
I've spat a few shims on std WRX engine so I was a little keen on changing them...
Best follow what cam specs the manu states...All should be fine.. I used Kelford billet cams..
Best to use steel / Cometic, MLS gaskets .. Or Gaskets from Lextreme...
Just be aware gasket thickness BEFORE ordering custom pistons or working out compression ratio, piston to valve clearance etc...

 

[renfen]

im keeping standard pistons and standard cams at this stage just trying to build a strong stock motor. forgive me but what do you mean by sim over or under? mine has buckets with the shims on top. i havnt really changed the valve seat height by much just cut and lapped them

 

[BigSteve]

Shim over is exactly what you said. Shim over Bucket. With regrind cams the Base circle is reduced so you have to get thicker shims or caps.

Without stronger springs, a shim over bucket setup may spit your shims out of the bucket and have it's way with your engine.

Performance Springs Australia have a specific set for 1uzfe for a good price.

78lbs pressure @ 1.290
148lbs pressure @ 0.915
Bind @ 0.855

It's probably worth doing while the head is off for peace of mind. Later model 1uzfes need a 0.030 shim due to slightly different install height.

 

[ash]

im keeping standard pistons and standard cams at this stage just trying to build a strong stock motor. forgive me but what do you mean by sim over or under? mine has buckets with the shims on top. i havnt really changed the valve seat height by much just cut and lapped them

as soon as you put the cutter on the valve seat or grind the valve face, the installed height changes
if you want the oem install height to remain the same, shims are required under the spring, where it meetings the head ( spring pocket area)
if your keeping std cams, but just want more spring pressure, aim for the 70-80 lbs installed.
you shouldnt have shim problems with that.
there are engines up here with double that pressure and oem shim over bucket applications, and approx 2mm more cam, with 9500+ rpm, and shim over still works ok..
i wouldnt run it on the street though , as the extra spring / lift wears items out quicker.

 

[XR8tt]

A reground cam requires thicker shims...
To make up for loss of base circle..
Clearance between cam and bucket..

As said .. Then there's the spring tension which can be shimmed ..
To require desired spring tension while keeping an eye on coil bind..

 

[renfen]

so worth doing now? will have turbos or super charger in the future

 

[XR8tt]

Yes IMO .. Saves going over things twice..
Turbo cam's generally have wider LSA [very little overlap] than S/C cams..
But a GT type cam will be VERY streetable for both..

 

[ash]

you can change the valve springs , with out removing the heads
also change the cams , with out removing the heads

just need an adaptor to fill cylinder with compressed air ( 100 psi air compressor) , and tools to remove retainer / locks...
then have tools to measure / change shims on the buckets

will take a bit of time to do all 32 valves

 

[spf_lexus]

Since FI + valve springs are being discussed... I always wondered this:

An engine builder once told me that adding pressure (boost) to the engine can reduce seat pressure resulting in float under high boost. Im picturing an intake valve thats finishing the intake stroke and then the boost pressure acting as an opposite force to the spring's force. Is this false?

 

[BigSteve]

A reground cam requires thicker shims...
To make up for loss of base circle..
Clearance between cam and bucket..

As said .. Then there's the spring tension which can be shimmed ..
To require desired spring tension while keeping an eye on coil bind..

Ah oops, got it backwards. thicker shims! Fixed post.

 

[BigSteve]

Since FI + valve springs are being discussed... I always wondered this:

An engine builder once told me that adding pressure (boost) to the engine can reduce seat pressure resulting in float under high boost. Im picturing an intake valve thats finishing the intake stroke and then the boost pressure acting as an opposite force to the spring's force. Is this false?

I'd imagine the pressure being applied to the back of the valve would cause valve float at a lower rpm.

Just a guess here but if the Radius of the valve is 0.76 inches. Then the surface area of the back of the valve would be around 1.81 inches squared.

So if you're running 5lbs of boost that would be around 9.05 lbs pressure on the back of the valve.
78lb spring pressure at installed height would actually be about 69 lbs under boost.

 

[XR8tt]

Back pressure on exhaust side plays havoc too....
Esp where turbine size and A.R is small...

 

[ash]

I'd imagine the pressure being applied to the back of the valve would cause valve float at a lower rpm.

Just a guess here but if the Radius of the valve is 0.76 inches. Then the surface area of the back of the valve would be around 1.81 inches squared.

So if you're running 5lbs of boost that would be around 9.05 lbs pressure on the back of the valve.
78lb spring pressure at installed height would actually be about 69 lbs under boost.

in a dynamic sistuation, there is pressure on the piston side on the valve still...
dont get 100% concerned with sq area on the back side.
the valve collets will show , if more spring is required..