Running Lean?

ian.stewart · Post by **ian.stewart** » Sun Jan 18, 2009 5:10 am

That suggests the valve is either not shutting or burnt allowing excess combustion in the exhaust, if it was all of them it would then suggest your timing is way out,
have you still got your lifters in order, you may have a lifter pumped up and jammed, or even one pushrod longer than the others.

Post by **Coops** » Sun Jan 18, 2009 8:02 pm

right checked valve install height today

that icon explains it above,

they all need shiming, and they vary from 10thou upto one that needs 45thou shim,

hope i checked them right,
how does every one else check the install heght?
weturned a piece of bar down the install height of 1.54" then fitted collets and cap to valve with no spring and measured the gap between the bar and underside of cap with feeler gauges, i know this is not going to be 100% correct, but gave me an idea how far out the heights were,

so if someone has a better way then fire away please, im ordering a shim kit this week from v8tuner.

stevieturbo · Post by **stevieturbo** » Sun Jan 18, 2009 8:37 pm

The only way to change the installed height of the valve...is with either longer/shorter valves...or recutting the valve seats.

Adding shims etc to the springs, will only adjust spring seat pressure. If valves are varying heights....you need to either use adjustable pushrods, or try and shim the rocker gear to the best compromise.

Ideally you want all installed valve heights to be the same though. Which can be a PITA.

Post by **Coops** » Sun Jan 18, 2009 8:47 pm

Hi stevie,
the springs i got from RS (DW060) says in the instructions to get the correct installed height of 1.54" (75lb) shimming up of the spring maybe required etc and shim kits are available in different thicknesses,

ChrisJC · Post by **ChrisJC** » Sun Jan 18, 2009 9:20 pm

I just had my heads done, and I specified that I wanted all the seats cut to the same height. This was because previously they weren't, and it was impossible to set the preloads as they were all different!

I set mine by using different wire radii and sticking them in the lifter between the lifter-piston and retaining wire clip.

Chris.

Post by **Coops** » Sun Jan 18, 2009 9:26 pm

and i use adjustable pushrods for lifter preload.

Paul B · Post by **Paul B** » Sun Jan 18, 2009 10:36 pm

stevieturbo wrote:
Perhaps no spark on that cylinder...and only dumping fuel through it, could cause it to be clean.

There's a simple test for that: run the motor for five minutes, and ask a buddy to press his finger hard against that header.

If you hear a scream and foul language, you DO have at least some fire going on. If buddy just asks you "how much longer?" then chances are you have a dead cylinder.

stevieturbo · Post by **stevieturbo** » Mon Jan 19, 2009 12:45 am

thev8kid wrote:Hi stevie,
the springs i got from RS (DW060) says in the instructions to get the correct installed height of 1.54" (75lb) shimming up of the spring maybe required etc and shim kits are available in different thicknesses,

That's the installed height of the spring, not the valve.

All an incorrect installed spring height will do, is give differing seat pressures.

Differing valve heights could play havoc with lifter preload if you shimmed the pedastols, and didnt check every single lifter preload.

bones · Post by **bones** » Mon Jan 19, 2009 7:01 pm

could,nt you just hold the valve upto the seat and measure with a digital caliper thing, from the valve guide top to top of valve, assuming valve guides are the same ?

rich

mgbv8 · Post by **mgbv8** » Mon Jan 19, 2009 8:40 pm

Tony
I normally just stick a straight edge across the valve stem tops and use a feeler gauge to get an idea of the variance across the valve stem tops.
As long as these dont vary more than 10 thou I'm not that bothered.

But are you actually talking about the fitted height of the valves themselves. Or are you just talking about the fitted spring length/height?

Bung the springs back on and make sure the valve stem heights are ok first before you start machining and shimming the valve spring pans.
Dont be too sure that the srping pans will all be the same depth either as some of mine varied by 20 thou.

As Stevie says, the differing spring height will just affect the closing pressure on the valve seat.

If you have as you say up to 45 thou variance on the valve stem heights this could lead to all sorts of trouble when you set the pre loads unless you use adjustable rods and check and set each one very carefully.

Could it be that at high rpm some of your valves may have been fluttering and not closing fully??

45 thou doesnt look much when you set it on the vernier does it. But imagine having one valve fully shut with the right settings. And the one next to it is 45 thou less closed at high rpm.

Post by **Coops** » Mon Jan 19, 2009 9:28 pm

im refering to the spring fitted install heights mate,
i think i have said this a few times now

and i use adjustable pushrods for the preload said that also

will do the straight edge across the valve tops the weekend when i can get to the heads,

it may off been the problem all along the valves fluttering, but until i get an engine back in the car and tested will not know mate.