Hello. Does the subject
Im running 8.6:1 compression being optimistic of a re-tune to 14 psi. with a Garrett GT2560r ( I was tuned to 10 psi. prior to cylinder head removal), with a bigport head equipped with stock valves and Poncams with HKS springs.

When running Tomei Poncams or any aftermarket camshaft in a turbo setup, is it better/safer to run the exhaust valve lifters clearance to the maximum spec? I understand the Fsm calls for 0.20mm- 0.30mm cold, but the Tomei spec sheet calls for 0.25mm... This became a question when i stumbled on a Tacoma 5VZ-FE diy valve clearance topic where the creator said, "the exhaust valves should be set on the loose side, measuring AT LEAST the max clearance (0.37mm for 5VZ-FE), 0.381mm is a good cushion." " Intake valves run much cooler than exhaust valves, so the clearances are less crucial. If an exhaust valve is to tight, it will burn and then you're bummed." Is compensating for metal expansion with the largest clearance on the Fsm's clearance range the optimal setup for longevity, durability, and reliability of the engine's valvetrain? or is this compensation specific to this engine and to this one "mechanic?" http://www.yotatech.com/f128/5vz-fe-3rz-fe-2rz-fe-valve-adjustment-tech-226997/

I don't want to run the risk of a burnt valve or tapping because I exceeded either end of the Fsm's valve lifter clearance, assuming the Fsm's range is acceptable in a higher heat forced induction setup with the use of an aftermarket camshaft. I planned on setting the clearances to 0.25mm on the exhaust side, which is what Tomei calls for with use of the Poncam. Coincidentally, that clearance is right in the middle of the range the Fsm specifies for stock camshafts. This led me to assume a clearance of 0.25mm +/-0.01mm will suffice, till I read the topic for the 5VZ-FE. It makes sense that compensating for metal expansion is more of an issue for exhaust valves compared to the intake valves since they are the ones seeing all the heat on the exhaust stroke, but does the 4age have its own rules to go by? Do I have a cushion?

Perhaps there is someone who can provide guidance, based off of their own experience and expertise. Thank you in advance to those who choose to reply to this topic. I look forward to your insight.

The reason you have more clearance on the exhaust is already do to heat/expansion. Did the article mention anything about more valve to guide clearance, metal expands in all directions.....

I'd set the clearances to the Tomei spec. I try to get to the spec, never under. What are you using to check, blade feeler gauges? Most blade gauges are in SAE, not metric, so .25mm is actually .254mm

Nope. The article didn't mention anything about valve to guide clearance. I use feeler gauges that i measure with my micrometer, to be as accurate as possible. Sometimes a combination of a few gauges and a little math can allow me to check clearances in increments of about 0.005mm, but sure is a pain... I really wish they sold a set in 0.005 increments.

I'll take your advice. I think I will shoot for 0.25mm and 0.20mm on the intake, but not less. I think I will run into more problems if I go with a tighter clearance...

Use the cam manufacturer's spec & error on the loose side if you have to error.
This is something that no one ever has a problem with.
Your head is going to hurt very soon when you actually have a real problem to ponder.
There are way too many things to do, valve lash being about the most difficult to F'up, though working with dirty seats & ports can drive you crazy by holding it open a bit.

oldeskewltoy wrote:The reason you have more clearance on the exhaust is already do to heat/expansion. Did the article mention anything about more valve to guide clearance, metal expands in all directions.....

I'd set the clearances to the Tomei spec. I try to get to the spec, never under. What are you using to check, blade feeler gauges? Most blade gauges are in SAE, not metric, so .25mm is actually .254mm

Or you drop the $6 on metric feeler gauges.
http://www.amazon.com/uxcell-Metric-Thi ... eler+gauge

4agtee wrote:Nope. The article didn't mention anything about valve to guide clearance. I use feeler gauges that i measure with my micrometer, to be as accurate as possible. Sometimes a combination of a few gauges and a little math can allow me to check clearances in increments of about 0.005mm, but sure is a pain... I really wish they sold a set in 0.005 increments.

I'll take your advice. I think I will shoot for 0.25mm and 0.20mm on the intake, but not less. I think I will run into more problems if I go with a tighter clearance...

.01mm is .0004" that is more than enough for something like this. It's also really pretty close to the practical limit for feeler gauges. With .0005 you would just have three different ones that fit. One that was kind of loose, one that was kind of tight and one that fell somewhere in the middle. Even just generally speaking once you start talking in tenths of a thousandth of an inch you are in territory that a lot of professional machinists don't mess with.
.005mm is .0002" That is a range that very few people mess with and you need tools a lot fancier than feeler gauges to play around there.

On that subject not only was the article TLDR but he is measuring shims with calipers so I wouldn't count on anything they say that didn't come straight out of a FSM.

On the subject of boost.
1. I have never heard of anyone having issues with this on a turbo build. That doesn't mean it didn't happen or if it did they would be able to relate it to this being the issue but it's definitely not a common problem.
2. We are lucky enough to have had a boosted version of the 4AGE. If you look in the BGB you will see that it only specifies one spec for both 4AGE and 4AGZE.
3. One thing to remember is that everything is expanding. Yes the 30mm or so of the valve that is in the exhaust flow will be hotter than everything else around it but that is only a small part of the stem. Then there is the aluminum head surrounding it that also expands with heat. In fact aluminum's coefficient of thermal expansion is much greater than steel so even though it's not as hot as the valve it's expanding more per degree.
4. With any setup the goal is to keep as much heat from leaving the combustion chamber as possible. Heat is energy and the more that goes out the tailpipe the less energy goes to the output shaft. Now it is true that high performance NAs and turbos will tend to have slightly higher EGTs but the mission is to keep them low and put that energy into the crank.

Tomei's one number is what you call nominal whereas Toyota gives an acceptable range or tolerance. The latter is much more technically proper because in the real world there is no such thing as perfect, only as close as your tools and skills can achieve so you should have a tolerance to know if your tools and skills can get you into an acceptable range.
If no other nominal is given then when you are given a min and max you can assume that nominal is in the middle so for the exhaust valve .2-.3 .25 would be nominal or your target but as long as you are within the tolerance it's acceptable.
With a high power build I might tend to steer away from the very lower end of that spec.

yoshimitsuspeed wrote:

oldeskewltoy wrote:I'd set the clearances to the Tomei spec. I try to get to the spec, never under. What are you using to check, blade feeler gauges? Most blade gauges are in SAE, not metric, so .25mm is actually .254mm

Or you drop the $6 on metric feeler gauges.
http://www.amazon.com/uxcell-Metric-Thi ... eler+gauge

[

.005mm is .0002" That is a range that very few people mess with and you need tools a lot fancier than feeler gauges to play around there.

so no need for the metric feeler gauges

Btw... please pass on to us your vast experience in setting valves???

I did not intend on making this thread because setting valve lash is difficult. It actually is quite simple. My goal was to find out if anyone has come across a problem setting their clearances tighter or looser than the nominal clearance with whatever set up they may have.

I spoke with my machine shop today and asked what their procedures were when setting lash for customers. They said that for any cylinder head they are setting lash for would consist of them researching the range of clearance for that specific engine cylinder head, determining nominal clearance, and setting the clearance anywhere between the nominal and maximum clearance. They stated that being dead set on 1 measurement to shoot for when setting valve lash would be a hefty bill for whoever contracted them do so, which would result in no benefit in performance and/or reliability.

oldeskewltoy wrote:

so no need for the metric feeler gauges

Btw... please pass on to us your vast experience in setting valves???[/quote]

Sure you can convert but that's just extra work. Or you can just work in inches if you insist but if you are going to work in metric why would you not use metric feeler gauges?
It's so much simpler when you have nice even numbers to work with.


You really have nothing better to do than question my experience all the time these days? Especially with boosted builds, are you frikken kidding me?
Get a life old man.

yoshimitsuspeed wrote:

oldeskewltoy wrote:

Btw... please pass on to us your vast experience in setting valves???

You really have nothing better to do than question my experience all the time these days? Especially with boosted builds, are you frikken kidding me?
Get a life old man.

I'm not sure why you continue to insult me when I ask serious relevant questions.... I asked you about your experience in setting valves... and you respond with insults... selling parts has nothing to do with the intricacies of doing the actual WORK.

Lets make this simple, yes, or no - Have you ever set valve clearances on a 16V?

Yoshi can question everyone else, but no one else can question yoshi. And if you do question him, you either an insult or some crazy ass metaphor that doesn't make any sense lol.

as to why I use SAE instead of metric for setting valves..... each OEM spec is every .05mm, or .002"... but I have the major spectrum covered in .001" increments... or finer then the .05mm



So when I say I can set the valves to .001", I can get it to perfect

oldeskewltoy wrote:

yoshimitsuspeed wrote:

oldeskewltoy wrote:

Btw... please pass on to us your vast experience in setting valves???

You really have nothing better to do than question my experience all the time these days? Especially with boosted builds, are you frikken kidding me?
Get a life old man.

I'm not sure why you continue to insult me when I ask serious relevant questions.... I asked you about your experience in setting valves... and you respond with insults... selling parts has nothing to do with the intricacies of doing the actual WORK.

Lets make this simple, yes, or no - Have you ever set valve clearances on a 16V?

Yes, including boosted motors.
Happy now?

ogdougynutty wrote:Yoshi can question everyone else, but no one else can question yoshi. And if you do question him, you either an insult or some crazy ass metaphor that doesn't make any sense lol.

I'm perfectly happy discussing theory or trying to learn more but when someone belittles your knowledge and experience in every single thread it starts to get very annoying and IMO little more than trolling.