Machine shop wants to grind tip of valves rather than shim. Opinions?

So i have 2 sets of 5vz heads im about to have rebuilt at the local machine shop (napa)
Looking for yalls opinion on whenther grinding the ends of the valve, rather than using the correct shim. Id never heard of this and would line to know what you guys or gals think about this.

 

Grinding the tip of the valves is normal and the preferred method since valve jobs have first been done on shim over bucket design heads. The valves do not rely on their special coatings in the tip of their stem just on the valve seating surface. That also will place your shim size in the normal range which is much preferred over a head with the shims all at the low end of the shim range.

 

Im trying to explain what tge old fella told me exactly, but at the time i didnt grille him on exactly what that entelled. I need to gets these heads taken care of asap, but after hearing that ive been wandering if i should just have them do the rest an shim them myself, or just find another machine shop.

 

Odd, typically valves loose clearance (tapping) , not gain it (carbon build up), so shaving the valve tip would reduce clearance.

Honestly I rarely make any adjustments in my 20 years and numerous 3.4s. Is there clearance issues?

 

Hey, thanks allot ive been wandering about this for a week or two but just got to the point where i need to drop em off. So hearing that really helps... last heads i took were all 22r type

 

Im doin 2 3.4s at once.. both sets are goin to the machine shop.. i thought the same thing about losing height, bit they will both be being reground so they shud end up taller reducing clearance to the bucket i assume.. idk its been years since i had heads takwn to the machine shop.

 

But ride freak just made me feel allot better about it.

 

It's not odd, when they cut the new valve seats the entire valve sits further into the head then before necessitating some method of adjustment to regain the needed clearance, 2 options, use thinner shims or adjust the valve stem length the same distance as the valve moved up into the head from recutting the seat. By machining the stem the shim thickness will remain close to the same value it was before the valve job.

 

https://forum.ih8mud.com/threads/valve-clearance-after-valve-job.1192889/

Also when the thinner shim method to compensate you are reducing the valve spring tension on an already old valve spring (not ideal). Adjusting the tip length of the valve keeps everything inc shim size very close to where it was prior to the valve job.

 

Sorry its odd from my experience, we don't typically mill heads on Toyotas, I used to mill the old 3VZ heads back in the day but we just gave the machine shop full control.

We have the full bucket kit in my shop, but it makes sense with the seats.

 

Thanks for that. I am a welder, and was a machinist for a while, mostly running a 12ft lathe tho.. so i understood. I did search around to see if u cud find people doing that. Needless to say i didnt find anythingbclose to that article you referanced. So thanks a ton. Now i wont be so worried about about. Im redoing an 02 my friend had owned til 270k. He just changed the oil but i dint think he even knew adjusting valves was a thing..

 

No need to apologize, it can seem foreign if you've not had to deal with it before. I used to do allot of motorcycle work and we'd measure stem height of the old valves before starting the valve job, when we finished cutting the seat we'd remeasure then valve stem height and take off the amount it changed. If you were very careful and exact you could sometimes use the same shim in the same valve when it was done.

 

I couldn't explain to you why, but yes, it's very common for clearances to tighten up on these engines (and other over head cam engines). The 4cyl too. I had the owner of a reputable, Toyota specialized machine shop tell me he likes to check his 3.4l valve clearances every 50k. Said they are usually fine at that mileage but will tighten up.

 

the 02 after major cleaning boutta week ago.. heads ready to come off.. i love to get everything spick an span as possible before i start tearing inside.. i cud be ocd... used the old 6 point E6 or E sumthin sockets to remove the manifold bolts an then it just drops down a hair an no exaust removal required..thats awesome...