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Valve Clearance

RacerX

New Member
Working on a 1991 Toyota pickup 3L V6, automatic. Vehicle has about 160k on it. Valve cover gaskets were leaking, so I decided to change them. While I was there, went ahead and checked the valve clearances. All were in spec but 2. One intake valve was on the low side of the tolerance (.007 -.011") and 1 exhaust valve was out of spec by .001" (S/B .009" -.013") at .008". My question is, do I need to change the shim on the exhaust valve since it is tight??? I've never heard or seen clearance getting smaller over time, so to me I would just leave it. What do you think??
 

toyotafan

Toyota Truck Club Founder
Staff member
1000 Posts
How are you measuring this? The specs are so tight that the difference of .008 to .009 is pretty substation when you break it down by percentage. I've also not heard of these numbers getting tighter over time, but rather they almost always loosen up. Since you've only got 160k on the vehicle (and engine) I wouldn't think that any work was done to increase the mechanical performance, which might explain it.
 

RacerX

New Member
How are you measuring this? The specs are so tight that the difference of .008 to .009 is pretty substation when you break it down by percentage. I've also not heard of these numbers getting tighter over time, but rather they almost always loosen up. Since you've only got 160k on the vehicle (and engine) I wouldn't think that any work was done to increase the mechanical performance, which might explain it.
I am using feeler gauges to measure the clearance. It's the only tool that you can get in there to measure it. I see no other way to do it. As far as the clearance getting tighter, I've been told that this happens from wear on the valve seat and face. Back in the day when I was hot rodding, and mechanical cams were the deal, clearances ALWAYS loosened up. But the way the clearance was set was different too. So I am still considering what I am going to do. Will try to play with it in the next couple of weeks.
 

MuddyTacoma

Mechanic
1000 Posts
k2-_5a68158e-aaad-4d23-a296-c7223b7ba2d5.v2.jpg


Dumb question, but they're straight and all? I had a set of gauges that got crusted up somehow and ended up throwing off all of my gaps.
 

toyotafan

Toyota Truck Club Founder
Staff member
1000 Posts
View attachment 4991

Dumb question, but they're straight and all? I had a set of gauges that got crusted up somehow and ended up throwing off all of my gaps.
I only have one set of gauges like that, I grew up calling them a blade gauge, but I think that the term refers to each unit is a blade, the collection of them are feeler gauges.
 

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