drkblu4runner

just got this truck with my fav 3.slow...

previous owner had #4 ex valve ground and did NOT adjust valve... engine was missing so he sold it to me.

engine has 70psi on #4

took off valve cover and lucky me NO shim would fit,,, so how am i suppose to calculate the shim size? trial and air? what size should i start with

current shim size .113 in -(2.87mm)

book says 2.20mm to 3.4mm shims come in increments of .05

A7QG59F2

Well I don't know what year your truck is or if it is a 4runner or pickup... But either way, you need to download the Factory Service Manual for it. You will find a chart in the tuneup section that will cross reference your current installed shim and the measured clearance to tell you what number shim should be installed.

drkblu4runner

its a 95 4runner 3.0 3vze


im looking at the chart right now.


http://personal.utulsa.edu/~nathan-b...e/64tuneup.pdf


the problem is i have 0 valve clearance.

the valve were being kept open causing the low psi and mis.. im hoping that the valve isnt burnt now

A7QG59F2

Maybe the exhaust and intake shims got reversed? its a possibility. Otherwise the only course of action would be to put the smallest shim in there and remeasure. You might have a 2.2mm in one of the other spots. You could put it in place temporarily to measure it and figure out what you need then put it back where you got it from.

drkblu4runner

i was thinking i might need a 2.55 mm shim since the exhaust clearance should be 0.22 – 0.32 mm

MudHippy

2.87mm - 2.55mm = .32mm

That's correct. Atleast a 2.55mm maybe thinner.

scope103

That calculation would be correct if you (somehow) knew that the cam was just kissing the shim -- then you'd back it off by the desired clearance.

But you fear that it is not just kissing; rather it is holding the valve open. If it happened to be pushing the valve open by 0.32, then the new shim would just barely allow that valve to close, and you'd measure 0.00 clearance (just kissing).

Having said all that, 2.55 might be as good a guess as any, but don't expect the clearance to come out right. You need to install a shim thin enough so that you get SOME measurable clearance, then swap it out for the shim that will give you the correct clearance.

drkblu4runner

thanks for the help. i think im going with 2.45.. ill let you guys know how it goes


i took a grinder to the bottom of the"old" shim, got it close to specs and did a compression test and got over 140psi, so i think this will solve my misfire.

vital22re

iTrader: (2)

Its better to hear the valve than to worry about pulling the head later. a little loose is okay.

drkblu4runner

my question is who the H&## goes through the trouble of pulling the head and grinding valve. and doesn't adjust the valve? the owner said he found the guy on cl to do the work hahahahah and gives the car back with a mis

MudHippy

Yeah, the whole story sounds retarded to me too. On many levels. If he had to take one exhaust valve out and grind it, and the seat too I'm assuming, then why not do all the exhaust valves? I replaced all mine and their seats when I rebuilt my 3VZE. They were all pretty well worn, and in pretty much equal condition. It would have been ridiculous for me to have decided to only fix the one with the most damage/wear. My point being that if #4 needed attention then the other five, which have just as many miles on them, aren't likely to be in much better shape. And they will likely fail soon too.


Next level of stupidity, making one cylinder perform better than the rest on an engine. This throws the engine out of balance, and is not what one wants to achieve when making repairs to one. You don't just change one spark plug, you replace them all, right? Same thing applies here, not a smart move engine performance wise.

Oh well, it's like you said, the valve might be shot now. If so, you'll be wise to fix/replace them all at the same time.

Oh BTW, 140 psi is too low. The FSM says minimum pressure shouldn't be below 142 psi. With a difference of no more than 14 psi between cylinders.

scope103

While shopping for a machinist, I chatted with one (who I thought was very knowledgeable) about the annoyance getting new shims. I suggested I might take an old shim down to the community college and run it through a surface grinder to change its thickness. The machinist commented that it wouldn't work, because the shims are slightly domed (and a surface grinder would leave it flat). That made sense to me at the time, because I knew that the valve lifters are designed to rotate the shims slightly each revolution (to even the wear on the shims).

Well, I've got two old shims in my hand right now, and with my best straight edge they are perfectly flat on both sides. (In fact, they are SO flat on the cam side that I can "wring" them together.)

Has anyone else heard that valve shims are domed? Maybe on other vehicles?

MudHippy

No you're right. They are flat, or they should be. I recently reset the clearance on all of my intake and exhaust valves. Which means I used a micrometer to gauge the thickness of each individual shim and every replacement. They were all the same thickness in their middle and near their edge. I had to order thicker intake valve shims from Toyota, but I actually ground down the six exhaust valve shims instead of buying thinner ones. I made sure they stayed flat during grinding, and were perfectly so before installing them. They act as a roller bearing, spinning inside the cam follower when the cam lobe pushes on them. They need to be flat on their bottom so they're as flat as the surface area where they meet the cam follower. If not they might cause excessive wear to the cam follower. They also need to be flat so that as they spin the valve clearance isn't constantly changing(which would happen if they were at any angle other than perfectly flat). And so the force applied to them by the cam is directed inline with the cam follower/valve stem. So as to not influence/induce valve tipping/valve guide wear, and/or cam follower wear.

The cam lobe doesn't strike the cam follower directly in the center of the shim, just off-center. Which imposes spin on either the shim and/or the cam follower. The spin is necessary so that the roller bearing effect can be utilized to reduce friction/keep the shim from being repeatedly struck in the same spot buy rotating it slightly each duty cycle. Which I'm guessing is also why they should be flat, not domed, and should remain so during use.

CylinderHeadSupply.com has shims for Toyota engines too. But they only sell them 4 at a time. Toyota sells them individually, each has it's own part #.

TNRabbit

Wouldn't it be a hell of a lot easier to grind a little off the top of the valve stem?

MudHippy

You've got a point. But that means the valve's gotta come out. But other than that it would definitely take less time to grind the valve stem. It's gotta be perfectly flat too though. That's where I would be hesitant in doing so. I'm worried I wouldn't be able to measure that accurately enough.

I'll go ahead and reveal my secret for grinding the shims perfectly flat. I used a cam follower as a holding tool for the shim. Then just apply even pressure while swirling and turning the shim on the side of the grindstone(provided it's good and flat).

TNRabbit

I thought you could Dremel the top of the valve stem, but you're right; it would be practically impossible to make it perfectly flat....

drkblu4runner

ya i wouldnt want to do it by hand.
i want ahead and gor the 2.40 shim $15.00

drkblu4runner

installed the 2.30 shim today and had .35 clearance .03mm out of spec but w/e



RUNS GREAT!! now just needs to pass ca smog