Installing Cams: Clearance and Fitment Questions

[CBatstone]

My engine is going together, and the head has been mounted and torqued.
The Valves and guides have not bee changed on this head, it was checked
by a machine shop and certified as straight and good.

I bought a set of used cams from a 7MGTE that were in better shape than
the ones I had. They were installed along with a new set of lifters.
When the cams are on their base circle there is over an 1/8th in of
clearance between the cam and lifter. When you try to rotate the cams
the hit they hit the lip on the edge of the lifter and will not turn.

The Cams will not spin, it is slightly odd. We are going to check the
old cams to see how they fit up compared to these new ones. We do not
believe that either set of cams was ever modified.

Thanks for any help,
Craig

 

[IJ.]

Craig: Can you post some macro pics showing the Lobe to head interference please?

If they're regrinds there's nothing that could have been done that would make the lobe hit the head (which 1/8th clearence suggests)

I'm guessing maybe billets that have been ground on a non standard base circle to use jz valves.

 

[supraguy@aol]

Umm, aren't the shims about 1/8" thick???
PLEASE tell me you have the shims in on top of the lifter buckets.
Please?

 

[Mrbaboon]

Umm, aren't the shims about 1/8" thick???
PLEASE tell me you have the shims in on top of the lifter buckets.
Please?

At least I'm not the only person thinking this.

 

[CBatstone]

I mentioned to my mechanic (car is several states away) that I had read about spacers, but he did not see any when disassembling the head the last time.

We do not believe that the cams were ever reground, but that cannot be proven.

What is the purpose of the spacers, would this prevent the cams from spinning even if they are 100% required?

 

[starscream5000]

They are called shims. They sit in a little recess on top of the shim buckets, which slide over and cover up the valve springs. The shims ensure that the intake and exhaust valves open up to the required legths when the cam lobes pass over them per the TSRM specs.

 

[IJ.]

Craig: We need pics.

Anything else is just guessing and this won't help you.

 

[CBatstone]

Is there a standard thickness of the shims. Trying to figure out how these would be ordered.


I could get pictures taken but it sounds like this is a clear issue. I am not sure of the variables involved and can get some pics taken if it would really help.


"You can get replacement valve shims from toyota for $$$$$$ or you can
go to your local machine shop and get them $$. If your machine shop
doesnt stock them look around more. I get mine from a machine shop for
3 bucks a piece."

 

[supraguy@aol]

The shims are not added in case the clearances are off. It's true that they come in different thicknesses for adjustment, but they are a mandatory part of the valvetrain.

 

[jdub]

This makes the calculations easy:
http://www.supramania.com/forums/showthread.php?t=50674&highlight=valve+shim

Might want to read this:
http://www.supramania.com/forums/showthread.php?t=42226&highlight=valve+shim

An alternate source for valve shims:
http://www.supras.com/06/techcenter/display.php?QID=82


If the shims are too thick, the machine shop "should" be able to grind down to the correct thickness.

 

[IJ.]

Craig: Sorry it's NOT a clear issue in any way.

If you can arrange a pic it will be easy to tell if it's just some genius has removed the stock Shims or that you have some bizarre cam grind as I posted earlier.

 

[CBatstone]

So here is where we are at, and thank you for all the help everyone...

My mechanic honestly does not know where the shims went, and doesn't even remember seeing them. I personally saw a bunch of the buckets/lifters and did not see any other pieces of metal going along with the head, so now we are starting from scratch.

He called me today and asked me to find out how we are supposed to measure something that looks like an eighth inch gap down to .010 accuracy, especially when we don't have a starting point. (or a starting shim to use)

Any suggestions for how we should go about this having no shims at all. Toyota does not have a standard size, or a starting place to recommend. We could order some random ones, but I imagine you'd at least want to do one cam at once.

My whole car is being held up by this head issue, the head issues in the past being the single most complicated and pain-in-my-ass part of the build.

I was ripped off 175$ once by someone in Wisconsin, but still should have purchased a fully rebuilt head, had I known all of the costs and hassle.

Craig

 

[AJ'S 88NA]

So here is where we are at, and thank you for all the help everyone...

My mechanic honestly does not know where the shims went, and doesn't even remember seeing them. I personally saw a bunch of the buckets/lifters and did not see any other pieces of metal going along with the head, so now we are starting from scratch.

He called me today and asked me to find out how we are supposed to measure something that looks like an eighth inch gap down to .010 accuracy, especially when we don't have a starting point. (or a starting shim to use)

Any suggestions for how we should go about this having no shims at all. Toyota does not have a standard size, or a starting place to recommend. We could order some random ones, but I imagine you'd at least want to do one cam at once.

My whole car is being held up by this head issue, the head issues in the past being the single most complicated and pain-in-my-ass part of the build.

I was ripped off 175$ once by someone in Wisconsin, but still should have purchased a fully rebuilt head, had I known all of the costs and hassle.

Craig

If you could find a scrap head with the shims and buckets intact, you could have a starting point. Short of just buying some in different sizes from Toyota to see what you might need to clearance them. Your machinest should be able to check how much gap you have now without the shims, then check the sizes toyota has minus the gap you are supposed to have, buy a few sizes close to what you think you may need and see what they gap at. I think most dealers stock different sizes, or aleast they used to, to do the samething. Like IJ said it's not a straight forward thing. About the only thing you can do a this point is guess at some of the sizes you may need. Sorry Craig.