1HZ Head Rebuild Questions (1 Viewer)

[zuker81]

Hi Folks,

Putting on a new 1HZ head while re-using a few components and have some questions. If anyone has input on the following, I'd greatly appreciate it.

Lifters - In a very unfortunate event, I got the valve lifters/cups completely out of order when removing them. My assumption is they are identical regardless of the valve, but have worn differently. Am I fated to measure clearance and re-shim every single one? Or is there a trick I could use to try to get them back into order and not have to drastically re-shim? Valves and springs are new, camshaft is from the old head.

Camshaft and bearings - as the head is new, how risky would it be to install the old camshaft (assuming it meets tolerances in the service manual) onto the new head's fresh bearings?

Injection Nozzles - the service manual also mentions keeping these in order, however in my infinite wisdom i definitely did not do that. As long as they've been tested, how important is the cylinder order here??

 

[lelandEOD]

When my machinist built my head, he measured the individual shim thicknesses and ground each valve stem to set the valve clearance.

I'm not aware of any requirement to replace the head and cam as a pair so you should absolutely be fine reusing your old cam.

I think the intent of keeping things like your injectors in order is based on the assumption that you are removing something and reinstalling it without any further reconditioning. I had all six of my injector nozzles rebuilt so I didn't worry about which cylinder got which injector.

 

[zuker81]

Thanks a bunch - this all makes sense, except one part. I thought you add/adjust shim thickness on the lifters to obtain valve clearance, rather than grinding the valve stem?

 

[GTSSportCoupe]

Thanks a bunch - this all makes sense, except one part. I thought you add/adjust shim thickness on the lifters to obtain valve clearance, rather than grinding the valve stem?

The shim sits in a bucket which in turn sits on the end of the valve stem. Make any of the parts thinner/thicker shorter/longer and you've changed the valve clearance. Usually as the valve wears or is ground, the clearance between shim/cam gets too tight. By grinding the end of the valve, you can get the right clearance again.

It's standard for an automotive machine shop. They just measure everything with the head together, disassemble, grind the prescribed amount of each valve stem and put it back together. Voila, you have the right clearances.

Swapping out shims is the way to do it with the cylinder head bolted to the engine. Can't remove valves to grind them in that instance.

When I had the head on my 2LTE rebuilt, the automotive machine shop ground my valve stems too. I checked all the clearances when I got home with it and they were all perfect. Incidentally the 2LTE and 1HZ use the same valve springs/buckets/shims etc.. Also the valves are the same size (stem length/width anyhow). It's the same system used across the board for 1HZ, 1PZ, 1KZ, 1HD, 2L, 3L etc. motors. (1990+)

 

[zuker81]

Cheers - i see now. I hadn't thought about the additional height from grinding the valve seat being too high for a shim etc. In my case the head and valves are all new.

 

[mudgudgeon]

In my case the head and valves are all new.

In this case it doesn't matter which bucket goes on which valve. You'll be measuring and adjusting at each valve regardless because you have different components.

Shims are available in kits,
or you can reuse your original shims by measuring shim thicknesses and recording clearances, then shuffle shims to give you correct clearances where possible, then order new shims of the right thicknesses for remaining valves.

If your camshaft journals are in good condition, and clearances to new bearings are correct, there's no reason not to run existing cam.

I wouldn't worry about mixing injector positions either.