Zero compression on rebuilt engine

[NitroDann]

Remember there are hot clearances and cold clearances so you need to make sure you are calculating for a desired COLD clearance this way.

Dann

[project.r.racing]

valve were closing when you completed head rebuild?

[Mr Morlock]

I would recommend that you read the workshop manual info provided by Manga- not reading all this info may end yup with another prob- personally I think these are the best reference sources. I guess its pretty obvious that the valves are not seating. If after reading the info and you are not confident about doing it then perhaps pass it over to a professional guy.

[speed]

What Morlock said and if you do pass it over please remember to let us know what the problem was.


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[and1]

So finally had time to have a thorough check over this.

All the shims were indeed too thick after the new seats for the valves were done.

I had to call Precision Shims to sort out the new sizes. They ended up costing $9.90 ea inclusive of GST plus $12 for shipping. Costly adjustment

For reference here is my spreadsheet I made to measure the required thicknesses. Current shim thickness is around 3.1ish mm

My required shim thickness was calculated using the depth of the base where the shim sits to the lip of the bucket plus the clearance from the lip of the bucket to the camshaft base diameter (using feeler gauges) minus the required cold clearances for the lifters.



So hopefully the new shims arrive later this week and I can try to put everything back together by the weekend

[project.r.racing]

wow there is quite a large varience in all those.

[Mr Morlock]

As long as the correct methodology was used for the calculation then the shims ordered should be correct.

I agree that its costly but it has to be right - I would have thought Mazda would have a range of shims- apparently not.

On the exhaust range its only about 0.013mm 0.005 thou between the 2.97 / 2.84 shim variations. That variation does not seem much to me

I assume that the shim maker meets the +/-0.03mm / 0.001 tho tolerance stated by Mazda. It might not be a bad idea to check them before assembly.

Lets see how it all goes.

[greenMachine]

It might not be a bad idea to check them before assembly.

Lets see how it all goes.

ALWAYS check the clearances after assembly, and be prepared to replace a few. Odds on you mucked up at least one I know I did.

[project.r.racing]

I agree that its costly but it has to be right - I would have thought Mazda would have a range of shims- apparently not.

Mazda do. And they cost alot more than the above listed price.

[manga_blue]

When I bought from Precision Shims they offered to make to 0.02 or 0.01mm increments, as required. And yes, they're far cheaper and better than Mazda.

[project.r.racing]

Mazdas only come in 0.2 or 0.25 millimeter increments from memory. Heaps on Yahoo JP.

[Mr Morlock]

So what was the outcome?

[and1]

Shim specs were completely off.

After the correct size shims were fitted, compression was there. Happy days!

Now just trying to get my 949 Racing twin disk clutch to disengage properly

[mr bender]

have one with that^^^^


you need to make the throw smaller so it does not disengage then reengage.

I used a stop which screwed onto the middle of the clutch pedal arm, which hit the firewall at the right time the clutch disengage.

[Mr Morlock]

I think that was an interesting subject and seems to have ruled out the valve timing was a player. Excellent that its fixed.