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Not a good thing. Lousy quality control or training on their part for this step of the process You lost 25% of the vacuum transfer with this hole blocked. There should have been a pretty dramatic change in the lifting capability with sudden changes of the throttle. good catch on your part to see it when you disassembled it. Let us know if there was a change in reaction times once you put it back on the road.
to be honest, this ute ran quite well as a dedicated system, gave better economy compared to same equipped same model, same engine - just 450,000 fewer kms. One deliverewd 540kms to 70 litres. The one with fresh engine and three air transfer holes did 540kms to 65 litres - then I changed exhaust for slightly larger - went even better. Added a US market inlet manifold with an efi throttle body to better my adaptation of other components. The new manifold is 6mm larger ID to the heads then normal. Was drinking fuel, running poorly - all due to a pair of tight valves.
Before discovering the tight valves I added more power valve fuel. Gave variable poor economy. Cruise dropped from 15.5 to 15.1 , power down to 12.7:1 at times So added a leaning ring to see what I would get in AFR's, driveability etc - found this sticker placement..... Getting cruise of stoich and then higher as soon as level of road drops. Feels like good power at 14.9 and 15:1 on asking of the loud pedal at 110 kph !
Drives really well now, like it did before tight valves. No dyno to give true figures, but next tank full should give another indication .
Next tune may start with idle mixtures - just had something in its way to adjust.
Does anyone know about altering the hole sizes of the vacuum transfer holes in the pic ?
Damn u guys....if hadnt mentioned it I would not have worried...
Im pretty sure from memory the sticker on my valve is in a very similar position....
now reading this Im going to have to check... I think the engine is still under hood.. was at the last oil change
Nah leave it for next week sometime.. heading out for some serious fishing in a couple days 25+lb snappers , and 35+kg king fish....
Like C3H8 stated, the holes are there to transfer vacuum, with the blockage providing the results he stated. The hand written number indicates a flow bench rating as compared to a reference unit. Generally speaking, numbers below "90" are lean biased while numbers above that are rich biased.
I have been on the factory floor too many times to remember and saw them flow testing the units. If they were too far out of calibration, they used a jig with a brass mallet, and gave it a quick "whack", followed by another flow test. If it wasnt in calibration then, they tried one more time, but if it was still out, it went into a bin for more work, often winding up in the trash after the diaphragm was salvaged.
