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Subsequent step is to verify the massive finish clearances. I’ve measured the journals, however I wished to get some proof of the clearance that I had ended up with after becoming new -0.030″ shells. There is not a lot element on what the suitable clearance is earlier than you need to regrind, aside from the info describing the sizes you regrind to and the advice that there ought to be minimal clearance after regrinding.
Waller signifies 0.003″- 0.004″ for the massive finish shells used on 1948-1955 Sq. Fours (Fifth version web page 37); Phil Irving quotes 0.001-0.0015″ clearance per inch of diameter (Tuning for Velocity third Version), which equates to 0.00165 – 0.0025″ for my 1.65″ huge finish. Mr. Irving, in any other case often known as ‘Slide Rule’ utilizing these pleasant pseudonyms beloved of motoring writers within the ’40’s, additionally notes that the clearance will be a lot bigger so long as oil strain is maintained.
So, let’s introduce Plastiguage. It is a paste, extruded into rods a bit like Plasticene. You lure a bit within the bearing and squash it, in order that the recognized Plastiguage rod diameter is squashed to take up the clearance of the bearing – you then use the cardboard supplied to find out the clearance from the width of the squashed Plastiguage. Plastiguage is available in totally different sizes to measure totally different clearance ranges.
So, you chop a size to suite the bearing like this, and you then make up the bearing. You ensure the bearing is clear first.
If you open the bearing once more you may see the squashed Plastiguage and you’ll examine it to the cardboard. This implies one thing like 0.002 – 0.0025″ clearance for the drive facet. I am proud of that.
That is the timing facet, and it is about the identical:
All good there then. Subsequent job is to verify the oil flows into the massive ends. I am going to inject it into the timing facet oilway:
And it comes out the drive facet huge finish!
Blissful days.
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