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6 cyl Bristol cars Type 400 to 406 - restoration, repair, maintenance etc

B400 - rocker adjustment

 
 
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Old 07-06-19, 01:27 AM
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Join Date: Jul 2008
Location: Sydney, Australia
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Bela ,

although the scan is quite clear to view , the information is not written in a form to express the valve timing correctly.

But after trying to sort out the information ,my comments are as follows (assuming a 403 camshaft is fitted or camshaft ground to 403 spec )

Inlet lobe lift of .180 inch (should be .205)
Exhaust lobe lift .200 (should be .205)
So possibly a worn camshaft or reground to a completely different grind.

Timing Inlet opening 34 BTDC
Inlet closing 44 ABTC
give duration 34 + 44+ 180 = 258 degrees (close to early 403 of 260 deg)

But the original standard early 403 timing is 15 BTDC - 65 ABDC ,
So it looks like if the timing is set as per those notes and the camshaft is a 403 cam or 403 grind , it is set about 19 deg too far advanced. Probably one tooth .
But these notes could have been taken during initial assembly (how accurately is unknown) & was corrected before final assembly .

Do you have a TDC mark on the front pulley or damper with a pointer ???
If so , set the number 1 inlet valve clearance at .002 cold, turn engine over until the clearance just closes (when you can no longer move the rocker sideways) and measure the distance between the pointer and TDC mark . Then calculate the approx opening of the inlet valve.
This ,although not an accurate measurement , will still show if the valve timing is set too far in advance or they adjusted it on assembly.

I hope this helps
Geoff
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