Simon:
There is a very easy way to determing wear, in crank degrees,
of a timing chain/assy. It is assumed you have a timing degree
marker/tab/plate/etc that you can see (and clean first). Do it
this way...
(1) Pull distributor cap off and remove spark plugs to
bleed compression off as you...
(2) Turn engine BACKWARDS up to the indicated TDC mark
on vib-dampener at the pointer. Ie.. '0' deg. mark.
You must turn BACKWARDS first to take up all slack
in the cam drive chain/gears/dist/etc... as the wear
is in the FORWARD direction only. Then...
(3) Turn engine FORWARDS until the rotor on dist. just
starts to move. Stop and then...
(4) Look at the timing mark(s) and it will tell you how
many degrees the crank is running ahead of the cam
due to the wear/slack/etc.. in the whole valve train.
(5) Or, in other words, how many crank degrees the cam is
late (or behind) the crank due to drive parts wear.
(6) I have seen 289/302 Fords and many SBC engines show
wear in excess of the 8, 10, 12, degree marks on the
timing tab. If you don't have lots of degree marks
to use as indicators, make youself some 'guestimate'
marks to go by.
Cheers
Mr. Shadow (Ret)
At 10:07 99-02-08 +1300, you wrote:
>Bradley,
>
>Thanks for the reply. I was reading a book on the weekend and it suggested
>(as I had decided to try anyway..) using a dial gauge or vernier callipers
>to measure the valve lift from the rocker arms with the rocker covers off. I
>wouldn't expect to get totally accurate readings from this, but what I'd be
>looking for is one valve with less lift than another. From what I've read,
>camshafts don't wear out evenly, but tend to go on one or two lobes only. If
>all 16 valves have the same amount of lift, it would indicate to me that the
>camshaft is OK. Obviously I'll have a better look when it comes time to swap
>the cylinder heads over.
>
>The question of timing chain stretch is an interesting one, does anyone know
>how this could be looked at without dismantling the engine? Could you tell
>if the chain was stretched by moving the crank backwards and forwards to see
>if there is any 'delay' in the camshaft moving as well?
>
>Simon
>
>-----Original Message-----
>From: Bradley Temperley [mailto:braddles@bigpond.com]
>Sent: Sunday, 7 February 1999 02:02
>To: Simon Sparrow
>Cc: Buick-Rover-V8 mailing list (E-mail)
>Subject: Re: Camshafts
>
>
>You should also check the state of the timing chain. If this has stretched
>your
>cam timing will be out. You'll probably notice economy getting worse around
>town before any loss of upper end power.
>The original chain was single row with nylon toothed sprocket for quietness.
>An
>australian Rollmaster double row chain and sprocket set is about A$120 and
>about
>A$95 for a set of standard hydraulic lifters.
>I don't have any suggestions about checking the cam in situ but perhaps an
>engine builder can 'measure' the cam for you.
>I've been told by a friend who has swapped Rover cams that the Rover
>workshop
>manual records the angles differently to the way cam manufacturers do it so
>the
>numbers might seem way out. Most info I've seen suggests that the stock
>standard cam is great when you want to keep low end torque.
>#$^)
>
>
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