Simon:
(1) Optimally speaking, '0' degrees is what you would have
on a new engine. Practically speaking, on a conventional
OHV engine w/crank driven, chain-to-cam connection, you
should not have over '2' degrees of wear to be within a
reasonable wear-to-age reading. Meaning, on a 5-yr old
engine, less than '2' degrees if clean oil and proper
oil filtration was used. On a 10 year old engine it may
go into the '10' degree range. This depends upon the
physical design/type of the chain; whether the cam gear
is steel, aluminum or a nylon mold over a tooth pattern
as is the OEM GM gears. The nylon cam gears are VERY
dependent upon a clean, abrasion free, oil supply. And
the chain will erode the nylon in the presence of high
heat as encountered in a racing environment or normal
driving with dirty oil. I think '5' degrees would be
telling me it's time to get a new setup if I was using
it for racing. Grocery getters can get by with anything.
(2) Normally speaking, here in CONUS, we use Sealed
Power, truck, or roller chain with a matched steel
(two rows of teeth) gear. Usually as a set. GM uses
the nylon gear as it is a bit quiet-er. If you want
o spend big bucks, then go for one of the Hi-Perf brands.
But, trust me, the HD, truck, roller chain-n-gear from
Sealed Power is very hard to beat. But I speak from a
SBC/BBC podium. Not sure about Rover/B-215. Will have
to look it up and see what is offered by Sealed Power.
Cheers,
Mr. Shadow (Ret)
At 19:07 99-02-08 +1300, you wrote:
>Thanks, sounds like a good idea. What would you recommend as acceptable
>numbers for the timing chain? Maybe 5 degrees or less of slack?
>
>-----Original Message-----
>From: Shadow@RTD.COM [mailto:Shadow@RTD.COM]
>Sent: Monday, 8 February 1999 18:47
>To: Buick-Rover-V8 mailing list (E-mail)
>Subject: RE: Camshafts/timing gear wear test.
>
>
>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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