Cams and timing query..
Posted: Tue Jul 02, 2019 1:40 pm
Hi all
Apologies in advance for the length of this post..
My initial investigation into a leaky water pump now has me wondering what else may be uncovered as I pull things down...
Thought it would be a good idea to set cam timing before commencing the pull down of the head / front cover etc.
At this stage the lump is still in the car. This may change!
After getting it to TDC I looked at the cam marks and they were a bit out.
Exhaust when aligned horizontal required the timing to be around the 10? BTDC mark. The inlet mark was not pointing at the exhaust mark..
Thinking the mark on the pulley may also be slightly out I got out the dial gauge to double check and with a little bit of allowance for the dwell at TDC the pulley mark is pretty much spot on.
At least I have a base line, start to strip the head. Happy days...
Head is now off & I am kicking myself (to save you guys the trouble) as I really really should know better after all these years, that I did not take more measurements including getting a crank angle gauge and measuring the valve MOP.
Score 0 for patience.. Dohh!!!
Hell, I didn't even do the compression but that takes a bit of doing without a starter motor... another story..
Now, the curious thing is that one cam has a machined groove indicating a C type cam and one has no groove indicating a B type ??
Message to self, should have Noticed this rather obvious difference and put the sprockets back on & measured the valve opening with the dial gauge....before whipping the head off!
More self flagellation!
Quick and dirty check with cams in head indicates possible different lift... Though granted it was getting late & this is not exactly a scientific method!!
Have not measured the lobes or base circle as yet as now away from the car for a while but a point to point with a digital caliper when I noticed the oddity indicated 0.8 'taller' inlet cam. 36.46 mm V 35.68 base to tip.
This then had me looking at the cars previous history and there is an itemized bill from 20 or so years ago indicating head reworked and 2 x CPL2 cams.
I have some doubts on these as it was a non specialist garage only bill and the price was ?40 each... Nothing in the file from supplier to substantiate this or where the cams came from.
?40 seems cheap even 20 years ago but I guess they may have been reprofiled? If so is there anyway if identifying who by and what they did?
Has anyone come across this before? 2 x potentially different cams / profiles on a road car?
Could it be deliberate and not just a PO bodge?
Was it just what a can reproduce had available in an exchange basis hence the difference with the grooves?
Have done a lot of searching on here, the wider net and Mr Wilkins book and so far drawn a blank.
Odd thing is when I first got it home, after it had pretty much stood for 10 years, following an oil and filters service even with a knackered distributor (rotor arm was machining the cap away..) and over fuelling / spitting carbs it was pulling pretty well..
Although with hindsight it did seem to take an awful long time to fill with fresh oil..
Park it up for a couple of months for other work (rear A arms etc) and the water pump leaks...
Those seals don't like to be sat idle do they?
Currently reviewing possible options as have been finding a few other issues including a spurious looking bolt in the front of the timing cover, yet to be investigated.
The original plan was a rolling resto and try and use it this summer for more attention over the winter.
Now not sure as to the best course of action.
Not had chance to look in detail at the rest of the head or the bores for condition other than it looked a bit grungy especially number 4 but I was kind of expecting that next to the breather location in the air box. Really wish I had done the compressions when I serviced it...
Head bolts came out reasonably until trying to get them fully loose.. Looks like they may have been in / off and possibly over done as the washers have bitten the head in places.
next find was a considerable amount of very old and smelly oil in each head bolt hole
Bolt threads came out really covered in it and really carbonned up.
It absolutely stinks & has me a little concerned as the previously drained oil other than having a slight whiff of fuel (hardly surprising given the above) seemed quite clean.
The memory of how long it took to refill it makes me wonder if the oil ways / drains are clear?
Now, the big question:
Do I bite the bullet, pull the block out and do a full rebuild or do I get and just do a top end refresh, new pump and gaskets and try and 're time the possibly spurious cams?
Any advice, spare parts, beer vouchers, full engine for free or a pittance or the loan of a car for the summer welcome
Regards
Mel.
S3 SE: getting less complete and more expensive by the day..
But still smiling ... For now.
Apologies in advance for the length of this post..
My initial investigation into a leaky water pump now has me wondering what else may be uncovered as I pull things down...
Thought it would be a good idea to set cam timing before commencing the pull down of the head / front cover etc.
At this stage the lump is still in the car. This may change!
After getting it to TDC I looked at the cam marks and they were a bit out.
Exhaust when aligned horizontal required the timing to be around the 10? BTDC mark. The inlet mark was not pointing at the exhaust mark..
Thinking the mark on the pulley may also be slightly out I got out the dial gauge to double check and with a little bit of allowance for the dwell at TDC the pulley mark is pretty much spot on.
At least I have a base line, start to strip the head. Happy days...
Head is now off & I am kicking myself (to save you guys the trouble) as I really really should know better after all these years, that I did not take more measurements including getting a crank angle gauge and measuring the valve MOP.
Score 0 for patience.. Dohh!!!
Hell, I didn't even do the compression but that takes a bit of doing without a starter motor... another story..
Now, the curious thing is that one cam has a machined groove indicating a C type cam and one has no groove indicating a B type ??
Message to self, should have Noticed this rather obvious difference and put the sprockets back on & measured the valve opening with the dial gauge....before whipping the head off!
More self flagellation!
Quick and dirty check with cams in head indicates possible different lift... Though granted it was getting late & this is not exactly a scientific method!!
Have not measured the lobes or base circle as yet as now away from the car for a while but a point to point with a digital caliper when I noticed the oddity indicated 0.8 'taller' inlet cam. 36.46 mm V 35.68 base to tip.
This then had me looking at the cars previous history and there is an itemized bill from 20 or so years ago indicating head reworked and 2 x CPL2 cams.
I have some doubts on these as it was a non specialist garage only bill and the price was ?40 each... Nothing in the file from supplier to substantiate this or where the cams came from.
?40 seems cheap even 20 years ago but I guess they may have been reprofiled? If so is there anyway if identifying who by and what they did?
Has anyone come across this before? 2 x potentially different cams / profiles on a road car?
Could it be deliberate and not just a PO bodge?
Was it just what a can reproduce had available in an exchange basis hence the difference with the grooves?
Have done a lot of searching on here, the wider net and Mr Wilkins book and so far drawn a blank.
Odd thing is when I first got it home, after it had pretty much stood for 10 years, following an oil and filters service even with a knackered distributor (rotor arm was machining the cap away..) and over fuelling / spitting carbs it was pulling pretty well..
Although with hindsight it did seem to take an awful long time to fill with fresh oil..
Park it up for a couple of months for other work (rear A arms etc) and the water pump leaks...
Those seals don't like to be sat idle do they?
Currently reviewing possible options as have been finding a few other issues including a spurious looking bolt in the front of the timing cover, yet to be investigated.
The original plan was a rolling resto and try and use it this summer for more attention over the winter.
Now not sure as to the best course of action.
Not had chance to look in detail at the rest of the head or the bores for condition other than it looked a bit grungy especially number 4 but I was kind of expecting that next to the breather location in the air box. Really wish I had done the compressions when I serviced it...
Head bolts came out reasonably until trying to get them fully loose.. Looks like they may have been in / off and possibly over done as the washers have bitten the head in places.
next find was a considerable amount of very old and smelly oil in each head bolt hole
Bolt threads came out really covered in it and really carbonned up.
It absolutely stinks & has me a little concerned as the previously drained oil other than having a slight whiff of fuel (hardly surprising given the above) seemed quite clean.
The memory of how long it took to refill it makes me wonder if the oil ways / drains are clear?
Now, the big question:
Do I bite the bullet, pull the block out and do a full rebuild or do I get and just do a top end refresh, new pump and gaskets and try and 're time the possibly spurious cams?
Any advice, spare parts, beer vouchers, full engine for free or a pittance or the loan of a car for the summer welcome
Regards
Mel.
S3 SE: getting less complete and more expensive by the day..
But still smiling ... For now.