bumpy
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| posted on 24/10/14 at 08:10 AM |
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Valve timing and the use of a camshaft vernier pulley.
If its OK with you good people I would like to have a bit of discussion about using a vernier pulley on a 2 litre Pinto engine (no valve to piston
issues).
First point to debate is:
What is the effect on performance when one adjusts the valve timing more advanced or more retarded?
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Paul Turner
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| posted on 24/10/14 at 09:25 AM |
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Only adjusting the valve timing will have very little effect. To get the best out of any vernier you need to have the car on a rolling road so the
fueling and ignition can be optimized to suit.
But the important thing to remember is there is no such thing as free power. Any gains you make in one area will mean losses in a different area.
In most cases mid range torque is way more important than top end power.
Its always a compromise and the manufacturers generally quote the best one with their figures.
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britishtrident
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| posted on 24/10/14 at 09:46 AM |
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With a single can engine unless you have a fairly hot cam the timing has to be be pretty far out to make much difference.
Twin cam engines are a more sensitive as with both cams adjustable the overlap period can be altered which can make a huge difference to the
driveability - maximum power trade off.
[I] “ What use our work, Bennet, if we cannot care for those we love? .”
― From BBC TV/Amazon's Ripper Street.
[/I]
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bumpy
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| posted on 24/10/14 at 10:08 AM |
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Thanks guys. In summary, even if the valve timing is a bit out, then I am unlikely under normal road running to notice much difference.
That's taken the wind out of my sales, as me engine is lacking in torque and I was hoping this would be the way to go.
I have a 'mild road' camshaft in my Pinto, of unknown heritage. Am I right in saying that with standard camshaft pulley it should be
aligned with the standard Ford engine markings.
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Dingz
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| posted on 24/10/14 at 10:52 AM |
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Possibly, the cam manufacturer will state the timing required at maximum lift ie Piper 285 for a pinto is 108° as you don't seem to know what
yours is then it is pot luck I'm afraid. But as said, for ultimate results you will need a RR session.
A piper 'mild road' is given as 113° btw but I don't know what the standard ford set up would be.
[Edited on 24/10/14 by Dingz]
Phoned the local ramblers club today, but the bloke who answered just
went on and on.
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mark chandler
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| posted on 24/10/14 at 11:27 AM |
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I disagree, moving the timing on a pinto does make a big difference.
You need to get it set up as per standard, so full overlap at TDC then advance the cam between 5 - 7 degrees, this will improve bottom/mid range by as
much as 10% at the cost of top end performance.
If you retard the cam by the same amount you will gain top end, maybe 5% but lose mid and low range by around 5%, so in the real world you drive
middle as that is where you drop the gears when thrashing it so get a little advance going.
Of course you will need to play around with mixtures and timing to get the full benefit, but you need to do this with standard settings so it's
not a problem, the cam is more a fixed item.
Regards Mark
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bumpy
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| posted on 25/10/14 at 12:51 PM |
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Probably worth experimenting as I have tried everything else to pep up the engine.
Does this strategy make sense?
With engine at the correct TDC, ensure the current camshaft is aligned properly against the engine markings.
Using white Tipex mark the position of the belt relative to the engine and camshaft pulleys.
Set the vernier pulley at its midpoint, then remove old camshaft pulley (without moving the camshaft or crankshaft positions)
Transfer the white Tipex markings to the vernier pulley and bolt that into place aligning all Tipex marks.
Fire up the engine and adjust the vernier back and forth to optimise torque output.
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Paul Turner
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| posted on 25/10/14 at 05:05 PM |
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quote:
Originally posted by bumpy
Fire up the engine and adjust the vernier back and forth to optimise torque output.
It will only work if the engine is on a dyno or the car on a rolling road. Without either you will never know if its better or worse.
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mark chandler
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| posted on 25/10/14 at 05:33 PM |
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No that will not do, it's guess work.
Weld a rod into an old spark plug then fit a timing wheel and work out exactly where TDC is, half the distance between each point that the engine
locks up when turning carefully by hand forward and backward, then adjust the timing wheel and pointer so this is exactly true then remove the welded
spark plug.
Next using a DTI gauge measure the cam followers at 1/4" lift and make a note of the timing, this is very important with a pinto, if the valves
are recessed in the head it affects the timing or the followers may not be ground true.
Now devide the degrees and set the camshaft to exactly marry with TDC, the Middle of both cam lobes lift point making sure you only rotate the engine
forward,
Now advance the cam by 5-7 degrees and lock it in place and leave it alone.
Regards Mark
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bumpy
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| posted on 26/10/14 at 09:29 AM |
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quote:
Originally posted by Paul Turner
quote:
Originally posted by bumpy
Fire up the engine and adjust the vernier back and forth to optimise torque output.
It will only work if the engine is on a dyno or the car on a rolling road. Without either you will never know if its better or worse.
Believe me, this engine is so down on torque that I would know. I'm not trying to wring the last few BHP out of it, but merely to get it to
pull at least as well as the 2 litre Cortina I used to drive (not the same engine BTW).
[Edited on 26/10/14 by bumpy]
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Paul Turner
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| posted on 26/10/14 at 06:23 PM |
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quote:
Originally posted by bumpy
Believe me, this engine is so down on torque that I would know. I'm not trying to wring the last few BHP out of it, but merely to get it to
pull at least as well as the 2 litre Cortina I used to drive (not the same engine BTW).
If the engine does not pull as well as a similar engine in a much heavier Cortina there is more wrong with it than valve timing.
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mark chandler
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| posted on 26/10/14 at 06:56 PM |
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It will run one tooth out on the cam pulley, but will be pretty hopeless in the power stakes.
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bumpy
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| posted on 27/10/14 at 08:35 AM |
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OK, What do I target as I think I've run out of other options?
1. Engine has only done 3000 mile since complete rebuild - low annual mileage. After a bit of a thrashing it runs a bit smoother but no increase in
torgue.
2. Head was off about a year ago. All valves good, unleaded seats reground, guides good, pistons and bores all good
3. New plugs and HT leads
4. Distributor changed for similar - vacuum and bob weights working fine.
5. All accessible jets on 32/36 Weber checked for cleanness
6. Air mixture screw optimised - all plugs nice golden brown
7. Ignition timing examined over the full range, from well retarded to too far advanced, to examine if there is a torque sweet spot - now set at best
point
8. Induction side checked for air leaks.
9. Air filter is new K&N.
10. Redex treatment tried.
11. Full throttle checked to ensure both chokes are fully open.
12. Camshaft and rockers almost new and valve clearances perfect.
13. Garage check of exhaust showed it to be just on the side of rich, but OK
I will recheck the camshaft alignment this morning.
The engine is standard, aside from a mild polishing of the head ports, a mild road cam fitted of unknown origin, and the air filter. It has standard
exhaust manifold, and dual downpipe, but the exhaust is short with twin silencers in line and exits under the drivers door.
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mcerd1
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| posted on 27/10/14 at 09:28 AM |
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your carb and dizzy don't sound like the issue here, but the are not exactly the highest performance options...
quote:
Originally posted by bumpy
The engine is standard, aside from a mild polishing of the head ports
what porting work was done ?
pinto's actually have ports that are too big - so any porting work should be to improve flow around the horrible sharp turn and around the valve
stem etc..
over polishing the ports does nothing for the airflow (it can even make things worse)
or has there been material removed in the combustion chamber to de-shroud the valves ?
if that's the case has work been done to restore / increase the CR ?
or even worse has it got the transit style low CR pistons ?
quote:
Originally posted by bumpy
a mild road cam fitted of unknown origin
this could be a big part of the problem !
Assuming its got no markings on it at all you need to at least workout what the max. lift is on the inlet and exhaust as well as the timings for these
(duration is a little harder to measure but can be done)
for this you'll need to know where true TDC is (the piston stop method is plenty good enough) so you can set your protractor on the crank
correctly as a reference point.
then you'll need the cam cover off and a dial gauge to measure the valve lift on No1 cylinder (measured in the same way as true TDC - to find
the middle of the max. lift)
its always worth a vernier to fine tune the cam position (as above you need a rolling road to measure the difference as you do it - how it feels
leaves too much room for error)
there is always a tolerance on the factory timing marks - and skimming the head doesn't help either - so who says the factory marks are
anywhere near the true positions ?
at least then you'd know what sort of cam your dealing with and that its timed 100% correctly 
quote:
Originally posted by bumpy
It has standard exhaust manifold, and dual downpipe, but the exhaust is short with twin silencers in line and exits under the drivers door.
the length of the primary exhaust pipes has a big impact on the torque and the rev's where the peak torque occurs
the stock ford manifolds are rubbish, a 4-2-1 setup is normally best for low/mid end performance and a 4-1 best for top end rev's
generally the longer the primary pipes the better...
[Edited on 27/10/2014 by mcerd1]
[Edited on 27/10/2014 by mcerd1]
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Paul Turner
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| posted on 27/10/14 at 12:31 PM |
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For what its worth here is my personal experience of adjusting cam timing.
Although I have been playing with engines since the mid 70's I never fitted one with a performance cam until about 1989 in a x-flow. Timed it
into Kents figures and performance was fine. After that I fitted another 3 different Kent cams in x-flows of different sizes, all timed to Kents
figures, all fine. During that period I was Hill Climbing and Sprinting, got a cabinet full of trophys so not doing too bad.
When I fitted the Zetec I bought a pair of Kent FZ2002 cams from my usual supplier, an engine builder of great experience. He knew the FZ2002 well and
his recommendation was to fit them using the slots just like you would standard Ford cams. Said he had tried timing them in to Kents figures as well
but the performance difference was minimal for the effort needed although he did add it was much easier using verniers.
Anyway, fitted the cams using the slots, new followers and off to the usual RR for setting up. Operator had no issues, 179 bhp at the flywheel which
he was happy with on a well used motor with 36mm chokes. Power peaked at 7200 rpm and the torque peaked at a surprisingly high 5700 rpm but it was a
very "flat" curve (if that makes sense).
Did several sprints that year, decent results, brilliant on a performance per pound basis.
Next winter I decided to check the cam timing, it was quite a few degrees out on both inlet and exhaust. Timed it to the correct figures using the
standard pulleys (what a pig of a job) and off to the RR again. On the way there it felt different. It took longer to set up than the previous year,
he really struggled to get the fuelling correct in the mid range. After his efforts it was producing 174 bhp at 7000 rpm but peak torque was now at
5000 rpm with gains of between 10 and 15 lbs/ft between 3000 and 5500 rpm.
So on paper it looked great, a small loss at the top end but very decent gains over the mid range.
On the road it still felt different. The extra torque was not really noticeable but low down it was not as docile as before. But I consoled myself
that it would be better on the track, surely it would punch out of corners way better with the extra mid range.
At the track my times were no different to the previous year.
So was my time and the expense of the RR session worth it. Basically no.
At least I was not slower.
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bumpy
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| posted on 27/10/14 at 04:34 PM |
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quote:
Originally posted by mcerd1
your carb and dizzy don't sound like the issue here, but the are not exactly the highest performance options...
quote:
Originally posted by bumpy
The engine is standard, aside from a mild polishing of the head ports
what porting work was done ?
pinto's actually have ports that are too big - so any porting work should be to improve flow around the horrible sharp turn and around the valve
stem etc..
over polishing the ports does nothing for the airflow (it can even make things worse)
or has there been material removed in the combustion chamber to de-shroud the valves ?
if that's the case has work been done to restore / increase the CR ?
or even worse has it got the transit style low CR pistons ?
quote:
Originally posted by bumpy
a mild road cam fitted of unknown origin
this could be a big part of the problem !
Assuming its got no markings on it at all you need to at least workout what the max. lift is on the inlet and exhaust as well as the timings for these
(duration is a little harder to measure but can be done)
for this you'll need to know where true TDC is (the piston stop method is plenty good enough) so you can set your protractor on the crank
correctly as a reference point.
then you'll need the cam cover off and a dial gauge to measure the valve lift on No1 cylinder (measured in the same way as true TDC - to find
the middle of the max. lift)
its always worth a vernier to fine tune the cam position (as above you need a rolling road to measure the difference as you do it - how it feels
leaves too much room for error)
there is always a tolerance on the factory timing marks - and skimming the head doesn't help either - so who says the factory marks are
anywhere near the true positions ?
at least then you'd know what sort of cam your dealing with and that its timed 100% correctly
quote:
Originally posted by bumpy
It has standard exhaust manifold, and dual downpipe, but the exhaust is short with twin silencers in line and exits under the drivers door.
the length of the primary exhaust pipes has a big impact on the torque and the rev's where the peak torque occurs
the stock ford manifolds are rubbish, a 4-2-1 setup is normally best for low/mid end performance and a 4-1 best for top end rev's
generally the longer the primary pipes the better...
[Edited on 27/10/2014 by mcerd1]
[Edited on 27/10/2014 by mcerd1]
Very minor removing of casting marks and smoothing (not mirror finish). Very little metal was removed from around the valve guides, which I have read
can become a weak point
No evidence of metal removed from chambers
Pistons fitted are level with the top of the block
I just took the car out for a bit of lively driving it seemed reasonably happy revving to 4000rpm, above which it made hard work of getting to
5000rpm. Foot was on the floor to achieve this and although keeping up with the traffic it wasn't a blistering pace.
Is this typical of a fairly standard 2l Pinto?
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bumpy
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| posted on 27/10/14 at 04:45 PM |
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Here's one bit of info that may prove helpful in your diagnostics.
When I had the head off (unleaded seats) the ignition timing was set accurately at 8 deg BTDC with vacuum disconnected using a professional gun.
Driving home, the performance was pathetic and the car would not have pulled the skin off a rice pudding 
So I advanced it by ear and some performance came back. It was easy to tell when over advanced as the starter motor struggled to get it over the
ignition stroke. Even here I don't think there was any real evidence of pinking, but then the car is quite noisy and I may just have missed it.
As expected, when over advanced the performance fell off again.
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mark chandler
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| posted on 27/10/14 at 05:48 PM |
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A pinto will happily Rev out to valve bounce and beyond, do your advance weights work correctly in the distributor, if not I would look at the cam
being out a tooth or blocked carb, where do you live?
[Edited on 27/10/14 by mark chandler]
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bumpy
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| posted on 27/10/14 at 07:50 PM |
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quote:
Originally posted by mark chandler
A pinto will happily Rev out to valve bounce and beyond, do your advance weights work correctly in the distributor, if not I would look at the cam
being out a tooth or blocked carb, where do you live?
[Edited on 27/10/14 by mark chandler]
Thanks again for your continuing advice. I will check the bob weights on the 'new' and 'old' dizzy. I guess if they are the
same then its OK.
After driving the Pinto around 'rapidly' for some time I went out in the Astra 1.4 family saloon. Oddly, it leaves the Pinto for dead in
terms of torque typified by a kick in the rear when putting the pedal to the floor in 1st and 2nd gear. It also revs quite happily into the red at
6500rpm.
Also tomorrow, I'm going to recheck that the accelerator pedal is fully opening the carb and am going to swap out the mechanical fuel pump.
BTW
I'm in Bishops Stortford in Herts.
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bumpy
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| posted on 28/10/14 at 12:06 PM |
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quote:
Originally posted by bumpy
It was easy to tell when over advanced as the starter motor struggled to get it over the ignition stroke. Even here I don't think there was any
real evidence of pinking, but then the car is quite noisy and I may just have missed it.
Well had a quick look this morning before going out.
A few months ago I took off distributor 1 as the vacuum advance/retard did not work and replaced it with distributor 2 off a working engine, where of
course the vac system was working.
Today I checked the bob weights on distributor 2 and aside from moving a bit they are not operating over anything like the range of distributor 1.
This could explain why distributor 2 has a better tickover but wont pull. It also explains why the engine never pinks. 
This afternoons job is to build one good distributor from the two and see where we go.
Out of interest, I have heard of people disabling the vac system, but is there any good reason why the bob weights would be disabled on purpose?
[Edited on 28/10/14 by bumpy]
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Paul Turner
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| posted on 28/10/14 at 12:24 PM |
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When early incarnations of mapped ignitions were introduced they normally used the distributor as both a pick up and for spark distribution. If the
mechanical advance was not locked the system would simply not work as designed.
So if the mechanical advance is locked or disabled there is a chance it could have been used with an early ecu.
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bumpy
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| posted on 28/10/14 at 01:06 PM |
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Sorry guys but a false alarm on this. I rapidly checked distributor 1 this morning on my spare engine under the bench in the dark.
What seemed to be a big movement of the bob weights was the distributor rising up on its worm drive, where it was merely resting in the hole and not
bolted down
Bottom line is that the current distributor has fully functioning vacuum and bob weights.
Its amazing how one can fit a good explanation to any 'facts'
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mcerd1
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| posted on 28/10/14 at 02:47 PM |
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quote:
When I had the head off (unleaded seats) the ignition timing was set accurately at 8 deg BTDC with vacuum disconnected using a professional
gun. Driving home, the performance was pathetic and the car would not have pulled the skin off a rice pudding
8° static advance seem very low for a pinto - even stock camshafts normally need 12° advance as a minimum - and the wildest cams are all the way up
at 20°
of course that's assuming all your timing marks are spot on - unless you've checked this then your just guessing...
I still think the cam is suspect too - measuring the actual valve lift its giving you would at least eliminate it as a reason if nothing else
the pinto valve train has a strange geometry so things like longer valve stems actually reduce lift (common on some aftermarket oversized valves) and
so does using the wrong followers or ball studs
measuring the actual valve lift and timing will answer a lot of questions 
if you don't have the tools to do this you can get a DTI with a magnetic stand for less than £20 these days:
linky
and you normally get a timing disc (aka protractor) for the engine thrown in with a vernier pulley or camshaft, but they are normally less than £5 if
you've not got one linky
and a piston stop tool is just an old spark plug with the middle hollowed out and a bit of bar welded/bolted in place
even s/h timing strobes are dirt cheap on the likes of ebay etc..
it might seem like a lot of hassle to check the timing marks and measure the lift - but knowing that its all 100% correct is worth it the long run
[Edited on 28/10/2014 by mcerd1]
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bumpy
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| posted on 28/10/14 at 04:06 PM |
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Changed the mechanical fuel pump for a much more modern version. The improvement was worth the effort, but not solved my initial problem.
Checked the full opening of both chokes in the carb by pulling on the cable cam near the carb - both opened nicely
BUT
When I got the wife to sit in the cab and floor the throttle the first choke opened but the second choke barely twitched .
I am optimistic this could be it.
There is no obvious adjustment up at the carb, but the cable attachment to the throttle pedal looks suspect. It attaches the cable at least an inch
below what looks to be the normal attachment point. This makes it closer to the pivot point and will give reduced travel to the cable, so I will have
to work out how to fix it.
 
throttle pedal
[Edited on 28/10/14 by bumpy]
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Paul Turner
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| posted on 28/10/14 at 04:13 PM |
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On the 32/36 carb I had back in the early 80's the 2nd choke was operated by vacuum. If there is none it won't work.
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