Pinto timing = i'm confused
jps - 4/5/18 at 06:54 AM
I'm just about to take the timing belt and all the pulleys off my Pinto and am confused!
For refitting the Haynes manual tells me that the TDC pointer on the camshaft sprocket should be lined up with the mark on the head. And the TDC mark
on the crank pulley should be lined up with the ridge used for setting the timing. But currently they are not. The only thing I have done is taken the
crank pulley off then refitted it. But that has a spline - so it's not like I can put it back on 'wrong'.
Pics here show how the marks (don't) line up at the moment.
Camshaft sprocket lined up to its mark
Description
Crank pulley is way out - the TDC mark is about 45 degrees of where I think it's supposed to be?
Description
What confuses me is: the timing belt has not been touched on this engine since it was in my Sierra - and it ran fine (I did about 200 miles in it
before removing the engine).
So what have I got wrong / misunderstood? Why don't the marks line up (but the engine ran like this)?
Smoking Frog - 4/5/18 at 07:35 AM
Have you got number 1 piston on compression stroke. Line up the crank shaft pulley on compression stroke, not exhaust stroke.
theconrodkid - 4/5/18 at 07:54 AM
timing is out, start again, crank to TDC,cam as it is and rotor arm pointing to NO 1 segment on the dizzy cap....job done
nick205 - 4/5/18 at 08:13 AM
From memory of stripping and rebuilding a Pinto the crankshaft keyed not splined.
I guess the pulley could be fitted backwards, but even then it seems odd that the engine ran OK in the Sierra.
Maybe the cam belt had been changed before (in the Sierra) and the engine timed a different way?
jps - 4/5/18 at 09:03 AM
quote:
Originally posted by theconrodkid
timing is out, start again, crank to TDC,cam as it is and rotor arm pointing to NO 1 segment on the dizzy cap....job done
Cheers chaps, I have since pulled the spark out to see what's going on in more detail, although the crank and cam move in sync surely so whether
it's compression or exhaust TDC it won't alter the 'gap' between the two surely? When number 1 cylinder is at TDC the crank
pulley marks are in the right place. The cam marks are not, the cam is 'behind' the crank so the valves open 'late'.
I guess whoever did the last timing belt change just didn't line things up properly? What confuses me is that it ran like this?
[Edited on 4/5/18 by jps]
adithorp - 4/5/18 at 09:22 AM
But they only stay in sync' due to the belt. When you've taken that off one has moved and you've put it back wrong.
nobby_the_sheep - 4/5/18 at 09:32 AM
Hi there
Don't want to muddy the waters further, but as others have said No 1 piston will be at TDC twice in a single engine cycle - end of compression
stroke and end of exhaust stroke.
Looking at it another way. The cam and the crank do move in sync, however the cam rotates at half crank speed (bigger sprocket on cam than crank). The
crank will rotate twice for every cam rotation (four stroke engine).
You need to make sure you're at the top of the compression stroke before you can check the timing. As mentioned, the distributor rotor arm should
be pointing towards No 1, inlet and exhaust valves closed too.
It may still be out, but as you say it was running ok so can't be too far wrong?
Hope this helps
ETA : Does anyone know if the pinto is an interference engine or not?
[Edited on 4/5/18 by nobby_the_sheep]
[Edited on 4/5/18 by nobby_the_sheep]
jps - 4/5/18 at 09:37 AM
quote:
Originally posted by adithorp
But they only stay in sync' due to the belt. When you've taken that off one has moved and you've put it back wrong.
But I had not touched the belt when I took those pics, so whoever changed the belt before I bought the Sierra got it wrong it seems...
jollygreengiant - 4/5/18 at 10:00 AM
Undo the bottom pulley bolt and make sure that the bottom pulley still has an intact woodruff key in it. The Key way should (IIRC) be vertical (edit
bit) to the top.
[Edited on 4/5/18 by jollygreengiant]
FatChapChipChop - 4/5/18 at 03:32 PM
quote:
ETA : Does anyone know if the pinto is an interference engine or not?
Not an impact engine in standard trim (or even a mild cam fitted) if no skimming / decking has taken place, lost a few cambelts in the past before I
knew what I was doing ..
However, valve / piston can kiss with high lift cams and skinned / decked block / head if you don't time the cam right. You soon know when that
happens as it pops the valve rocker off the top of the valve ..
Cheers !!
mcerd1 - 4/5/18 at 03:56 PM
what he said, the key way on the crankshaft should be at TDC
The key way on the cam is the only thing that holds the back plate with its pointer too
the pulley looks the right way round to me (its the early carb'd type pulley without the rubber isolator or maybe the bigger diameter one off the
transit)
so it does look a lot like the belt's on wrong, only thing for it is to actually check the position of the true TDC - you can do this with a
piston stop if you don't want to take the head off
I made this one from an old sparkplug
Piston Stop 1
Piston Stop 2
and then check the actual cam timing if you've got the figures for your cam and a dial gauge.
quote:
Originally posted by nobby_the_sheep
ETA : Does anyone know if the pinto is an interference engine or not?
As i remember it a stock 2.0 pinto isn't an interference engine
that is until its been skimmed / modified - it doesn't need much to make it into an interference engine....
snapper - 5/5/18 at 07:05 AM
Not that It should make a difference but the cam sprocket is back to front, picture shows the rear of the sprocket
snapper - 5/5/18 at 07:37 AM
A good and easy check is to set No.1 at TDC and look for equal lift on inlet and exhaust
What cam have you got, standard?
jps - 5/5/18 at 10:10 AM
quote:
Originally posted by snapper
A good and easy check is to set No.1 at TDC and look for equal lift on inlet and exhaust
What cam have you got, standard?
My assumption is that the whole engine is standard, it's a 1600 and out of a base model Sierra that I think had done about 100k miles so I have
no reason to think it's ever had any work beyond routine maintainence.
