popping/misfire?/couching

Post by **cadetchris** » Tue Sep 22, 2009 2:28 pm

owing to the lack of starter handle, ill have to go buy a dial gauge. how does one check with the aid of a dial gauge?

Post by **bmcecosse** » Tue Sep 22, 2009 2:56 pm

Why do you need a starting handle!!!!! ? Just turn the engine by hand - the plugs are out! And it's only one turn!!

Post by **cadetchris** » Tue Sep 22, 2009 6:00 pm

right, so this is what i have done
"So - rocker cover off - spark plugs out - turn the engine so #4 cylinder is firing - both valves will be closed -and set it exactly at Top Dead Centre. Looking now at #1 cylinder - the two valves will be slightly open (this is the overlap at TDC) , if the timing is right they will each be open by exactly the same amount. If you had a dial gauge - you would use it to measure how far each is open. Since no dial gauge - you need to slacken off the valve gap adjusters on both valves until there is the slightest of gap at each valve - check with say 5 thou feeler. Now crank the engine over one turn - and measure the valve gaps now on that #1 cylinder - they should both be the same at ~ 40 thou or so. The value doesn't matter - but they should be the same! If not the same (within 5 thou) - then the camshaft is not timed in correctly."

now, couple of idiot questions.
1. my feelers have a range from .035 to .0015 which is the same as .889mm to 0.38mm. so what is 40 thou and 5 thou?
2.
when #4 is tdc, with both valves closed, #1 has the valves just opening, is this right?
3.
a complete turn? i turned the engine over with the fan belt (and carefully removed the top of my index finger in the process) untill #4 had the piston at the top and both valves closed, does this count as a complete turn

the engine is still in the car and very stiff, hence i asked about the method using the dial guage, as i diont have a starter handle, which would make so much easier.

after this, i checked the gaps on #1 with a feeler. if i have done it right, the inlet valve has no gap and the exhust valve has quite a large gap. does this mean that the camshaft is ever so slightly out?
if so, how does one fix it?

Post by **eastona** » Tue Sep 22, 2009 6:56 pm

"what is 40 thou and 5 thou?" seriously?

OK,
0.001 is a thou (sandth) of an inch
0.010 is ten thou (sandths)

so, 0.035 is thirty five thou 0.0015 would be one and a half thou (or 1 and five ten thousandths if that makes sense).

forty thou is 0.040, five thou is 0.005

and so on...or do you mean in mm?

to turn the engine over either put it in fourth (IGNITION OFF) take the handbrake off and push the car forwards or jack up a rear wheel and turn a rear wheel forward.

if the plugs are out you can grab the fanblades and turn it with them (probably even if one or two are out you can do that).

Andrew

Post by **cadetchris** » Tue Sep 22, 2009 7:24 pm

right, that makes more sense, no one has told me that. the manuals have said it as 0.0etc, not in 0 thou form, hence i havent a clue.
tried the fan blade way, but it kept slipping (even after i tightened it up)
so i have given up. it runs, it stops and turns. i can ignore the misfire, but to be honest, all my cars have been classic's and i have never had as much trouble with them as i have with this thing. i am sure the clutch is going, the interior is badly trimmed, the b post has fractured mid way up, at the point where the rear passenger window bar meets it. the exhust is throaty, regardless of the exhust pip on it, (we tried 4, but still it sounds like the exhust is holed)
so all in all, after the amount of problems that i have had, i am sick to the back teeth of it.
tomorrow is a new day, and i might resist the urge to push the car into the garage and cover it and forget about it.

Post by **bmcecosse** » Tue Sep 22, 2009 8:47 pm

Hmm - with the plugs out (which was almost the first instruction) the engine should turn over VERY easily on th fan. The 'thou' thing ahs been explained - and you are correct on the TDC moves in both cases. So - if the exhaust has no gap - and the inlet a large gap (assuming you are EXACTLY at TDC (you guage that with a pencil down #1 spark plug hole - watch it bob up and down to get precise TDC) then indeed you have proved that your camshaft timing is NOT correct. Almost certainly it's one tooth (or possibly more!) advanced. But - do the test again - very carefully and double check the result. The valve gaps on #1 vlaves must be set correctly at the start of the test - of course! And the engine must be exactly at TDC in both instances. If you had a dial gauge - you would measure how much the vlaves are lifted using the gauge - the 'feeler' method is second best - but all you can do under the circumstances. Presumably you were aware of the overall condition of the car when you bought it - or was it a dark rainy night ?? Minors are not generally troublesome if properly cared for - you must have some 'catching up' to do following neglect by PO!

Post by **cadetchris** » Tue Sep 22, 2009 8:58 pm

thanks for the info, ill have a fiddle tomorrow.
we have actually had the car for a few years, it was brought for my brother and restored to a fantastic standard. since my brother was let loose on it, (being a mere 17 when that was), he has wrapped it around the front of a volvo, killed the engine twice, made the rear diff evaporate into a cloud of small metal droplets by somehow putting it into reverse whilst doing 50. so its been threashed about severaly by my brother who just didnt comprehend how to drive and care for such a lovely charming car.
its taken my the best part of 7 weeks to get it back to some standard of drivability, but slowly getting there.
anyway, i think a large glass of white wine will clear the mind and settle ones nerves

Post by **cadetchris** » Tue Sep 22, 2009 9:00 pm

ooh, btw, if i have to take off the timing chain cover and retard it a tooth, which way would that be? clockwise or anticlockwise?

Post by **eastona** » Tue Sep 22, 2009 10:52 pm

It's been a while since I looked, but don't you just align the two dots on the timing gears?

Andrew

Post by **bmcecosse** » Tue Sep 22, 2009 10:58 pm

You would turn the cam sprocket anti-clock by one tooth. But - the main thing is to align the dots accurately. But before doing anything like that - check and double check the rocker gaps !

Post by **cadetchris** » Thu Sep 24, 2009 3:03 pm

right, a new devlopment has occured.
this morning i got a new gasket so i could take off the timing cover and retard the timing chain a tooth. but before i did that i sorted out the blowing exhust manifold joint and left it to get nice and hot so the paste could harden off.
next a trip into grantham to get some gasket paste, so the timing gasket would be truely oil leak proof.
after the 12 mile round trip it ran beautifully. not a pop, cough, back or misfire. infact it was beautiful and ran fantastically.
could resetting the tappets on #1 cylinder have rectifed this? or could have stopped the exhust blowing helped?

Post by **bmcecosse** » Thu Sep 24, 2009 7:32 pm

You said before that you had sorted the blowing exhaust. And gasket goo is definitely NOT a good idea anyway. Exhaust blow will always upset an engine - but if you found the gaps were not the same during the 'test' then the cam timing is not correct - but if it's running ok - leave it be for now !

Post by **eastona** » Thu Sep 24, 2009 8:07 pm

and retard the timing chain a tooth.

presumably only if it needed it?

As BMC says, a blowing exhaust can make it run quite rough, but it'd have to be a bad one in my experience. With a "mild" one, the idle will suffer and acceleration/economy won't be as good, but it'd have to be quite bad to stutter/cough etc.

If the tappets were way out it could cause poor running, and may also may cause damage if they were too tight and the valves not seating properly.

I'd also say if it aint broke....but I'd also be tempted to check the tappets to make sure the rest are set right.

Andrew