Carburetor Heat Shields

[Paul Amey]

5 hours ago, Pete Lewis said:

 Paul  ...yes just to follow Ian's  post ....whats a piston stop  >>>>>>>>>>>>>>

you can use a stop often made from an old spark plug so it protrudes into the chamber and you with care turn the engine by hand so the piston makes contact

with the stop,  mark the pulley  turn the engine backwards to again make the piston touch the stop and mark the pulley   

top dead centre is exactly half/midway between the two marks 

on some engines the timing damper ring bonding fails and the ring moves around the pulley giving false timing positions 

if that sums it up

and always remove the stop before you wander off and forget it ...

Pete

Could you use a D.T.I. with a prong down the spark plug hole to do this?

 

 

[johny]

Think the angle of the sparkplug hole means any standard DTI will jam as the piston comes up to it and of course then risk being damaged...

[Pete Lewis]

agree it needs a positive stop a DTI might  work if you could get it to give a reading you can replicate when you reverse the rotation  point

so you know the piston is in the same position clockwise as anti clockwise

pete

 

[Unkel Kunkel]

7 hours ago, Pete Lewis said:

 Paul  ...yes just to follow Ian's  post ....whats a piston stop  >>>>>>>>>>>>>>

you can use a stop often made from an old spark plug so it protrudes into the chamber and you with care turn the engine by hand so the piston makes contact

with the stop,  mark the pulley  turn the engine backwards to again make the piston touch the stop and mark the pulley   

top dead centre is exactly half/midway between the two marks 

on some engines the timing damper ring bonding fails and the ring moves around the pulley giving false timing positions 

if that sums it up

and always remove the stop before you wander off and forget it ...

Pete

Last  week I saw someone determine TDC  in an old side valve engine with no timing marks and where the plug  is not anywhere near the piston.

I hadn’t seen this before:

The  base of an old sparking plug hollowed out and a small balloon attached.

The inflation/deflation transition determined TDC.

Seemed to work.

[Anglefire]

I used a DTI when I had the head off to find top dead. Repeated several times to try and avoid errors. 
 

[Iain T]

I think it's easier and possibly more accurate to use a dead stop of some kind whether that's through the spark plug or a bridge across the block if the head is off. 

With the stop I bought the rocker assembly had to be removed as the opening valve hit the stop. 

 

[Wagger]

2 hours ago, Iain T said:

I think it's easier and possibly more accurate to use a dead stop of some kind whether that's through the spark plug or a bridge across the block if the head is off. 

With the stop I bought the rocker assembly had to be removed as the opening valve hit the stop. 

 

That is because it was not on the firing stroke. Another turn of the crank (with the stop removed) and that would not have happened. Do you have a picture of the timing marks? That part has a key to set it on the crankshaft, so should be 'Impossible' to get wrong, unless it is the wrong part or the key is missing. Mine has markings before and after TDC, so corrosion would make reading it ambiguous.

 

2 hours ago, Iain T said:

I think it's easier and possibly more accurate to use a dead stop of some kind whether that's through the spark plug or a bridge across the block if the head is off. 

With the stop I bought the rocker assembly had to be removed as the opening valve hit the stop. 

 

 

[Iain T]

3 minutes ago, Wagger said:

That is because it was not on the firing stroke.

Good point! I must learn to use my brain..... 

The markings on the pulley are faint so when I had the engine out I marked tdc and 13 degrees btdc with a white tipex. On checking using the piston stop the pulley outer ring hasn't moved and tdc is in fact in line with the pointer on the cam cover. 

[Wagger]

27 minutes ago, Iain T said:

Good point! I must learn to use my brain..... 

The markings on the pulley are faint so when I had the engine out I marked tdc and 13 degrees btdc with a white tipex. On checking using the piston stop the pulley outer ring hasn't moved and tdc is in fact in line with the pointer on the cam cover. 

It is easily done! My 2500TC engine will run at any setting between 20 deg BTDC and 10 deg after. I set the engine to run at 2500 RPM, peaked the rpm by rotating the Dizzy, then backed it off by 2 degrees when static. It pulls with no pinking from 1000 rpm. I use Tesco E5. It's marked 99 octane at the pump??

[Iain T]

29 minutes ago, Wagger said:

then backed it off by 2 degrees when static

Do you know what the actual timing is? I set by vacuum and backed off 1 but this was 20btdc and it pinked on load. I've backed off to about 15 degrees and seems to be ok. I too try and fill with Tesco Momentum 99 Octane. 

[NonMember]

1 hour ago, Wagger said:

Do you have a picture of the timing marks? That part has a key to set it on the crankshaft, so should be 'Impossible' to get wrong, unless it is the wrong part or the key is missing

... except that the 6 cylinder one has the timing marks on an outer ring attached by a rubber "vibration damper", which has been known to fail, in which case the ring rotates.

[Wagger]

3 hours ago, NonMember said:

... except that the 6 cylinder one has the timing marks on an outer ring attached by a rubber "vibration damper", which has been known to fail, in which case the ring rotates.

When I joined, somebody sent me pictures of different bottom pulleys. Do they all incorporate the damper, and, can it be assembled at 60 degree intervals. (Six holes) If this was the case, then timing would be 120 degrees displaced when using a strobe.

[Wagger]

4 hours ago, Iain T said:

Good point! I must learn to use my brain..... 

The markings on the pulley are faint so when I had the engine out I marked tdc and 13 degrees btdc with a white tipex. On checking using the piston stop the pulley outer ring hasn't moved and tdc is in fact in line with the pointer on the cam cover. 

Apologies! If you use the piston stop and rotate the engine backwards, then it will end up on the wrong stroke again. It is safer to disable the rockers so that the valves remain closed.

[Iain T]

7 minutes ago, Wagger said:

It is safer to disable the rockers so that the valves remain closed.

Downside is having to hand crank the engine to readjust the tappet clearances. On a 6 pot the radiator is mighty close and scrapes your knuckles. 

[PeteH]

20 minutes ago, Iain T said:

Downside is having to hand crank the engine to readjust the tappet clearances. On a 6 pot the radiator is mighty close and scrapes your knuckles. 

Ahh! The days of the old "Starting Handle"?. Used one most mornings in winter on the Ford Side valve 1173.!😭. NEVER put your thumb around the handle, sure way to a busted one if it backfires!.😭

Pete

[Iain T]

9 minutes ago, PeteH said:

Ahh! The days of the old "Starting Handle

No I used a spanner on the pulley nut, I still have the knuckle scars! 

It must have been dangerous hand cranking a big four pot engine. 

[PeteH]

1 minute ago, Iain T said:

No I used a spanner on the pulley nut, I still have the knuckle scars! 

It must have been dangerous hand cranking a big four pot engine. 

Single and twin cylinder Diesels are the worst, especially ship lifeboat ones. We still had the Start Handle on the Wolsley 6/50. Big old Ex police straight six, that was a good workout.

But at least we did nor have to hand crank this one after we had rebuilt it in the apprentice school:-

Pete

[Pete Lewis]

starting handles  !!!! as a 2nd year apprentice a visit to the Commer showroom to start the 1913 fire engine pictured here  

right Lad  said the fitter (techy not invented yet )  you swing it over and i will adjust the controls  , this turned out to be his party trick 

the handle is pretty high and getting any swing was a challenge for a weedly 18 year old   and bang off i flew over the showroom 

landing in a heap on the floor....   come lad  whats up     i gave him whats up  with the few expletive's i knew 

on the second swing she started 

[Wagger]

2 hours ago, Iain T said:

Downside is having to hand crank the engine to readjust the tappet clearances. On a 6 pot the radiator is mighty close and scrapes your knuckles. 

If the ground is level, remove piston stop, engage top gear, disengage handbrake, disconnect battery, roll it gently and use the sequence described in the manuals.

[Pete Lewis]

do that on a bit of a slope with a piston stop will bend the conrod or punch the piston if you get a runaway 

same as rope in the  bore to lift the head  as approaching TDC there will be high loads into the con rods 

Pete

[Iain T]

19 minutes ago, Pete Lewis said:

do that on a bit of a slope with a piston stop

I took it out as some as I had marked the points on the pulley!! My short term memory ain't what it used to be. 

[Wagger]

55 minutes ago, Pete Lewis said:

do that on a bit of a slope with a piston stop will bend the conrod or punch the piston if you get a runaway 

same as rope in the  bore to lift the head  as approaching TDC there will be high loads into the con rods 

Pete

Only meant this suggestion for adjusting tappets. Not using the piston stop. Never on a slope either! I usually combine tappet checks with a plug change. Turns over easily then.

[Wagger]

42 minutes ago, Iain T said:

I took it out as some as I had marked the points on the pulley!! My short term memory ain't what it used to be. 

Never use the piston stop in gear or with the battery connected. Too easy to press that start solenoid.

[Wagger]

21 hours ago, Iain T said:

Do you know what the actual timing is? I set by vacuum and backed off 1 but this was 20btdc and it pinked on load. I've backed off to about 15 degrees and seems to be ok. I too try and fill with Tesco Momentum 99 Octane. 

6 t0 8 degrees static. Points just opening, checked with a meter across them. rotating engine slowly in normal direction.