Thotneycroft 90 - BMC 1500 Questions

[alvicchas1]

Greetings All,

 

Want to set the tappets but the crankshaft pulley nut is not easy to get at and I don't have a big enough spanner or socket at present. Any other ways of turning the crankshaft? (suspect I might get a a few comic replies!!!!!!!)

 

Also I want to reduce the idle speed. I have a Calcutt manual but it says use the idling stop screw but does not show where it is!!!!! Where the throttle cable attaches to the fuel pump there are two screws with locknuts on the top of the fuel pump - Is it one of these?

 

Info gratefully received.

 

Thanks

 

Vic

[larkshall]

Thats a bummer... You can try (with assistance) turning via alternator pulley,increase tension between pulley and flywheel? The nut can usually be shifted with 1 1/2AF, (think so I tend to use an oldt whitworth socket brazed to a 4ft iron bar)

 

Alternatively from the propshaft end with a pipe wrench.

 

will nothing get onto crankshaft pulley????

 

there is one other way...On your own head be it though. Use a large old screwdriver to slowly turn crank via starter ring gear access can be gained either by an inspection hatch, or better by temporarily rmoving starter motor..

 

It has to be tdone though as loose tappets = a rracket, and loss of power, tight one though well burnt valves, seats, no power and even worse.

 

If you can remove rocker shaft and check for wear first... Had a recent example where tappet adjustment didn't cure constant rattle, was a worn shaft, in this case also had to rebush the rockers

Edited August 18, 2010 by larkshall

[David Schweizer]

Greetings All,

 

Want to set the tappets but the crankshaft pulley nut is not easy to get at and I don't have a big enough spanner or socket at present. Any other ways of turning the crankshaft? (suspect I might get a a few comic replies!!!!!!!)

 

Also I want to reduce the idle speed. I have a Calcutt manual but it says use the idling stop screw but does not show where it is!!!!! Where the throttle cable attaches to the fuel pump there are two screws with locknuts on the top of the fuel pump - Is it one of these?

 

Info gratefully received.

 

Thanks

 

Vic

The normal; proceedure is to use a socket on the pully nut, without checking, I am not sure of the size, but I know that i have got one. You may be able to turn the engine by pulling on the alternator belt, but make sure that you hve jammed the decompressor open first to make it easier to turn the engine

[alvicchas1]

The normal; proceedure is to use a socket on the pully nut, without checking, I am not sure of the size, but I know that i have got one. You may be able to turn the engine by pulling on the alternator belt, but make sure that you hve jammed the decompressor open first to make it easier to turn the engine

 

Hi,

 

Thanks for your reply, but is there a decompressor on a BMC 1500?

 

Vic

[Albion]

Hi,

 

Thanks for your reply, but is there a decompressor on a BMC 1500?

 

Vic

 

No, there is no decompressor on a 1500 (or 1800 for that matter).

 

The idle setting can be adjusted by one of the two screws that the fuel lever on the distributor injection pump abuts against (one will be idle and the other max speed). Ensure that this adjustment isn't being affected by the throttle cable, probably best to remove it from the engine, do the adjustment and then refit making sure that it drops in place with no effect on the adjusted throttle. If there is an effect then alter the setting of the cable until there isn't.

 

To turn the engine over in your situation, as others have suggested, your best bet is to use the alternator pulley nut with care. Ensure that the alternator belt is correctly adjusted, turn the alternator nut slowly over in a clockwise direction (facing the nut) and, at the same time, pressing on the run of belt that is above the alternator (difficult to describe but you are just tensioning the belt to make the run approaching the alternator pulley tighter). Alternatively, over-tighten the belt so that the belt runs are pretty rigid and turn the engine over BUT DO NOT FORGET TO DE-ADJUST THE BELT WHEN YOU'VE FINISHED THE VALVE ADJUSTMENT

Roger

Edited August 19, 2010 by Albion

[alvicchas1]

No, there is no decompressor on a 1500 (or 1800 for that matter).

 

The idle setting can be adjusted by one of the two screws that the fuel lever on the distributor injection pump abuts against (one will be idle and the other max speed). Ensure that this adjustment isn't being affected by the throttle cable, probably best to remove it from the engine, do the adjustment and then refit making sure that it drops in place with no effect on the adjusted throttle. If there is an effect then alter the setting of the cable until there isn't.

 

To turn the engine over in your situation, as others have suggested, your best bet is to use the alternator pulley nut with care. Ensure that the alternator belt is correctly adjusted, turn the alternator nut slowly over in a clockwise direction (facing the nut) and, at the same time, pressing on the run of belt that is above the above the alternator (difficult to describe but you are just tensioning the belt to make the run approaching the alternator pulley tighter). Alternatively, over-tighten the belt so that the belt runs are pretty rigid and turn the engine over BUT DO NOT FORGET TO DE-ADJUST THE BELT WHEN YOU'VE FINISHED THE VALVE ADJUSTMENT

Roger

 

Hello Roger,

 

Thanks for your comprehensive and knowledgeable reply. I will try your suggestions.

 

Kind regards

 

Vic

[David Schweizer]

No, there is no decompressor on a 1500 (or 1800 for that matter). <snip>

If it isn't a decompressor, what does the engine stop do? the engine scertainly will not start if it is left open.

 

This is a serious question, not a sarcastic one. I really do not know the answer.

[alvicchas1]

If it isn't a decompressor, what does the engine stop do? the engine scertainly will not start if it is left open.

 

This is a serious question, not a sarcastic one. I really do not know the answer.

 

Hello David,

 

The engine stop cable attaches to the fuel pump - I think it just cuts of the fuel supply to the engine.

 

Kind regards

 

Vic

[David Schweizer]

Hello David,

 

The engine stop cable attaches to the fuel pump - I think it just cuts of the fuel supply to the engine.

 

Kind regards

 

Vic

Thanks, I will try and trace the cable route next time on the boat. I must admit that I had aways thought that it was a decompressor, but have never checked it out.

[RobinJ]

If it isn't a decompressor, what does the engine stop do? the engine scertainly will not start if it is left open.

 

This is a serious question, not a sarcastic one. I really do not know the answer.

The stop lever is directly linked to the metering valve, so stops fuel going to the injectors and the engine stops firing!

 

Another option is to slacken off the injectors a little, thus allowing the comprssion to escape and turn the crank, however, you need to make sure they are seated properly and retighten afterwards.

 

If you look at the throttle cable, it is fastened to the arm on the pump and the idle screw is the one that the lever moves away from as the throttle is opened!

[Tony Brooks]

No, there is no decompressor on a 1500 (or 1800 for that matter).

 

The idle setting can be adjusted by one of the two screws that the fuel lever on the distributor injection pump abuts against (one will be idle and the other max speed). Ensure that this adjustment isn't being affected by the throttle cable, probably best to remove it from the engine, do the adjustment and then refit making sure that it drops in place with no effect on the adjusted throttle. If there is an effect then alter the setting of the cable until there isn't.

 

SNIP

 

 

Some (early?) 1.5 pumps used a single screw that looked a bit like a carburettors mixture screw with a spring on it to set the idle. It sets at an angle at perhaps 30 degrees to the vertical in the "turret" that houses the governor and on other pumps the two screws mentioned above.

[Reginald]

Remove the heater plugs to reduce the compression. From experience they should be removed on a regular basis and the holes cleaned out with a drill to remove the carbon built up. (13/64th I think). This can make a big difference if you have a starting problem. I always replace them smeared with copper grease. You can try removing the fan belt and coiling a rope around the crankshaft pullley and pulling or with it fastened off tight pull at right angles like a bow.

[alvicchas1]

Greetings,

 

Thanks to everyody that responded to my post. The method that worked was to tighten the alternator drive belt and then use a socket on the alternator pulley nut. There was some slipping but this was overcome by turning the alternator pulley in short jerks rather than in a smooth movement.

 

Thanks

 

Vic

 

Greetings,

 

Thanks to everyody that responded to my post. The method that worked was to tighten the alternator drive belt and then use a socket on the alternator pulley nut. There was some slipping but this was overcome by turning the alternator pulley in short jerks rather than in a smooth movement.

 

Thanks

 

Vic

 

Greetings,

 

Thanks to everyody that responded to my post. The method that worked was to tighten the alternator drive belt and then use a socket on the alternator pulley nut. There was some slipping but this was overcome by turning the alternator pulley in short jerks rather than in a smooth movement.

 

Thanks

 

Vic

[WotEver]

Glad it worked out for you, worked out for you, worked out for you.

 

Tony