8 replies to this topic

[nickewall]

Standard Deluxe 998 ...
1979

Advice please ...I am doing full nut/bolt restore on the above even
thought it was in reasonable nick when i bought it ...

I have just come to do head gasket (may as well while stripped)
and notice that according to my twisted logic the pistons may be
in the wrong way.

The block has on it a B at the rear of the block.
The actual pistons are installed so that the B is actually at the front
and the words 'FRONT M2039 D6'' are actually readable from the
rear of the engine

this would seem to be the wrong way round to me .. am I wrong, and
will it make any real difference. I bought the car running ok but have
only driven it up and down the street once then put onto a trailer to
bring home. I have started and warmed it up a few times until the overhaul.

Am i doing any damage or can I leave it.
Head is not unleaded yet and will run with an additive for a while as is in as
valves and seats are in good nick and I will be upgrading in the future ..

It is for my Son to learn in and have his first 'knocks'

thyanks .. in anticipation ..

Attached Files

•  B.JPG   155.49K   43 downloads
•  A.JPG   185.34K   29 downloads

[AlexMozza]

I did not think they could go in on the wrong way.
I know on newer engines 16v etc that the piston heads are shaped to allow an optimum combustion space and to allow the valves room to open.

I could be wrong though...

[Sprocket]

The front of the engine is the end where the water pump is, since the A series was originally an inline engine.

Some pistons, mainly older split skirt type are 'directional' and need to be installed in the engine the correct way round. usually the word 'front' is accompanied by an arrow pointing the direction, or, the word 'front' is stamped into the 'corner' of the piston to which it should be installed closest to the front of the engine, in a similar way to how cylinder head gaskets are stamped.

I see no arrow on those pistons, but the word 'front' is installed closest to the front of the engine.

Edited by Sprocket, 07 August 2011 - 01:30 PM.

[nickewall]

The front of the engine is the end where the water pump is, since the A series was originally an inline engine.

Some pistons, mainly older split skirt type are 'directional' and need to be installed in the engine the correct way round. usually the word 'front' is accompanied by an arrow pointing the direction, or, the word 'front' is stamped into the 'corner' of the piston to which it should be installed closest to the front of the engine, in a similar way to how cylinder head gaskets are stamped.

I see no arrow on those pistons, but the word 'front' is installed closest to the front of the engine.

I see what you are getting at that the word Front IS near to the front ..
but why the 'B' and there is a'B' on the block .. if this is relevant it on wrong side.???

[nickewall]

The front of the engine is the end where the water pump is, since the A series was originally an inline engine.

Some pistons, mainly older split skirt type are 'directional' and need to be installed in the engine the correct way round. usually the word 'front' is accompanied by an arrow pointing the direction, or, the word 'front' is stamped into the 'corner' of the piston to which it should be installed closest to the front of the engine, in a similar way to how cylinder head gaskets are stamped.

I see no arrow on those pistons, but the word 'front' is installed closest to the front of the engine.

I see what you are getting at that the word Front IS near to the front ..
but why the 'B' and there is a'B' on the block .. if this is relevant it on wrong side.???

here is a larger view of pistono (same orientation)

Attached Files

•  DSC02942.JPG   196.41K   15 downloads

[Sprocket]

The 'B' is a size grade used at the factory. Blocks were bored then measured and marked either 'A' or 'B' depending on the final size. Pistons with a slightly different clearance were then installed, either 'A' or 'B' to ensure that the piston to bore clearance fell within the allowable tollerance, therefore a 'B' block will have 'B' pistons installed

Edited by Sprocket, 07 August 2011 - 01:45 PM.

[nickewall]

The 'B' is a size grade used at the factory. Blocks were bored then measured and marked either 'A' or 'B' depending on the final size. Pistons with a slightly different clearance were then installed, either 'A' or 'B' to ensure that the piston to bore clearance fell within the allowable tollerance, therefore a 'B' block will have 'B' pistons installed

Great that ticks all the boxes then .. thanks for the assistance ...hope I can help you some time ..

[Paul Wiginton]

The 'B' is a size grade used at the factory. Blocks were bored then measured and marked either 'A' or 'B' depending on the final size. Pistons with a slightly different clearance were then installed, either 'A' or 'B' to ensure that the piston to bore clearance fell within the allowable tollerance, therefore a 'B' block will have 'B' pistons installed

Maybe they used to belong to someone called Brian...........................

[Ethel]

It wouldn't matter if they were wrong, once it's run in it should go back together the same way.