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        General >> Give/Need advice to/from others >> Bob crankshaft spec & Piston Position
        
(Message started by: dave73 on Mar 19^th, 2018, 11:01pm)

Title: Bob crankshaft spec & Piston Position
Post by dave73 on Mar 19^th, 2018, 11:01pm

Hi what’s the best way of telling if the crankshaft needs grinding

1. I will measure it, for size and ovality.........not done yet
2 scoring, faint lines - visual......................mine has some
3. Touch the surface, is this good enough......appears smooth, can’t feel lines
4. Finally, could use a surface checker ?

*also, as I’m new to this engine, the con rod big end diameter in the specs, below, 56.820-56.840 IS THIS WITHOUT THE BEARING SHELLS FITTED?

Connecting rod
Bore diameter, big end mm 56,820 – 56,840
Bore diameter, small end mm 23,958 – 23,976
Connecting rod, distance between bores mm 130,515 – 130,585

Piston TDC level

Could not see this in the specs but, where is the piston TDC position, is it level with the block, above or below

Thank you.

Title: Re: Bob crankshaft spec & Piston Position
Post by Torbayboy on Mar 20^th, 2018, 8:02am

Take it to a local engine specialist

Title: Re: Bob crankshaft spec & Piston Position
Post by Scorpio_Mike on Mar 20^th, 2018, 8:13am

on 03/20/18 at 08:02:18, Torbayboy wrote:

Take it to a local engine specialist

What he said !

Title: Re: Bob crankshaft spec & Piston Position
Post by dave73 on Mar 20^th, 2018, 6:43pm

Hi, thanks for the reply,s, would like to get some opinions on my points first.

Any thoughts on those specs for the con rod big end sizes

56.820/56.840, is this without the bearing shells.

Piston position on top of block, level, above or below

Thanks

Title: Re: Bob crankshaft spec & Piston Position
Post by Scorpio_Mike on Mar 20^th, 2018, 7:51pm

Just dug out my copy of the Haynes manual for a 2.9 12v Mk3 Granada which gives the following specs and may give you some guidelines :

Big end journal on crankshaft diameter 53.980mm to 54mm
Big end parent bore diameter 56.820mm to 56.840mm
This implies the measurement is without the bearing shells

Small end bush internal diameter 23.958mm to 23.976mm
Gudgeon pin diameter RED 23.994mm to 23.997mm or BLUE 23.997mm to 24.000mm
This implies the small end measurement is with the bush in place - have a feeling these are reamed to fit the gudgeon pin

The edge of the piston is normally level with the block face at TDC with flat topped pistons although with angled valves they usually have machining for clearances.

There are some FORD technical tutorial videos for the BOA 24v V6 on YouTube which you may want to look at - probably quite useful - search on ford boa rebuild - they have been uploaded by someonr called Beaksterboy

Title: Re: Bob crankshaft spec & Piston Position
Post by dave73 on Mar 20^th, 2018, 10:10pm

Thankyou very much Mike, appreciate the size confirmation

Title: Re: Bob crankshaft spec & Piston Position
Post by Snoopy on Mar 21^st, 2018, 7:56am

All the workshop manual is on the main site the engine manual for the 24 v is http://fordscorpio.co.uk/engdata24v.htm