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Topic: Bob crankshaft spec & Piston Position (Read 728 times) |
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dave73
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Bob crankshaft spec & Piston Position
« on: Mar 19th, 2018, 11:01pm » |
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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.
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Torbayboy
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Re: Bob crankshaft spec & Piston Position
« Reply #1 on: Mar 20th, 2018, 8:02am » |
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Take it to a local engine specialist
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Cosworth Scorpio only 46 on the road now NOW down to 42.
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Scorpio_Mike
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Jeep Grand Cherokee 3.0 V6 & 2.8 Sierra XR4i 4x4
Posts: 2354
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Re: Bob crankshaft spec & Piston Position
« Reply #2 on: Mar 20th, 2018, 8:13am » |
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on Mar 20th, 2018, 8:02am, Torbayboy wrote:| Take it to a local engine specialist |
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What he said !
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Sierra XR4i's are great...especially when fitted with 4WD 
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dave73
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Re: Bob crankshaft spec & Piston Position
« Reply #3 on: Mar 20th, 2018, 6:43pm » |
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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
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Scorpio_Mike
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Jeep Grand Cherokee 3.0 V6 & 2.8 Sierra XR4i 4x4
Posts: 2354
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Re: Bob crankshaft spec & Piston Position
« Reply #4 on: Mar 20th, 2018, 7:51pm » |
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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
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Star sign is Scorpio !
Sierra XR4i's are great...especially when fitted with 4WD
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dave73
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Re: Bob crankshaft spec & Piston Position
« Reply #5 on: Mar 20th, 2018, 10:10pm » |
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Thankyou very much Mike, appreciate the size confirmation
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Snoopy
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Re: Bob crankshaft spec & Piston Position
« Reply #6 on: Mar 21st, 2018, 7:56am » |
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All the workshop manual is on the main site the engine manual for the 24 v is http://fordscorpio.co.uk/engdata24v.htm
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