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 Opinion on bore surfaces requested.
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andydeans3
V4 Guru

United Kingdom
1994 Posts

Posted - 24 Jan 2022 :  21:49:36 Show Profile Reply with Quote
What does the collective think of these bore surfaces.
There is a very small perceptible lip at the top.
No vertical scratch marks in any of the bores.



1978 LHD SAAB 96
1978 MGB Roadster
2008 LHD "Classic" Renault Twingo
1991 Nissan Figaro

Edited by - andydeans3 on 24 Jan 2022 21:50:15

SAAB96L
V4 Mad

United Kingdom
501 Posts

Posted - 25 Jan 2022 :  09:00:22 Show Profile Reply with Quote
Good Morning, Andy.

As far as a bore goes its knackered !! However, it will run and work but nowhere near its optimum, plus it will probably use oil. Depends what you want from the engine.

Sorry to be the bearer of such news.

Regards.

Richard.
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andydeans3
V4 Guru

United Kingdom
1994 Posts

Posted - 25 Jan 2022 :  11:45:30 Show Profile Reply with Quote
Richard
Thanks for the info.
It's not my engine, it's the engine of another 96er, in the county, that I'm helping out.
Why exactly do you think it's knackered?
The black ring at the top, though there is not a big step there, or the blotchy marks further down the bore.

1978 LHD SAAB 96
1978 MGB Roadster
2008 LHD "Classic" Renault Twingo
1991 Nissan Figaro
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Derek
V4 Guru

United Kingdom
2187 Posts

Posted - 25 Jan 2022 :  13:58:05 Show Profile Reply with Quote
If heavy honing gets rid of the black splodges/corrosion it might might be usable as is. Are all bores like that? Otherwise a rebore is on the cards.
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SAAB96L
V4 Mad

United Kingdom
501 Posts

Posted - 25 Jan 2022 :  19:11:55 Show Profile Reply with Quote
Hello Andy,

The black spots are usually signs of water ingress into the cylinder bores, either as a result of a failed head gasket or poor storage allowing moisture to settle against the bores as the thin oil mist disappears. As a result the corrosion eats into the bore & becomes less smooth, then as the piston travels up and down it catches (picks-up) on this and accelerates the wear producing these permanent black spots.

The issue with heavy honing is that you enlarging the bore dimension and that will allow greater gapping between the rings and the bore with the inevitable burning of oil plus a reduction in performance due to a reduction of compression.

By all means go for the hone, but it will be a case of spending twice to properly rectify the issue.

What's the history of the engine ??

Regards.

Richard.

Edited by - SAAB96L on 25 Jan 2022 19:13:42
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andydeans3
V4 Guru

United Kingdom
1994 Posts

Posted - 25 Jan 2022 :  19:51:57 Show Profile Reply with Quote
My mate bought the car as a part finished project, which he has completed, but I don't think he knows anything about the history of the engine.


1978 LHD SAAB 96
1978 MGB Roadster
2008 LHD "Classic" Renault Twingo
1991 Nissan Figaro
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andydeans3
V4 Guru

United Kingdom
1994 Posts

Posted - 25 Jan 2022 :  19:54:17 Show Profile Reply with Quote
quote:
Originally posted by Derek
If heavy honing gets rid of the black splodges/corrosion it might might be usable as is. Are all bores like that? Otherwise a rebore is on the cards.


Derek
I'll have a look at the other bores next time I'm up at my mate's place.

Andy

1978 LHD SAAB 96
1978 MGB Roadster
2008 LHD "Classic" Renault Twingo
1991 Nissan Figaro
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Woody
V4 Guru

United Kingdom
2758 Posts

Posted - 26 Jan 2022 :  10:11:57 Show Profile Reply with Quote
Might as well strip it down. Have block and crank and pistons checked at an engine shop.
They will advise if light hone will do the trick. Good opportunity to check condition of
Cam and balance shaft bearings.
My 1971 block was stripped at 115000 miles as core plug rotted and the top end needed a decoke.
Bores were glaze busted and new cam and balance shaft bushings were put it, and new piston rings
after the pistons were cleaned up. Had new mains and big ends.
This was in 1987 when parts availability was good.
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Derek
V4 Guru

United Kingdom
2187 Posts

Posted - 26 Jan 2022 :  12:22:58 Show Profile Reply with Quote
I was saying heavy honing as apposed to just a glaze busting exercise. What's shown looks to be beyond the capabilities of multi ball hone. A rebore is never cheap but it will fix the problem.
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SAAB96L
V4 Mad

United Kingdom
501 Posts

Posted - 26 Jan 2022 :  14:46:14 Show Profile Reply with Quote
Agreed, Derek, a rebore is the logical route and best option.
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andydeans3
V4 Guru

United Kingdom
1994 Posts

Posted - 26 Jan 2022 :  16:46:02 Show Profile Reply with Quote
Chaps
Re-boring is an obvious answer, but where do you get the oversized pistons from?
I'm led to believe, (please correct me if I'm wrong), that you would have more chance of finding a hen with teeth, (or hear a well known politician telling the truth), than be able to source decent, oversize pistons!

1978 LHD SAAB 96
1978 MGB Roadster
2008 LHD "Classic" Renault Twingo
1991 Nissan Figaro

Edited by - andydeans3 on 26 Jan 2022 16:47:13
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SAAB96L
V4 Mad

United Kingdom
501 Posts

Posted - 26 Jan 2022 :  18:35:11 Show Profile Reply with Quote
If you are going for oversize, then I would suggest that the bore is taken out to accommodate alternative marque pistons - pinto might be an option ??

They are the pistons I will be using, albeit the engine is being increased in cc significantly; which may preclude pinto for what you want Andy.

I'm sure there is a pinto guru on here that can advise, if that is an option for your requirements.

Regards.

Richard
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christophe
V4 Fanatic

France
224 Posts

Posted - 26 Jan 2022 :  20:03:20 Show Profile Reply with Quote
Motomobil got them, but at 129€ each.
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andydeans3
V4 Guru

United Kingdom
1994 Posts

Posted - 26 Jan 2022 :  21:39:39 Show Profile Reply with Quote
quote:
Originally posted by SAAB96L
If you are going for oversize, then I would suggest that the bore is taken out to accommodate alternative marque pistons - pinto might be an option ??

They are the pistons I will be using, albeit the engine is being increased in cc significantly; which may preclude pinto for what you want Andy.

I'm sure there is a pinto guru on here that can advise, if that is an option for your requirements.

Regards.

Richard




If I'm not mistaken, pinto pistons are only used in 1700 cc engines.
For 1500 cc engines you cannot use Pinto pistons.
I was hoping that Melle would come on, he's the guru on this sort of stuff!

I should point out that this is not my engine, it belongs to another 96er in the county.

1978 LHD SAAB 96
1978 MGB Roadster
2008 LHD "Classic" Renault Twingo
1991 Nissan Figaro

Edited by - andydeans3 on 26 Jan 2022 21:46:32
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andydeans3
V4 Guru

United Kingdom
1994 Posts

Posted - 26 Jan 2022 :  21:41:43 Show Profile Reply with Quote
quote:
Originally posted by christophe
Motomobil got them, but at 129€ each.


Pistons for 1500cc engines, or Pinto pistons?

1978 LHD SAAB 96
1978 MGB Roadster
2008 LHD "Classic" Renault Twingo
1991 Nissan Figaro
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christophe
V4 Fanatic

France
224 Posts

Posted - 27 Jan 2022 :  07:16:06 Show Profile Reply with Quote
As far as I can say, they seem to have pistons for every iteration of the Cologne engine. Burton mentions the use of 94mm Pinto pistons, by the way.
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