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Guesses As To What May Have Caused This? (Pics Inside)


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#1 jameswildcooper

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Posted 06 March 2012 - 06:00 PM

ill start from the begining.
i bought a 1977 GT off ebay around christmas its done a genuine 49000 miles and has 3 owners from new. it doesnt need any welding and is in excellent condition.
its been sat in a shed since 1988.

i bought it as a non runner with a electrical fault.
the guy couldnt get a live to the engine (turns out to be problem with the solenoid) lol.

I did the headgasket on it as soon as i got the car and to my amazment i found the block had been honed and it had +30 pistons in it meaning its 1303CC so who knows whats been done to the bottom end as it already had a electric SU fuel pump on there and twin inch and qaurter carbs.

ive had it running a couple of times and im trying to get the carbs to run right i took it for its first drive in 24 years sunday night to which it ran very lean, got hot and decided to blow the head gasket i had fitted.

So today i took the head off to replace gasket and i found that cylinder 2 had two deep marks in which what looks like maybe the grudgen pin has come loose?

im hoping a rebore may sort the block out as they are pretty deep so might mean going 1380 but what do other people think?

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Edited by jameswildcooper, 06 March 2012 - 06:03 PM.


#2 benspickup2011

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Posted 06 March 2012 - 06:04 PM

Looks like you've hit the nail on the head, in line with the pin etc. Unlucky!

#3 LTSwaby

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Posted 06 March 2012 - 06:06 PM

could be compression rings, some grit or other small particles of something

#4 Jordie

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Posted 06 March 2012 - 06:17 PM

had this before with my turbo engine

gudegeon pin moving side to side in the conrod.

probally caused by heating the conrod up too much when fitting the new pistons. eventually the heat from the engine loosens the pin and u get that damage.

#5 charie t

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Posted 06 March 2012 - 11:33 PM

cant got 1380 as they have offset bores to get the extra cc, so knackered block
i thought 1275 gudgeons were pressed into con rod?

#6 mk3 Cooper S

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Posted 06 March 2012 - 11:46 PM

How hot did you get it ??

#7 Jordie

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Posted 07 March 2012 - 06:32 AM

cant got 1380 as they have offset bores to get the extra cc, so knackered block
i thought 1275 gudgeons were pressed into con rod?


they are, but heating the conrod and freezing the pin can help with fitment.

heat the conrod too much.....it seems ok when it cools, gripped the pin etc.....but once in the engine and allowed to get hot, it releases its grip on the pin, allowing the pin to float side to side in the conrod/piston and damaging the bores.

#8 samsfern

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Posted 07 March 2012 - 08:32 AM

Thats a loose gudgeon pin, and depending how deep the score is, a scrap block :( ive come across this on an mg midget once, not nice.

Edited by samsfern, 07 March 2012 - 08:33 AM.





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