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Comp: 140, 140, 140, 90

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Bruce V. Avatar
Bruce V. Bruce Varty
Lakewood, WA, USA   USA
Looked at Moss, Nada.....Looked for it at Northwest British, they don't have Standard but do have ..20, .30. I am not sure how to measure to see if what they have will work. I was going to measure the pistons and cylinders and let Hastings do there magic but this is a bit different..


Mehot smiley

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GottaSpit Avatar
GottaSpit Duncan A
Folsom, CA, USA   USA
Spitbits has them.

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Doug in Vegas Avatar
Doug in Vegas Douglas D
Las Vegas, NV, USA   USA
In reply to # 1539350 by Bruce V. The ridge reemer I picked up from Autozone will not fit into the cylinder. Can I hand sand the small ridge as prescribed in MY Haynes manual?? ANd what kind of sandpaper would be best to use. I have a de glaze device I purchase for the drill after I have the pistons removed..

How bad is the ridge?

A grape hone can handle it if it's minor.

clshore Carter Shore
Beverly Hills, FL, USA   USA
In reply to # 1539437 by Bruce V. WELL. I now know why I have a cylinder that is low... The piston is cracked between the first two rings in and a crack between the them and the oil ring.... I guess I kind of wanted new pistons to go with the new rings..

Any suggestions on the new pistons,

Also as long as I am in this deep I am thinking about new crankshaft bearings....

Thanks
Bruce

Pistons don't just spontaneously crack.
Until you identify and/or eliminate the cause, replacement piston can suffer the same fate.

Post pictures please?

Lacking actual facts, we have been speculating about how many angels can dance on the ridge in a cylinder bore.

Given the excellent consistent compression numbers of the other 3 cylinders, it's worthwhile to consider replacing just the damaged piece.

But the bore of the damaged piston must be evaluated (yes, for a ridge, but also scratches, surface finish, and bore wear)

Lizzard d id
san jose, CA, USA   USA
In reply to # 1539463 by Doug in Vegas How bad is the ridge?

A grape hone can handle it if it's minor.
How would a grape hone pull that off ?
While the grape hone is removing the metal of the ridge it will also be removing the metal just below the ridge / exactly where you don't want metal removed .

Voda2000 Avatar
Voda2000 Andrew McMillan
Winnipeg, MB, Canada   CAN
I believe Ted at TSI has single pistons.



1978 Triumph Spitfire

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clshore Carter Shore
Beverly Hills, FL, USA   USA
In reply to # 1539528 by Lizzard
In reply to # 1539463 by Doug in Vegas How bad is the ridge?

A grape hone can handle it if it's minor.
How would a grape hone pull that off ?
While the grape hone is removing the metal of the ridge it will also be removing the metal just below the ridge / exactly where you don't want metal removed .

A 'grape hone' will start rounding off the edges of the ridge, but unlike a rigid stone hone that will hit the 'high spots' first, as Lizzard says, also does the bore.
And given that the bore surface and finish on the ridge section above the rings is not critical, a ridge reamer is still the preferred tool.

clshore Carter Shore
Beverly Hills, FL, USA   USA
Step ONE is to measure the bore, do not assume that it is the same size as the others.
The bore must be assessed for damage, wear, taper, surface condition, etc. to see if it can be
used as is, with honing, or requires a re-bore to next size.

That will determine what piston(s) will be required.

It's common to find singleton pistons an eBay and 'for sale' section of various websites.
Don't discount used pistons in good shape.

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Bruce V. Avatar
Bruce V. Bruce Varty
Lakewood, WA, USA   USA
Spitbits was very helpful, Thanks

Bruce V. Avatar
Bruce V. Bruce Varty
Lakewood, WA, USA   USA
The Haynes Manual says the Connecting Rod Bolt Torque is 50 ft lb if colour dyed, OR, 46 ft lb if Phoshated?????

And does any one know what the plastigage spec should be after being torqued...


Thanks in advance,
Bruce

spitfire50 Avatar
spitfire50 Paul Mugford
Rochester, N.H., USA   USA
Bruce,
Connecting rod clearance spec is 0.001- 0.003" So that is what the Plastigauge should show.
All the best,
Paul

Bruce V. Avatar
Bruce V. Bruce Varty
Lakewood, WA, USA   USA
Thanks everybody. Going to begin the reassembly process and would like confirmation on the following specs...thumbs upthumbs down

Rod Bearing Clearance .001 to .003

Connecting rod bolts torque,, 46

Rings in cylinder gap, 1st and 2nd ring, .012 to .022
Oil rings in cylinder gap, chrome top and bottom, .015

The small ridge is gone.

Deglaze with honing tool (could have rented it from Auto Zone for free)

Stepped up and purchased a new digital torque wrench. I just don't trust the ones at Auto Zone to be accurate. Fathers day gift to me.

Rebuilt head

All new gaskets

Break in Oil

Should have bought a new car(lol)

Lizzard d id
san jose, CA, USA   USA
In reply to # 1540699 by Bruce V. Should have bought a new car(lol)
Not many can say they pulled the motor apart and put it back together , you will be one of the few who can say , been there , done that .

Bruce V. Avatar
Bruce V. Bruce Varty
Lakewood, WA, USA   USA
Just waiting for some confirmations that my specs are correct before I proceed. Would hate to get something wrong at this juncture.


Thanks

Bruce

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