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 Posted: May 20, 2019 09:13PM
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All,

Getting closer to get it all back together.  Block and head are nice and flat, head cleaned up, put on and torqued down.

On to flushing the coolant, changing the oil and doing a few other finicky things in the engine bay, then adjust valves and timing, and start it up.

Will keep you posted!

Scott

New Zealand - The only place where a kiwi can mean a fruit, bird or mini owner...

 Posted: May 9, 2019 10:01AM
 Edited:  May 21, 2019 06:55AM
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Make sure the surfaces are nice and flat. I use a steel block with wet/dry sandpaper and a lubricant, a few runs across and you will see any high or low spots. Yours should not be too bad as it was only rebuilt recently.
Just follow the torque wrench settings and sequence and re torque after 50 to 100 miles i then re check at 1000 miles and adjust the valves if needed.


If in doubt, flat out. Colin Mc Rae MBE 1968-2007.

Give a car more power and it goes faster on the straights,
make a car lighter and it's faster everywhere. Colin Chapman.

 Posted: May 9, 2019 07:51AM
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Absolutely right, was cylinder 2 (from the radiator end), not 3.

Will fit the gasket dry as well, run it in with just water as coolant, and then add water wetter.

Thanks all!

Scott

New Zealand - The only place where a kiwi can mean a fruit, bird or mini owner...

 Posted: May 9, 2019 07:47AM
 Edited:  May 21, 2019 06:56AM
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Quote:
Originally Posted by spectre1275
..and of course, the red "X" just marks cylinder 3, which had the low compression figures.

Scott
According to your first post #2 had low compression.

I would not use any sealant on the head gasket, fit it dry.


If in doubt, flat out. Colin Mc Rae MBE 1968-2007.

Give a car more power and it goes faster on the straights,
make a car lighter and it's faster everywhere. Colin Chapman.

 Posted: May 8, 2019 08:50AM
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For the basic 9 stud setup the tapped holes in the block are 3/8-16.  The other end of the stud that gets the nut is 3/8-24.

Doug L.
 Posted: May 8, 2019 05:56AM
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Thanks for that Doug/Willie - what's the pitch/size for the head studs?

Scott

New Zealand - The only place where a kiwi can mean a fruit, bird or mini owner...

 Posted: May 8, 2019 04:35AM
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Quote:
Originally Posted by spectre1275
QUESTION:  I'd like to chase the head stud threads in the block - what's the correct pitch/thread to get?

If you are planning on doing a lot of work buy a full set of taps and dies.  Spend at least $50 for a set made of ground high-speed-steel.  If you want to buy individual taps to clean the majority of block and transmission holes, buy 1/4, 5/16, and 3/8 taps in both UNF and UNC pitches (6 taps total).  It is also a good idea to use a countersink tool to remove the thread burr that is often kicked up around the tapped hole.  Use the countersink tool to leave a slight chamfer all around the hole.
UNC       UNF
1/4-20    1/4-28
5/16-18   5/16-24
3/8-16    3/8-24

Doug L.
 Posted: May 8, 2019 04:28AM
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For chasing threads I use this so you do not cut the threads down. It is made slightly undersize so as not to remove metal.

https://www.summitracing.com/parts/sum-900200/overview/

"How can anything bigger be mini?"

 Posted: May 7, 2019 08:50PM
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..and of course, the red "X" just marks cylinder 3, which had the low compression figures.

Scott

New Zealand - The only place where a kiwi can mean a fruit, bird or mini owner...

 Posted: May 7, 2019 06:59PM
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An update for those that might be interested.

My son and I pulled the head after confirming that cylinder 3 compression was South of 100, and 4 was on it's way at 120.

We undid the head nuts, pulled the pushrods (keeping all in order), but late at night were stymied by the exhaust manifold, so closed up for the night.  We did learn that the rear nuts were significantly tighter than the front (though I failed to check torque before pulling them off, to see which ones were too loose and/or too tight)

Next day we managed to get the manifolds off, and pulled the head.  It may be that overnight with the head loose oil leaked between the block and head, but the gasket was pretty shiny with oil.  See attached picks - we saw that the valves looked relatively buff and dry apart from the large valves in cylinders 3 & 4 (with 3 being much more sooty, even wet).  In the pic the rough edge you may see on the valve in cylinder 4 is just dry debris from pulling the head and whisking a finger around the valves to see if it was wet or dry).

Any thoughts on the interesting patterns seen on the head and block?  Looks like moisture got in there somehow, either from oil or water.  

No scoring on the cylinder walls (still see the marks from the honing, as this engine only has about 1,000 miles on it), and all 4 plugs are uniform and grey.  No noises from the water pump, and oil pressure was high if anything, so not going to replace either of those.

I've got a new gasket coming, along with thermostat & gasket, valve cover gasket, manifold gasket and bypass hose.

Looks to me like I just didn't re-torque the head down after a few hundred miles, or didn't have it right to begin with, and got lucky with not driving it much/hard to damage anything.  Anyone see something else I should investigate?

Planning to whack it together, perhaps using copper coat on the head gasket, change the oil/filter, coolant and gas filter, and see how she runs.

QUESTION:  I'd like to chase the head stud threads in the block - what's the correct pitch/thread to get?

Scott

New Zealand - The only place where a kiwi can mean a fruit, bird or mini owner...

 Posted: Apr 15, 2019 04:21PM
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Fire it up, let it idle.  Pull off one spark plug wire at a time, then put it back on.  If the rpm drops and the engine idles roughly, that cylinder was firing OK.  If all were firing OK, move on to other debugs as described above.  But if you pull off a plug wire and the engine sounds the same as it did with it on, that cylinder was not doing anything, so swap spark plug from that cylinder with one in a good cylinder.  If the problem follows the plug, the plug is bad, if it stays with the cylinder, replace the plug wires.

 Posted: Apr 15, 2019 12:08PM
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Finally got a chance to do a dry compression test, and believe things are pointing to a head gasket.

Cylinder 1:  135
Cyl 2:  115
Cyl 3:  170
Cyl 4:  165

May do a wet test as well, but gasket is very suspicious with two cylinders experiencing low numbers.

The engine was rebuilt less than 2,000 miles ago, oil changed 3 times since, pulled and drove well until last week. 

Next steps: 
Check head studs for correct torque
Check exhaust and intake manifold bolts for tightness
Compression test again, and perhaps do a wet test
Pull the head to see what's what...

Scott

New Zealand - The only place where a kiwi can mean a fruit, bird or mini owner...

 Posted: Apr 12, 2019 11:57AM
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After reading the responses from others I agree that it would be a good idea to perform a compression test.  Also, if you have the ability, a leak down test can be very informative as well... often highlighting problems a compression test does not show.

Doug L.
 Posted: Apr 11, 2019 10:56AM
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Could it be an intake leak, try spraying some starting fluid around the intake manifold, carb area and see if any increase in engine speed. I once had an intake come loose and, I have also seen the end of an intake manifold slug fall out too! These are easy checks.

 Posted: Apr 11, 2019 09:49AM
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Quote:
Originally Posted by spectre1275

<...> (though smells a little rich).

Last week on the way home, it started losing power, and sounding like it was running on 3 cylinders. 

I had the exact same set of symptoms a month or two back. It turned out that it *was* running on 3 cylinders. The engine had ingested something small that crushed the end of the spark plug on #1. There was no spark, so no power AND the extra fuel smell. It idled fine and ran fine once I got to a steady speed, but had no pick up at all and was pretty jerky on acceleration / deceleration. It only takes 5 minutes to check plugs and leads. I'd add it to your troubleshooting list.

I never did find out what the #$%#@ went through the engine, but there appear to be some small pits on the piston head. I haven't had time to get in there with my borescope for a better view. It's on the list...

-------------------------------------------------------------
Scott | 1963 Austin Cooper | 2003 MINI Cooper S | 2018 MINI Cooper 4-door
 Posted: Apr 11, 2019 09:26AM
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CA
"sounds like it is running on 3 cylinders"

If it happened all of the sudden, it could mean a head gasket. Pop all of the plugs out and do a compression check. I have has HG failures that didn't affect cooling. If the gasket lets go between #2 and #3 cylinders, the oil and coolant can stay where it belongs, but have no compression on those two cylinders.

My experience is that coils are pretty bulletproof, unless you get a Lucas Sport Coil, those can be pretty crappy. A known good coil is and easy test though.

Sean Windrum

1996 MGF VVC
1970 1275 GT Racer
66 Austin Countryman
63 997 Cooper (Under Construction)
63 MG 1100

 

 Posted: Apr 11, 2019 05:15AM
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It sounds to me like the timing may be way off. I don't know how a Pertronix works but here's some ideas.

If timing is badly retarded, idle can still be smooth, though you won't get good combustion and thre's be loss of power. Causes could be the timing has slipped or the advance system isn't working.

It could also be that the base timing is OK but the vacuum advance has failed (e.g. broken spring) in the full on position. Idle would be OK because the mechanical (or electronic) advance curve is not in effect. When you increase rpm, the curve might be adding to the vacuum advance resulting in excessive advance and loss of power and rough running - vacuum advance is supposed to fall back as the throttle opens.

.

"Hang on a minute lads....I've got a great idea."

 Posted: Apr 11, 2019 04:47AM
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1.75" Carb?  HS6?

It could be the fuel delivery to the carb is insufficient, the float bowl level could be way too low, the air filter could be plugged, or yes... maybe even the coil could be bad.  Go through the basics.  Set the valves on the engine when cold.  Tune the ignition system.  Save the fuel system for last.  You said this is a car with Pertronix.  At least temporarily refit points and condenser.  

Make one change at a time and test drive between each subsequent change so you can tell what the problem really is.

Doug L.
 Posted: Apr 11, 2019 04:19AM
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"....I've not yet taken a closer look, but thought y'all might give me some "check this first" ideas.

 - float bowl?
 - coil?
 - Petronix kaput?
 - fuel delivery?

It's the idling fine thing that's got me stumped..."

Float bowl? .... unlikely ..you'd notice the overflow ...and easy to check if empty  (the float bowl is not the problem)

Coil?  .. my pick - BTDT.... a couple to times... clean the points, optimise timing etc and things go fine ..until you ask bit more and then things start to break down.  The engine will run without (or with low) load but the compromised spark just doesn't cut it with a richer mixture....  I had  a Volvo that ran fine with a sick coil  ...until you tried to pass a 
truck.  At about 4K in top ... just about when you drew level with the cab .... it would die in the bum. Coil tested fine; eventually we ran out of ideas and tried a replacement .... VOILA ... as the Froggies say.. 

Petronix Kaput... also BTDT... its obvious .. nothing happens...

Fuel delivery . possible... pull the fuel line and check flow.  

Cheers, Ian

 Posted: Apr 10, 2019 01:37PM
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Hey all,

'68 mini has been running fine, (though smells a little rich).  1275, 1.75 carb, electronic ignition and fuel pump.

Last week on the way home, it started losing power, and sounding like it was running on 3 cylinders. 

I pulled over for a quick look - Oil pressure & level were fine, water temp fine.

Normally I'd suspect either an air leak, ignition issue or fuel problem, BUT it idles fine.  It's just when I put it in gear and try to drive away, I'd say I'm down power by 70%, and can barely limp along at 20mph in 2nd gear.

I've not yet taken a closer look, but thought y'all might give me some "check this first" ideas.

 - float bowl?
 - coil?
 - Petronix kaput?
 - fuel delivery?

It's the idling fine thing that's got me stumped.

Thanks!

Scott

New Zealand - The only place where a kiwi can mean a fruit, bird or mini owner...