This might go very good, or very bad.

Progress! .... Well, maybe, maybe not.
Despite me having timed the life out of the thing it has still been giving me trouble when trying to accelerate from modest speeds (e.g. 30MPH) if there is any "load" involved (e.g. starting to climb a hill). The choices are:
  1. Push hard on the gas pedal and the car goes all "throaty sounding" on the induction side followed by a predetonation in the inlet.
  2. Drop down into a lower gear and rev the nuts off her and then up into higher gears.
Trawling the miniforum I found a post that said predetonation was a sure fire [pun?] symptom of the engine "leaning out".
So I got the SU Carb workshop manual out and went to "Tuning", followed the instructions:
  • Set the idle speed.
  • Richen the mixture screw until the revs stop climbing.
  • Back it off until the revs start to drop again.
  • Reset the idle speed.
Gave it a try on a local long & fairly steep hill and where it would normally grumble and "pop & bang" in the process as you demand it speed up once you get out of the 30 limit to the "unrestricted" hill. No hesitancy, no pops-n-bangs just great acceleration. :)

We may be making progress at last.
 
DannyC said:
Reset the idle speed.
Click to expand...
I recall something about SU carbs, from back then -
At least on the older models I worked with, the throttle shafts were not sealed or bushed at their ends.
After some miles of use, the shafts would wear in the body castings, and cause a small air leak.
This made setting the idle problematic - You couldn't really tell at higher revs, but it was hard to get a consistent idle, especially with a dual set up.
At the time, the cure was to get an oversize throttle shaft, and carefully ream the bores to fit - We did this pretty often.

So, maybe they changed the carb bodies for later years, but if you can wiggle the throttle shaft at all ...........
The things you remember from 40 odd years ago :rolleyes:
 
undertoad said:
I recall something about SU carbs, from back then -
At least on the older models I worked with, the throttle shafts were not sealed or bushed at their ends.
After some miles of use, the shafts would wear in the body castings, and cause a small air leak.
This made setting the idle problematic - You couldn't really tell at higher revs, but it was hard to get a consistent idle, especially with a dual set up.
At the time, the cure was to get an oversize throttle shaft, and carefully ream the bores to fit - We did this pretty often.

So, maybe they changed the carb bodies for later years, but if you can wiggle the throttle shaft at all ...........
The things you remember from 40 odd years ago :rolleyes:
Click to expand...
I checked when I rebuilt the carb, there was no perceptible play and the newer seal materials are far better than the old ones.
Interestingly, you can put the shaft seals on either way round. For normal induction they go round one way, for forced induction you fit them round the other way. It is to do with the pressure difference across the seal making the seals work properly. :)
 
...and in a fascinating fun-packed fiasco today we took the mini's plumbing apart a little bit to confirm the total lack of a thermostat [shock-horror].
So the correct 88° thermostat was inserted in the housing and just because we already had the plumbing undone I chose to remove the "straight through" heat-out fitting and pipe from the cylinder head for one with an inline on/off valve. That's when things went sideways. :(
Some kind soul had fitted the "straight out" fitting with incorrect bolts that were wrong thread and wrong length so the correct heater on/off valve is hanging on (not by a thread [pun]) but by a wing and a prayer.

The correct bolts/studs/nuts to use would have been 1/4" UNF, but no, they had forced metric 6mm bolts in there instead.
So, I have put it all back together (with these incorrect bolts (that you dare NOT tighten). I started it up and let it run for a while.
Well blow me down with a feather...... As I had predicted the water temp gauge actually worked and went all the way from "C" to the midpoint "Normal" mark and then dipped when the thermostat opened and rose back up to normal after a few minutes.

So another problem resolved, and another one discovered. Correct thread bolts arriving Wednesday. :)
 
undertoad said:
Do you have a tap to clean up the bunged-up threads?
Of course, you do - Silly me :rolleyes:
Click to expand...
Actually I don't think I do.
I might have to use an angle-grinder to cut lines up the threads of one of the bolts and then harden it and use it as a thread chaser. :)
Let's see what happens when the bolts arrive.
 
Continuing on from yesterday's fun and games I received some new 1/4" UNF bolts this morning.

The front fixing seems pretty much ok and I can get a 1/4" UNF to get a decent purchase.
The rear fixing is an entirely different case, you can push a 1/4" UNF bolt all the way in to full hole depth and pull it out again without bothering to turn it at all.
I used some spare (and overly long) bolts and nuts to see how deep the holes in the head are and it seems that both holes are drilled to the same depth but one has lost all its threading through someone taking a "that'll do" approach.

What options are there to remedy this?
  1. Try and drill the failed hole out in-situ and attempt to put a helicoil insert in there? - Sounds awkward in-situ.
  2. Clean, flush the hole out and chemically bond a split-tailed 1/4" UNF stud into the existing hole and hope it does not pull out.
  3. What else can I do?
I can't be the first person to pick up someone elses' "bodge" to a head, can I, so what is the standard approach to fixing this?

Anyone had a similar situation and resolved it satisfactorily?

Many thanks in advance.
 
These are blind holes in the head casting - Not into the water jacket ?
If there is enough meat to even think about a helicoil, then why not just drill to the root size of the next bolt size up (either imperial or metric, shouldn't matter), and series-tap, finishing with a bottoming tap, and be done?
Once again, though, I am likely missing something :unsure:
 
undertoad said:
These are blind holes in the head casting - Not into the water jacket ?
If there is enough meat to even think about a helicoil, then why not just drill to the root size of the next bolt size up (either imperial or metric, shouldn't matter), and series-tap, finishing with a bottoming tap, and be done?
Once again, though, I am likely missing something :unsure:
Click to expand...
Yes, they are blind holes in the head either side of a water-space, so I am conscious that I mustn't drill into anything vital.
I have ordered a 1/4" UNF helicoil kit (cheap really at £25) and I will try that first. If it fails then I can indeed drill out for M8 or similar (or maybe not as 1/4" is 6.24mm and the helicoil will be 2mm bigger than that I guess. The issue being that you then have to increase the hole size on all of the fitments that the bolts are trying to secure. :)
 
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I think you should take the opportunity to dispose of the A series boat anchor and put a V-Tec in. Given that you probably won't I think you've covered the options exhaustively other than moving the valve somewhere else.
 
Popshot said:
I think you should take the opportunity to dispose of the A series boat anchor and put a V-Tec in. Given that you probably won't I think you've covered the options exhaustively other than moving the valve somewhere else.
Click to expand...
Ta! No Vtec required, it shall be powered as God and BLMC intended with the faithful A-Series. ;)
Although there are a lot of Vtec monsters out there and Z cars too. :)
 
I am pleased to report that the helicoil repair was eventually successful. ;)
1st go would not let the bolt thread in. :eek:
Managed to prise the tip of the coil up and pulled it back out with some pliers and bit of a twisting motion. Phew!
I then recut the thread for the helicoil and washed the hole out with brake cleaner and this time it worked fine.
Lots of faffing to get the bolts the right length so they had decent thread purchase and yet did not bottom out in the casting hole.
Reconnected all the plumbing and ran it up to temp. No leaks. :LOL:
Went for a little blast....... still no leaks. I'm calling that a fix then. :cool:
 
undertoad said:
I have read, that 90% +/- of fastener strength is in the first 6 threads - Any depth past that, is mostly going along for the ride :)
Click to expand...
Absolutely, only 3 whole threads are generally required for a really strong fixing. Checked the coil inserts against the bolts before installation and there were at least 5 and a half turns from top to bottom of the insert, so I am confident that it will hold. :)
 
Yesterday was very bad.
Well she gave me another sound kick in the nuts yesterday afternoon. :(
I was taking the G-kids home from school back to their house and part way there the car started making a strange clattering/jingling noise. I pressed on (wish I had not). I turned of a main road into a side street and "boom" a very loud noise and then a deafening unsilenced exhaust note. The girl started crying and the boy started giggling and winding her up.
I pulled in and parked and looked under the car and 1/2 the exhaust system was not there. Looking back up the road at the junction I had just turned and there was the back box sat there. I then had to walk the kids home (15 minutes) and get a cab back to my place to gather tools etc. to try and rescue the car.

Job done (with some really hairy moments like the car nearly toppling off the jack while I was under it).
I managed to reattach the 2 halves at the broken joint with a pair of jubilee clips, and I gently drove it back home to safety.
A visit to an exhaust shop today I think. :)
 
Back in the day, I had a friend that raced an AH Sprite, BRG paint job and all -
On the back of the car, he had a sticker that read "All parts falling off this car are of finest British manufacture"
 
undertoad said:
Back in the day, I had a friend that raced an AH Sprite, BRG paint job and all -
On the back of the car, he had a sticker that read "All parts falling off this car are of finest British manufacture"
Click to expand...
Yes, Paul made the point this morning on our call that my car is now truly a "collectors item" as I have to collect all the bits that fell from it. :)
 
Yesterday was a bust. :( The new exhaust clamp didn't fit. My Bad... I measured the exhaust pipe and forgot that that pipe (50mm) inserts into a 52mm pipe so the 50mm clamp just would not work.
A representative of Mr. Besos delivered a 52mm clamp this morning and it has now been installed and tightened to within an inch of its miserable life. A test run has been enjoyed, although I could hear it "missing" on a steep uphill section in top-gear.
I also discovered the lower gasket on the thermostat stack is weeping, so I tightened it up a little. Will check to see if it has stopped. :)
 
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