Engine Stumbles

[DS1980]

Checking valves and doing a compression test, decided to change spark plugs while I'm at it. Taking off NGK BP6ES and noticed I only have BP7ES to replace. I just read that the higher number on the NGKs represent a colder plug, and that's ok. Just confirming.

[DS1980]

Well, setting valve clearances and am having troubles. Out of the 8 valves, one adjusting screw spins freely. I managed to snap off one with apparently my super human strength. Any suggestions on why these screws will not turn? Oh, and what to do with this one.

[towjoe]

Did you loosen the nuts below the screws? You can replace the adjusters.
I always wandered why allen heads were not used. I guess $$$.
Regards
Joe   77.gif

[MiniDave]

They should turn freely if you loosened the nuts first. Sometimes one will get stuck but if you work it back and forth with a little spray penetrating oil on it, it should come loose. You could remove that end rocker arm easily enough by taking off the cotter pin on the end of the rocker shaft and sliding it off. Then once on the bench remove the nut and use a pliers or something to carefully work it back and forth till it's loose again. You can still use it till you can order a new one (or several so you have spares next time) once it moves freely you can simply turn it with a pliers till you get the adjustment right, then lock it down with the lock nut.

7Enterprises is not too far from you since you're in Colorado, they'll have the new rocker screw adjusters.....but I wouldn't be surprised if someone local doesn't have some old ones lying around too, I know I do.

Another place you can get those is Victoria British here in KC.....same as a Sprite.

Vicky Brits part # 12-4316, $1.45 ea   (800) 255-0088
7 ent part #12H3376  $3.99ea           (800) 992-7007

However once you remove the rocker arm you might find wear on the shaft, which means you really should replace the arms and shaft.....

[DS1980]

Heat, hammering, penetrating oil......they are not budging.

On MM I'm seeing:
http://www.minimania.com/part/12A1215/Rocker-Adjuster-Screw-Small-For-Orig-Pressed-Steel--Sprite--Mg-Midget--Mini

and

http://www.minimania.com/part/AEG167/Rocker-Adjuster-Screw-For-Forged-Type--Sprite--Mg-Midget--Mini--Morris

I think I have the pressed steel rocker so I need the first screw, or am I wrong?

Also, this is my first time doing anything valve train related. I read the Haynes and I don't know what the rocker retainer screw is, nor does it describe it. The dark blue on says the cylinder head must be removed, the light blue one says nothing about it. Can I just take the cotter pin out on the thermostat side of the engine and pull the shaft through?

[John Gervais]

Wow, it really sounds like you're having trouble, and with so much to read, I thought I'd just post what I do.  It almost seems as though you're battling the valve spring - that is to say that the rocker isn't rocking prior to your trying to loosen the adjuster.  Remember, number 1 is closest to the radiator, number 8 is closest to the clutch.

Here's what I do:

1.  Remove the spark plugs
2.  Remove the distributor cap
3.  Remove the valve cover
4.  Lift one front wheel off of the ground (emergency brake on)
5.  Put the engine in 3rd gear
6.  Rotate the tire as if the car is rolling forward - you'll see the valves opening and closing, as well as the distributor rotor turning counter-clockwise.
7.  This is the tricky bit - find Top Dead Center (commonly known as TDC). Continue to turn the tire until the rockers over cylinder number 4 are loose (rocking in free air) and the distributor rotor is pointing at the number one cylinder.  You'll see that the marker on the crankshaft pulley (if it has one) or the marker on the flywheel (visible through the little cover on the 'wok' clutch cover) lines up with the pointer above the pulley (on the timing chain cover, again, if it has one.) or moulded inside the peephole in the 'wok'. 
8.  Now rotate the engine 360 degrees and align the timing marks the same way, this time with the rockers on number 1 cylinder rocking in free air.
8.  Have a sip of beer...
9.  Adjust the valves, using the rule of 9 (when valve number 2 is fully pushed down, adjust number 7 (2+7=9))

Adjust them sequentially, and try not to rotate the engine backwards.

The images are from an old factory manual, don't worry about them - I suspect you'll only need the 3rd image which is to adjust the valves.

Edit:  Was just thinking bout this - no need to find TDC after all, just follow the 'Rule of 9' -

And, how did the BP6ES sparkplugs look?  They've a wide temperature range, so I'd replace with the same.

Check out this .pdf from NGK classic vehicle catalogue - it lists the BP6ES for the 0.8L Austin mini.  A good download for the PC...
http://www.ngkpartfinder.co.uk/files/NGK_Classic_Vehicles.pdf

[MiniDave]

You do have the pressed steel rockers, so you need the small screws.

You cannot just pull the shaft out, there will probably be just enough misalignment of the rocker towers that some would bind, plus some of the valves will be open, putting pressure on those rockers. You might be able to get that end one off by simply removing the cotter pin and sliding it off, but not the rest.

Some of the bolts that hold the rocker assembly are head bolts, I don't know if you can successfully remove those without disturbing the head gasket, but I think I'd take the chance. Once you get the rocker assembly off you can take the cotter pin off the end and slide the shaft out. Some have a retaining bolt that locks the shaft into the correct position so that the internal oil holes will line up right - be sure to put it back exactly the same way. (In the pic below, the retaining bolt is in the center of the 2nd left tower) When you remove the rocker arms there is a sequence to the various parts, lay them out in order and put them back exactly the same way. Take many pictures along the way to help your memory.

When you reinstall the assembly be sure to torque those head bolts to the right torque setting....all the headbolts, not just the ones you removed

I have a set of used pressed steel rockers I'll sell you pretty cheaply - you can use them as is or just take the adjusting screws out and use them if your rockers are in better shape than these. I replaced mine with forged rockers.

Are you using enough heat? Getting them cherry red?

Victoria British only charges $12 ea for the forged rockers with adjuster screws and bushings, if you go that route buy a new shaft (also $12) and you will have to have the bushings reamed to fit the shaft, but I don't think that will cost more than about $20.

Or buy my used ones and replace as many or few as you need and keep everything the same.

[DS1980]

John-Yes, yes I am having troubles. All of this because I wanted to check my valves. I may just adjust the ones I have loosened, they are not that far off from 0.012. This has turned into a nightmare. I have no problems doing the task, and was good up to the point of adjusting the screws. Thanks for the info on the spark plugs!!!

Dave - To clarify, what are the small screws? Let me guess! The expensive ones? I don't have a torch so wasn't able to get them that hot. In your experience, is that the difference maker?
I may just adjust the ones I have been able to loosen and call it done. However, I want to open it back up next spring and do it again fully. How much for your rocker assembly shipped to 80015?

[DS1980]

So.......
Changed condenser, low tension lead, and spark plugs. Still waiting on the GG needle from 7ent. Fired it up and now it requires healthy choke and will not idle. Set a high idle and took it out. Produces hardly any power. Had to use first gear to get up a mild incline. Looks like I have some adjusting on the carb to do. Will do than when the needle is in.
It didn't stumble though....well, except when the RPMs got too low. #funtimeswithbritishclassics

[94touring]

Could that be related to your valve adjustment woes?   

[DS1980]

I don't think so. The engine mechanically sounds fine. It just runs very rough.

[DS1980]

Just an update.
Sat down with it and did some serious carb adjustments. Got it to run good with the air cleaner off, but as soon as I put it on, it dies. Does anyone have experience with the K&N? I need more air to it. This altitude does not do it any favors.
On a side note, I drove it all over town today. I drove it more than I have in the last 2.5 years. Did not stumble. It just might have been that condenser. I changed the low tension lead and spark plugs as well. I forgot what a great little car it is. And thumbs up everywhere.

[MiniDave]

Have you cleaned the filter lately? Soapy water and let it dry thoroughly before you lightly re-oil it.

[DS1980]

Nope, I will do that. It would need to make a BIG difference. It chokes it a lot.

[94touring]

Stock filter box?

[DS1980]

Yes.

[94touring]

Depending on your box I might have a brand new filter...well barely used for 100 miles. 

[MPlayle]

I've used the "stock replacement" K&N filter in the round plastic stock filter box when I was living in Fort Collins, Colorado.

I also did the modification to the box as recommended by Calver: drill about 6 holes (about 3/4" diameter) along the bottom of the front edge of the box outside the actual filter to draw additional fresh air from above the manifold (gets slightly heated by the manifold).  These holes provide as much air volume in as the single large stock opening.  Thus you are allowing more air flow to reach the filter.  The K&N filter also flows more air than a stock paper element.

This helped the Mini I had at the time run much better in the local altitudes.

[DS1980]

Thanks 94-I have a new filter, I just wanted to see if anyone had experience with K&Ns.

I will look for a junk box to drill into. Mines the original box, and that just doesn't seem right.

[MiniDave]

I may have a spare box I can sell you pretty cheaply, post up a pic of yours with basic dimensions and I'll compare it to mine.