Morris Minor Owners Club

Hi there Iv ordered a alloy inlet manifold which I will be fitting on the weekend, however I forgot to order the blanking nut, could I use anything else to blank the hole off like a nut from a hardware store? Also the studs that stick out from the carb side Arnt present. Where do I get the screws so that the carb can be bolted onto it? Sorry if the answers are obvious, I'm still a learner. Any help will be appreciated

Regards

Sam

I don't understand the 'blanking nut' idea......do you mean the alloy inlet has a port for a vacuum servo? If so - no - you won't find anything (and certainly not a 'nut' ) in a hardware store...... I think it is 5/8" UNF.... You will remove the studs from the old cast manifold - and fit them to the new manifold. What will you do for an exhaust??

Hi it's a nut that's supposed to blank off the hole on the manifold, I think, it's designed if your car has a brake servo something like that, I think it's a 22mm nut. In fact it's a bolt not a nut lol. I will
Be angle grinding the original inlet off the exhaust manifold, it's because iv got a stainless steel exhaust system so I want to keep that. Will I need the optimising timing and air/fuel ratio with the new inlet?

Of course you will! But what carb are you using with the new inlet manifold? It won't take the standard HS2 carb...... The blanking plug is certainly NOT 22mm........

Iv already installed a hs4 carb. I did that with your help before about 2 months ago. I want to cut the inlet manifold from the exhaust manifold and use my stainless steel exhaust system. The hole is on the left hand side of the manifold I attached. Could any bolt fit ?[frame][/frame]

Not 'any' bolt - it will need a 5/8"UNF plug. Sorry - I had forgotten you are on an HS4. Interesting to hear what improvement changing the manifold makes. You should cut the exhaust off a standard Minor manifold - not the rather better manifold you have with the HS4. Make sure you cut into the inlet manifold - and then tidy up the rump left on the exhaust.

Like this.
Regards
Declan[frame][/frame]

Great help one again i fitted to today finished about half hour ago. Looks and sound nice, but first when warmed up with no choke it would kind of die, I then adjusted the idle speed and got that set ( I could be wrong), it was fine after that then drove around and the revs seemed high and when acclerating I would let go off the pedal and it would still feel like it's at high revs but slowly drop, not enough though to call normal. The exhaust sounds like a few gunshots are being let off inside on idle aswell.

Sticking throttle cable? How did you plug the servo hole? Is the carb sitting with the float chamber absolutely vertical? And - look for air leaks - is the manifold held TIGHT against the head? Are you sure the inlet manifold has clearance off the exhaust - otherwise it may be held slightly 'tipped up' causing an air leak at the manifold/head interface.

From that picture it doesn't appear to be a servo hole at all but rather a hole that goes to the water passage in the manifold perhaps for a thermostat.

If that is the case it wouldn't even need to be plugged unless you're circulating coolant in the manifold.

The 5/8" hole is in the No: 3/4 inlet tract.
The water tube is just a straight through pipe.
The blanking plug is available from Mini Spares Pt No: ADP210 £2.88 inc VAT plus P&P. Use washer 1B3664 also available from Mini Spares. You can also use blanking plug Pt No: 5-8UNF also available from Mini Spares.

Thanks guys. Everything all seems held in place. My idle speed is just so high and when I adjust it it's either too low as if it's about die or too high . When braking and putting the car into neutral and then downshifting the revs increase which is making it hard to drive, if I put the car in second, the car will just keep running without any throttle pressure. Also sometimes when stood still with no choke I will rev it and as the revs slowly come down it will stArt to die until I give a little more revs to keep it running. I know if I get it set right I will see the difference in the new inlet mani but for now it's become a bit of a problem.

You haven't answered about sticking throttle cable? Is there an adequate return spring? And is there a GAP between the inlet manifold - and the (now cut off) exhaust manifold? Is the carb piston free to rise - and does it fall back with a nice clunk? Have you set up the idle mixture? And - how have you plugged the servo hole??

how have you plugged the servo hole??

That was my thought also, probably sucking air in there.

I would suggest that if the 5/8" blanking plug has not been fitted it would run really awful; much worse than described above.
If the hole has been plugged with a non standard plug, yes there may be a weakening of the mixture as air is sucked past the ill fitting plug. The correct 5/8" blanking plug must be fitted.

Just a thought....is a spark plug 5/8" UNF....?

No
The blanking plugs advertised (Part No: 5-8UNF) are 5/8" UNF x 18TPI (I purchased several to use in blanking the oil galleries).
The spark plug is 14mm x 20TPI.
Have checked both the 14mm spark plug and manifold blanking plug with a thread gauge.
I have just also removed a blanking plug from an alloy manifold and the thread used is 5/8" x 16TPI Unified National Special (UNS). I believe that this is the correct thread for the manifold blanking plug.
So there may be variations in plugs used to blank holes in inlet manifolds.

It was just a thought......thinking back, I suspect I tried a spark plug many moons ago...and failed. Strange that a 'metric' thread would have 'tpi' - is that just a 'nearness' ?

bmc
A good question well put.
The three thread gauges I have
Whitworth - Threads per inch.
UNF - Threads per inch.
Metric - Gives the pitch from i.e. 0.5mm - 1.75mm.
As regards the metric TPI it is a generalisation (nearness) term as pitch is the correct term when describing metric threads.
A 14mm (13.5mm actual) spark plug should be deemed as being 14mm x 1.25mm pitch.

5/8" Whitworth is 11 TPI.
5/8" UNF is 18 TPI.
5/8" BSP is 14 TPI.
5/8" BSF is 14 TPI.
5/8" UNC is 11 TPI,
5/8" (16mm) ISO Fine in mm is 1.50 pitch.. ISO Coarse in mm is 2.00 pitch.
5/8" UNS is 16 TPI.

Have just been reading my copy of the British Standard for Unified Threads & how the British Standard for UNC/UNF & UNS came about after WW2. The designations adopted were the nominal diameter and the Threads Per Inch (TPI).
Interesting reading. Well someone has to read it!!!!

" Have just been reading my copy of the British Standard for Unified Threads & how the British Standard for UNC/UNF & UNS came about after WW2. " A quiet day then Phil ......... I do know that metric are expressed as pitch - I was just asking a 'leading' question...