Engine - idling speed problem

[Telpet]

I have recently installed a fully reconditioned 1098 engine in my 1964 Minor 1000. However, I am experiencing problems in achieving a satisfactory smooth low idling speed. I have carried out the usual adjustments utilising the recommended sequence but to no avail.New gaskets were installed and I have not detected any air leaks either at manifold or carb flange. The original engine employed the straight down tube breather system but its replacement came with closed circuit pipework. so I have had to source the necessary components, eg. diaphragm, valve etc.,. Also, I have had a local firm drill and tap the manifold to enable the new system. Section AAA.17 in the workshop manual illustrates this. The engine starts readily and is correctly timed. It runs smoothly at higher revs. The carb itself is I suspect the original unit installed when the car was built. The speedo shows 64,000 plus miles which is probably correct although I have no actual, proof Wear and tear are obvious likely explanations so a rebuild may well be on the cards. Given that it is a 'new' engine' I suppose I can rule out leaking or sticking valves, likewise a faulty head gasket. Faulty high tension leads could be checked out by installing replacements. However, if members could think of something I may be overlooking I would be delighted to hear from you. Cheers! Telpet.

[philthehill]

The respective section is AAA19.
(Section AAA17 is relative to bores and piston sizes)

The sealed system is applicable to 10ME engines.
Have you tried the test procedure as outlined in AAA19.

What number is on the tag attached to the carb float chamber.

A photo of the current set up would be appreciated.

[Telpet]

philthehill, yes, thanks for your response, you are of course correct, I should have said AAA.19. Will follow your advice, investigate, and report back, hopefully with a 'photo. Telpet

[ArunW]

Don't forget to check the vacuum advance, I had a split in the rubber connector (to the carb) causing a rough idle before I pulled apart my car (and some of the engine) for the ongoing restoration!

[Telpet]

Hello philthehill. Apologies for the delay in getting back to you, occasioned by an unanticipated health issue, now resolved. Returning to my crankcase breather problem the letters/numbers on my carb tag are AUD 13. The components for the valve were obtained locally from a car restorer's bits and pieces bin. He wasn't sure of their origin but thought possibly Triumph or Vauxhall. Have tried your suggestion but it made no difference to engine speed. Disconnecting the valve resulted in a regular engine idle without the previous rise and fall effect . Have taken 'photos and will send them as attachments in a followup message. Telpet.

[philthehill]

The valve (Smiths FVP) is the same whether fitted to Triumph, Vauxhall or any other car.
A dismantled photo of the valve and its fitment to the manifold would be appreciated.
Where does the inlet pipe to the valve originate from? i.e. the front cam follower cover with oil separator.

With the valve the main problem is the diaphragm which when holed does not allow consistent idling.

I would check the diaphragm, the plate under the diaphragm and the spring for serviceability.

Whilst the valve below is listed for a MG Midget it is the same as fitted to a Minor it does show the component parts.

https://www.moss-europe.co.uk/shop-by-m ... 098cc.html

[Declan_Burns]

When I installed the Smiths valve on my MG TD I had to install a restrictor to each carb to get a decent idle. I spent a long time measuring the crankcase vacuum pressure with a U tube manometer and testing various restrictor sizes. I finally ended up with a 1.7mm diameter restrictor to each carb. Others who installed the system on XPAG engines found the same. It works wonders on the rear scroll leak!

Regards
Declan

[Declan_Burns]

Here's the installation drawing on the MG.
Regards
Declan

[philthehill]

Declan
Whilst you may have had to fit a restrictor to your MG TD there is no restrictor fitted to the manifold suction pipe on a Minor.
I have just examined a Smiths valve and manifold union and there is no restrictor to be found. The manifold union is straight through as is the vacuum pipe exiting the bottom of the valve towards the manifold adapter though there is a non return (flame?) valve fitted into the bottom of the valve which could be considered as a restrictor.
I am not saying that a restrictor is of no benefit but the restrictor is not a standard factory fitment so it is no good looking for one.
Phil

[Declan_Burns]

Phil,
There is no way the XPAG engine will idle without the restrictor. I know there was none fitted at the factory.
Regards
Declan