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MG MGA - Fitting early MGB PCV Valve to MGA

Has anyone out there fitted the early MGB PCV valve to an MGA inlet manifold. I would like to do it to eliminate the oil drop from the draft pipe and I have all the bits required.

What is needed is a 1/2" hose connector on the inlet manifold. I have the MGB bit that screws into a threaded boss on top of the balance tube but of course the MGA inlet manifold doesn't have the boss making this method difficult if not impossible. Perhaps it could be fitted to the flat ends of the inlet manifold balance tube?

If anyone doesn't know about this see Barney's pages CV102/103.

Ideas and experiences would be appreciated.

Paul
3:0:1

Hi 3:0:1, etc.
Any chance you could change your sign-in so we can see your name and place of residence like others do. It just makes the forum that bit more interesting to a world-wide audience. If it's a necessary anonymity thing then just ignore me!
Best
Bruce.
B Mayo

Yes, I wondered whether aerial small was your name or the font you were using!!.............Mike
Mike Moore

I really don't know what happened here but I first lost all my formatting, on iPad and PC, and then this bizarre change of name. I believe it is now sorted. Has anyone else had this issue?

Any answers to the question in the thread?

Paul
Paul Dean

Paul
I got hold of a PCV set up for my mga to use on my 3- bearing 1850cc engine.
It dripped quite a lot of oil and it had an unvented alloy rocker cover which I thought may be causing excess crankcase pressure.

I managed to find an early MGB inlet manifold which has all the relevant vacuum take offs for the PCV.

I never got to fit to fit it as I was advised that it may upset the carbs quite a bit.

Colyn
Colyn Firth

Colyn

Surely to make the early B manifold work you have to also change the carbs to HS4s with the diagonal fixings to the manifold rather than the horizontal ones on the MGA's H4s?

Or have I missed a something, which I hope I have?

Paul
Paul Dean

If you remove the brass firing order plate from the existing manifold, and remove the studs, you will find that one threaded hole is blind, the other goes into the manifold void. If you can find a suitable fitting, you can mount the PCV to the remaining stud, and connect the PCV vacuum hose to the new fitting.
dominic clancy

I will look at the manifold again next week Paul, I'm away from the car just now.
I seem to remember that it was the same as the original but with the extra vacuum take-off points points.

I will let you know.
Cheers
Colyn
Colyn Firth

Colyn - Did you get a chance to check out the inlet manifold as above. No rush and from the parts drawings I think you will find it is offset but if it wasn't that would the perfect solution.

Paul
Paul Dean

Dominic, or anyone else.

Any likely source of the fitting Dominic is suggesting above?

My other thought is to fit the MGB 5/8" UNF fitting into one end of the inlet manifold. I do have a spare inlet mainifold so wouldn't be risking the one on the car..

Paul
Paul Dean

I have had a look for the manifold and the PCV unit which is all in the same container, but...
I cant put my hand on it yet!

It is in there somewhere, I think I may have put it away up in the roofspace somewhere, not expecting to ever need it.

I will keep looking for it for you.

Colyn
Colyn Firth

It's in the boot Colyn, wrapped in a poly bag. Check your inventory!

Steve
Steve Gyles

IIRC the fitting in the manifold that goes through to the void also has a large hex top. so removing it may well give you the same threaded boss as the MGB
dominic clancy

Dominic

I must be stupid but I don't understand your response . IIRC? Can you explain a bit further. Thanks.

Paul
Paul Dean

No he is not calling you an "Iirc"! Paul,
it just means "if I recall correctly".

I never use that acronym as I never seem to recall anything correctly ☺

Colyn
Colyn Firth

Paul..a cautionary note which may be relevant.
When I fitted the judson and SU HIF44 manifold to my car I noted that the HIF44 had a nozzle designated for pulling on the sump vent and passing any vapours etc through the cylinders. A much better way to vent the sump said I .I hooked it up to the sump vent pipe and discarded the draft vent . My oil consumption went up considerably and I was looking at many reasons ..even though there were no drips or exhaust indications.
I pulled the Carb connection a few months ago and reinstalled the original vertical velocity pipe.and oil consumption is now normal.
Lesson for me was that the original designers knew best on this topic ...and a few drips on the cardboard in the garage is normal for Uk cars of the time .,
Neil Ferguson

I concur with Neil. I played around with options a few years back and ended up with the white sludge inside the rocker box. Following discussions with Barney ( somewhere in the archives) I reverted to type, much as Neil says, and it all cleaned up and vented correctly.

One of those instances when originality is probably best.

steve
Steve Gyles

Paul
lm inclined to agree with Neil and Steve on this.
The reason I never went beyond getting together all the parts needed for the PCV set up was a conversation on the subject with Bob West. I seem to remember that he said something about it messing up the carburation on one of the cylinders.

Even if you only have an open half-inch crankcase vent pipe from the tappet side cover, there is no way that there can be any build-up of crankcase pressure.
I agree that you would need the rocker cover vent installed as well to fully ventilate the engine bit there would be no pressure in there.

Colyn
Colyn Firth

Gents, I have an MGB PCV fitted to my roadster - 3 brg 1800 engine with H4 carbies, non-vented aluminium rocker cover (other than the hole and filter built into the oil filler cap). I have had no issues with the setup.
Mike

Mike Ellsmore

Mike..do I understand correctly..you have a mgb pcv fitted to your mgb engine.
Neil Ferguson

Neil, yes but with a manifold to suit H4 carbies (With an MGA inlet manifold - see Paul's comment 22 June). Note how and where pcv valve has been attached.
Mike
Mike Ellsmore

If I remember correctly. The MGA inlet manifold has two threaded holes where the heater tube and the firing order plate are mounted. One of these has a hex uround and goes through the wall of the manifold into the Balance tube. Try removing this, you may find it is threaded the same as the fitting on the B manifold

I can't go look as I am in Bourmpnemouth and nowhere near an pay MGAs
dominic clancy

I hear the cautionary points but what I am trying is to implement is completely standard for an MGB 18GA engine, except H rather H4 carbs. My engine is a 3 bearing 1800 B unit and I am using the Pressure Control Valve that came in with the GA version of the 3 bearing units. Also I have the correct tappet cover, rocker cover and oil cap. I realise there is the potential for these issues but that is what MG solved with the clever PCV. Perhaps I will ask the MGB forum if there are any issues with this early B set up.

I have already had two unsuccessful attempt taking the low pressure from between the carbs and the manifold using the special adaptor Steve used at some point for another purpose. Firstly without a PCV and it just sucked lots of oil into the manifold and black smoke out of the back. Secondly I tried it with the PCV and all seemed fine until is disconnected and it was clear hadn't been doing anything, or having any problems.

I would still like to do it mainly as while I don't mind the drips my daughter does on her new light red brick drive.

Paul
Paul Dean

Dominic,
This is an MGA manifold. The tapping on the left is an extra (maybe for a vacuum gauge). On my roadster the extra tapping for the PCV fitting is 80 mm from the left hand extremity.
Mike

Mike Ellsmore

This is the sketch of the MGA inlet manifold from the parts book showing the original tappings.

My roadster is car that went on the Euro Lejog 2015 tour - 9,000 kms without any engine issues.
Mike

Mike Ellsmore

These are pictures of the original GA engine setup courtesy of the Moss cattle dog. It is very similar to my setup using the MGA inlet manifold - just eyeballing the PCV fitting is midway along the balance pipe.

By the way my oil consumption over the 9,000 kms was 5 litres (1 quart per 1059 miles). A bit more than modern day cars but in line with the mgaguru oil usage figures quoted below from
http://mgaguru.com/mgtech/engine/be104.htm

"I do have to add about a quart of oil every 500 miles "

500 is border line normal for an MGA, nothing to worry too much about, as oil is still cheaper than internal engine work. 700-800 per quart is honorable mention, and 1000 per qt is very good. 1200 per qt is very unusual, and maybe only with a new engine just run in. Anyone who claims to go 3000 miles between oil changes with stock MGA engine without adding oil is lying.

A quick qualifying note here. Later model MGB engines with a vacuum drawn on the crankcase via emissions controls may not leak oil at all. Then an engine in good condition may exhibit lower oil consumption. Even then more than 1200 miles per quart of oil is very good for a vintage MG."

Mike

Mike Ellsmore

Just to clarify what my version was umpty ump years ago, an 'expert' told me to connect the tappet vent to the rocker cover vent, to the front carb filter box via a 3-way adapter. Result was the white sludge inside the rocker box. Other than that the engine ran fine. Barney explained the issues. I have been standard set-up for a long time now.

By the way, I have never had to top up my 18V between oil changes. The slight drop in level on the dip stick during the period has never warranted a fill-up.

Steve
Steve Gyles

Steve

Your expert certainly wasn't one. This neither the early late way of doing it

Paul
Paul Dean

My memory is according to the drawing correct. As Paul is just looking for a way to add a PCV to the standard manifold my suggested approach would work. There is no need for the PCV to be in the centre of the manifold.

Paul, you can probably get the fitting you need from the same place as your PCV. It is the same valve and fitting on MGB and midget
dominic clancy

I am away from home hence can't check latest comments. I have the adaptor that screws into the MGB manifold so I can try Dominic's plan. It is 1/2" hose on top and 5/8 A/F on the other.

Paul
Paul Dean

I assume the original factor setup on GA engines being located at the mid point of the balance tube was that any minor effect from pcv operation would effect all cylinders equally.
Drilling and tapping the balance tube is a simple job.
Mike
Mike Ellsmore

Now back home I have found my 2 manifolds are different. My spare is per the 1500 spares list as shown above in Mikes photo, and also as in my spares list. The one that is on the car varies in there is no adaptor, 20 in drawing, but the stud is tapped directly into the manifold. Interesting when was this change made, or were the ones with adaptor just using up old stock. I would have thought both mine came from my February 1958 cars.

This accounts for why I didn't understand Dominic's proposal as I was looking at the manifold on the car. I have now successfully fitted the standard MGB PCV adaptor to my spare manifold. It was a pig to get the MGA adaptor out which I presume was down to it and the manifold being different metals. I will report back when I have fitted it to the car. Thanks to Mike and Dominic in particular.

Paul
Paul Dean

Colyn - Clearly I no longer require you to hunt out your early B manifold as problem solved. Thanks.

Paul
Paul Dean

This thread was discussed between 20/06/2016 and 16/07/2016

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