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PCV on 18GB "big-bore"

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tourtelot Avatar
tourtelot Gold Member Douglas Tourtelot
Seattle, WA, USA   USA
1976 MG MGB "Heathcoat"
Anyone tapping their block to set up a more efficient crankcase ventilation than that supplied by a 1/2" breather in Basil's lovely side-cover. It seems that my engine is still pressurized and is misting out in a few places under high RPMs. Mostly, it seems, around the front seal.. Also seems like the top mounted breather is actually putting out pressure.

Rings are new-ish but bedded, valve cover cap is vented, 18GB engine with no obvious place to put an extractor fitting to a catch can.

What are folks doing?

D.



Douglas Tourtelot
Seattle, WA

"Every education has a tuition"

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pinkyponk Avatar
pinkyponk Gold Member Adrian Page
Berwick, NS, Canada   CAN
Doug, does your engine not have the blanking plate for the mechanical fuel pump? I thought mine was a GB and it has one.

Adrian



Home built Eaton M62 Supercharger with 7.6psi boost, 8:1 compression, custom "supercharger" cam from Schneider Cams, Mikuni HSR48 Carburetor, cold air intake, ported head, matched manifolds, CB Performance computerized ignition, Fidanza 9 pound flywheel, Maxspeeding rods with Teflon wrist pin buttons.

tourtelot Avatar
tourtelot Gold Member Douglas Tourtelot
Seattle, WA, USA   USA
1976 MG MGB "Heathcoat"
Nope. Would be a perfect spot if it did. I think we are considering tapping a new fitting into the block. Ugh!

D.



Douglas Tourtelot
Seattle, WA

"Every education has a tuition"

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lewk Avatar
lewk Silver Member Keith Lewis
Cambridge, ON, Canada   CAN
I plumb my tappet cover vent pipe (Basil Adams one piece cover) to the air cleaner on my carb as I do not want too much vacuum pressure draw. As there is no oil mist trap with Basil's cover, I made my own from plumbing bits and pieces and filled it with stainless steel chore girl type wool. I'll post a picture but it is hard to see but I think you get the idea. The oil trap is before carb air cleaner intake. You'll also see a catch can in the shot but it is really there for show from another method I tried and didn't bother removing the catch can. Also note I vent at the rear of Basil's cover.


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tourtelot Avatar
tourtelot Gold Member Douglas Tourtelot
Seattle, WA, USA   USA
1976 MG MGB "Heathcoat"
I have a 1/2" pipe coming off the rear of Basil's side cover but I just don't think it's enough to take care of the chaos in the lower CC and pan that happens at higher RPMs. I will also need to come up with something to coalesce the vapor and I am leaning toward a can of some kind. And not a closed circuit either. If I felt no remorse, I might just bring another 1" breather off the block and let it road-draft. But that wouldn't be very eco-friendly would it? And no-one would let me on their track even if I ever decided to take the car on a track smiling smiley

D.



Douglas Tourtelot
Seattle, WA

"Every education has a tuition"

riley1489 Avatar
riley1489 Gold Member Bruce H
Great White North, QC, Canada   CAN
1953 Jaguar XK120
1959 Riley 1.5 "King George"
1973 MG MGB
In reply to # 3888030 by pinkyponk does your engine not have the blanking plate for the mechanical fuel pump? I thought mine was a GB and it has one.

Adrian if you are referring to your OE 1973 then it would have been fitted with a Black coloured 18V, and yes a blanking plate was present on 18V engines.

Doug
You are experiencing greater than normal crankcase pressure, if oil is escaping the engine, weird. This is not normal and should be investigated.

This absent oil separator on these solid side covers is a mega design shortcoming, and if this breather is drilled low on the cover you may be may be seeing oil splash from the cam followers.

This is difficult to put right with that design side cover so simply do as Keith shows, and so many others need and install a catch can?

B



Check your ego Amigo!

pinkyponk Avatar
pinkyponk Gold Member Adrian Page
Berwick, NS, Canada   CAN
Bruce, My original 18V is stored under my Bugeye bonnet. I found an early 5 main GB engine to build up for my MGA/overdrive project but ended up swapping it into my 73. It has a cover over the fuel pump hole.(I checked) I use one of the bolts as a brace for my supercharger to bolt to.

Adrian



Home built Eaton M62 Supercharger with 7.6psi boost, 8:1 compression, custom "supercharger" cam from Schneider Cams, Mikuni HSR48 Carburetor, cold air intake, ported head, matched manifolds, CB Performance computerized ignition, Fidanza 9 pound flywheel, Maxspeeding rods with Teflon wrist pin buttons.

tampaguy Avatar
tampaguy Jack Shea
Elgin, OR, USA   USA
I would suggest reverting back to original style side covers, doing so should provide you a simple method to properly vent normal amounts of blow by. I appreciate Basil’s attempt to eliminate the potential for leaks around the original style side plates. As others have proven , me included a simple K&N filter attached to the front cover is all that is needed to properly vent this little engine.


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ohlord Avatar
ohlord Gold Member Rob C
North of Seattle, N.W., USA   USA
1957 Land Rover Series I "EYEYIYI"
1971 MG MGB
1971 MG MGB "Bedouin 2"
What's your valve cover venting to CC like
Is the condition a recent onset?
Done a leak down test?



"I'm a long way gone down this wild road I'm on
It's gonna take me where I'm bound
It's a long way around"



"These are the days that must happen to you"

RD2 Radar/ Electronic Warfare Technician
Vietnam 1969-1972

pinkyponk Avatar
pinkyponk Gold Member Adrian Page
Berwick, NS, Canada   CAN
Doug, what carbs and breather setup does your car have? If you have twin SUs sucking air out of your crankcase vent it would need a properly sealed valve cover etc... and no vent in your oil cap.

Adrian



Home built Eaton M62 Supercharger with 7.6psi boost, 8:1 compression, custom "supercharger" cam from Schneider Cams, Mikuni HSR48 Carburetor, cold air intake, ported head, matched manifolds, CB Performance computerized ignition, Fidanza 9 pound flywheel, Maxspeeding rods with Teflon wrist pin buttons.

riley1489 Avatar
riley1489 Gold Member Bruce H
Great White North, QC, Canada   CAN
1953 Jaguar XK120
1959 Riley 1.5 "King George"
1973 MG MGB
In reply to # 3888086 by pinkyponk Bruce, My original 18V is stored under my Bugeye bonnet. I found an early 5 main GB engine to build up for my MGA/overdrive project but ended up swapping it into my 73.

now how am I supposed to know that?? grinning smiley smileys with beer

B



Check your ego Amigo!

pinkyponk Avatar
pinkyponk Gold Member Adrian Page
Berwick, NS, Canada   CAN
In reply to # 3888116 by riley1489
In reply to # 3888086 by pinkyponk Bruce, My original 18V is stored under my Bugeye bonnet. I found an early 5 main GB engine to build up for my MGA/overdrive project but ended up swapping it into my 73.

now how am I supposed to know that?? grinning smiley smileys with beer

B

I don't know... I'm not even sure I remember why I did it. spinning smiley sticking its tongue out

Adrian



Home built Eaton M62 Supercharger with 7.6psi boost, 8:1 compression, custom "supercharger" cam from Schneider Cams, Mikuni HSR48 Carburetor, cold air intake, ported head, matched manifolds, CB Performance computerized ignition, Fidanza 9 pound flywheel, Maxspeeding rods with Teflon wrist pin buttons.

tvrgeek Avatar
tvrgeek Silver Member Scott S
Hillsborough, North Carolinia, USA   USA
1965 MG MGB
"Religious" topic. Search some. I also suggest going to WIKI and reading how PCV is supposed to work, then look at how MG did it with their evap controls ( a bit different)

The side cover does not have a vapor separator so you need an external one, running to a PCV valve and into the manifold. The vent into your valve cover should then be only intake. This is how just about all cars did it for about 15 years. When they added evap controls, the valve cover became sealed and you suck through the charcoal canister. MG used a pinhole in the valve cover intake rather than a PCV valve. Don't know why.



Cogito ergo sum periculoso

MG Logic Phil Pierce
Newtown, CT, USA   USA
Might be worth noting that if you are using carburetor/air cleaner vacuum to help vent the crankcase you should use the Factory tappet cover. Not only does it serve as an oil separator but it also functions as a flame arrestor. In the event of a carburetor backfire it prevents any flames (I.e. oil mist) from getting into the crankcase and blowing up the engine. That's why the Factory put it there.

gray Avatar
gray Graham Moore
CAMBRIDGE, CAMBRIDGE, UK   GBR
i was *advised* not to bother renewing the mesh in the can on the front cover. when i removed the old one, the can just contained a solid lump of wire mesh/gunk that i had to dig out. as a newbie i took that advice.

WRONG!

so i hooked up the breather to the carb. running fine. apart from the fact i was using a pint of oil every 300 miles. but the engine was newly rebuilt so i did not know what to expect. i had no reference.

had an idea to try one of the MGB V8 flame traps - they have a mesh inside. they are also a standard rangerover part # 603330. cost about £3.

oil consumption down to a pint every 900 miles.

so the trap is doing a good job of condensing. no negatives.

G


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