# MGB question



## mgbrv8 (Feb 5, 2012)

Gentelmen I have a question about this photo? I know it isn't machining related but I am trying to help a friend of mine and a new and slightly frustrated mg owner. In the picture do you see any issues with the way the emission tubing is routed? I like how the gas tank vent goes through the carbon canister and then into the valve cover then out of the PCV port on the drivers side of the block of the engine and then into the intake or exhaust I'm not sure. First off is this a good solution and is the PCV port going into the intake or the exhaust? This I picture I found and website from were it came has no others. 








Thank you for your time and input Gentalmen 

Dave


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## John Rudd (Feb 5, 2012)

From my tinkering with cars from an early age, Positive Crankcase Ventilation normally connects to the Inlet Manifold...

However I stand to be corrected......

and a quick Wiki....reveals all.

A crankcase ventilation system is a way for gases to escape in a controlled manner from the crankcase of an internal combustion engine. A common type of such system is a positive crankcase ventilation (PCV) system, the heart of which is a PCV valvea variable-restriction valve that can react to changing pressure values and intermittently allow the passage of the gases to their intended destination (which nowadays is the engine's intake stream).


Just as I thought..


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## bearcar1 (Feb 5, 2012)

If I am seeing this correctly, the hose connecting the tappet cover crankcase breather tube is being routed to a fitting on the intake manifold just under the carburetor. I believe that connection is wrong. The manifold fitting is meant to be used as a means to circulate hot water to the manifold in order to assist air/fuel mixing and has nothing to do with the engines ability to breathe. (I *think*) If I may suggest, post up this question on the MGBE board as those guys are all about these cars and these 18V engines.

http://www.mgexperience.net/article/weber-hose.html

BC1
Jim


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## Stan (Feb 6, 2012)

Don't expect anything on a MGB to be conventional. Their design people tended to take the long way around to solve a problem. For example, instead of a $2.00 thermostatic switch to close a choke plate for starting, they invented a million dollar carburetor that controlled the fuel. The vacuum operated pistons were nothing but trouble.


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## dgjessing (Feb 6, 2012)

From my limited experience that looks like an after-market carb. Mine had the twin round ones Stan describes... Don't remember how the various hoses were routed but I'd expect the crankcase vent should be connected to manifold vacuum (or just open to the atmosphere with a filter). 



			
				Stan  said:
			
		

> Don't expect anything on a MGB to be conventional. Their design people tended to take the long way around to solve a problem. For example, instead of a $2.00 thermostatic switch to close a choke plate for starting, they invented a million dollar carburetor that controlled the fuel. The vacuum operated pistons were nothing but trouble.


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## DICKEYBIRD (Feb 6, 2012)

Looks OK to me as long as there's a PCV valve at the connection with the inlet manifold, the correct restrictor is in the valve cover elbow and it has the correct vented oil filler cap on the valve cover.

That's a 66-67-ish model, right? The crankcase vent system all looks stock other than the hose going into the lower section of the aftermarket intake/carb. As originally built, it was routed up to the PVC valve in the top-center of the twin SU carb manifold. The valve was an approx 3" round gizmo with a rubber diaphragm inside that would get gooey with age and split causing vacuum leaks and a rough idle.

All english rubber used to do that over here in our atmosphere. A Brit I used to work with said their rubber parts were made from "old wrestling trunks & used condoms." :big:


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## GWRdriver (Feb 6, 2012)

There was nothing wrong with SU carbs, I wish my present car had them, you just had to know how they worked and how to tune and balance them which anyone with a SU kit could do under a shade tree. (Former owner, '48 TC, '53 TD, '56 A, '69 B)


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## bearcar1 (Feb 6, 2012)

Say Dave, I've been staring some more at that picture and am wondering now, does the owner of this car have that crankcase tappet chest vent hooked to a fitting welded into the exhaust manifold? There would be a venturi effect in that location but I would think it to also be a potential source of pressurization as well. Can you clarify where said hose is connected? In addition, I always thought this connection should go to a source of low pressure like the base of the aircleaner if no PCV valve was in place. Does this car exhibit any tendencies of excessive oil consumption?

BC1
Jim


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## MachineTom (Feb 6, 2012)

The connection that looks incorrect is the tube from the valve cover going to the carbon cannister. That could not be correct, that hose should have a inline PCV and go to a fitting under the base of the carb. The oil filler looks to be a sealed cap, there should be a second connection that would have gone to the clean air side of the air filter base, this would allow filtered air into the engine crankcase, to make up for the dirty air that is passed through the PCV on its way to intake manifold to be burned. It is possible that the tube welded to the valve cover is the clean air tube, and the PCV was located elsewhere on the engine. 

A carbon canister was used to collect fuel vapors, then permit them to be burned in the engine. It was usual to have a small filter in the bottom, This was to provide clean air to the charcoal which carried the fuel vapors, then on to intake manifold to be burned. There would be 2 large hoses for vapors, one to the tank, the other to the engine and a small hose for venturi vacuum, Large hose to carb base small hose to venturi vacuum port. Connecting a oily air hose to the carbon cannister would likely kill the usefulness of the charcoal, as well as mess up the running of the engine.

 I worked at a MG dealership in the early 70's, before most of this stuff was added to the vehicles. Find a manual for that year vehicle there would be a hose diagram in there.


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## HS93 (Feb 6, 2012)

as has been pointed out this car has an after market carb fitted and a filter to match , on "UK standard cars" they had the pipe from the rocker cover going to one air filter and the pipe of the cam follower covers (only one had a pipe) also came up to the bottom of the standard air filter. on a lot of the Early A series this pipe had a loop in it and went to atmosphere. the manifold on this car should be heated via the heater water pipe that comes from the top of the hose that comes from the water pump , doing away with the pipe on the rocker cover that goes to the heater to warm the manifold, is there another pipe coming off on the bulkhead side of the inlet manifold if you get really stuck I may be able to source a aoutodate page with some info on

Peter


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## mgbrv8 (Feb 6, 2012)

Gentlemen I appreciate your input and insight but I am receiving a number of very angry and just plain mean messages from Senior members. so tomorrow I will make it a note to delete this post from the break room portion of this site. My intent was not to cause a hurtful avenue for bully's to attack. Your advice has been very helpful to my friend. And with your help and his southbend lathe he has engineered and fabricated a solution. Thank you for your time and thoughtfulness gentleman. 

Dave


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## steamer (Feb 6, 2012)

Dave,

I don't know whom you are speaking about.  But I don't approve of bullying, or PM harrassment.

This is the Break room.  It's a little bit of anything goes area. You posted appropriately.

If someone has a problem with Dave.  WE have a problem....Bring it up with me or anyone from the managment team then!

Dave your welcome to leave this post as is , right where it is, for as long as you like,


Steamer


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## GWRdriver (Feb 6, 2012)

Dave,
Well that's kind of a shame. I've been the target of one such individual since I've been here and the way I look at it, if you leave they win and the rest of us lose a little bit, so I just ignore them and keep on going.


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## 1Kenny (Feb 6, 2012)

Dave,

No problem from me. I have been kind of following this wanting to know what the fix is going to be.

Kenny


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## Foozer (Feb 6, 2012)

I thought the PCV system was composed of two separate circuits. One was the PCV valve ported to the intake at or near the carb base. This handled crankcase pressure at low to part throttle (intake vacuum present) The other half being a larger tube from the valve cover to the base of the air cleaner for low vacuum high carb airflow times (full throttle) Might have a one way valve in case of carb pop backs.

Been a few days

Robert


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## bezalel2000 (Feb 7, 2012)

Quite Ingenious - putting the rocker cover on back to front   so the vent faces the carbon canister - so where else could it go? when the original Carby isn't there.

Am I getting warm?????????? ???

Bez


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## GailInNM (Feb 7, 2012)

Dave,
There is nothing wrong with your posting this thread in the Break Room. The Break Room is for posts that may be off the main purpose of the main HMEM forum.

As long as a post does not violate rules of polite behavior, safety, is generally family friendly and is not spam then it is OK for the Break Room. I think that you will find that the administration is quite liberal in this respect. We want HMEM to be a place for everyone to enjoy themselves.

If ANYONE has a problem with a post the only correct avenue of approach is to click the "Report to moderator" link at appears at the bottom of every post. This sends a report, which may include comments, to all moderators and administrators. It is only a moderator or administrator that can ask some one to modify or remove a post or in the case of a serious infraction of the rules do it themselves. 

Gail in NM
Moderator


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## DICKEYBIRD (Feb 7, 2012)

Bezalel  said:
			
		

> Quite Ingenious - putting the rocker cover on back to front


I don't remember ever seeing a 'B engine with the oil filler cap at the rear though.


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## mgbrv8 (Feb 7, 2012)

You know after reviewing your comments i completely agree, this is the break room. This avenue if posting was used to aquire educated advice and to then fabricate a solution so there is nothing wrong with this post. Using you advice and info from other web searches He devised a solution. Starting at the carbon canister he ran the fuel tank vent throught there. He then made a nice and neat bent aluminum tubing to route the output of the carbon canister to the carb. He then took the vent from the top of the valve cover and tee'ed in to the aluminum tube via machined bird mouth fittings he fab on his lathe. He is now fabbing up a blow through oil seperator on the lathe to prevent too much oil coating the induction system I told him that that was a touch over kill but he wants to go above and beyond. Thank u all for you input gentalmen. If he sends any pictures I make sure to post them.


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## DICKEYBIRD (Feb 7, 2012)

Here's a pic of a '72 engine compartment. Looks very similar to your friend's other than the Cannon intake setup.

The way they work is the fuel tank vents to the canister where vapors are temporarily stored. There's a slight depression in the engine crankcase applied from a metered orifice or PCV valve in the inlet manifold, through the tappet chamber oil seperator/hose. This one has metered pipes on the carbs & a 'Y" fitting. There's also a metered hole in the rocker cover elbow that sucks vapors out of the canister when the engine is running.

Very simple until the next year when they had to add an anti-dieseling system when they had to switch to regular fuel. If that system failed, the thing would run-on for days. ;D


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## ksouers (Feb 7, 2012)

Damn, seeing these old roadsters makes me miss my old Fiat Spyder. 
But I do enjoy my MX-5 (a true British roadster, so says Jeremy Clarkson.)


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## rake60 (Feb 7, 2012)

There is nothing wrong about this thread Dave.
I am enjoying it! 

Rick


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## bezalel2000 (Feb 7, 2012)

DICKEYBIRD  said:
			
		

> I don't remember ever seeing a 'B engine with the oil filler cap at the rear though.



Thanks for the photo DickyBird, it clearly shows I'm Not even close. 

Leaves me with a question now. In both photos there is a triple bend in the heater tube. It lines up with where the oil cap would be if the cover was other way round. Apart from the obvious answer "its British" whats it there for?

Bez


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## steamer (Feb 7, 2012)

When I was in college, there was this kid with either an "B" or a "C"(?) that he had put a 283 chevy in......HOLY(&#38;#(@ did that thing go!

I think it was described as bi-stable....Out of line , or , About to be out of line! :big:

Dave


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## HS93 (Feb 7, 2012)

mgbrv8  said:
			
		

> Gentlemen I appreciate your input and insight but I am receiving a number of very angry and just plain mean messages from Senior members. so tomorrow I will make it a note to delete this post from the break room portion of this site. My intent was not to cause a hurtful avenue for bully's to attack. Your advice has been very helpful to my friend. And with your help and his southbend lathe he has engineered and fabricated a solution. Thank you for your time and thoughtfulness gentleman.
> 
> Dave




so what is the sites policy on Cyber bullying, can these Senior members be exposed and Banned or are they allowed to do it because they are "Senior members" if this is a regular occurrence surely something should be done,
 I hope whatever action is taken is done Publicly to put off any other potential Bullies 
Peter


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## Maryak (Feb 8, 2012)

Guys,

As the once proud owner of a 1964 MGB, (the last of the 3 bearing crankshafts), I too am enjoying this. I can't offer any advise because years of killing off my brain cells have left this area a complete blank. If memory serves me correctly my crankcase vent was to atmosphere, out of the rocker cover and down the side of the block, no PCV valve involved. 

Best Regards
Bob


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## Groomengineering (Feb 8, 2012)

ksouers  said:
			
		

> Damn, seeing these old roadsters makes me miss my old Fiat Spyder.
> But I do enjoy my MX-5 (a true British roadster, so says Jeremy Clarkson.)



I'm right with you Kevin! Finally let go of my '79 Midget and my '74 1/2 B-GT last summer, proceeds to go to 'tweaking' my MX-5. woohoo1

BTW, my first car was a '70 Fiat Spyder. Those were the days....

Cheers

Jeff


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## Omnimill (Feb 8, 2012)

Is this of help Dave, http://www.burtonpower.com/tuning-guides/tuning-guide-pages/engine-breather-system.html

Vic.


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## mgbrv8 (Feb 8, 2012)

Thank you Vic

Dave


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## ksouers (Feb 8, 2012)

Groomengineering  said:
			
		

> BTW, my first car was a '70 Fiat Spyder. Those were the days....



Mine was a '70, also! It was dull red when I got it but I repainted it Ferrari Racing Red. My friends called it "Arrest-me Red".
As soon as I could afford it I put a pair of Weber DCOE's on it. Man, it would scoot then!

Now I just like to run up a winding hill by the house and the occasional autocross.


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