Engine Breathing

[Westfield 129]

The fuel pump boss is pretty easy. Drill a hole for a hole and tap it 3/8" NPT. Or, you can install a pump block off plate thick enough to support the threading, bolt that on with a 3/8" NPT hole in the middle. A -8 hose barb will work perfectly with a push on hose. The fuel pump is far above the oil line in the pan, so oil will not be pumped overboard so long as the breather tank is higher than the oil level.

You can drill and tap the block if you use plenty of grease on the drill and tap to catch the filings (and some way to hold the drill steady agains the block), but you are right. It 's best to do the drilling when the block is stripped and prior to hot tanking.

[jonclancy]

Splat, do you habe a link to your MGB pcv please? I have the Midget one, and can modify it to flow more, but a proven and quick solution is what I need right now!!!

Cheers Chap!

[Westfield 129]

Do you need a PCV? It's not necessary if you are using a breather tank and no connection to the intake manifold. .

[jonclancy]

Yep - good point. I'll just block off the relevant pipe on the HIF44.

I'll get there - it's just very, very busy at the moment!

[jonclancy]

Finally, I saw a pic of a catch tank mounted fwd of the engine; I was thinking bulkhead on the hot side myself. Where did you guys choose? Hose runs are a consideration, and I'll get a new length of 3/8" and the unions to suit from Somerford Mini when I drop the rocker into Gary at Loaded Gunn for modification.

[Westfield 129]

On my early car, I have a small JAZZ catch/breather tank mounted forward, hanging off the frame tube immediately in front of the engine. This gives an easy hose run from the block vent (at the fuel pump boss) and the rocker cover. I use a separate filter on the front cover breather.

The other cars that I have built have the two inlet breather/catch tank mounted on the hot side, but forward of the engine mount. I use rivnuts and the tank's own mounting tabs to attach it to the top frame tube. This also works well for front mounted rocker cover breather hose, and block breather. All use pipe thread adapters and push on hose, swivel seal 90º AN fittings with -6 and -8 hose. Again, the front cover breather uses a small filter attached directly, though you may add a 3rd bung to the breather can and use that if you wish. Or, you can forgo the rocker breather if you have both a front cover and block breather hoses.

I mount the breather can so that draining it is easy, and install a short tube so that any condensation or oil will not gather on the frame when the valve is opened.

You can also leave the valve off, and attach a tube to your front cover, above the oil level, to drain the collected blow-by back into the engine.

[jonclancy]

That sounds like a plan. I'll let you know how I get on!!

Cheers

Jon

[jonclancy]

Finally got my tester from storage and headed over to Mooch's to run the test today.

I ran the test cold, WOT, and all plugs out.

Got 13,10,13,13 bar. Around 190 psi.

A few CCs of oil down the Cyl 2 had the re-run up to 13.

So, it looks like I have a ring or bore problem. You can hear the wheeze in the engine.

So, when I have time, the head will come off to inspect the bore. IIRC, the piston can be removed with the engine in the car, maybe try this approach, but I don't have access to a ramp. It's a shame, but it looks like the car will be moved to my new place when I can get it into the garage, and it's going to have to sit there over the Winter. What with the new house soaking up all available funds, another rebuild is off the cards. So I am hoping a new set of rings will do the job. I suppose it was too much to hope it was a maladjusted valve!

Any suggestions gratefully received. Last thing my wallet needs at the moment!

[Westfield 129]

You might want to try the test with the engine warm. You may also try a cylinder leak down test, as they are far more accurate than the normal compression tests.

Rather than pulling the head, try a bore scope and take a look. I did that after my engine failed a leak down test (about 10 psi over 80 psi), and I saw the top ring land was, well, missing. Not an uncommon occurrence when you twist an old A series to 5000 RPM on our freeways day in and out. Perhaps someone in Maintnance has a bore scope (smal diameter rigid is preferred. but a good flexible will do) you can use to inspect the cylinder walls and piston top. Make sure that the engine is cold when you stick that scope into the cylinder bore.

The main symptom I had was crank case over pressure, and the poor thing was blowing oil everywhere and killing the mosquitos, along with applying to my garage floor a protective coating of oil. I ended up rebuilding the engine, boring it to 1380.

[jonclancy]

Here's an update and request for directions to look into.

In short, we re-ringed the #2. The head gasket, bore and piston all looked perfect. No evidence of blow-by.

Got it all together, but still have excessive crankcase pressure. A vinyl glove will inflate when held over the oil filler hole in the rocker cover. The car idles well, pulls, makes reasonable power, doesn't pink. Starts on the button. I have the timing cover pipe to the catch tank. Then to a flying saucer PCV, into the HIF44.

Cold, dry compression test showed 188-195 across the bores. That equates to my 13 bar. So the no 2 is now up to spec.

Excellent news.

But, having tried another PCV, the catch tank was empty, but the oil was going of of the rear scroll.

I will be looking at fitting my ventilated rocker cover... Got lost in the noise over the last years worth of entertainment.

Ken's MGB has negative pressure at the oil filler - same glove test. Is it an A Series thing?

Oh, and on blipping the throttle, I am getting some greyish smoke puffs. But that settles with steady running. The mixture is only approximate, and is a little rich.

It was suggested that I get the head vacuum tested. Thoughts?

Thanks guys... Pointers appreciated. Le Mans is coming up FAST!