Blitz Posted June 24, 2018 Report Share Posted June 24, 2018 Right my spit4 shouldn't have a breather outlet from the rocker cover only a breather on the oil filler cap. However I have a newer cover so it does although it's capped off. Two questions really. First will opening this up and adding some piping help me in any way ? Secondly why are these breather pipes usually attached to the carbs and do all the SU carbs allow for this or only later ones. Thanks Grant Link to comment Share on other sites More sharing options...
Colin Lindsay Posted June 24, 2018 Report Share Posted June 24, 2018 It relieves crankcase pressure; early cars have a pipe on the side of the block so don't need additional relief from the rocker, hence no take-off. You'll need one or the other. Link to comment Share on other sites More sharing options...
Badwolf Posted June 24, 2018 Report Share Posted June 24, 2018 My SU2 carbs don't have the fittings for the breather pipes. The Su hs4s do (I think). The pipe from the rocker box just dangles behind the main bulkhead, just below the engine so that the fumes don't go inside the car. No doubt Uncle Pete will have something to say about my dangly bit!! Before I fitted the pipe, the back of the carbs were covered in a coating of oil spray and other yuk, Link to comment Share on other sites More sharing options...
Anglefire Posted June 24, 2018 Report Share Posted June 24, 2018 Hs4’s have the connection. ? Link to comment Share on other sites More sharing options...
dannyb Posted June 24, 2018 Report Share Posted June 24, 2018 You could fit an oil catch tank to the rocker cover, Link to comment Share on other sites More sharing options...
Clive Posted June 25, 2018 Report Share Posted June 25, 2018 The "middle aged" cars had a pcv valve fitted into the inlet manifold. And the late cars to the carbs (as posted) Applying the inlet vacuum helps keep the crankcase pressure low and reduces oil leaks. At high rpm it is amazing how much blowby pressurises the engine. I have seen a tr6 racing engine fitted with a 32mm hose from the rocker cover to a catch tank. For an engine that is in decent condition and not revved over 6000rpm any of the normal solutions work. Be careful if the hose just goes to the road that it doesn't drop ANY oil, really that just causes danger to other road users, when a simple catch tank would solve the problem. ie a coke bottle etc will do, cable tied in place. The other solution is to run the breather hose to the air filter. I am looking into this for my car if I can find a place to attach the hose (proving difficult, but then again mine is not typical) Whatever you do, do not think poking the hose into the chassis is a good idea. Saw that, chap though oil mist into the chassis rails was a good idea. What he forgot was that most of the stuff that comes out is water..... Link to comment Share on other sites More sharing options...
Pete Lewis Posted June 25, 2018 Report Share Posted June 25, 2018 i guess this is a alloy cove r? with a outlet stub about central ready for the later breather ?? what would concern me is you now wont have the gauze filled and vented oil filler cap, the early cars all used breathing is air transfers from in through the tube mounted in the o/s crankcase and out via the filler cap or the other way round it can flow both ways but the tube has no gauze so this is generally the exit this is an open breather system , you need to open the plugged spout and fit a filter to the cover outlet or a short hose into a catch tank leaving it plugged will restrict the breathing so air moved freely between the two vents , ideas see https://www.carbuildersolutions.com/uk/filterSearch?adv=true&cid=0&q=%23bfil15&sid=true&isc=true there are 10/12/15/25 mm inlet dia. pete Link to comment Share on other sites More sharing options...
dougbgt6 Posted June 25, 2018 Report Share Posted June 25, 2018 The purpose of the gauze is as a fire trap (Pete didn't want to tell you that for fear of causing anxiety and panic ) A lot of alloy jobbies don't have it and expect an external trap. Link to comment Share on other sites More sharing options...
Pete Lewis Posted June 25, 2018 Report Share Posted June 25, 2018 Doug thanks...........i remember some things some of the time .. .........other things less of the time, and everything else is just ......gone its begauze of senior moments Pete Link to comment Share on other sites More sharing options...
Anglefire Posted June 25, 2018 Report Share Posted June 25, 2018 51 minutes ago, dougbgt6 said: The purpose of the gauze is as a fire trap (Pete didn't want to tell you that for fear of causing anxiety and panic ) A lot of alloy jobbies don't have it and expect an external trap. So should the arrangement i have have a gauze fire trap in the spout off the rocker? Cos it don't ? Link to comment Share on other sites More sharing options...
Pete Lewis Posted June 25, 2018 Report Share Posted June 25, 2018 you want something like this , commonly used on many 70/80 cars, good at filling with mayo as they get cooled in the air flow http://www.paddockspares.com/603330-engine-flame-trap-v8.html?gclid=Cj0KCQjwpcLZBRCnARIsAMPBgF3l4v8GDkKloYlJO1dLNSqe3PVwBQJQzIo2xaXKwe1DnqKZi6S80jYaArstEALw_wcB no idea what the hose diameter is on this idea Link to comment Share on other sites More sharing options...
Anglefire Posted June 25, 2018 Report Share Posted June 25, 2018 If I get one of those, does that mean I can call my spit a V8? ? Link to comment Share on other sites More sharing options...
DanMi Posted June 25, 2018 Report Share Posted June 25, 2018 The MK2 spitfires have a tube on the air filter box so a pipe goes from the rocker box to the air filter housing. Link to comment Share on other sites More sharing options...
Badwolf Posted June 25, 2018 Report Share Posted June 25, 2018 What is the normal way of terminating the rocker pipe on a MkIV Spitty with HS2 carbs, water bottle on the bulkhead? Link to comment Share on other sites More sharing options...
JohnD Posted June 25, 2018 Report Share Posted June 25, 2018 "Flame trap"? Where from and to? The nearest flame is in the combustion chamber. In the way are piston rings and a very narrow clearance piston to bores, and a long path to the inflammable fuel-air mixture, but I really don't see how the flame can get past the pistons, unless one is holed. Anyway, oil mist saturates the crankcase gas beyond inflammability. IMHO, the gauze is there as a droplet catcher and condenser. Oil filtered out drips back into the rocker cover and thence to the sump. Remaining oil, and yes, water vapour, escapes through it. If you can't, or don't want, to direct to the inlet, then a catch tank, but let's use a bit more tech than just a bottle on the bulkhead (and not some old plastic pop bottle either,please!). The catch tank is away from the engine, cooler so will allow more oil and water to condense, but gases remain and need a vent. Small air filters, cylinders the size of an apple, do a similar job to the gauze, so that its mostly gas and some water that escape - less polluting! Now you have two choices. Empty out the catch tank regularly - those with a sight tube on the side are useful - or have drain tube in the bottom that goes back to the sump. Water will be returned too, but no harm there, as long as you change the oil regularly. This needs the catch tank to be higher than the block, but gives you an excuse for a smart alloy tank on the bulkhead. Shiney-shiney! John Link to comment Share on other sites More sharing options...
daverclasper Posted June 25, 2018 Report Share Posted June 25, 2018 Just a comment on my experience of breather tube into air filter box. It appeared to oil up the filters some. Dave Link to comment Share on other sites More sharing options...
dougbgt6 Posted June 25, 2018 Report Share Posted June 25, 2018 Odd then that most call them flame or fire traps. And what is that strange arrangement on the late GT6 MK3 rocker cover? An assembly of interleaved plates that can't do much as a droplet catcher? Doug Link to comment Share on other sites More sharing options...
Blitz Posted June 25, 2018 Author Report Share Posted June 25, 2018 Thanks for the replies. Yes I'd hered about the Mrk 1 gause filter. So mine has the crank case air inlet pipe I guess but no decent air out as it's a later rocker cover with just the little hole in the filler cap.. I will investigate opening the breather pipe and looking at an oil trap of some sorts on the end. Many thanks chaps Grant Link to comment Share on other sites More sharing options...
Pete Lewis Posted June 25, 2018 Report Share Posted June 25, 2018 https://www.canleyclassics.com/triumph-spitfire-mki/ii-engine early open breathers item 40 poked into the block on the rear crankcase below the exh manifold they show the mk3 as having a smiths PRV valve in the manifold and sealEd filler cap ??? pete Link to comment Share on other sites More sharing options...
dave.vitesse Posted June 26, 2018 Report Share Posted June 26, 2018 The original engine design had two breather. i.e. A crank case and a top breather (Oil filler cap). Two vents were required because one alone would not vent off the pressure built up throughout the engine. Due the revolving parts and temperature differences within the engine it is not possible to vent off all the pressures with one breather. Hence the designers used two. With the induction of emission regs venting oil fumes directly out into the surrounding air was considered a bad thing to do. So the close circuit systems were introduced where the oil fumes are introduced into the inlet gasses and then burn in the engine. The system operates at a small vacuum to ensure no pressure builds up in any part of the engine. This system only works with one breather because it maintains a small vacuum. The problem with only using only one breather that vents out into the air is there is no vacuum hence pressures can still build up within the engine. In the case of only using the top breather then crank case pressures can build up and cause leaks from oil seals. You can end up with what is known as a sweaty engine as oil film appears all over the engine. I have seen some of the track cars using an electric fuel pump and a breather pipe fitted, pointing upwards to stop the oil leaking out, to the hole vacated by the mechanical fuel pump. You have to be careful to ensure the engine oil does not leak from the breather, hence the V design of the original crank case breathers. Dave 1 Link to comment Share on other sites More sharing options...
Blitz Posted June 30, 2018 Author Report Share Posted June 30, 2018 Quick update. Fitted an oil catch air breather yesterday. Run the pipe round and sat the canister in a nice place next to the starter motor so I didn't have to drill for brackets etc. Not driven her yet so fingers crossed the location is ok. Grant Link to comment Share on other sites More sharing options...
PeteH Posted July 29, 2018 Report Share Posted July 29, 2018 On 6/25/2018 at 12:53 PM, dougbgt6 said: Odd then that most call them flame or fire traps. And what is that strange arrangement on the late GT6 MK3 rocker cover? An assembly of interleaved plates that can't do much as a droplet catcher? Doug I have not seen that particular system. But interleave plate coolers etc work by virtue of the rapid change of direction of vapour flow and heat transfer and deposit droplets due to the motion and temperature changes. All sorts of Physics are involved, 98% of which I have forgotten it being that long since I did them. (Boyle and Charles laws etc?, along with others). Pete 1 1 Link to comment Share on other sites More sharing options...
Pete Lewis Posted July 29, 2018 Report Share Posted July 29, 2018 think of it as a Davey lamp the gauze dissipates the flames heat al lot of 70s had these often filled with nylon pot scourer type mesh so what did that do apart from fill with Mayo. ( dont remember Brylcream) Pete Link to comment Share on other sites More sharing options...
dougbgt6 Posted July 29, 2018 Report Share Posted July 29, 2018 We're going round in circles. I haven't got gauze, I got interleaved plates! db Link to comment Share on other sites More sharing options...
PeteH Posted July 29, 2018 Report Share Posted July 29, 2018 5 hours ago, dougbgt6 said: We're going round in circles. I haven't got gauze, I got interleaved plates! db Got pictures?. I would like to see that.? Link to comment Share on other sites More sharing options...
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