craig1410
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posted on 30/8/06 at 11:39 PM |
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Rover V8 crankcase ventilation - What to do?
Hi,
Does anyone out there know how best to ventilate the crankcase on a Rover V8 engine? The SD1 donor had a large flame trap on one rocker cover which
connected to the carbs via a T-piece and a small vent pipe on the other rocker cover which originally connected to the air filter assembly.
My flame trap is a real mess and the wire wool inside is all falling to bits (not good for the engine if I was to refit it...) so I am looking for
options.
I can get a little K&N filter for the small 8mm hose on one of the rocker covers but I don't know what to replace the flame trap with. I
want to avoid the flame trap feeding the carbs because I understand this upsets the engine idle. I can get a new flame trap from Rimmer Bros but it is
not cheap and I'm not sure if there is a better way forward (eg. Catch tank).
Any advice/ideas most welcome.
Cheers,
Craig.
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ceebmoj
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posted on 31/8/06 at 06:51 AM |
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hi,
im ready to be told this is wrong. but I replaved the rocker covers with thoes from an earler RV8 that have equal sized vents on each side ran a pipe
from each vent to a catch tank the catch tank has an out let on the top witch I atached a K&N filter to.
works well for me
blake
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Agriv8
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posted on 31/8/06 at 06:58 AM |
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I am venting the two rocker covers and the one that comes out the back of the block just above the bellhousing all to one catch tank.
I am also running the rocker covers that have a small vent pipe
Seems to work ok.
Regards
Agriv8
Taller than your average Guy !
Management is like a tree of monkeys. - Those at the top look down and see a tree full of smiling faces. BUT Those at the bottom look up and see a
tree full of a*seholes .............
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johnemms
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posted on 31/8/06 at 07:10 AM |
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Was'nt the vents not only there to suck off vapours but also to make a partial vaccume inside the engine block so as to minimise oil leaks on
oil seals etc..while running??
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Agriv8
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posted on 31/8/06 at 07:25 AM |
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Yes I belive that was the idea. Dont belive it quite works in principle ? but burning the vapors makes em not run as nice - running EFI Hotwire
Still like the article I saw in PPC a while ago somthing like .....
The Tvr has a unique chassis anti corosion device fitted its called the Rover V8 engine which constantly cotes the chassis with oil .......
regards
Agriv8
[Edited on 31/8/06 by Agriv8]
Taller than your average Guy !
Management is like a tree of monkeys. - Those at the top look down and see a tree full of smiling faces. BUT Those at the bottom look up and see a
tree full of a*seholes .............
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craig1410
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posted on 31/8/06 at 07:30 AM |
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Thanks guys - I've asked RPI Engineering the question as well so I'll let you know if I get a response. I'm using SD1 rocker covers
so I think I'll get a K&N for the little pipe and run the bigger one into a catch tank.
Do you know if the flame trap is required given that I won't be connecting the breather to the carbs? I'm not sure which way the flame was
expected to travel - from carbs to crankcase or the other way around. I would expect it is to stop a blow-back in the carbs from igniting the
crankcase in which case I shouldn't need the flametrap any more. Does that sound right?
Cheers,
Craig.
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v8kid
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posted on 31/8/06 at 07:43 AM |
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Craig,
I've been running mine for 2 years now with the breather pipes from each bank connected directly to the carbs to suck the fumes and occasional
bit of oil vapour out.
No flame traps, no problems so far and idle is as good as a v8 can be. Mind you I hammer the engine so it would burn off any deposits before they get
a chance to form.
Cheers
David
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craig1410
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posted on 31/8/06 at 12:02 PM |
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Hi David,
Do you just use the standard flame trap without any of the wire mesh installed or have you made something up?
I thought about cutting the flame trap down to half size (for bonnet clearance) but I don't have any of the wire mesh and I don't think
you can just use steel wool. The proper stuff seems to be more like lots of chain links rather than wire wool. Come to think of it I'm not sure
where my flame trap is any more... Maybe I'll just fit a second oil cap in place of the flame trap and drill a hole in my rocker cover for a new
breather pipe.
Cheers,
Craig.
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robinj66
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posted on 31/8/06 at 02:48 PM |
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I have been running my RV8 without any breater pipes but it does "chug" a little bit of oil vapour once the engine gets hot.
Latest atempt is to use a filter on the small (8mm) outlet and to place an in-line PCV (positive crankcase ventilation) valve from the top of the
flame trap to the base of the carb (inlet manifold). Doesn't appear to upset the idle at all.
Whether this works for you will depend on your setup but my view is that the engine was designed to run with some sort of breather system.
I agree that you shouldn't be using wire wool inside the flame trap - it will act as a barrier more than a filter.
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robinj66
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posted on 31/8/06 at 02:48 PM |
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I have been running my RV8 without any breater pipes but it does "chug" a little bit of oil vapour once the engine gets hot.
Latest atempt is to use a filter on the small (8mm) outlet and to place an in-line PCV (positive crankcase ventilation) valve from the top of the
flame trap to the base of the carb (inlet manifold). Doesn't appear to upset the idle at all.
Whether this works for you will depend on your setup but my view is that the engine was designed to run with some sort of breather system.
I agree that you shouldn't be using wire wool inside the flame trap - it will act as a barrier more than a filter.
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robinj66
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posted on 31/8/06 at 02:48 PM |
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I have been running my RV8 without any breather pipes but it did "chug" a little bit of oil vapour once the engine gets hot.
Latest atempt is to use a filter on the small (8mm) outlet and to place an in-line PCV (positive crankcase ventilation) valve from the top of the
flame trap to the base of the carb (inlet manifold). Doesn't appear to upset the idle at all.
Whether this works for you will depend on your setup but my view is that the engine was designed to run with some sort of breather system.
I agree that you shouldn't be using wire wool inside the flame trap - it will act as a barrier more than a filter.
[Edited on 31/8/06 by robinj66]
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craig1410
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posted on 31/8/06 at 06:00 PM |
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Hi,
Yes I've been readin up on PCV systems a bit and found the following article quite interesting. I think this is defintely the way to go:
https://www.burtonpower.com/technical/tt_eng2.html
Since I'm not using the vacuum take off from my manifold for a brake servo I might be able to use it for the PCV take off. I need to do a bit
more reading up on the subject first. The main thing I want to achieve is to blank off the unions on my SU carbs which normally connect to the flame
trap. I know from personal experience how much smoother the idle can be on an SU carb'd engine with these blanked off.
Cheers,
Craig.
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craig1410
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posted on 31/8/06 at 06:16 PM |
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Here's something else I just found on the TR7 V8 forum:
http://www.tr-register.co.uk/forums/index.php?showtopic=1341
The guy is talking about 4 barrel carb conversions by the way.
quote:
PCV system. The Rover V8 requires to be POSITIVELY Crankcase Ventilated. Most of the oil related problems in a RV8 in otherwise good condition can be
traced to the PCV system or lack of it.This means that the engine internals should be subjected to a mild vacuum by the sucking the air OUT of the
flame trap and IN through the small vent on the opposite rocker cover. The vacuum in the air filter is NOT sufficient for this, despite a number of
installations I have seen with this feature. The pipe from the flame trap should be connected, via a PCV valve, to full manifold vacuum. The brake
servo should be connected to a fitting on the manifold, and the PCV hose should be connected to the big inlet in the centre of the carb base. A PCV
valve MUST be used or the vacuum will be too great and the whole engine will whistle. Suitable PCV valves can be obtained from Real Steel 01895
440505, part no BYFV184, cost about £2, it fits in the neck of the flame trap. Don't ask them for the Rover V8 PCV vave, they don't know
about this trick.
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Simon
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posted on 31/8/06 at 07:12 PM |
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Craig,
I did this
basically, removed the flame trap part, made new cap (old too high anyway) and connected to the vacuum. Other side has a filter
ATB
Simon
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craig1410
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posted on 31/8/06 at 07:39 PM |
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Hi Simon,
Thanks for that.
Are my eyes deceiving me or does your "flame trap" hose have the mandatory split in it? I have the hoses from the donor car and they are
the same - must be a design feature eh?
Cheers,
Craig.
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02GF74
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posted on 31/8/06 at 08:38 PM |
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quote: Originally posted by Agriv8
I am venting the two rocker covers and the one that comes out the back of the block just above the bellhousing all to one catch tank.
I am also running the rocker covers that have a small vent pipe
Seems to work ok.
ooh no no no - you guys should read the haynes manual
the engine, p6 anyways (I'd need to look at the SD1 book) has an open breathing system; basically the crankcase is connected to the air box to
draw in filtered air and the two rocker covers are connected to the carbs to burn off vapours, oil etc:
If you block of the crankcase, then bad things happen but not so bad that many people ^^^^ do this and see nothing bad happen, in the short term
anyway.
if you are running without the air box e.g. K&N, you fit a mini K&N filter to the crankcase and route the rockers via flame traps to the
carbs. (see left in photo below)
for cheaper flame traps, see paddocks (LR parts supplier), in Range Rover sections.
the tubing from the rockers to the flame traps to the carbs varies; on mine the FT are horizontal so quite low down.
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craig1410
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posted on 31/8/06 at 11:09 PM |
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quote: Originally posted by 02GF74
the crankcase is connected to the air box to draw in filtered air
On the SD1 it also draws in air from the airbox but this is non-filtered because the filters are connected to the large bore pipes which feed the
SU's. The principal is the same though as the air goes in to the small rocker pipe and comes out the large flame trap along with the oil fumes
and blow-by gases.
As I understand it, the flame trap used on the SD1 is basically a poor man's PCV valve. Having said that, PCV valves can be unreliable if not
kept clean so in that respect a can full of steel mesh is likely to be more reliable. Having said THAT, the mesh tends to get clogged up with gunk and
will barely flow any air after a time...
From what I have read in the Burton Power link I posted earlier, the PCV valve will act as a flame trap and will regulate ventilation flow rate
according to manifold vacuum (inversely proportional to vacuum level in fact) and does not interfere with the function of the carbs in any way. To my
mind this is the ideal setup - maintain a slight vacuum in the crankcase without affecting engine idle. You might need to replace the PCV valve every
20000 miles but at a few pounds each this is no big deal.
So, I'm going to get a PCV valve and connect it to my brake servo vacuum port on the inlet manifold and on to either a cut down flame trap with
the guts removed or to a new pipe installed in the rocker cover. I will also fit a K&N mini-filter to the other rocker to avoid sucking in dirt. I
might also fit some sort of valve (eg. fishtank air valve) between the PCV valve and the rocker cover so that I can vary the amount of ventilation in
case the PCV valve is letting too much air flow.
I'll let you know how I get on...
Cheers,
Craig.
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ceebmoj
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posted on 1/9/06 at 12:31 PM |
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hi,
does any one have a vlear picture of where the chank case breathers are located?
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craig1410
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posted on 1/9/06 at 05:35 PM |
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Hi,
Simon's photo above is pretty much as clear as you can get I think. Note that the "crankcase" breathers are on the rocker covers
which is maybe what is confusing you. There are no breathers (that I am aware of) on the crankcase itself.
Cheers,
Craig.
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ceebmoj
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posted on 3/9/06 at 06:36 AM |
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thanks for the info.
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