mr henderson
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| posted on 14/12/09 at 09:27 PM |
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crossflow problems?
I've got a 1300 crossflow in my workshop. It's fitted in a car which has come in for fimishing. The outside is nice and clean and the
ancillaries are new or reconditioned. The owner knows nothing of the history of the car.
I took the (big) 4 branch exhaust manifold off because it's preventing the enigne from being fitted in its correct location, and looking in the
exhaust ports it's quite sooty inside, and has deposits on the walls of the ports that can be dislodged with a screwdriver.
Next I took the rocker cover off, and can see that there are only single valve springs, so it's not a tuned engine. What's more, I can see
that the valve oil seals have ridden up the stems, which brings be to the actual question- would the valve seals not being in the right place lead to
oil getting down the valve stems and making the engine sooty, or is the soot more likely to be caused by some other problem or wear factor?
Any thoughts appreciated.
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David Jenkins
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| posted on 14/12/09 at 09:33 PM |
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There may be very little wrong with it. The x-flow is a crude old engine, and doesn't run anywhere near as clean as a modern engine.
The exhaust manifold on my reasonably well-tuned 1660 x-flow has a lining of soot, and I expect that it would get quite caked if I ran it for a few
years.
Saying all that - resetting the seals would certainly help!
[Edited on 14/12/09 by David Jenkins]
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trextr7monkey
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| posted on 14/12/09 at 09:41 PM |
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It all sounds a bit tired , x flow is a heavy breather at best of times- is there much thick black oily crud inside rocker cover as that seems to be a
better indicator of a tired engine? Seals harden over time and prob worth swapping them
Perhaps worth suggesting to the owner that whipping head of checking bores/ changing rings/ decoking might lead to peace of mind and less hassle
further down the line or he could keep an eye out for a spare engine- still plenty about for little money, we have 3 or 4 here which mightbe a
cheaper belt and braces option
http://www.flickr.com/photos/14016102@N00/ (cut and paste this dodgey link)
Our most recent pics are here:
http://s129.photobucket.com/albums/p211/trextr7monkey/
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Memphis Twin
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| posted on 15/12/09 at 08:52 AM |
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It's not worth spending a lot of time on a tired 1300 crossflow, although there's probably not much wrong with it. The easiest and
cheapest way to sort out a 1300 is to chuck it out and fit a 1600 .
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prawnabie
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| posted on 15/12/09 at 10:10 AM |
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I have had this problem witht he stem seals before. Ieven a new set of standard items didn't last long either before they rode up the stem.
I fitted seals from a 1275 mini as these were a tighter fit on the head. This is also the method of choice when fitting twin springs.
HTH
Shaun
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MikeRJ
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| posted on 15/12/09 at 12:00 PM |
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quote:
Originally posted by mr henderson
Next I took the rocker cover off, and can see that there are only single valve springs, so it's not a tuned engine. What's more, I can see
that the valve oil seals have ridden up the stems, which brings be to the actual question- would the valve seals not being in the right place lead to
oil getting down the valve stems and making the engine sooty, or is the soot more likely to be caused by some other problem or wear factor?
The valve stem seals on crossflows inevitably ride up the stem, even when new. They are just not a very good design.
Single valve springs are not a good indication that the engine has not been tuned; uprated single valve springs are perfectly adequate for fast road
cams, e.g. the Kent BCF3 which is a pretty hot road cam comes with single valve springs.
Soot deposits in the ports would more likely indicate the engine is running rich, quite likely if it's never been set up properly.
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02GF74
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| posted on 15/12/09 at 01:50 PM |
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quote:
Originally posted by Memphis Twin
The easiest and cheapest way to sort out a 1300 is to chuck it out and fit a 1600.
trust me, it is neither simple, quick nor cheap 
the standard seals are cups that will rid up, not good design for styaing put.
you can get seal which have a metal clip so are really tigh fit. you'd think a bit of oil on the stems would be a good thing to lubricate them,
the problem with oil getting down the guides will show up on start up, I doubt that you can get enough oil down the guides to carbon up the engine.
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D Beddows
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| posted on 15/12/09 at 03:10 PM |
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They all do that....... not a problem really - not ideal either but the seals just act as an umbrella rather than a proper seal but they work.....
750MC Locost race engines don't have a problem with it..... The exhaust ports will be a bit coked up as well but again... they all do that! and
all crossflows blow out a bit of oil, it's part of the charm
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NS Dev
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| posted on 15/12/09 at 03:13 PM |
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re. the oil seals
They are umbrella seals and are not supposed to stay on the end of the guide, they have no method of retention. They just stop oil from running down
the valve stem too much.
With decent guides they do the trick fine
Retro RWD is the way forward...........automotive fabrication, car restoration, sheetmetal work, engine conversion
retro car restoration and tuning
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