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ealandbob Snailer
Joined: 28 Jan 2009 Posts: 90 Location: France 79 Deux Sevres
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Posted: Sat Oct 08, 2011 10:50 pm Post subject: Lowering compression on visa engine |
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Hi All
This may sound strange as everyone seems to be looking for higher C.R. but for a project I have I want to lower the C.R on my Visa engine from 9:1 down to 7.5:1
Any ideas? Is modifying the pistons the way to go, or is shimming the heads the way to go?
All info greatly appreciated.
Im away til Wednesday so plenty of time to put thinking caps on
Cheers
Boggy _________________ Plastic is Fantastic |
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Jasu Dropped
Joined: 30 Sep 2007 Posts: 211 Location: Finland
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Posted: Sun Oct 09, 2011 10:31 pm Post subject: |
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There is thick gasket between block and cylinder, put two of them, problem solved...
There is made lower compression by that way... _________________ Make it today, tomorrow it's probably illegal... |
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Pietro Snailer
Joined: 17 Aug 2007 Posts: 13
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Posted: Mon Oct 10, 2011 8:06 pm Post subject: |
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Jasu wrote: |
There is made lower compression by that way... |
Hi,
I just had a look at the photobucket pictures. Looks very neat work!
This picture puzzles me: on a visa engine I would not expect this extension on the camshaft.
Could you please explain?
Thanks |
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Jasu Dropped
Joined: 30 Sep 2007 Posts: 211 Location: Finland
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Posted: Mon Oct 10, 2011 9:39 pm Post subject: |
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There has been made modification to use contact breakers, because in this engine was some serious problems with original Visa ignition system (with previous owner). But after all, this started to leak, quite much, so we took it away...
These parts was taken from 2cv4 camshaft, if I don't remember it wrong..? _________________ Make it today, tomorrow it's probably illegal... |
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Rusty Dropped
Joined: 19 Jun 2007 Posts: 142 Location: Koudekerk ad rijn Netherlands
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Posted: Tue Oct 11, 2011 8:57 am Post subject: |
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Hi Jasu,
In holland there are several specialists that have a way to put a electronic ignition on a visa engine (on the same place as a 2cv engine) this might be an option, they adapt the engine with an extra oil seal and camshaft as well.
I'm running a visaengine with original computer and had some problems in the past, but all of those were related to broken wires or faulty sensors. it's an ok system, just the computer limits the revs to i think 6500 rpm.
if you need more information let me know!
greetzzzzzzzzzzz
Rusty _________________ Dyane1983 daily driver (will soon get bmw power)
2CV Pick-Up custom
AK400 in parts |
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Pietro Snailer
Joined: 17 Aug 2007 Posts: 13
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Posted: Tue Oct 11, 2011 8:48 pm Post subject: |
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Jasu wrote: | There has been made modification to use contact breakers...
But after all, this started to leak, quite much, so we took it away...
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I am surprised about the leaking unless the front end was wobbling like this one.
When properly alligned and secured to the camshaft the probability of leaking should not be higher than on a 2cv engine?
I was considering to try a similar adaptation to yours one day. |
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Pietro Snailer
Joined: 17 Aug 2007 Posts: 13
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Posted: Tue Oct 11, 2011 9:17 pm Post subject: |
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Rusty wrote: | it's an ok system, just the computer limits the revs to i think 6500 rpm.
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Hi,
When the engine is unloaded you may perhaps reach 6500 rpm because you do not need much torque to displace the pistons.
Under load the power of the visa engine drops very quickly after 5500 rpm and on the road you will reach no more than about 6000 rpm.
From what I read the visa electronic system is not able to produce sparks of good quality at these revs.
What about the other electronic systems ?
Do you know if they perform better at high revs or are they also limited? |
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