| Author |  Topic  | |
john-saab
Administrator
United Kingdom
2679 Posts | |
melle
V4 Guru
United Kingdom
3833 Posts |  Posted - 20 May 2012 : 22:58:51  
| Looks like a PVS-valve, strange location though.
1970 96V4 "The Devil's Own V4"
1977 95V4 van conversion project
1988 900i 8V |  |
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pchristy
V4 Guru
United Kingdom
1790 Posts | Posted - 21 May 2012 : 09:50:56
| It looks very similar to something I had on a Ford V8 some years ago. Just about everything on that car was vacuum operated. IIRC, vacuum from the manifold went in on the big pipe, and the small ones went off to various heating / air conditioning bits, like a crude form of climate control. I think one of them also went off to the distributor, so that if the engine got too hot, it would bleed more vacuum to the distributor, advancing the timing and speeding up the tickover. This would pull more air through the radiator, cooling it down. Well, that was the theory, and no it didn't work very well......!
As an aside, what is it about Ford and running everything of vacuum? It took years for them to realise that vac operated windscreen wipers were a very bad idea, and they must have spent a fortune on vacuum tanks and pumps to try and keep that naff idea going......!
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Pete
"Duct tape is like the Force: It has a light side and a dark side, and it binds the Universe together!" | |
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melle
V4 Guru
United Kingdom
3833 Posts | Posted - 21 May 2012 : 10:32:12
| Later V4's (from '77?) had the P(ositive) V(acuum) S(upply) -valve as standard. The valve works as described above by Pete. Here is one on the VeGe engine in my 96:
(Follow the red vacuum hoses to learn how it's connected.  )
I can tell from experience that it works (if in good condition), especially in traffic jams.
1970 96V4 "The Devil's Own V4"
1977 95V4 van conversion project
1988 900i 8V | |
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thesaabologist
V4 Fanatic
319 Posts | Posted - 21 May 2012 : 23:21:21
| it is part of the emissions control system that was required in 1973+ in the USA in order that the car would meet emissions requirements. It connects to an extra valve that bolted on the side of the fomoco carb. The 3 connections - one goes to the "deceleration valve", one went into a port in the carb and one to an extra port in the side of the vacuum regulator. Its on the thermostat as temperature is in someway effecting the vacuum fed to the deceleration valve and vacuum regulator and supposedly improving emissions. It just screws out of the thermostat housing (as mine did) and can be replaced by a plug.
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1974 Sonett III
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pchristy
V4 Guru
United Kingdom
1790 Posts | Posted - 22 May 2012 : 15:14:54
| I've been trying to recall exactly what it all did on the V8 I had. I *think* this is how it worked......
Manifold vacuum goes in on the big pipe. One of the small pipes went to the air-filter air intake. When the engine was cold, it drew air in from over the exhaust manifold to speed up the warm up. As the engine got up to temperature, a vacuum servo controlled by that valve switched the air supply to cold air via a flap on the intake.
One of the other two pipes went to the carb vacuum take-off, and the other to the distributor. Normally, the distributor was controlled purely by the carb vacuum. BUT, if the engine started to get hot, the valve would open, allowing more manifold vacuum to reach the distributor. This would advance the ignition, speeding up the tickover and (ahem!) cooling the engine.
This was on an Australian Ford V8. The Aussies appear to be even more environmentally conscious than the Californians! It didn't work very well, and I threw it all away when I fitted a Holley carb and an Edelbrock manifold.......!
--
Pete
"Duct tape is like the Force: It has a light side and a dark side, and it binds the Universe together!" |
Edited by - pchristy on 22 May 2012 15:15:35 | |
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TTruckie
V4 Fanatic
United Kingdom
320 Posts | Posted - 22 May 2012 : 15:54:06
| | As the 'ologist says Californian emmisions caused these mods - best bet most people just take it off and blank the hole. |
Edited by - TTruckie on 22 May 2012 16:18:25 | |
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| | Topic | |
Sonnet thermostat housing
