Does anyone have a diagram of the vacuum advance for the HZ 253 and its components. I have a broken switch I need to replace that has been previously bypassed by someone that i now wish to replace.
I appears to be made up of several units.
* TVS unit in front left side of manifold. 3 ports. D Distributor vacuum, M Manifold vacuum, P Ported vacuum.
* Vacuum diaphragm on Distributor. 1 in
* Electrical vacuum solenoid. 1 inlet & 2 outlet
* Backflow valve. 1 in 1 out
I'm looking for a diagram of the vacuum hoses.
Any help would be appreciated.
Thanks all those who are helping me I’m on a steep learning curve I had no idea what ADR27a was but up to speed now. Jump in if my assumptions are wrong. ADR27a has three basic parts.
1 - Positive Crankcase Ventilation System.
2 - Evaporative Emission Control System
3 - Exhaust Gas Recirculation System.
I’m talking HZ 1977 4.2 and how ADR27a was implemented.
1 - PCVS Fresh air is drawn from the air cleaner assembly into the crankcase via a hose from the Air Cleaner to the front of the drivers side tapped cover. The fresh air is drawn in to the crank then out via a PCV valve at the rear of the passenger side tappet cover and into the base of the carburettor via a hose.
2 - EECS. Vapour is drawn from the fuel tank via 3 vent hoses on the tank to a jbox just above the diff then to a canaster in the front drivers side engine bay. The 3 vents on the tank are to ensure that no matter the angle of the vehicle one of the vents will be venting an not submerged in t
Fuel. (Note Station Wagons have an extra vent for filling as the filler hose is at the bottom of the tank. This vent connects to the filler inlet at the top.
Back to the canister, the canister itself is a simple carbon canister
That stores fuel Vapour with 3 connections. One to the tank as described, A purge line to the carburettor, and a third to the carburettor to collect vapour from the float bowl. As I have said mine has been messed with so I only have the fuel tank connected to the canister and will have to work out other 2.
3 - EGR This is where it starts to get complicated. My understanding is this to reduce peak combustion temptress buy reducing the fresh air mix by introducing exhaust gases into the combustion chamber. This is done via the EGR valve connecting the exhaust system to the intake system and doesn’t involve hoses it’s incorporated in the engine design and facilitated buy the ECR valve that is controlled by a heat sensitive vacuum control switch. This switch improves drivability when the engine is cold and is mounted on the front of the inlet manifold on the drivers side.
How did I do. Other components added to the ganging associated with the introduction of ADR27a was the Controlled Combustion System CCS this if fairly simple and involves a thermostat in the air cleaner that controls a flapper valve that draws hot air off the exhaust manifold this improves economy.
The last piece of the puzzle is the Vacum advance on the distributor that combines engine temperature manifold vacuum and gearbox gear. I’m still working on this and would love some help on how all the components link together.
Look forward to hearing form you
Regards
Edited by user Thursday, 26 September 2024 10:11:38 AM(UTC)
| Reason: I found out more
