Warmup Regulator Rebuild

Warmup Regulator Rebuild

Unscrew two halves of casting. Separate. Dig crummy old oring out of groove in one side of casting and save till later. Carefully look at guts so you remember how they will go back together. Remove screws that hold inner cover over diaphragm area. Remove cover taking care not to loose anything or hurt the wafer thin stainless diaphragm. Dig crummy oring out of groove and put aside. Take two crummy orings to oring supplier and match as close as possible. Bigger is not better!!!!! Sorry didn't take measurements (next time). Once you have orings and are ready for reassembly start by checking heater for continuity. Also, plug it into 12v and see if you can feel the bimetallic element warm. Clean the screen in the fuel entry port with brake parts cleaner. clean the orifice at the center of the fuel exit port. Clean the diaphragm (careful!) don't be afraid to put a little penetrating oil on things. Reassemble diapragm, pushrod seat, oring and cover to top half of casting. Next, check for operation of the vacuum servo at the bottom half of the casting. You can suck on it with your mouth or use a mitivac type setup. It should lift the spring seat a fixed amount I think a little less than a millimeter (1/32"). There is no setting and don't worry about the dimension it is just a test to see if the diaphragm still works. If so put the springs on the seat and the pushrod back in place with the bottom half sitting on the bench. Next reinstall the heater in the top half of the casting with spacers and or washers exactly as before you took it apart. Next, put the big oring back in the groove between the top and bottom halves. This is the trickiest part; lower the top half of the assembly back down over the bottom. Straight down so that the pushrod goes back in the little seat in the center of the diaphragm.

Here is how the thing is supposed to work when you have it back in the car. Don't use the fuel pump jumper method it just floods the car.

Put the gauge on as it says in the manuals. Open the valve and start the car. This has to be done cold but your car has been apart for a day or two at this point so that kinda works out. You should see 25 +- 5 psi ish. Close the valve on the tester quick and you should get at least 65 psi but 85 is ok too. Open the valve and let the car finish warming up. You should now get 50ish psi and the car should run smooth and not smell overly rich. If you got all of these you're done. If not this was a good gross check. While I am messing with this stuff I just leave the gauge attached and drive around with it for a few days. Tie wrap it to something under the hood so it doesn't get caught in the fan.

The bimetallic element pushes on the spring pack when cold to reduce spring force and reduce regulated pressure. If it isn't adjusted right but your spring pack is right you will get 50 psi cold and no change. Your engine will miss at idle cold because it is too lean. The good news is that because it is so lean it will warm up quick. The bad news is that most people try to do a mixture adjustment to compensate and blow the whole fuel map. If this is the problem you can adjust the lever arm of the heater or shim its mount to adjust it. This is an annoyingly iterative process without a flow bench. Get it close and leave it alone if you can and that will be fine.

If you are seeing between 50 and 65-75 psi out of the gun cold the diaphragm/orifice is not regulating properly. If it goes right to 75 it isn't working at all and you didn't put something back together correctly most likely. If it is middle ground or just over 50 ish you can push the whole diaphragm housing into the casting to adjust the overall spring preload. This is how the factory adjusts these things (no kidding). This is not as annoyingly iterative but if you drive it in too far you have to disassemble and press it back out and start over.

After this gross adjustment is producing a rock solid 50psi warm (Oh and BTW this has to also still keep the emissions at 2-3% CO at 800 RPM warm, disabled air pump) then you have to go back and check the cold pressure again to make sure you haven't made one adjustment at the expense of another.

One last thing. If you get no pressure on the tester and you know the tester works properly you have a blockage either between the fuel distributor exit or in the line. Deal with this first because it will make you chase your tail if you don't. Trust me on this one. If this happens remove the line at the distributor and put the tester on there and that will isolate it to a fuel distributor problem. Then you are bummin. But you've already been there and done that and had great success so far Dennis. Still Going....

Did I forget anything???

Oh yeah, glad to hear you had good luck with the cam belt tensioner. The pictures in the instructions ought to look scarily familiar for a guy with your driveway collection.

Jay Kempf
79 US 5-speed

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