Installed a M30 head on my 1979 528i questions

metsfan3321 · Post by **metsfan3321** » Thu May 19, 2016 6:52 am

I installed a used m30 head on my 1979 528i. I had a shop adjust the valves and I cant get the thing to idle right. Its popping in the intake manifold and I have to keep my foot on the gas to start it and keep it running. Since im putting a different head than is suppose to go on the car is there anything differnet like timing adjustments or something im missing? All vacuum hoses are connected, new plugs, cap, rotor and plug wires. Its getting fuel. Any help would be greatly appreciated. Thank you.

franky2fingaz · Post by **franky2fingaz** » Thu May 19, 2016 8:02 am

I'm assuming the shop checked and cleaned the head right? either intake valve not closing fully or timing chain off few too many teeth.. . if one or two valves not seating you can kinda feel it on the individual intake runners or by using a stethoscope .... cheers

Mike W. · Post by **Mike W.** » Thu May 19, 2016 11:16 am

Check the valve adjustment and the timing.

metsfan3321 · Post by **metsfan3321** » Fri May 27, 2016 1:31 pm

Does it matter where all the vacuum hoses go? They are all connected and new but my question is do the two that come off the distributor have to go to a specifc spot? I cant find decent pics of the top of the engine or vacuum hose routing... thanks

RandyM · Post by **RandyM** » Fri May 27, 2016 2:32 pm

On my 181 528i which only has one hose for advance, ->from advance diaphragm unit on dizzy to green dual port on thermostat housing (see #4 http://www.realoem.com/bmw/enUS/showpar ... Id=11_0665) then another from said dual port to throttle body angled port near top facing cabin between #1 & 3 on following diagram, I believe the other goes from dizzy to angled port facing front near bottom front of throttle body see #5 on diagram
http://www.realoem.com/bmw/enUS/showpar ... Id=13_0170

Diagrams are both from 77 530i

Mike W. · Post by **Mike W.** » Fri Jun 03, 2016 2:25 pm

Yes they are specific and yes 79 does have a dual diaphragm distributor. They are ported vacuum, not manifold vacuum so the retard side releases with a lack of vacuum and the advance side advances with vacuum. Interesting system, makes sense with enough thought although I thought it was nuts when I first looked at it. Both need to be present and working for the car to run right.