I've got an issue with my car that I have done hours of research on and twice as many hours work on. Now i'm stumped. Any and all advice would be appreciated. It's a 1973 toyota corona mark 2 with an 'M' engine. Which is a 2 litre 6 cylinder. The initial symptom was that it was stalling at idle in drive when stopped. Idle just seemed to drop so low it would cut out. Sometimes it would 'click' and 'whir' then stall.
I've got a moderate amount of skill when it comes to be being a 'home mechanic' and I knew that this issue could be a vacuum or fuel problem.
this is what i've done so far and the results.
1)carby repair kit, including, new gaskets, throttle plunger, inlet valve and seat, and gaskets. Float level adjusted to factory settings. Cleaned the whole carby out.
2)new fuel lines and fuel filter.
3)new dizzy cap, leads, rotor buton, condensor and points, adjusted heal gaps(.2-.4) and point gaps(.4-.5) to factory settings. Adjusted dwell angle(38-44deg) it doesn't vary more than 3deg whilst
increasing rpm to 2000. Checked dizzy advance was working.
4)adjusted fuel mixture, and set min idle speed(600-650rpm in drive). In between tunnings car was 'dieseling on' every now and then, but hasn't for a while. Was trying to increase idle speed so it wouldn't stall,
but it didn't really work and caused 'dieseling on'.
5)checked compression. Factory settings are 900-1100kpa, no more than 70 kpa between cylinders. Cylinder 1- 1190, cylinder 2- 1185, cylinder 3- 1190, cylinder 4- 1170,
cylinder 5- 1100, cylinder 6-1120. Now its my understanding that high compression could be due to carbon deposits on top of the pistons. Which there is. By the way
this was a dry compression test. So cylinder 5 and 6 are the low ones. Even though they're at the top range of factory settings. Head gasket leak? Maybe (was replaced a year ago so doubt it).
bad valve guides or seals? Maybe. But the low compression shouldn't have anything to do with stalling in idle.
6)adjusted timing(8deg btdc). Timing mark was flickering in between 8-11 deg. Not steady. Could be related to cylinders 5 and 6? Or maybe the harmonic balancer rubber has perished,
so I was told, which could cause the timing mark to be inaccurate aswell. I checked this but, and number one cylinder is at tdc when the mark is lined up.
7)vacuum pressure test. Ok it's flickering between 13-15 when at running temp. I realise this is low. But doesn't flicker when rpms increase. Flickering could be related to cylinders 5 and 6.
8)vacuum leak 'whistle' from within the carby. The only vac lines are to the dizzy advance, to the BSV in the aircleaner, to the PCV valve, to the brake booster, replaced and checked all of
these. Propane tested everywhere, with no change to idle, intake manifold bolts are tightened, carby baseplate and all gaskets are good.
9)check all spark plugs, they're all light brown to a greyish tan so all good.
10)adjusted all the valve clearances to specs.
So basically, it sounds like its running crisp when the throttles open, and at idle its a little rough, but you do have to open the throttle every now and then to stop it from stalling
. This is totally annoying. 'Two foot' driving an auto just to be safe and not stall at lights is driving me crazy. At the end of the day the carby has still got that whistle that I can't find. Cylinder 5 and 6
are a little low on compression. The vacuum is low and flickering. And that low idle and stalling is annoying. I know there could be a few issues. But if I could only sort out the stalling issue i'd be happy.
apart from this the car is in excellent condition, i'd hate to get rid of it, but if this continues I just don't know. Maybe someone with more auto smarts than me could see a connection with all this.