freakin' tester!!!

[lance1a]

Ok, so I sold my E30 to a guy in Dublin, but it developed a misfire before he could pick it up. So I told him I would sort it out. What a nightmare!!

Firstly, my car is running a set of bike carbs on the M10 motor.

The symptoms were as follows....

misfire across the rev range intermittantly dissapearing above 4000 rpm.
Fuel smoke out the exhaust.
Compression ( with a borrowed tester from the guy who did the vales) test shows loss of compression in no:1 and two (at about 70psi).

So I figure either burnt valve or blow in the head gasket between the two pots. I haul the head off (now got it from running to head off in 25 minutes!) and the gasket seems fine. I do a test on the valves and they seem ok-ish. I put a new gasket on the car and re-assemble it all only to get exactly the same issue.
Head off again and where I cleaned up the pistons and valves previously I notice that no: 2 is not firing as it's as clean as a whistle. I did notice that pulling the plug lead off no: 2 didn't have any effect on the poor running so assumed this was the guilty pot anyway.
I ask a mate to put some new exhaust valves in while I was at work in exchange for me fixing his MG BGT, and he did but put the spacer on the rocker shaft the wrong way round so I had to take it all apart anyway to turn the spacer around.
New head gasket, put it all back together and gues what......? the same!
I remove the custom manifold and the bike carbs, fit the old manifold with a hastily modified Weber 36/36 from one of my old Lancias, and the car ran much smoother. So I stripped the bike carbs for the fourth time to make sure the needle and seats were doing their job.

I then found the problem....the Pilot jet on no: 2 carb was completely loose. But hard to tell as when you turned the carbs upside down to get the float bowls off, the jet fell back into it's hole and seemed ok, but when fitted, the jet would fall to the bottom of it' recess and allow fuel to blast past drowning the cylinder.
screwed it back in, fitted the carbs and manifold and Ye--haaa! all singing and dancing again!
Though this still didn't explain the poor compression. I bought a new tester screwed it in and got 170psi across the board.

So... the tester was faulty. I took it back to my mate and asked him how many head jobs had he managed to wrangle from the piece of rubbish!

So now the car runs well again, so well I am reluctant to sell it! Ah well....at least it's going to an enthusiast!

[Jeron]

Sorry for your trouble.

Nice looking engine though.

[lance1a]

Cheers bud, I replaced it with a Porsche 924S that I intend to restore. See Porshe pages. Hopefully a new DME relay will sort the non starting issues on this.....

[Manolito]

Having a cylinder washing down with excess fuel will reduce the compression on that cylinder, but I have never seen it reduce compression that much.