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Discussion Starter #1
Hi guys.
I have a bit of a headache at the moment.
My engine is running bad.
So the history is. I have been adjusting to get my fresh rebuild engine running well. It’s a 2.0 with raised pistons and 12,3-1 compression and 45 DCOEs. Firstly today I mounted a direct wire to the coil which is a 3ohm, and the distributor is a 2.0e with pickup and no vacuum as standard and then the original 2.0e ignition module.
With some playing with the idle mix and ignition point (10deg at idle) I got it to run really well in the garage almost perfect. So I figured I wanted to take it for a drive. But first I wanted to check everything and get some hanging wires up arround the fuse box and cleaning the spark plugs. When everything was done I pushed it out and started it and it ran pretty bad and not smooth at all. The cylinder 4 exhaust pipe was not hot at all and the others was burning. But it was spitting fuel out of the carburettor.

Things I have checked.
  • the spark plug didn’t show signs of combustion, it was just wet.
  • switched two spark plugs and that did not help.
  • too out the plug on cyl 4 and turned the engine, it has got spark but a weak one.
  • cylinder 3 spark looks weak too. But it have had combustion as it was black.
  • I pulled out one of the other spark plugs (cyl 3) while it was running and It did not change anything, so I assume it is a general thos about the ignition.
  • I measured the coil and it showed 5-7v. And 12v from the + to ground.
  • I changed the coil, with no result
So now my questions is
Do any of you have any ideas about what I do next.??
Maybe a bad ignition module or distributor.?? How does the 5/7v on the coil sounds?

Thanks in advance :)


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Opel Rallier since 1977
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  • 5-7 volts sounds reasonable.
  • Measure the spark plug wires for resistance end to end. If they are standard resistance wires, then in the range of 3,000 to 7,000 ohms is to be expected. Checked to see if you have a loose end on that #4 wire.
  • To check spark, place the end of the spark wire from the coil about 6-8 mm from a metal surface, crank the engine, and look for a good blue spark to jump that gap in open air.
  • If you have a compression gauge, I would check all cylinders for cranking compression.
  • What sized cam do you have? 12.5 compression ratio is too high for a standard stock cam and even 98 octane fuel. (European octane when is the Research octane number).
  • Do you have a solid lifter cam?
  • The fact that both cylinders 3 and 4 are showing problems suggests that something may have changed or failed in that back carburetor.
 

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Discussion Starter #3
I have a 326 deg. Cam and the engine have had break in before going in to the gt, in an other car. So the engine should be 100p.
it’s just really strange that it ran so good and then I shut it off and now it runs really bad.
But I will try to do the tests and see what it shows. And then give an update. But it will be tommorow as it is 22.00 here in Denmark


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Opel Rallier since 1977
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OK. with that cam I would think you should get around 11 to 11.5 bar or cranking compression. This is usable with premium fuel. The way cams are specified in Europe is different and translation to specs for the US is not always 100% clear.

No you must work all night :D
 

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Discussion Starter #5
Okay thanks.
I will try to make a compression test.
Haha. I have done so many all nighters to get to this point but I had to get back to my quarantine place (you know this are taking off here in Europe) as I just got back from France.


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Opeler
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Hi guys.
I have a bit of a headache at the moment.
My engine is running bad.
So the history is. I have been adjusting to get my fresh rebuild engine running well. It’s a 2.0 with raised pistons and 12,3-1 compression and 45 DCOEs. Firstly today I mounted a direct wire to the coil which is a 3ohm, and the distributor is a 2.0e with pickup and no vacuum as standard and then the original 2.0e ignition module.
With some playing with the idle mix and ignition point (10deg at idle) I got it to run really well in the garage almost perfect. So I figured I wanted to take it for a drive. But first I wanted to check everything and get some hanging wires up arround the fuse box and cleaning the spark plugs.

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Any chance something got messed up with the wiring when you were doing this? Seems to me to be a variable.
 

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Discussion Starter #7
Yes in deed.
I didn’t unplug anything on purpose but if you have anything on your mind I could check, then let me know. There should only be the plus for the ignition coming from the fuse box, shouldn’t there?
I tried to move arround the wires in the engine bay while running, but it did not change anything.
I think it will help getting back with some fresh energy tommorrow


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Über Genius
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In 1986 I bought a 1972 Ford Wagon with a 400ci motor. It barely made it down the road. It was running on 5 cylinders.
After I got it home I started to diagnose everything.
FIVE minutes later it was running on all 8.

I merely replaced the cap AND wires
 

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X2. Had simular problems in the past with 3 vehicles witch includes my GT
 

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Yup
 

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Just Some Dude in Jersey
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Wow, that's a lot of compression.

Dual carbs and the cylinders fed by the back one are suddenly misbehaving or acting strange. Check for vacuum leaks. You say that you actually DO detect spark, but maybe not as much as you want. I recently had my car with a single side draft at a tuning shop and the tuner guy discovered that the aluminum tip on one of my plugs had unscrewed. I never knew why spark plugs had those unscrewable tips on them. He said that VW's and other cars used them. He found that one of them had unscrewed completely and was stuck inside the spark plug wire. He tightened all the tips very forcefully and the car ran much better. Check all the electrical stuff that the other guys have mentioned.
 

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Opel Rallier since 1977
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It is indeed a lot of (static) compression ratio. But that is not what counts in the end. It is the static compression ratio combined with the cam size, which determines how many degrees that the intake closes after the start of the compression stroke; that sets the final actual pressure in the cylinder. This is called dynamic compression ratio and accounts for the static compression ratio (the 12.3 in this case) plus the effect of the cam size.

Which is why the question about the cam. The OP's cam is quite large, so the intake closes very late on the compression stroke, which avoids an excessive pressure build prior to the start of the combustion. That is seen in the computation of the cranking compression.. the 11-11.5 bars is around 160-165 psi which is workable on pump premium, with some reasonbaly careful tuning of ignition timing.
 

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Discussion Starter #14
Now i finally found the cause.
One of the carbs was floated due to a punctured float. Found that both cylinder 3 and 4 was not firing right. So looked in to the carb and found the float with fuel in it :( this also explains why it was after half an hour to an hour of stand still the problem occurred. It must have totally floated the cylinder.


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I have a 326 deg. Cam and the engine have had break in before going in to the gt, in an other car. So the engine should be 100p.
it’s just really strange that it ran so good and then I shut it off and now it runs really bad.
But I will try to do the tests and see what it shows. And then give an update. But it will be tommorow as it is 22.00 here in Denmark


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Sounds like an awful lot of duration for such a small engine. What is your rear axle ratio ?
 

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Discussion Starter #17
OK, good that is a very clear cause! Make sure you smell the engine oil to see if there is gas in it; if it smells of gas, change it now. And squirt a bit of oil in cylinders 3 & 4 before you start it again.
Thanks a lot for that. It had a slight touch of gas so I’m gonna put new on and change it again after a startup. Damn I hope there is no more damage. Might be a good idea with a compression test now??
What a day.... at least I got a advance restricted distributor made, with other spring too, it ran really good arround 18 deg in idle and then I’m going for arround 36 deg total.
 

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Discussion Starter #18
Any og you know if the newer type Weber dcoe plastic float fits the old “made in Italy” dcoe?


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No.. please change the oil now before startup. Gas is a not a lubricant at all. If you can smell it in the oil, then it is too much. There is no good reason to take a chance with a new engine. If you put a little bit of oil in the cylinders now, that is to replace the oil on the cylinder walls that got washed off by the gas. I would run a compression test; I am not sure it is important if you do it now.

Keep your ear open for knocking (detonation) when you get up to middle RPM's and wide open throttle on the road tests. Do you know at what RPM's the advance reaches the full 36 degrees?
 

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Just Some Dude in Jersey
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I think that the height of the posts that the floats pivot on might be different, although that might only apply to the newer DCOE's. I ran across this problem when I swapped the cover from my DCOE9 with one from the latest DCOE 132(I think). I really hate those plastic floats, they fit too tight and you have to be really careful removing the lids.
 
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