1256 engine woes

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1256 engine woes

Postby rodgerq » 26 Sep 2006, 14:05

got this chevette here. its got the 1256 engine and is running on lumenition electronic(i assume breakerless) ignition. it just doesnt run right though. any full load and it struggles and sometimes cuts out till you back off.

the plugs are a dusty grey normal running type colour so i assume the mixture is ok. im wondering if it may be the timing side of things but never having worked on one of these im dont know common faults etc to check for. i assume the dizzy has been changed to facilitate the lumenition. the leads plus arm and cap are all new.

it looks like an aftermarket carb aswell but i may be wrong. its alloy at the top with a small plunger tye thing that comes out. K n N filter on the side of it aswell.

can get pics if needed.

anyone maybe point me in a direction to start looking

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Postby Shellysowner » 26 Sep 2006, 16:17

Well the carb sounds like a normal one to me mate - you should have a Stromberg 150CD comme ca:

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Is it a Delco dizzy or a Bosch one?

My initial hunches are:

1/ Carb Diaphragm

2/ Something that Andy said to me at the national would suggest you might like to try binning the electronic ignition for the time being and getting some points and a condensor back in there!
Doive wrote:I remember last summer being in another Chevette with a quite mad driver, and we were drifting round A class roads at 65mph with the tail sliding progressively on the corners. It was fantastic.

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Postby rodgerq » 26 Sep 2006, 16:42

checked the diaphram its ok. and its that carb.

unsure about the ignition though, dont want to spend much cash on it as its making way for somethin bigger pretty soon, i just wanted it running better to get a decent shot in it. tried adjusting the timing at the dizzy but it made no difference.

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Postby jifop » 26 Sep 2006, 17:35

vacuum advance working properly?

have you checked the timing?

is there oil in the plunger on the carb? i used 3 in 1 oil
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Postby Shellysowner » 26 Sep 2006, 19:14

Also check the leads are in good nick! A condensor and some points can't set you back more than a fiver surely?!
Doive wrote:I remember last summer being in another Chevette with a quite mad driver, and we were drifting round A class roads at 65mph with the tail sliding progressively on the corners. It was fantastic.

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Postby rodgerq » 26 Sep 2006, 19:16

topped the oil up in the carb. havent check the timing belt onyl had a playw ith the advance on the dizzy. dunno if the vac advance is working, how would i check it?

leads etc are all brand new and in good order. i had a feel about each to see if i got a shock lol. i didnt

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Postby Shellysowner » 26 Sep 2006, 19:23

Check the vacuum advance while checking the timing with a stroboscope type timing light by leaving the vacuum advance pipe connected and revving the engine. You should notice the white mark on the timing belt move.
Doive wrote:I remember last summer being in another Chevette with a quite mad driver, and we were drifting round A class roads at 65mph with the tail sliding progressively on the corners. It was fantastic.

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Postby rodgerq » 26 Sep 2006, 19:25

ok i'll get hold of a timing light then. where are the marks on the engine to check it?

argh, give me an ecu any day lol

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Postby Shellysowner » 26 Sep 2006, 19:39

rodgerq wrote:where are the marks on the engine to check it?


Its a little metal tab that forms part of the timing cover and sticks out above the crank pulley. There's 2 marks, 0 and 9 degrees BTDC IIRC.
Doive wrote:I remember last summer being in another Chevette with a quite mad driver, and we were drifting round A class roads at 65mph with the tail sliding progressively on the corners. It was fantastic.

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Postby chris(not) » 27 Sep 2006, 21:36

Timing Belt??? What timing belt- AFAIK there's chain in there behind the timing cover...... :?
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Postby Shellysowner » 27 Sep 2006, 21:47

chris(not) wrote:Timing Belt??? What timing belt- AFAIK there's chain in there behind the timing cover...... :?


Pah, fan belt..pulley.. thing lol
Doive wrote:I remember last summer being in another Chevette with a quite mad driver, and we were drifting round A class roads at 65mph with the tail sliding progressively on the corners. It was fantastic.

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Postby rodgerq » 27 Sep 2006, 21:48

lol cmon now lads its gettin too technical for me now :p

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Postby UpNorth » 28 Sep 2006, 09:51

Shellysowner wrote:Check the vacuum advance while checking the timing with a stroboscope type timing light by leaving the vacuum advance pipe connected and revving the engine. You should notice the white mark on the timing belt move.


The white mark will move anyhow as the mechanical advance does the bulk of the work. If you want to check the vacuum advance, switch off the engine, remove the distributor cap & dust cover, disconnect the pipe at the manifold end and suck :shock: , if the guts of the distributor move then the vacuum advance is okay.

A question though - what happens when you're carb diaghram splits?
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Postby Doive » 29 Sep 2006, 08:56

You drive everywhere at 6mph as the engine will usually refuse to rev.
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Postby Shoveitpusher » 29 Sep 2006, 12:26

get some points and a condensor before anything else. luminition is notorious for being a bit hit and miss, some go on for ever others can be a real pain.

the vacuum advance is proably a red herring - it has finished working at anything over a fast idle speed anyway.

other options could be shaft bearings in the dizzy, worn needle?

try the simple stuff first though
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Postby rodgerq » 29 Sep 2006, 12:48

got a wanted up for some points n stuff to take it back to standard. hopefully it'll cure it

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Postby shuvit-tim » 01 Oct 2006, 22:11

Doive wrote:You drive everywhere at 6mph as the engine will usually refuse to rev.


and misfire horrendously until it eventually forces its way up the revs?
when all else fails, rivets, cable ties and bodge tape will see you through

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Postby rodgerq » 06 Oct 2006, 13:31

ok i had a wee play about with this. set the timing back to standard on the dizzy and checked it was ok on the marks. it was fine.

still doesnt like any load at all though, but seems to rev fine sat still and definately goes better with the air filter off and revs cleaner if i spray carb cleaner straight into the throat.

i didnt think the mixture could be adjusted on these but today i was given a wee tool for doin just that. it consists of a wee sleeve thats an allen key goes down through. it located into the wee pot in the top and adjusts the needle height so im gony give this a go aswell.

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Postby Neilyman » 06 Oct 2006, 13:51

Try adding a couple of thou to the points gap, & then try static timing, like this.

Run the motor to normal temp. Slacken the dizzy pinch bolt & with the engine running at tickover, 8k ish, turn the dizzy slightly either way until the point of max revs is found, then nip the bolt up again. adjust idle again if ness.

This is the way my motor was setup, & it goes like a good `un! :)

It will be something silly that`s causing your problem, Chevette engines ain`t the most technically advanced things in the world. :)
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Postby Doive » 06 Oct 2006, 14:10

Have you checked the compression at all?
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Postby rodgerq » 06 Oct 2006, 15:09

no actuallyi havent. bit of a school boy error that TBH. :oops:

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Postby Shuvit-pinto » 06 Oct 2006, 18:06

Hi rodgerq

Gona have to use the ignition bits I had in stock for my Motor.

Last night I drove it into my workshop and adjusted the tappets and topped up the diff and nearly empty gearbox with oil. Restarted the engine to listen to the now quiet tappets. Left it on the workshop over night as the weather was foul out there.

Went to move the car this morning outa the workshop and bugger all ignition. Plenty of battery but no go. Checked it over and it looks like the dizzy has a dead short on it some were as no spark t points or from the coil. Disconnect the low tension wire from the coil to the dizzy and there is a reading on the meter, reconnect it and there is nowt. :(

I will change the dizzy and all the other gubbins from coil right through to the plugs if necessary as I am of to Vauxhall heritage on Sunday and need it going. :roll:

Odd, as one minute all is hunkydory and the next nufink!! :evil:
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Postby Harry Flatters » 06 Oct 2006, 18:11

Neilyman wrote:... with the engine running at tickover, 8k ish, turn the dizzy slightly either way until the point of max revs is found, then nip the bolt up again...


You'll tend to get the timing slightly overadvanced that way.

BTW Neily, you don't really set your initial timing at 8000 rpm?! :shock:
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Postby Neilyman » 06 Oct 2006, 19:31

Harry Flatters wrote:
Neilyman wrote:... with the engine running at tickover, 8k ish, turn the dizzy slightly either way until the point of max revs is found, then nip the bolt up again...


You'll tend to get the timing slightly overadvanced that way.

BTW Neily, you don't really set your initial timing at 8000 rpm?! :shock:


It might/could well be `slightly overadvanced`, but I don`t give a hoot, as my Chevette goes like stink, so it can`t be a bad thing. :)
It`s something I, & quite alot of mates did/do with simple ignition systems, with no ill effects that I know of.

Hehe, nicely spotted Sean!......I cut n pasted it from an old post of mine, & I remember I got picked up on the `mistake` in that one too, .........800 rpm. ;)
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Postby Shuvit-pinto » 07 Oct 2006, 18:04

Odd, as one minute all is hunkydory and the next nufink!!


Turned out to be the condenser. Complete dead short!! No hint of any trouble and it then dies, both me a nd Dad have never heard of a condenser doing this :?

Still already to roll for tomorrow now. :D
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