Lumpy Idle

[Guest jetskijase]

HI All

Managed to borrow a strobe light, adjusted tappets as where a bit loose/gappy, Couldn't get it to idle so re checked and found two valve's a bit tight so re done.

 

Now it idles like a lumpy thing, chugging away, got it to idle roughly and checked timing, the mark's where well short of the pointer even with the vac pipe disconneted.

 

So i went to the dizzy and adjusted until I could hear it smooth out slightly, checked marks and still nowhere near the pointer on block.

 

Any idea's guy's??

 

Would the accel cable need readjusting at the carb end (tick over ) after you take out of the donor car??

 

Jase

[Longboarder]

Mark the 8 degrees BTDC slot on the crank pulley and the pointer with tippex or white paint. Start the engine. Adjust the idle speed using the idle speed adjustment screw on the carburettor body till the rev counter shows 850rpm or so (not the accelerator cable which should have slight slack when you are not pressing the pedal). Then fit the strobe light, disconnect and plug the vacuum advance pipe and slacken and rotate the distributor till the strobe illuminates the mark on the crank pulley and the pointer lined up. If the engine is now running much faster, twidle the idle speed screw to slow it to 850rpm and recheck the timing marks and rotate the dizzy again if necessary and repeat till it all lines up and the idle is 850. Switch off, reconnect the vacuum pipe, remove strobe and drive.

 

Nigel

[Peter Bell]

Jase just a thought, you have fitted the strobe to no.1 cylinder haven't you?

Peter

[Guest jetskijase]

Hi All

Ye peter on no1 (nearest to cam pulley/water pump)

 

I've been reading the haynes and i have a later type weber 2v which the idle is controlled by the esc2 box, the one i've removed and replaced with the simple transit ign system. Also when i bought the car and drove it home fine it has a manual choke mod fitted and no stepper motor fitted.

 

Also when i took a spark plug out it had the dry black soot on it so i presume it's to rich. I have found the idle mixture screw at the base of the carb on the cam cover side, Any idea's of a starting point on this screw???

 

 

Has anyone who has changed the ign had these probs?? :boohoo:

 

Thanks everyone, nearly there.

 

Jase

[Guest Andy Hamilton]

Also check the crank to cam timing.... you might say duh, already did this, but from my recollection of setting this up, when the crank TDC markers are ligned up, you seem to get a choice of where you line the camshaft marker up, either to the right of the dot on the block or to the left! For some reason, they don't line up perfectly.

 

It may be that you are one tooth out on the cam timing.

 

Just another thought

 

Good luck

[Longboarder]

If the stepper motor is removed then you have no idle speed control on the carb. You can make up a bracket designed to attach to the stepper mounting bolt holes to hold a new idle speed screw and bear on the same point that the stepper motor operating rod used on the throttle arm. Bingo, idle speed adjustment.

 

Nigel

[Big Jim]

Everything that Nigel & Andy have told you is correct,

But seeing that you've obviously had the cylinder head off, the first thing to double check is the cam timing, also make sure the "window" with the pointer on, is squarely sitting behind the hole in the cam gear, if it's not, then it's come off the key and moved, so you'll have to pull the gear off a bit to get it back on. turn the engine in the direction of rotation, and check that the marks line up, everything OK, then we go to the timing.

 

This now depends on what camshaft you have fitted, but I assume that you still have the standard one (remembering the thread from previous week)

 

Remove & plug the vac pipe from the dizzy. if you're using a cheapo timing light, then highlight the 8º mark with tipex or something as Nigel says, you may have to speed up the idle to stop it stalling, but set the timing on that mark. now fit the vac pipe and set the idle to around 850-900rpm.

I don't particularly like messing with carbs, a specialist can always do a better job, but if you feel that it's a long way out, a start point is 1½ turns out with the idle mixture screw, slowly turn it inwards until you notice a change in the engine, then bring it back to where it was plus ¼ turn extra.

 

Note; An engine will always run more freely at idle with more advance than you're setting it at, that's why you'll need to adjust the idle screw (not the idle mixture screw)

[Guest jetskijase]

HI Guys

Thanks for above advice, checked cam timing all fine and tappets fine, removed vac pipe and blocked and generally went round carb/manifold checking for leaks.

 

But i think the main prob was that the instructions for the strobe clamp on the lead had two differant pics, so turn it round so arrow pointing towards spark plug ( thought it would be this to start) and the marks started to line up, got it on 10btdc, idling nicely.

 

I had to change the rev counter on this binacle and i think the needle doesnt work properly I have a tacho with light and stickers, do i stick the reflective bits on the crank pulley? to get an rpm reading?

 

Thanks again everyone

 

Jase

[Peter Bell]

Jason, just check that as you rev the engine up you are getting more advance on the timing, the marks will appear to move anticlockwise. This is to check that the mechanical advance in the dizzy is working. If this happens leave it as it is, well remember to reconnect the vacuum pipe!

Peter