Popping And Overrun

[Guest kleighton]

Afternoon all,

 

I'm still having a few problems with my engine. I've got the timing somwhere near I think, and I've got a new 38 DGAS. When I start the engine from cold, it doesn't try to fire on the first attempt, but will do eventually. If I press the accelerator when trying to start, there's a pop and a backfire through the carb with some smoke.

 

I've taken it for a little drive today, only 50m or so, but when it's warm sometimes the revs stay at around 2000rpm. Sometimes a blip of the throttle sorts this out, sometimes it doesn't. When I turn the engine off at this point, the engine over runs, and again I get some backfire with smoke through the carb.

 

So far I've made the mixture a little richer (1/8th of a turn), and have adjusted the dizzy, and I start to think the rpoblem is sorted, but it isn't. Is it just a matter of getting the carb and timing spot on, or do you think there's something else I should be looking at ?

 

Thanks in advance for any replies,

 

Cheers

 

Keith

[Guest robinj66]

Is your carb jetted for a 2.0? They were used a lot on V6's with bigger jets.

 

Here's a link to the manual which might help. I would also recommend blowing the idle jets through (and possibly the main jets too).

 

DGAS Overhaul Manual

[Guest kleighton]

Thanks Robin, the link looks great.

 

It is a new carb that is jetted for a 2.0 litre engine.

 

Cheers

 

Keith

[Tazzzzman1]

Hi Keith,

 

I also have the 38DGAS fitted and suffered similar issues. Worth checking you have no air leaks around the Carbs where it could be sucking in air. I found that even with correct jets the carbs overjet (too much fuel). Only way I could get to run well was to play with the mixture (running very lean)...

[Guest kleighton]

Thanks Terry,

 

When I fitted the new carb I sealed the inlet manifold, and there's a new gasket on the bottom of the carb. As far as I can tell there are no leakes, but it wouldn't hurt to spray some DW40 around and see what happens.

 

Cheers

 

Keith

[Guest mcramsay]

sounds like your timing is off, and your running rich, if your running rich the engine will get hotter which would cause a bit of over run, you might also have too much coke in the engine, you can get decoking stuff to put in which cleans the tops of valves and the pistons and gets all the carbon off them although i dont know how good it is. i would most definatley get a strobe gun and check the timing double check everything for air leads (if your running a pinto then check the vaccume hoses ie vaccum advance to the dizzy. then make sure the manifold is done up tight, possibly even get a small feeler blade and try to insert it between the manfold and side of the head to see if there are any gaps. once you are sure the timing and air leaks(if there are any) are all gone then i would clean the carb out, reset the float level (possibly change the gaskets on the carb as you could be drawing air in there) and then readjust the mixture. however check how the engine runs after you check and amend each thing. that way you will know what the problem was! one last thing, if you adjust the dizzy ensure you tighten the little tab that stops it spinning! as the engine vibrating could cause it to turn if its not tight!

[Guest tommy holly]

Thanks Terry,

 

When I fitted the new carb I sealed the inlet manifold, and there's a new gasket on the bottom of the carb. As far as I can tell there are no leakes, but it wouldn't hurt to spray some DW40 around and see what happens.

 

Cheers

 

Keith

Hi keith it sounds like it could be a valve slightly open, do a compression test or check your valve clearances

 

Cheers tommy