fast idle

Hello,

I recently took the head off my 1974 mgb gt to have a look at the insides. This is the first time I've done this on this car and have repleced the head gasket on my old mini before.

I cleaned out all the carbon and put on a new gasket and rebuilt and put it all back together again. However when I started her up after doing so the idle speed was really fast at 25rpm. I adjusted the vale clearences and put in some new plugs thinking that I may of damaged them and now it's idle is 10 - 15rpm.

Is this normal and all I need to do is reset the idle and fast idle on the carbs or do you think I've messed up somewhere?

Thanks

Ste

If you can adjust the idle with the carbs, you are ok. Otherwise, you have a vacuum leak somewhere.

Shoot for a steady idle at 900-1000 rpm.

If the car is in tune, this should be no problem.

What was the idle speed before you pulled the head?

I would recheck valves and timing.

Cool, I'll have a look at the idle on the carbs and timing... . The idle was 5 - 7 rpm before i did the work.

thanks

Ok so now I'm pretty confused.

Re-did the valves, took the carbs off and put in new gaskets everywhere and ajusted the idle on the carbs. This has left me with an idle of 7rpm when she's switched on but as soon as I put any revs into her she holds the revs - eg, idling at 7 put foot on gas till revs are at 15 and they stay there, rev again to 25 and they stay there.

Went for a quick spin and found the car driving fine whenever I'm not in neutral or with the clutch down although this is acompanied by a burning smell.

Haven't checked the timing yet, do you think this could be the case or possible clutch slip?

Cheers,

Ste

I would think vacuum leak also.

oil in the carbs?
sticking throttle cable?
springs not set right ?
choke stuck ?

Had that problem once when I had new throttle shafts installed . The new shafts were a bit longer and when the carbs were bolted down they had no end play and would bind .Check for end play on both connecting shafts.You should be able to move them back and fourth just a tiny bit .

good luck