9 replies to this topic

[MikeJE]

I have a rebuilt 998 engine with 1275 head and twin HS2s. Whatever adjustments I try on the carbs the engine will either not tick over at all or ticks over at 1300-1400 rpm initially but slowly, very slowly, the revs drop to about 800 rpm. I have checked for airleaks around the manifold and I have serviced both carbs. I have also made sure the carb pistons move freely.

 

The wisdom of the forum with thoughts on a solution would be very much appreciated.

 

I do hope everyone is keeping safe at this difficult time

 

Best wishes

 

Mike

[MiniMadRacer]

When you say initially runs at 13 to 1400 revs, is this from cold when you pull the choke out...if so.. when you push the choke back in maybe both jets are not returning properly... have a look at the choke mechanisms to start with

[MikeJE]

Thanks MMR - but this is when hot. The choke is in (and I checked the cables and connectors). So if I am coasting in neutral up to traffic lights the revs are around 1400, then slowly reduce to about 800, but very slowly - perhaps over about a minute. All the carb bits move freely and there is nothing sticking on the throttle cable side, so I am baffled!

 

Best wishes

 

Mike

[MiniMadRacer]

If it doesnt happen cold, check for fuel vapourisation in the fuel pipe.. is it running too close to the exhaust manifold by any chance ?

[MiddletoM]

you checked the timing?

[MikeJE]

Many thanks, all these things now checked. And carbs cleaned and manifold nuts checked, but still she won't tick over until about a minute or so has passed. Any further thoughts welcome...

 

Best wishes, and stay safe, all...

 

Mike

[Quinlan minor]

Try a new throttle cable.

[DB1380]

Did you Balance the Carbs when you put them back on after cleaning ?

 

Dicky.

[MikeJE]

Many thanks again. It's a new throttle cable and runs freely and the carb linkages all move freely to the stops, but the engine still revs and drops slowly. I did wonder, DB, about balancing the carbs and plan to take it to someone with a rolling road to set them up correctly, but in the meantime used a Carbalancer to set them up although I appreciate they are not that accurate. Perhaps I will have another go at that to see if it helps - it is such an irritating problem as I arrive at traffic lights revving madly - well, about 1400 - and by the time the lights change to green she is ticking over nicely. Minis, eh!

 

Best wishes and stay safe, all...

 

Mike

[gazza82]

I tried a carbalancer back in the 80s on a neighbours MGB. After several attempts put it back in the box and used the old fashioned pipe to ear method ...