Gt6 running on post turn off

[Kevin.payne.15]

All.

 

The GT6 has started running on after turning off and occasionally I get a slight pop from the exhaust pipe. I cant be the only one to suffer this. It has a 123 distributer fitted as it previously had really bad timing issues and couldn't have the vac advance fitted Can this be the cause?

 

Thanks

 

Kevin

[Pete Lewis]

Running on is down to a number of ideas

Vac unit does little at idle its to aid economy and advances at light throttle openings most when criusing should have no effect on idle or wide throttle running

low grade fuel

retarded to suit

Over heated spark plugs

mixture too lean too rich

 

to fast idle speeds

stuffed overun valves in the throttle plates

poorly set temperature compensators leaking seals or open whe need to be closed

 

some late engines had a anti run valve fitted in the manifold which opened on shut down to stop this

[Kevin.payne.15]

Pete. Thanks. That's quite a long list. Where do you recommend starting

 

Temp compensators were new last year from Bodens (or something like that) who are the manufacturers. Other than replacing how does one check

 

Not come across valves in throttle plates. Where do I find?

 

Tickover is a bit fast ~1100 but if I slow down it goes from tick ove to stall almost instantly

 

Thanks

 

Kevin

[dougbgt6]

Kevin,

 

The temperature compensators should be mostly closed, particularly when the engine is cold.  Take them off and temporarily block the 4 holes. Try the engine again, if it's still got the same problem, it's not the TCs and you can put them back.

 

The tick over can't be set lower than 1100 sounds like mixture and/or timing wrong. Start the engine, undo the dizzy clamp bolt and turn the dizzy slightly backward and forward, listen to the revs rise and fall. Turn till the revs start to fall, then turn in the opposite direction and the revs start to rise, keep turning until the revs stop rising. Turn back very slightly and that should be the right spot

 

To check the mixture take out a plug from the front and one from the back, what colour are they? They should be the same biscuity colour. If they're black, mixture too strong, if they're grey/white mixture to weak. If they're different colours adjust the offending carb.

 

Once you're happy with all that try and turn the idle speed down, if it still won't go down to 8/900 there's something else wrong and we'll have to dig deeper. But try this first.

 

Doug

 

.

[Pete Lewis]

some later cars have a small oppet valve in the throttle plate it opens on decelerating from rapid throttle closing, if the small spring is stuffed the thing stays open  and you get uncontrolled high idle 

 

if they are not fitted ignore this idea

 

Pete

[DrKai]

Already been suggested but mine was overrunning every time on cheap fuel. Put a tank of v-power in, hasn't done it once since

[Pete Lewis]

Ues if you run on 95 ron you have to retard the timing, this raises temperatures reduces performance

And things start to glow inside

 

use v power or any 97-99 ron and timing is able to be pretty much factory specs and things run at the designed temperatures

 

when our cars were built you used 101 octane and only put 95 in motor mowers and low compression side valve engines