TR4/4A TR4A Engine runs on

[Paulus]

Ive just rebuilt my carbs and replaced the vacuum advance unit on the distributer. I adjusted the carbs so that the airflow was even between both. The engine seemed to run OK, when I turned off the ignition the engine ran on very unevenly for several seconds, any ideas?

 

[waltesefalcon]

Did it run on before? Where is your timing set? Did you check your timing after messing with the carbs, and replacing the vacuum advance?

 

[Tomster]

I've always had run on with mine. I hate it
Verified correct running temp. balanced carbs, timming set and checked Still happens HRMMMFFF !!

 

[Geo Hahn]

By all means check the usual stuff, timing, mixture, etc. Can't do much about modern gas formulation.

At the end of the day, everything set up right you may well find it still does that -- mine does (especially in hot weather).

Have it in a low gear, foot on brake, ease out the clutch to end it's misery. If anyone's watching try calling out 'Whooooa Big Fella".

 

[Keoke]

Hi Geo, Use Third gear its easier on everthing.---Fwiw---Keoke

 

[Paulus]

It ran on a little when hot but nothing like this /ubbthreads/images/graemlins/crazyeyes.gif
Anyhow all is better now, it was simply running rich.Thanks for the suggestions all!

 

[Tomster]

The last advice was: Rev it up prior to shutting off the ignition, when the igniotion is just shut off, floor the gas to flood the engine with cold gas therfor stopping the hot run on... this will save the broken engine parts from the gear stop method. I wonder abiout cylinder wash down though.

 

[Paulus]

Thanks Tomster, next time I hit the road I'll give it a try.
Cheers mate! /ubbthreads/images/graemlins/cheers.gif

 

[jsneddon]

In my opinion the gear stop method (if done correctly) would have less impact than flooding the engine with cold gas - I don't like the idea of leaving more unburnt fuel than necessary in my cylinder.

Provided that you have the brake on and s.l.o.w.l.y. let out the clutch in 3rd or 4th you aren't doing anything to the drive train that you don't do hundreds of times an hour when driving.

I could see broken engine parts if you dump the clutch.

As Geo said... EASE out the clutch.

 

[StevenNewell]

I rarely had problems with run-on until this summer's road trip with the boys (photo link below). I'd tuned the car a couple weeks before the trip -- which doesn't necessarily mean I set my timing right /ubbthreads/images/graemlins/wink.gif -- but I figured it was either the summer gas formulation or that darn thick air outside of Denver. I developed a good touch with the turn-key-then-dump-clutch-w/-foot-on-brakes technique. I used whatever gear the car is in when I roll to a stop.

https://newellboys.com/2005/roadtrip/index.html

 

[Tomster]

Loks like you three had a great time !

 

[trfourtune]

in roger williams book "how to restore triumph tr4 & tr4a" he talks about anti run-on valves. they are a solenoid actuated valve connected to the intake manifold tied into the ignition. when you turn off the car the valve opens and the motor sucks in air instead of fuel from the carb and stops. this must be a fairly common problem since it's in his book.this seems like the best solution.