The Jensen Owners' Club A technical and discussion forum for all Jensen enthusiasts It is currently Wed Oct 23, 2019 6:13 pm

V-8 Engine Tech

383 Vacuum advance leaking

Mopar Big Block Talk

by money_one_four » Wed Jul 17, 2019 11:28 am

Not sure if you have fixed this problem , but I would say it’s a choke problem rather than advance problem, if you try to give it more fuel and the choke is not working or fully closed it will miss /splutter even stall .How do I know this ? my car hasn’t got a choke fitted and does the same as yours, just needs a little more time to warm up before driving off and all’s fine .
CHEERS BE LUCKY ALAN
Jensen 111/440/1317 /OAR 298P
Jaguar 420G
Jaguar Sovereign v8
Winnebago M/H
money_one_four
 
Posts: 312
Joined: Mon Mar 03, 2008 1:59 pm
Location: DARTFORD

by Eddie » Wed Jul 17, 2019 8:37 pm

money_one_four wrote:Not sure if you have fixed this problem , but I would say it’s a choke problem rather than advance problem, if you try to give it more fuel and the choke is not working or fully closed it will miss /splutter even stall .How do I know this ? my car hasn’t got a choke fitted and does the same as yours, just needs a little more time to warm up before driving off and all’s fine .


Thanks for the heads up.

Yes nothing is leaking, so it’s starting to narrow down the causes. It only happens when the engine isn’t up to temperature so looks like it could be the choke.

Ta Eddie
Eddie

JOC 10030
Interceptor II 123/3901 CEA 1J
1970 Earls Court Motorshow Car
User avatar
Eddie
 
Posts: 682
Joined: Sun Oct 06, 2013 1:27 pm
Location: South Leicestershire

by RayR » Thu Jul 18, 2019 4:23 am

Another one to try is the distributor cap. I had exactly the same problem, the engine needed to properly warm up before the sputtering went away 5 or 6 miles or so with no choke. New cap and never happened again. Theory is a small hairline crack, and moisture condensed in the crack causing the misfiring and needed to get truly warm before the moisture evaporated out again.

Ray
MkIII Interceptor (140 8488)
User avatar
RayR
 
Posts: 182
Joined: Mon Mar 05, 2018 4:43 am
Location: New Zealand

by RichardGibson » Thu Jul 18, 2019 7:29 am

Hi All.
My 1971 Mk2 Interceptor has the same issues regarding a lack of smooth running when cold. It coughs and splutters if I drive it immediately on fire up after sitting for a few days. Once warmed up it behaves as it should.
On returning from the International at Hull I found I had an increasingly worsening issue with an intermittent back fire, investigation revealed a leak in the fuel feed pipe to the carb, it was cracked. I changed this. At the same time I changed the plugs, HT leads, dizzy cap and rotor arm. I noticed that the off side plug nearest to the bulk head (forget the number) was well carboned up showing intermittent firing, the next one down was not a lot better.
Anyway tomorrow the car goes in to my local tune up specialist (one who does not need a plug in computer to set the car up) to have the points and condenser fitted before tuning the old fashioned way.
Richard
RichardGibson
JOC Scotland Rep
 
Posts: 12
Joined: Mon Apr 29, 2019 11:47 am
Location: Inverness

by money_one_four » Fri Jul 19, 2019 7:51 am

Just goes to show how different things can give off the same symptoms, keep us posted Richard will be interesting to hear what they find.
CHEERS BE LUCKY ALAN
Jensen 111/440/1317 /OAR 298P
Jaguar 420G
Jaguar Sovereign v8
Winnebago M/H
money_one_four
 
Posts: 312
Joined: Mon Mar 03, 2008 1:59 pm
Location: DARTFORD

by RichardGibson » Fri Jul 19, 2019 12:40 pm

Hi again.
Just got the car back from the tune up specialist.
Three issues were discovered:-
1 The points were on their last legs so to speak, almost worn away. I asked the garage to replace these as I had no gap set information to do it myself, whereas they have equipment to check dwell angles etc.

2 When fitting the new dizzy cap I had bent the spring steel connector on the rotor arm and it was only just making contact. Apparently this is easy to do due to the access of the distributor and the fact that you do not know you have done it until you remove the cap again. This however is probably not the cause of the original misfire as I do not remember the rotor I took out as being bent. All is now bent back to its correct state.
Some thing to remember if removing the dizzy cap etc.

3 The points had been over greased when last fitted and there was grease everywhere, this can cause connection issues.

The car feels and sounds a lot better now although we suspect a very slight leak in the off side exhaust manifold, may need a new gasket in the future.
I will drive around a bit to see if it is better.

Richard
RichardGibson
JOC Scotland Rep
 
Posts: 12
Joined: Mon Apr 29, 2019 11:47 am
Location: Inverness

Previous

Return to V-8 Engine Tech