The Triumph Dolomite Club - Discussion Forum

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PostPosted: Thu Aug 22, 2013 7:15 pm 
Hi all !!!

I have had dolomites for a few years but thought I would try something new this time round and have just bought a spitfire, the car has done 24k genuine miles since full rebuild and new engine in 93. the car is in good condition but there is a major problem, the engine with not pul on the road, when I put my foot down it splutters and coughs and slowly (and against its will) accelerates. it has new k and n air filters fitted by the last owner. I noticed the fuel filter was around half full when running the pump seems ok, I cleaned the carbs and adjusted them a little but im no expert and it is still the same, I am at a loss as what to do I realy don't want to pay for it to be sorted I want to beat this myself. any advise would be great.

P.S. I know this is a dolly website but thought id give it a try before re registering on a spit/gt6 site


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PostPosted: Thu Aug 22, 2013 8:07 pm 
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What about a blocked filter on the top of the fuel pump? Thats my guess. :wink:


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PostPosted: Thu Aug 22, 2013 10:33 pm 
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Swap the K&N Filters back to the standard airbox and normal service will resume. SU carbs are hard to get right with anything other than the standard intake setup.

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PostPosted: Fri Aug 23, 2013 7:36 am 
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Swap the K&N Filters back to the standard airbox and normal service will resume. SU carbs are hard to get right with anything other than the standard intake setup.
Indeed - if the K&Ns were put on without changing the carb needles your fuel&air intake system isn't matched -- K&Ns will allow more air, changing the mixture on your standard-needle carbs.

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PostPosted: Fri Aug 23, 2013 8:07 am 
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Need some more info. Did the car run OK when you bought it or suddenly develop the problem? K&Ns need ricker needles but the car would still run better that how you describe.

Take the spark plugs out and take a picture of them to post on here. Depending on their colour,we'll know what to try next.

I've experienced (and resolved) most of these troubles with spitfires,heralds,dolomites and TRs over the past 25years so should be able to narrow it down for you.

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PostPosted: Fri Aug 23, 2013 8:35 am 
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Checked the ignition system?

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PostPosted: Fri Aug 23, 2013 10:52 am 
hi the car run this way when I bought it, the spark plugs where realy black when I took them out I gave them a clean and tried again, I guessed to rich, I think the needles where changed by the last owner. the pipe that connects from the rocker cover to the carbs was very loose (falling off) but I clamped it on a little better, and is still the same, ????
all help greatly recieved


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PostPosted: Fri Aug 23, 2013 12:40 pm 
Hi there

Concur with earlier posts as this is has v wide catchment for causes -

I had similar with my TR7 - Certainly need to match needles to K&Ns otherwise you may as well bin them, and must have ignition right so the pictures of the plugs would be v useful.

Not sure what mounting you have for the carbs to the inlet manifold but if its rubber a la' TR7 and Dollys then check its not split. Your mixture will be all over the place if it is and it will run under load like a dog. Lots of ways listed in forums for checking this but be VERY careful spraying anything at hot surfaces!!!

Also check the fuel tank breather isnt blocked / pinched. (NB - that tends to lead to a progressive strangling of power not instant - so if it doesnt do that ignore this . )


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PostPosted: Fri Aug 23, 2013 2:24 pm 
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Black plugs indicates too rich - so worth verifying with the previous owner if new needles were fitted. To be sure, you can whip the dash posts off and undo the needle grub screw and read off the 3 letter needle code at the top (where the little spring clips on). Once you know, tell us.

Does it start from cold without much choke? If so, it sounds like the mixture just needs adjusting - so maybe worth srcewing both carb jets up 4 flats and see how you go. Asides from that, get the timing checked. But from you said, it's overfuelling.

The other thing that I thought of is you could have the dreaded waxstat carb jets which look like this:

Image

rather than the earlier and superior red fixed jet:

Image

Waxstats were fitted to the 1500 (and other BL cars) as a tweek to help with emissions. They have a small wax thermostat in the base which shuts off fuel as the engine warms up. The theory is that the petrol gets thinner with temperature so they throttle the fuel flow down a bit to compensate. As far as I recall, they just give trouble and when they fail, they fail very rich.

There is an easy fix. By prising the tin cap off the bottom, you can remove the waxstat and replace it with two penny coins
Image
Just remember to put the little steel pin back. There are how-to guides around on the internerd if you need more guidance. Or you can see a guide here:viewtopic.php?f=4&t=11818

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Last edited by wiggybum on Sat Aug 24, 2013 9:29 am, edited 1 time in total.

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PostPosted: Fri Aug 23, 2013 2:30 pm 
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Why has this been moved to another area of the forum? It is for a spitfire owner but equally applicable to dolomite owners and topical.

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1972 Series 3 Land Rover diesel
2007 MX5 Sport
2010 Citroen C1
1993 Gas Gas GT32


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PostPosted: Fri Aug 23, 2013 7:04 pm 
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Whereabouts are you? I have a spit 1500 as well and know them backwards.

What Wiggy says is true enough about waxtstats. If they fail they fail rich as the pellet collapses and the jet drops. The 2p fix works....so I'm told.
I always get new ones if I can. Ignore the stuff people say about about changing to non waxtstat jets. Spits will ruin fine with wastats as long as they are kept clean and working as they should. It will aslso run ok with K+N's on standard needles up to about 3.5k rpm but will then feel a bit flat. Richer needles are
the solution but I took mine off and went back to standard after a while...but I have a different exhaust. Think I use ADH's.

It sounds to me as if you have one carb jet blocked. The car will start ok and idle but wont pull the skin off a rice pudding as you have 2 lots of air and only 1 lot
of fuel. You can diagnose this by revving up on each carb on its own...press the linkage close to each carb. If one revs up and the other coughs the coughing one is your blocker.....

If you are near west london PM me and you can bring it round tomorrow afternoon. If the car wont drive and you are anywhere between here and Luton I will come to you....and sort it, or tell you how to.

Jonners

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Note from Admin: sadly Jon passed away in February 2018 but his humour and wealth of knowledge will be fondly remembered by all. RIP Jonners.


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