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spark plugs normal or iridium ? my car wont pull


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just as in the title iam going to fit new plugs . Ive got a problem that in 1st and 2nd the car seems to pull ok past 3000 rpm but only ok but in 3 and 4 when the rpm reach 3000 it fluffs and spulters . Is there any benefit to iridium plug to justify ther money ?? The car is a tr4a with a 6 cylinder fitted on twin su. at malvern this year i fitted new eloctronic ignition and tuned the car but it did not alter it at all any help or advice would be gratefully received as overtaking is a pain thanks pete

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I can say that when I had a 6 engine on SU's and they were out of tune it ran like a dog, exhibiting some of the traits you describe. If the timing is close rather than perfect then I'd be looking at my carbs. There a lot of advise out there to tune them. It took me a couple of weeks researching and asking forum members but when I got the info and started from scratch my car went from a spluttering motor past 3k revs consuming a bit too much juice to a much quicker, very smooth beast. How long actually spent on the carbs , about 1 hour, research to know how to do it right , somewhat longer, but definatley worth it. I'd certainly check them out as part of the basic checks before thinking anything complex. If the plugs spark then it wont be them.

 

Robin

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Agree I'd start with the carbs. Clean, tune, balance. Do you have an airflow balancer?

I use the 'flat' type which was produced by Edelbrock in the 50s.

http://www.moss-europe.co.uk/Shop/ViewProducts.aspx?PlateIndexID=10770&SortOrder=2

 

Perhaps a rebuild kit from Southern Carbs or Burlen.

 

Fuel pressure should be 3psi. Does it have a suitable pump?

A Filter King pressure regulator is good to have.

Disregard the mention of 'Weber' here, it's fine for SUs.

http://cgi.ebay.co.u...=item3a5fdc6655

 

Check the existing fuel filter(s).

 

Check the CO. Aim for about 4%.

http://cgi.ebay.co.u...=item43a2a9bb6b

Money spent on tools never wasted.

 

Thinking about the distributor, a red rotor arm and new cap from Dizzie Doc would eliminate that from your enquiries.

 

Ivor

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hi - many thanks for your responses so far - i myself was pretty sure that the problem was carb based - prob fuel or mixture or bit of both , but was going to get the electrical side spot on first as this is what i am capable of doing! i did buy a new distributor cap and red rotor arm at malvern as a spare so will stick that on and a brand new set of standard plugs which i am sure wont make any difference but at least then i will be assured the electrical side is spot on then. does anyone advise whether to tackle the carbs myself - i am pretty mechanically minded when it comes to engines, pistons etc, or shall i send the car to one of the specialists to get the carbs set up

 

many thanks for all your advice so far, pete

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Hi Pete,

 

iridium plugs won't solve anything.

 

You're spot on, get the electrics right first.

 

Then play with the carbs - not rocket science, just follow the book. Patience is a virtue. And use your digital camera to remember how things looked before you dismantled them. ;)

 

Cheers,

 

Alec

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Hi Pete

 

Only to say I had carb issues on my 3A ( twin SU ) a few weeks back, and having canvassed opinion on the Forum set about to taking them to bits cleaning them, replacing the various internals using a service kit from Burlen fuel systems.

 

I did not relish the prospect, but by doing the job slowly, taking some pics as Alec suggests and following the manual I am glad to say all is back together and the car runs great. :D

 

I think the service kits were about £20 so minimal cost just a bit of time really.

 

Good luck. :)

 

Cheers.

 

Nick.

 

P.S. Anyone who knows me will confirm I am no mechanic !! :(

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This is a good link for tuning SU carbs.....

 

http://www.scribd.com/doc/12890423/Tuning-SU-Carbs

 

(I've just been given a copy of the original booklet too)

However I think the saying is that 90% of carburettor problems are electrical....

Are you sure that the ignition timing isn't too retarded?

 

john

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A number of years back I too got service kits for the SU HS6's for the TR4 I was restoring... Never done them before, but if you made Airfix Kits (remember 'Locate and Cement' written instructions!) and did Meccano as a lad, I am sure you will not have any problems.

 

Also, the satisfaction when it's all together and the engine runs well is enormous! Definitely 'Cheshire Cat' syndrome!

 

Good luck!

 

Brgds

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does anyone advise whether to tackle the carbs myself - i am pretty mechanically minded when it comes to engines, pistons etc, or shall i send the car to one of the specialists to get the carbs set up

 

I rebuilt the twin SUs on my present Rover V8, and on the previous engine, with kits from Southern Carbs.

I used the 'how to' in Haynes, but I think the Burlen kit comes with good instructions.

One needs to be fussy about setting the float heights, otherwise it's pretty straight-forward.

 

The carbs should be tuned at least annually, so if you don't equip yourself and learn how, you'll be forever in hock to paying someone else who may or may not do it properly.

 

Ivor

Edited by 88V8
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The carbs should be tuned at least annually

:huh:

 

What does that entail? When I ran Strombergs on stock '250 engines I didn't need to adjust them at all once they were set up.

 

I don't do anything on my Webers either aside from a little spray lube on the linkage once in a while...

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:huh:

 

What does that entail? When I ran Strombergs on stock '250 engines I didn't need to adjust them at all once they were set up.

 

I don't do anything on my Webers either aside from a little spray lube on the linkage once in a while...

 

Spray lube is a good idea. I use a long oil can on the linkage of my PI.

 

Fixed-jet carbs such as Weber... I must say when I had cars with Solex I didn't do anything with them either, although they were singles. What is it they said about Solex - guaranteed to provide the wrong mixture at all revolutions....

 

With the SUs, the dashpot oil needs topping up. The pistons and slides need cleaning. The air balance needs checking/rectifying as it's affected by the general state of the engine in addition to any wear in the linkage. The mixture needs checking/adjusting. And of course before all that the air cleaners get washed and re-oiled.

I suppose I could just give it all a good ignoring and see what happens, but it uses enough petrol when it's in good tune.

 

Ivor

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One needs to be fussy about setting the float heights, otherwise it's pretty straight-forward.

 

Ivor

 

 

Hi Ivor,

 

I've recently changed to Grose jets to prevent any chance of a blockage (they don't....)and with the one piece plastic floats there seems there is no way to influence the bowl level..... I'm getting an occasional strong smell of petrol when hard right cornering (roundabouts) and suspect they could be a bit overfilling? (Facet pump and pressure regulator fitted)....any ideas?

 

john

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Hi Ivor,

 

I've recently changed to Grose jets to prevent any chance of a blockage (they don't....)and with the one piece plastic floats there seems there is no way to influence the bowl level..... I'm getting an occasional strong smell of petrol when hard right cornering (roundabouts) and suspect they could be a bit overfilling? (Facet pump and pressure regulator fitted)....any ideas?

 

john

 

Fuel tank vent pipe.

Stuart.

Edited by stuart
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Fuel tank vent pipe.

Stuart.

 

Sorry for the deviation.

 

thanks Stuart, but there isn't one :o seems to vent through the magnetic cap (has always been OK) but since fitting electric pump/regulator/grose jets i've had the smell occasionally....thinking about putting some sort of 'overflow sensors' to the drip trays (luckily I have them as a Grose jet stuck open recently)....

 

john

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....thinking about putting some sort of 'overflow sensors' to the drip trays (luckily I have them as a Grose jet stuck open recently)....

 

What about a pilot light? :P

 

Seriously though, I'd be surprised if the carbs could overfill sufficiently during brief cornering to make them overflow. I would expect that more - if at all - on something like a lonnnnng curved motorway on-slip. I too would initially suspect something in the tank area.

 

 

Ivor

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Never knew of any vent besides the cap on a '250. As this cap wasn't used on RoW cars ( sfaik ) its discreet little vent may be not be familiar elsewhere. TR6 caps of later vintage on carb cars likewise had vents, but I don't know what was used when the carbon canister apparatus, etc. was fitted :huh:

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hi - once again many thanks to all the people who passed on valuable information regarding my car, i know the link got hijacked a bit at the end, but thats the idea of a forum !!

in short, i fitted the new red rotor arm and distributor cap which gave me a fantastic spark, but as most people expected, the problem was the carbs and as people said, the satisfaction is with doing it yourself, and that is no more true than today for me.

 

i basically read a bit about what to do, fettled with the carbs as i knew they were basically brand new anyway and everything in them was brand new, and lo and behold the engine now sounds fantastically crisp and pulls superbly right through the rev range and in every gear.

 

went for a quick 100 mile blast today (chasing our local bike club) and pretty much kept up all around the route.

 

only thing to mention, in between crossgates and newtown (in wales for those who dont know)i passed a tr4/a in powder blue - either a works car or a works replica - what a great feeling i was fair tanking it the one way, lovely welsh roads, and to see what looked like a works car coming the other way was a fantastic feeling , unfortunately at the speed i was going i couldnt catch the reg no.

 

many thanks once again for everyones help

 

pete

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