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valve guides or running in?
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triguarin



Joined: 02 Jul 2009
Posts: 2

PostPosted: Wed Aug 19, 2009 2:26 pm    Post subject: valve guides or running in? Reply with quote

Dear All,

having semi rebuilt the engine for a TR3A ( ie, everything except the head) I have had it running this week. The carbs are rebuilt too. I have black smoke on start up and when applying throttle in short bursts. At high revs no black smoke. Poor shaky idle, carbon building up on the plugs very quickly. In short hopeless to try and tune it. Even with weakest mixture setting its still a carbon nightmare. Yes, it's a smoker. As the pistons, rings and bores are brand new and the top isn't I am assuming valve guide wear. I hadn't seen the engine run before re build as entire car was a basket from the USA with nothing working. Pretty dim not to check the head while it was off I know. I intended to hand it in for unlead seats but, time goes by, expenses pile up....in the end I decided to run with an additive and get the engine back in the car. Advancing and retarding ignition doesn't seem to effect the general idle condition either. At 2000 revs the engine seems to run well with no shake and exhaust looks clear but I'm certain it doesn't quite sound as it should, sounds like its running weak but I know it's taking fuel like theres no tomorrow. Is this valve guide trouble...or does it just need running in? Embarassed
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peter scott



Joined: 18 Dec 2007
Posts: 6299
Location: Edinburgh

PostPosted: Wed Aug 19, 2009 3:56 pm    Post subject: Reply with quote

Black smoke = Too rich mixture.

If the smoke is black and not blue then you can breath a sigh of relief on all the oil burning type problems.


Is the fuel level correct in the float chambers. If you take off the dash pots and remove their pistons the fuel level should be perhaps 1/8" below the top of the jet tube. You might find that fuel is just pouring out of your jet tubes due to wrong float level.

Else...

Are you sure you have the correct carb needles? And are the jet tube holes worn?


Peter
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Nic Jarman



Joined: 05 Oct 2008
Posts: 1035
Location: Stoke by Clare, Suffolk

PostPosted: Wed Aug 19, 2009 4:31 pm    Post subject: Reply with quote

Is the choke stuck on?
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Brian M



Joined: 23 Nov 2007
Posts: 783
Location: Leigh-on-Sea, Essex

PostPosted: Wed Aug 19, 2009 7:56 pm    Post subject: Reply with quote

I had a similar, but not so drastic, problem with my Amazon after fitting twin SU's.

Heavy black smoke unless I screwed the jets right up when it was too weak to start.

Mine was cured by a session on a rolling road that I detailed in this thread:

http://www.oldclassiccar.co.uk/forum/phpbb/phpBB2/viewtopic.php?p=36289&highlight=#36289

You need a carb expert to set the SU's.

If you can't solve it and want to get rid of the car, let me know - the TR3a is one of my favourite classics.
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1970 Volvo Amazon and 1978 Safari 15-4 Caravan
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victor 101



Joined: 03 Apr 2009
Posts: 449
Location: East Yorkshire

PostPosted: Wed Aug 19, 2009 9:09 pm    Post subject: Reply with quote

I have spec sheets and workshop manual for S.U. carbs, so if you want to check if you have the right carbs and internals I will pm you a list.
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triguarin



Joined: 02 Jul 2009
Posts: 2

PostPosted: Thu Aug 20, 2009 10:14 am    Post subject: Reply with quote

thanks for the input people!

I went out again to the garage yesterday after leaving my post to look over the carbs. A few things I found coincide with your advice Peter! I have two unmatched needles to start with, they have different numbers. I also found one float lever bent and was likely to having been failing to close its needle valve shut. I have adjusted it back to the correct clearance and put two new needle valves in both float lids. ( How the heck did it get so bent?). The jets are brand new as are all the seals but evidence thus far would hint at an over rich situation with those faults. I think the suggestion of the petrol pouring through the jet hole on that carb has to be on the money. Have a new correct set of needles on order. Will let you know how things continue when I'm back with a fresh supply of petrol and new needles! Many thanks! PS. interesting rolling road feature in Prac Classics this month with an Amazon. Have you seen? I ran a 1968 Amazon for three years 10 years ago. A great car, one of the best you could own.
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47Jag



Joined: 26 Jun 2008
Posts: 1472
Location: Bothwell, Scotland

PostPosted: Thu Aug 20, 2009 10:46 am    Post subject: Reply with quote

Triguarin,

If the jet seals are new then you should also check that the jet has been centralised. It's easy to see. With the pistons out you can see if has the same gap all around otherwise the needle can drag on the side of the jet.

Art
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