running problems

My old TC engine had worn out bores and low compression, but other than smoking under hard acceleration it had no other problems.
It always started without too much effort, and had reasonable performance.
Eventually, i replaced it with a rebuilt one, because the valve clearances were way too tight, so i was probably in for a head rebuilt.
I would suggest you not to rush things. Check the valve clearences as Harvey suggested and if they are within the required specifications then your running problems should be due to fueling or ignition. If you want the car for moderate and infrequent use, it could go on for years and years like this, if you sort out the running issues that is...
 
I'd recheck everything, check the valve clearances, and then see whether there is an improvement. I'd want a reason to remove the head, rather than taking it off just because I couldn't think of anything else...........
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I agree with Harvey. Intermittent running of this nature is usually electrics (though sometimes carb). I would re check (by substitution where possible with known good s/hand items) all the ignition components (even the new ones could be faulty the only way to be 100% certain is known s/hand bits). You do not say you've changed the dizzy cap. May be worth doing, look for cracks which could lead to tracking though this is usually more prevalent as a misfire at tickover and can disappear when revved.

I would certainly check and re check everything before lifting the head or you could find you put it all back and the rough running still exists.
 
hi i have changed the following parts so far. dizzy cap, condesor, points(not new for me but i do have a new one which i will fit just in case), plugs leads, coil, inlet manifold gasket as it was leakingand air filters not that they matter. i think that is everything all with new parts not secondhand. I cant my thinking was its electrical could the wire be breaking between the coil and dizzy would this cause the problem. im getting to my wits end with it. i am meant to be using it to go to weymouth at the begining of may but its looking doubtful at the moment.

i hope someone can advise me i really didnt want to remove the head unless i have too


thanks again jason
 
You don't mention the spark plugs, have you done those too?

Did you set up your points using a dwell meter instead of the old feeler gauge approach? that would help keep it in the right 'zone' in case you have wear in the dizzy spindle.

Brian.
 
i have changed the plugs forgot to put a commer between plugs and leads opps. have set it to a dwell meter i think it read around 60 if i remember correctly.

how do you check valve gaps and adjust please
 
arcadejay said:
i replaced that as well. what is O/P?
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I would think he means "Original Poster", ie yourself.

There are a lot of poor quality Rotor Arms about but they do tend to fail in such a way that the engine won't run at all. The only exception to that would be the rev limiting ones as fitted to the later TC's which were always a problem.

I still say that your problem of a misfire under load, and erratic running on tickover is more likely engine tuning rather than rings/low compression/head gasket.

IIRC 4 cylinder Dwell is 57-63 and if so you're spot on.
 
Checking valve clearances is easy, leave the car overnight, remove the cam cover, and check the clearance between the heel of the cam and the cam follower. Inlet 8-10, Exhaust 13-15. (It's on the cover on early engines)

Adjusting them is a little more complicated.................
 
Can I just do a quick summary so far?

As I read it you've pretty well eliminated an electrcal cause. Electrics are always the most likely for the symptoms you describe - except I wasn't sure whether or not you had a new coil? Only remaining electrical malady to match the symptoms would be something odd and obscure like a dicky ignition switch generating an intermittant feed to the coil.

There are then two broad areas of possibility. First is closed up valve clearances / burnt valves. The latter are pretty well eliminaterd by the even compression readings, but the 4 cyl is known to be sensitive to tight valve clearances, and they do close up with time as the valves hammer the (soft) valve seats into the head.

Then there is petrol maladies. The intermittant nature of the problem suggests a fuel supply issue. Worth checking the condition of the fuel pump diaphragm and / or rebuilding the pump with new diaphragm and O rings. Another likely would be "crud" working through from the tank. Over a period of use (ie several tank fulls of fresh petrol) this ought to clear, alternatively pop an in line fuel filter into the engine bay fuel line and see what it collects. Then you are on to a carb rebuild. The critical areas would be to renew the float chamber needle valves and the floats (which can develop leaks). Then read the other write ups on here about carbs. A clean up of the insides of the dashpots and the pistons so that the fall times are equal would be a good plan and then you can move onto carb set up, dealt with in other posts.

Hows taht? Break it into logical chunks and just keep going until the problem disappears. Don't necessarily expect there to be a singole fault - you could have a number of minor faults adding to a significant effect when taken together.

But first I'd check those valve clearances. Then you've eliminated the basic engine build.

Chris
 
As I have been reading all this, Chris has mentioned the next area that I began to suspect. The float valves in those carbs are notorius for leakking, and the floats for taking on petrol. When I started my newly rebuilt engine, I was baffled to find two cylinders hardly firing. I had rebuilt EVERYTHING, carbs included ,but I had left in the float valves since they had been replaced by an improved type earlier.
The rear float valve was stuck CLOSED, starving the rear cylinders except for what they recieved through the common tube.
So I think it would be good as Chris suggested to look at those float chambers and the fuel sytem ,in general.
 
Not got in till late and losing the light not got time to check valve gap so tried the petrol pump. i removed the plugs and turned the engine over for 30 seconds and got half way between 1/2 and 3/4 pint of petrol would this is what you would expect from a good pump or should it be more. There was no back pressure ie my finger over the end of the point so not sure if there was a pressure on the pipe would this effect it any?

sorry help once again


thanks in advance again jason
 
we did have a look at the floats and they seemed to be floating and not stuck. i think it may be something really stupid that im not seeing.

thanks again jason
 
Hi Jason

That sounds like an entirely adequate performance by the petrol pump. I wouldn't rely on anything visual with the carb floats and needle valves though - just change them on principle.

You say you think it must be something really silly? Just a quick joke against myself then. Many years ago I had a Morris Minor convertible and rebuilt the engine with a stage 3 head. First trip on the new engine was Bristol to Rome (excellent for a nice steady runnning in !!), so engineering attention was limited to oil changes (and a new radiator in San Morino!). The engine was really disapointing, running very rough until really revved - although it would see off Alfa Suds on the Autostrada :LOL: . Back home in the UK I puzzled over the rough runnning for ages. Turned out I'd set the plugs and points with the set of feeler guages from my work toolbox. Duuuh - work was metric, Lucas still worked in imperial. For 25 thou read .25mm. Not the same at all!! Wonder it ran at all really!

Chris
 
It could well be something hiding that when looked seems fine. Like the wire inside the dizzy, I changed mine the other day as it finally gave way, I knew it was a bit old so had the spare to replace before the car completely died.

Yours maybe breaking down effecting the spark and the dwell angle? (stab in the dark) I know it's a wire that does get overlooked.
 
i may have had progress with it. I removed the plugs and disconected the fuel line. when the engine is cranked the petrol comes out in spurts not continous. If i put my finger over the end there is no pressure from the pump i would assume this is not normal. What do you think

thanks jason
 
had a bit of progress i think i took the fuel pipe off and when you crank the engine it comes out in little spurts not a continuos flow and if you put ur finger over the pipe it stops completly. so could this be my problem a knacked fuel pump?Also found that the automatic advance retard is stuck as well which obviuosly wont help either. Any thoughts on the performance of the fuel pump?


Thanks jason
 
I think that this is how this type of fuel pump is supposed to work.
If you want to test it you should measure the flow i.e. the volume of the fuel it pumps per minute.
 
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