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The 4A Engine Rebuild


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Guest ntc

Hi Folks,

well, after a couple of days faffing around, a little frightened of something nasty happening, I turned the key and the engine build came to life.

 

I had already spun the engine over to get oil and petrol where they needed to be.

It started with no hesitation or anything untoward. It sounds quite smooth.

 

It ran at about 2000rpm for almost 10 minutes then I stopped it as the temp was going stratospheric

 

I need to do a fair bit of tinkering now to get the spark timing and tick-over sorted.

 

Phew - this is the first time I have had butterflies about starting an engine..

 

Roger

Roger

Jobs a good un :) no leaks? then run again and enjoy

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...the umpire struggled into his Souwester, slid his feet into his galloshers opened the door to the club house.

He dipped his hand into his pocket and withdrew various weather forecasting implements and his note pad.

The note pad got wet.

The umpire declared 'rain stopped play'.

They all had a cup of tea and went home.

 

Today I draped a blue tarpaulin over the car with the foolish idea of working under it.

The moment it was up the rain came down harder then wind started to blow.

I was getting seriously wet.

 

Logic and common sense was then engaged and abandonned the car as a bad idea till tomorrow. Yuk!!

 

Roger

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Hi Folks,

the car is now finished (except for the rad cowl - tomorrow)

 

An interesting thing I found was that the OD brass nut underneath was covered in oil. This had not been disturbed during the rebuild.

So, off it came, gave it a good cleaning and put it back with some Hylomar.

This was possibly the source of the serious oil leak I had all last summer.

 

Everything appears to work. So after tea tonight I shall take it for a short spin.

 

It must be the end as the 'shed' was taken down this afternoon for a new home tomorrow - there was a nice false widow spider lurking.

 

Roger

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Everything appears to work. So after tea tonight I shall take it for a short spin.

 

It must be the end as the 'shed' was taken down this afternoon for a new home tomorrow - there was a nice false widow spider lurking.

No way to talk about the missus.....

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Not as bad as the mahoosive spider in the hotel room in Brecon two weekends ago.

To think I walked through its web the night before and was very brave and didn't wake the whole place up, I just got back in bed.

If I had seen how big it was then, there would have been one hell of a shindig in the middle of the night.

When Roger trapped it in a glass with TR Action underneath, it ran round and round in circles stamping its feet. Boy was it angry.

 

 

Spiders in the shed? I've never set foot in it.

I expect now that I can have the pool re- erected the summer will be over!

Edited by SuzanneH
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I just got back in bed.

If I had seen how big it was then, there would have been one hell of a shindig in the middle of the night.

 

 

 

 

 

I think Roger and Sue are busy! ;)

 

Les

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Hi Folks,

hopefully this will be the final installment of the 5 week engine rebuild that started in November.

 

Having got it all together the engine, although running, wasn;t happy. I could only get a low tickover if the spark was retarded to about 10'ATDC.

Something clearly not right.

The front carb would not return to its bottom stop on a gentle throttle.

 

So I took the carbs off and dismantled them. Only to find the spindles were quite worn - 0.005" at the lever end and 0.002 at the plain end.

Today I popped along to the TRShop to see about new carbs (£500 :o ) Thankfully they didn't have any - nobody has, it appears.

So Lukas the cunning salesman convinced me to buy a rebuild kit (£58 :unsure: ) rather than a lonesome spindle (£10 :) ).

 

As all the parts on the carb are 17years and +170Kmiles old I bought the rebuild kit.

 

The original bushes were still in good order. All the wear was on the spindles.

So it was a simple task to install the spindles and fit the new butterflies.

I then attempted to fit one of the feed pipes from the float chamber - the plastic receptacle did not align with the choke actuator.

Amazingly the other pipe was also out of alignment with the other choke actuator - for a moment this left me scratching my head :huh:

Then a little bird suggested why not swap them over (thank you Sue :wub: ) (I would have got there B) )

Having fitted the pipes I then tugged one of them and it came off. It is a very simple compression fitting - always test after fitting

The kit also has the new Viton float chamber valves - so these were also fitted.

 

Carbs fitted to the engine and blast off.

 

An amazing difference. The engine must have been bad before but the gradual decline covered up the worst bits.

The new head and sorted carbs make a big change.

 

Tickover can be as low as one needs, the timing can be adjusted as required.

 

All in all a result.

 

So if you find you are requiring extra springs to help close the throttle or the revs can't be reduced from being too high then take the spindles out and see how they are. Extra air leaking in will cause chaos.

 

Roger

Edited by RogerH
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Good result Roger, I'm glad you did not go for new carbs, I was thinking that should not be necessary.

Will be nice to see you turn up at our meetings in a TR for a change :P

 

Bob.

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  • 1 month later...

Hi Folks,

I thought I would add one final note to this thread.

I've just come back from a 2400 mile trip around the Scottish Isles and have done apprx 4000 miles since the rebuild and it hasn't conked out yet.

It did apprx 30mpg overall - scottish Islands are generally slow and hilly. Scotland can be fast and hilly and 70+ on the motroway- all guzzle fuel.

 

My only concern is whether the valve timing is spot on.

I've read John Davis's article in TRAction and may well take the head off during the summer and give it one more go. What could possibly go wrong!!!

 

So my 5 week target was just met :rolleyes: - once I adjusted the figures :o

 

Roger

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Hi Pete,

the crank is performing well - cranking away all day long.

I did various speeds - up to 85mph (on private land of course).

Various acceleration - I dropped out of overdrive to put the revs up to about 4500 instantly (that was quite a fright).

 

I've been waiting for others to get things sorted but it is slow. It would be nice to see some action before the year is out.

 

I'll probably strip the engine sown in the autumn (another 5 week overhaul) to do a visual.

 

So far so good for the actual lump though.

 

Roger

Edited by RogerH
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Yes but will it stand redlining in top overdrive for hours on end? (Asking for a friend ;) )

Stuart.

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Hi Stuart,

that is a very good question that may never be answered.

 

Would a new original ST crank, back in the day, survive such a test.

There are many broken cranks around so it would be reasonable to say that eventually it would fail.

 

The new crank is virtually identical to the original with the exception of a simplified oil gallery in the crank webs.

The quality of the machining is top notch - equal to or better than ST.

 

From a pragmatic point where would you drive red lining in 4th OD for hours on end.

A race track would be your only option due to the high speed. For this you would invest in a modern steel billet crank.

Why would you red line in OD 2nd or 3rd for any lengthy time?

 

So if the new crank is used for normal use - touring, everyday shopping etc - then it should perform as per the ST product.

As mentioned I did 70 - 85 mph from Glasgow to London (on a private road) apprx 7 hours with no issue.

 

As for a production crank I believe the basic plan is to get the blank castings rough machined in India and then detail machined in the UK

This should reduce the manufacturing costs significantly. The UK machining for the two prototypes was frightening and would make the exercise uneconomic.

 

As an aside to get things on the move we bought a new Fergy TRactor crank. It was quite impressive.

The only major differences from the TR are the plain journal at the back where the scroll oil seal would be and the lay-out of the oil galleries.

Fergy used a mighty great lip seal - quite effective, cheap and would work OK on the TR.

Careful measurement showed it to be pretty close dimensionally but not perfect - but usable.

 

It would be nice to think that things could be progressed and that we have a crank on the counter within a reasonable time frame.

 

Roger

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Roger - if a brand new crank can't stand continuous running at 5,000 rpm and occasional running at 5,500 rpm it is not TR Gold standard IMHO.

Original cranks were designed for such used and proved to be completely reliable in creating the TR2/3/4 reputation in rallies and events.

 

If you frightened yourself when the engine went to 4,500 rpm then we need a new engine tester for assessment of high speed use.

 

:) :) :)

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