Story so far series 1 resto

[lancianut666]

and even later...

[lancianut666]

the sharp eyed among you will have noticed cylinders 1 and 3 are losing paraffin by 18.41...by  19.04 1 and 3 are empty 2 and 4 still have some paraffin in this might be because unequal amounts of paraffin were put in each cylinder. I might have to try something a bit more scientific tomorrow. The head seems fine
Clarkey

[lancianut666]

Another possible problem was the lack of squashing down on the head gasket so I took Jaydub's advice and measured the fire rings of the used head gasket against a new one see pics The lack of squash can be seen in the last two pics
Clarkey

[lancianut666]

final pictures from earlier this morning cylinder 2 is still going strong and the valves in the head seem OK. So some good news regarding the valve seats but bad news regarding the bores/pistons/rings on 3 of the cylinders. Will get the sump off and get the pistons out next.
Clarkey

[lancialulu]

I think it is an unfair test on an engine that has not run and bedded in..... Did you not rebore (or at least honed the bores). If anything it shows the ring gap on #2 is too tight??!!

[chriswgawne]

I think there is something odd here because 4 stroke engines will often run even if they are absolutely clapped out. The bores look OK and the rings must be reasonable so either the valves aren't seating or you have a timing issue. Very easy to diagnose at a distance but it all seems a bit odd.
Chris

[lancianut666]

Hi all
The block was rebored (allegedly) and the pistons have new rings. the vale seats were all lapped in. Further back in the thread the psi on the cylinders were 30-50 psi dry this went up to 85-100psi with engine oil in the bores. The valve timing will be an issue but the oiled bores psi readings are a clue something is wrong with the pistons/rings/bores.
Exasperated of Scarborough

[DavidLaver]

Following on from Chris's point I think the test with an Austin 7 for piston to bore wear is how much daylight

[DavidLaver]

Just went back in the thread - copied below.  Was March 1st the last time you got a pop or bang out of it?  Could you post a "one message" summary of the facts since? 

01 March, 2019, 03:12:30 PM »
Reply with quoteQuote
Hi all.
Decided to bypass the petrol tank by clamping off the feed from the tank and putting a length of fuel pipe from the pump inlet side to a container of nice clean fresh petrol, put some new plugs in and rigged up an under bonnet starter button...no it didn't start! lots of bangs and pops but with my hand over the top of the carb I could feel back pressure and petrol vapour is coming out of the carb i.e. it is going the wrong way...checked the plugs 2 and 4 are sooty so firing but 1 and 3 are clean. So I have to decide to...

A. drain the sump, jam the crankshaft and get the crank pulley nut of and reset the timing that way
or
B. take the engine out and get the engine on a stand and do the timing that way
or
C. Thrash the damn thing with a stick!

[lancianut666]

update
1 broken piston ring, others stuck in groove see pics...back to square one this is uncannily like the first time I took the pistons out...I think the engine block is cursed!!!
Sick as a chip Clarkey

[fay66]

Any scoring of the bores?
Brian
8227 

[Jaydub]

As Chris said, something strange going on there.
 I am baffled by your comment about boring etc.  Earlier in this thread you said your original block was worn and needed reboring but your spare only needed honing so you were going to use that, but then you said you had one of them bored, old pistons and new rings. Which is it? How can you bore a block and use old pistons unless it`s specifically bored and honed to suit the old pistons.
You don`t know what the piston/bore clearance is. You don`t know what the ring gaps are. You don`t know if the pistons were liberally coated with oil/ graphogen when the machine shop fitted them do you. The first few seconds of an engine starting from a new assembly is critical so that the pistons don`t pick up in the bores and the rings don`t scuff in a dry cylinder. You have been cranking it over for a long time with fuel washing the bores. It`s no wonder something has gone wrong. I don`t wish to be disrespectful but you seem to be stumbling from one crisis to another ( non starting, Valve timing etc) It would have been more cost effective timewise, parts, gaskets etc  to have got a professional to assemble it don`t you think. I know we all have to learn but it`s becoming a problem to you. We are all trying to help but it`s difficult not knowing if the basics are right.
Never the less, good luck, and I will continue to offer any advice if I can.

[lancianut666]

Hi all
For clarity the block was rebored, the pistons cleaned and checked, the new piston rings were fitted and the pistons fitted to the block all by the same engineering shop. All I did was put the crank in and lap the valves in, unfortunately it has never really shown any sign of starting and the compressions are low so I took it apart and found a broken ring and the others stuck in the grooves. The machine shop was a well established company but examining the pistons today the rings seem very tight in the grooves so it looks like a new set of matching pistons and rings are needed.
 I am going to lie down in a darkened room for a week and when I surface the elves will have fixed it and the engine will be back in the car. Anyway in the real world I had to deal with the gouts of brake fluid all over the front wheel and the garage floor so I took the drum off and it was a mess so I probably need at least one new cylinder and possibly some new shoes.
Clarkey

[Jaydub]

Hi Clarkey, hopefully you should get some redress off the machine shop as it seems they didn`t fit the correct rings  or measure the clearance in the grooves before fitting.

[lancianut666]

Hi Jaydub
The consortium has some piston ring gauges so I will check the rings against them and also check the ring clearance in the piston grooves and then probably chase up the machine shop. If I am lucky we might have a set of new rings that will fit failing that I will have to get some new pistons to the correct oversize. The pistons I used came from a running engine but the rings were replaced by the machine shop with a new set I supplied.
Clarkey