Post valve grind discoveries 1933 10/4

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GaryCullen
Posts: 37
Joined: Wed Nov 20, 2019 1:34 am
Location: New Zealand

Post valve grind discoveries 1933 10/4

Post by GaryCullen » Sat Jan 09, 2021 8:40 pm

As promised this is a new thread, hopefully not as long as the last one.
After the valve grind I wasn’t happy with the compression measurements on cylinders 3 and 4.
Decided to extract #4 while the car was still up on its stands.
I have discovered I have 4 x ring pistons and the bottom oil scraper was broken. Fortunately it hadn’t damaged the bore.
Put the top compression ring back in the bore and the gap is huge. Didn’t even bother trying to measure it. 1/8 inch at least.
Should be from 6 to 8 thou according to my Austin manual.
Pulled out the remaining pistons and two more broken oil scraper rings but this time the ones above the gudgeon on pins.
Compression rings same as for #4.
So all runs are badly worn.
Each piston is stamped STD and the bores measure an average of 2.4998 in three places up and down and at 90 degrees.
Known miles for the car is only 5,687 since 1973. Previous history is lost as the Speedo was service then and zeroed. Considering the bore measurements I think I have a low mileage vehicle.
So plan is to buy a set of standard rings with new big end tab washers, de-glaze the bore and rebuild the engine.
Plan is also to use some running in oil while the rings bed in.
Any other advice grateful received.
Our local VAR has rings for these engines manufactured in NZ.

Kind regards
Gary
Auckland VAR

GaryCullen
Posts: 37
Joined: Wed Nov 20, 2019 1:34 am
Location: New Zealand

Re: Post valve grind discoveries 1933 10/4

Post by GaryCullen » Tue Feb 09, 2021 10:00 pm

Progress update.
Newly made STD rings have arrived and I need to get the corresponding piston slots widened to fit. My mini Lathe is not up to this as I don't have the right cutting tool bits.
The rings have been made slightly wider in thickness so the slots in the pistons can be enlarged to maintain the recommended gap.
I placed a couple of the new compression rings in a cylinder and the end ring gap is now about 5 thou. Brilliant. I might now have some compression!!
I will follow Jim Butterworths advice on how to compress and insert the piston with only the bottom ring fitted. Same as Jim I "modified" an old ring compressor to get the blue spring steel wrap out and trimmed it to size. Using a tie wrap to compress the ring in the bottom slot (I used one of the old oil rings), added some oil and did a practice fit in the engine and it work great. The new rings will be a bit tighter going in.
I am waiting for new big end and little end bolts and new lock washers for both to arrive from the UK before I can complete the job.

While waiting I have made a new sump gasket so I have everything ready.
However, I discovered a short piece of oil sodden felt ( I think ), about 4 inches long sitting in a slot in the sump pan, athwart ships, toward the rear.
It sticks up a bit and seems to press against the oil drain plate when the sump is offered up.
After much consideration I can't understand what it is for. Best guess is it is some sort of splashed oil deflector to keep oil splashed at the back to a minimum as the sump mates to a a thin piece of the bell housing with maybe only 1/4" wide of sump gasket to seal the sump.
Can the members advise what it does? and/or is it really required ?

Regards
Gary
Auckland VAR

peter_christie
Posts: 235
Joined: Wed Nov 20, 2019 3:46 pm
Location: Newton Mearns, Glasgow

Re: Post valve grind discoveries 1933 10/4

Post by peter_christie » Wed Feb 10, 2021 11:43 am

Hi Gary,
I'm not a Ten man, but the felt you refer to is common to a lot of pre-war Austin engines.
Crude it may be, but as long as it is 'proud' of the surface it acts as an oil seal bridging the area between the rear main bearing cap and the corresponding break in the rear rim of the crankcase. Replacement felts can be difficult to insert in the 'pocket' but if the felt is well soaked in clean engine oil it will go in, as I said, it should be slightly proud of the surface level of the sump joint. It is easily compressed by the sump setscrews.
Good luck with your restoration.
Peter C.

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peter_winney
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Joined: Wed Nov 20, 2019 3:31 pm
Location: BATH

Re: Post valve grind discoveries 1933 10/4

Post by peter_winney » Wed Feb 10, 2021 12:35 pm

peter_christie wrote:
Wed Feb 10, 2021 11:43 am
Hi Gary,
I'm not a Ten man, but the felt you refer to is common to a lot of pre-war Austin engines.
Crude it may be, but as long as it is 'proud' of the surface it acts as an oil seal bridging the area between the rear main bearing cap and the corresponding break in the rear rim of the crankcase. Replacement felts can be difficult to insert in the 'pocket' but if the felt is well soaked in clean engine oil it will go in, as I said, it should be slightly proud of the surface level of the sump joint. It is easily compressed by the sump setscrews.
Good luck with your restoration.
Peter C.
Gary
Replacement Felt Sump Rear Seal is available from Club Spares along with gaskets for head, sump, oil filter, and sump oil drain plug - https://parts.austintendriversclub.com/shop/

Peter W
Member since July 1972

GaryCullen
Posts: 37
Joined: Wed Nov 20, 2019 1:34 am
Location: New Zealand

Re: Post valve grind discoveries 1933 10/4

Post by GaryCullen » Thu Feb 11, 2021 12:09 am

Thanks for the advice guys.
I have ordered a couple from club spares.
I did some small research to obtain some suitable felt in NZ but most is thin sheets 2 or 3mm thick designed for home craft use.
It is also all acrylic. So not suitable in a a hot oily environment I would think.
cheers

Gary

Rod
Posts: 44
Joined: Sun Nov 24, 2019 9:44 am

Re: Post valve grind discoveries 1933 10/4

Post by Rod » Thu Feb 11, 2021 1:49 am

Hi Gary,
I'm not certain what part of NZ you are in but Shuk and Felt Supplies New Zealand [at least] have sheets of industrial felt suitable for what you need it for.

GaryCullen
Posts: 37
Joined: Wed Nov 20, 2019 1:34 am
Location: New Zealand

Re: Post valve grind discoveries 1933 10/4

Post by GaryCullen » Thu Feb 11, 2021 5:40 am

Thanks Rod, they did not come up in my internet searching.
I’ll try again not withstanding I have a couple coming from the UK.
Good to also have a local source,
Cheers
Gary
Auckland VAR

GaryCullen
Posts: 37
Joined: Wed Nov 20, 2019 1:34 am
Location: New Zealand

Re: Post valve grind discoveries 1933 10/4

Post by GaryCullen » Sun Mar 28, 2021 8:35 pm

Hi All, latest and hopefully the last update:
I received the Pistons and new rings back from my engineering outfit with newly cut slots in my STD pistons to fit the newer ( and slightly wider ) rings. All fitted to the engine using Jim Butterworths' system. No ring breakages thank goodness!
Fitted the Head, manifold, Carb, water pipes, added SAE 30 Running-in Oil, new Coolant with a corrosive inhibiter.
Did a "cold" compression check and got 90, 91, 90, 90 PSI on cyclinders1,2,3,& 4. Brilliant I am thinking, we are away.
Hand cranked the engine over quite a few revolutions to get the oil pump primed and send some oil where it needs to go.
Re-gapped the NGK AB-6 plugs which were bought new last year but have done almost no miles, as the car has been in the garage since June last year.
Turned on ignition , pressed the starter and wound the engine for a bit. Stopped and tried again and it started, well sort of. I saw 25 lbs oil pressure registered on the gauge.
The engine did not seem to be running properly, it had no pickup when manually lifting the throttle, and using my fingertip as a temp gauge I found the top of the head was getting warm only around Cylinders 3 and 4.
Using screw driver I shorted out the plugs for 1 and 2 with no change in engine note. so something wrong with 1 & 2.
Mmmm, what to do now?
Rechecked timing, Points distributor cap. Decided to fit a complete spare distributor I have. no change to engine on restarting.
I then pulled off the plug lead to number 1 and it had a big blue spark leap to an adjacent engine head bolt, same for plug lead number 2.
Ah, must be the plugs. Took them out and sure enough both had a leakage resistance of 45 to 67 K ohms, centre electrode to the outside of each plug.
Took out 3 & 4 for comparison and they measured infinity on my multimeter.
Purchased 4 x replacements, gapped and installed, the engine now starts easily on the button, gets to water temperature quickly and has plenty of
"blip" on the throttle. Running 30 lbs of oil pressure. I might ease this back after the engine rings bed in a bit as I think 30 lbs is quite a lot, 25 is probably more the mark.
Anyway I now have 200 miles to motor to run the rings in then drop the running-in oil out for SAE40 classic and vintage.
I can't recall ever having relatively new sparkplugs fail on me over 40 years mucking around with engines.

Thanks to all the members who contributed advice and guidance over past quite a few months.
it is very much appreciated.

Gary
Auckland
VAR

Rod
Posts: 44
Joined: Sun Nov 24, 2019 9:44 am

Re: Post valve grind discoveries 1933 10/4

Post by Rod » Mon Mar 29, 2021 3:17 am

Hey Gary,
good to hear you're on the road again. Can't say I've ever heard of NGK plugs failing basically straight out of the box, but I have experienced similar issues a few years ago with Motocraft plugs, specifically the (Ford) Cleveland V8 ones. There must've had a bad batch out there, the symptoms were that the plugs were replaced at tune-up but one or more of them would fail shorted to earth, where the insulator was sealed and swaged into the shell. Always on road test [or worse, the first time the customer drove them hard]. We got in the habit of testing each replacement plug before fitting it using the ubiquitous Champion 800 spark plug cleaner's pressure chamber before fitting (its no fun changing Cleveland plugs on a red-hot engine)which weeded out 90% of the duds.

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