Alta and MM porn?

for those with Series MM sidevalve cars produced between September 1948 and February 1953

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RobThomas
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Re: Alta porn?

Postby RobThomas » Sat Apr 22, 2017 9:12 am

Replacement valve guides in the process of being machined from a solid bar, the samples of valve springs are in the post, the valve caps and keepers (Thanks to David Stroud!) are in the lathe today to be tinkered with. Progress at last.

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Re: Alta porn?

Postby BLOWNMM » Sat Apr 22, 2017 2:04 pm

Rob
I have been out of action for a bit and meant to catch up with you re valve guide material. Looking at the first link aluminium bronze has a thermal expansion of 9.0 inches/inch/degree F X 10 -6. For ease of explanation I will only list the first relevant no. The second link on page 62 dependent on the type of Meehanite you are using states an expansion rate of 6 to 6.5. Not knowing the alloy composition of your head, using the first link choosing an expansion rate of 2011 alloy at 12 would seem a reasonable choice. Given these figures it would seem to me that for a given temperature rise the aluminium bronze guides would expand considerably more than the Meehanite therefore maintaining a better interference fit to the head. These figures may need to be massaged to suit the alloy used for the head casting and the type of Meehanite used. I’m no metallurgist but I think these numbers may deserve some thought.
Bob
http://www.engineeringtoolbox.com/therm ... d_859.html
http://meehanitemetal.com/wp-content/up ... DBOOK2.pdf
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youngcamper
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Re: Alta porn?

Postby youngcamper » Sun Apr 23, 2017 12:03 am

RobThomas wrote:Replacement valve guides in the process of being machined from a solid bar, the samples of valve springs are in the post, the valve caps and keepers (Thanks to David Stroud!) are in the lathe today to be tinkered with. Progress at last.


Sounds exciting Rob, I look forward to reading about more progress!
Will
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RobThomas
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Re: Alta porn?

Postby RobThomas » Mon May 01, 2017 3:11 pm

altaguide.jpg
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First one machined up with the main body left 1 thou oversize and the bore left about 5thou undersize for reaming out after fitting. I hope I can make 2 the same. Hard to do with a small metric lathe, a set of imperial calipers and a calcuator.

RobThomas
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Re: Alta porn?

Postby RobThomas » Fri Jun 02, 2017 3:16 pm

Getting there. Just a bit more polishing to do...
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ianpolished.jpg
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amgrave
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Re: Alta porn?

Postby amgrave » Fri Jun 02, 2017 3:49 pm

It's looking good. Be a shame to fit it in case it gets dirty :lol: :lol: :lol:


RobThomas
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Re: Alta porn?

Postby RobThomas » Fri Jun 02, 2017 3:58 pm

Just waiting for any last requests for valves before I put in the order for new sets of them. The new guides went in perfectly (phew!) and the welding of cracks and gouge marks from the screwdrivers previously used to lift the head...well...eventually we got there.
Ideally I'd get hold of a set of those old valve seat cutters to taper down the bottom of the valve seats since there is a step left in them from decades of valve regrinding. Too expensive to buy so it will have to wait, unless anyone has a set they want to sell?

youngcamper
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Re: Alta porn?

Postby youngcamper » Fri Jun 02, 2017 5:14 pm

Looking great Rob!

I'll hopefully be doing a similar job to my head when I need it. You've already got me down for a set of valves haven't you?

Thanks,

Will
Will
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RobThomas
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Re: Alta porn?

Postby RobThomas » Mon Jun 05, 2017 3:02 pm

Picked up a large chunk of 8mm 6082 Ali sheet to fabricate a new rocker cover. Should be fun trying to cut that lot!!!

I'll start with a simple box version (like the Mazengarb) and maybe look later at forming one on a press to get the original profile. I really need a helper with a strong arm to beat seven shades out of the sheet for me.

Sides are pretty much done so I'll attack the top of the cover tomorrow. Will, do you have the brass acorn nuts for the cover or do you need those made as well? About 5/8 inch AF and about and inch long?

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Re: Alta porn?

Postby RobThomas » Tue Jun 06, 2017 2:43 pm

rocker1.jpg
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BIG hammer. Maybe get round to welding tomorrow, carve the lid section and get the sides tidied up.

youngcamper
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Re: Alta porn?

Postby youngcamper » Tue Jun 06, 2017 11:43 pm

RobThomas wrote:rocker1.jpg

BIG hammer. Maybe get round to welding tomorrow, carve the lid section and get the sides tidied up.


Great progress Rob! I'm astounded at the speed you work!
Will
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RobThomas
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Re: Alta porn?

Postby RobThomas » Wed Jun 07, 2017 8:18 am

Bottom half welded up before breakfast.

What distributor do you expect to be using? It shouldn't matter toooo much but I need to make sure there is enough clearance for it to be swung all the way round without touching the rocker cover. I was also thinking about putting an A-series oil filler neck in the lid so that you could dispense with the long neck down the side of the block that gets in the way of getting the starter out?

Burnt my ickle finger where the tips of the glove had worn through. :(

Update. 10 o'clock teabreak and the sides are complete but it is useless trying to photograph it until the shape is ground smooth. I couldn't get the 8mm sheet to bend tightly enough to replicate the original cast profile so I cheated and welded the edges of the curves so I could grind them into shape afterwards. The multiple curves and steps behind the distributor hole are a nightmare to weld and it's giving me a bad back again. :roll:
rocker2.jpg
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RobThomas
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Re: Alta porn?

Postby RobThomas » Wed Jun 07, 2017 11:24 am

rocker3.jpg
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rocker4.jpg
rocker4.jpg (185.58 KiB) Viewed 1144 times


Weldy-weldy-weld. Grindy-grindy-grind. Time for a cup of tea.

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Re: Alta porn?

Postby RobThomas » Wed Jun 07, 2017 12:47 pm

rocker5.jpg
rocker5.jpg (172.41 KiB) Viewed 1142 times


Difficult bit to weld together, being thick material. Bit more grinding and polishing before getting the lid made up. May need to take it away to get the top and bottom sanded flat.

youngcamper
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Re: Alta porn?

Postby youngcamper » Wed Jun 07, 2017 2:05 pm

Looking good Rob!

I was planning on using a standard distributor with the engine. I haven't given much thought about the air filter, but is an interesting idea!

Keep up the great work!
Will
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RobThomas
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Re: Alta porn?

Postby RobThomas » Fri Jun 09, 2017 9:18 am

Getting there.
One more little weld required and then lots more grinding, filing and smoothing. Need to work out where to drill the 4 holes for the brass nuts to hold it down, make the filler cap neck, router out the badge and flatten off the bottom face for the gasket. Hard to get neat welds due to me choosing a too-thick material so it takes lots of Amps to get the metal hot enough to weld. A 160 Amp TIG is not powerful enough for this job, really.
Major disaster yesterday...I was wearing fireproof welding overall, silver leather welding gloves, a proper welding mask and filter but forgot that I had my new running shoes on. Welding sparp dropped onto the lightweight nylon and set my right foot on fire. expensive mistake in PPE.
rocker7.jpg
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rocker6.jpg
rocker6.jpg (160.57 KiB) Viewed 1132 times

RobThomas
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Re: Alta porn?

Postby RobThomas » Fri Jun 09, 2017 9:07 pm

rocker8.jpg
rocker8.jpg (134.49 KiB) Viewed 1123 times


Something like that?

youngcamper
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Re: Alta porn?

Postby youngcamper » Fri Jun 09, 2017 9:48 pm

RobThomas wrote:rocker8.jpg

Something like that?


Blimey Rob, you don't hang around do you?!

I wonder if it's worth fitting an oil filler cap? Presumably the original uses the filler neck at the side of the engine?
Will
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RobThomas
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Re: Alta porn?

Postby RobThomas » Sat Jun 10, 2017 10:50 am

I did wonder...

The original cap is unfiltered and collects dirt and dust inside. Closing it off with a bung would also allow more room to get to the starter motor and dipstick I guess I can leave it off and you can add one later if you want to. With a partially closed-off cap you could run a pipe from the rocker cover to the air filer assembly and make a partial vacuum in the crankcase. Bob might have some useful input on that idea.

Next job is to work out the positioning of the holes for the mounting studs. I placed some M10 nuts roughly where they need to be drilled. Problem is that your head might have holes slightly offset from mine. I may have to shave the bottom off of the cover to get the lid low enough to clear the clips that hold the dissy cap in place. I'd forgotten to factor them in. Doh!

There is one of the Aston Martin DBR9 GT1 main bearing cap studs in the picture with an M10 12.9 HT nut on it. Plenty of length to use on the 6 longest Alta studs. Not yet got anything for the 4 short studs.

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Re: Alta porn?

Postby BLOWNMM » Sat Jun 10, 2017 12:39 pm

Rob This is my answer to scroll oil leaks - guaranteed to work
When I built my side valve motor I decided to attack the problem of rear crank oil leaks and came up with the solution outlined. I chose to replace the tappet cover with a machined alloy one with a fitting to accept 10 mm. oil proof hose connected to a PCV valve on the blower intake side of my motor. The original oil filler cap and tube was replaced with a stainless steel one machined to accept a later A Series oil filler cap. This filler cap is connected to a catch tank with a filter to keep rubbish from being drawn into the crankcase due to the vacuum created by this setup. Initially The hose to the catch tank had a 3.8 mm. dia. restrictor. The
maximum crankcase vacuum measured at the dipstick tube with a non vented cap was 4.8 inches water gauge. With the 3.8 mm. dia. restrictor the crankcase vacuum was 1.8” WG leaving the rest of the max. 4.8” WG to purge the crankcase of water vapour and other combustion by-products. This setup worked well with minimum oil leakage on the drip tray which is always under my car. Recently when the motor was removed to fit a modified gearbox a check revealed no ‘mayonaise’ build up so I decided to decrease the dia. of the restrictor to 3.2 mm. This resulted in the crankcase vac. Increasing to about 2.1” WG. The car has since been driven hard on four occasions and there has been no oil dropped onto the drip tray after the car is parked. I feel confident in claiming this a success. Have attached pics of the manometer used to measure vac. and one of the A Series oil filler cap connected to the catch tank. I leave it to readers to determine the best solution to a long term problem.
Bob
By the way - did you receive the collets I sent.
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