G'day from Western Australia

[ColinB]

I have the Bantam book so I can always look up information for you.

[Oz singer]

Thank you Colin, very much appreciated.
By the way I read your engine rebuild topic, really helpful as well. That's got me thinking a the different cyl-head designs, So I removed the heads from the 34 and 36 engines I have.

34 and 36 heads

[Oz singer]

The spark plug opening to the combustion chamber on the 1936 is quite odd. Does someone has an explanation for it ? And does anyone ever tried to open it, like on a modern head ? I understand the meaning of, a bathtub combustion chamber as well now !
Except that, I am still in the process of straightening the two rails of my frame. Twist one way, bend the other way

left hand side

[jeans_old_man]

The odd spark plug hole is the compromise the designer had to make to enable him to make the combustion chamber hemispherical and the inlet valves bigger. It also means that the combustion chamber can be shallower thus increasing the compression ratio. You will notice that if you skim the '34 head you will encroach into the spark plug holes. The net result was an increase in power of the 'speed' head and later bantam heads.

I wouldn't open up the holes - the head has a tendency to crack without removing any more metal and you will reduce the compression ratio.

[ColinB]

Brian is giving wise advice - I had to try 3 heads before I found a good one so removing metal (or even worse having the valve seats updated with unleaded inserts) will leave you looking for another one!

[Oz singer]

Thanks Brian and you too Collin, I dread the day that I will have the '36 head checked, I will be sweating !!
Maybe I should start another topic now?

[jeans_old_man]

The most like place for a crack is along the top immediately underneath the cam shaft. If there is no crack there it looks good to go. Don't despair if it is cracked - it can be welded by someone who knows what they are doing but not a job for an amateur!

[Oz singer]

Thanks Brian
The 36' head is in the cleaning bath at the moment, another two or three days before I can give it a good look. Still working on the chassis rails, should be right tomorrow

[Oz singer]

The chassis is straight and square now I rewelded the cracked bits and I will had some reinforcements along the way.

[Oz singer]

[Phillip]

Wow..already looking good!

Additional to the head discussion. I had my '36 Speed head looked at by a guy that did racing cars and bikes, including Ducati and Harley. He was impressed with the design of the semi-hemi head. He was surprised this head was used on a saloon car of the 1930's and gave the overall design a thumbs up.

As Brian mentions, the early 33/34 head suffers from a limited combustion space and lack of range in skimming the head face because you cut into the spark plug hole. I think the standard plugs are short reach, thankfully, but there is not much scope for tuning. Brian has already pointed out the cracking issues with these heads, but welding any pre-war Singer casting should be approached with caution. The general rule is to only use 'cold' processes like metalock stitching. On another recent thread John Simister mentions new tech like laser welding and I would be interested to hear if anyone has experience with that. I've tried fusion welding and that was not satisfactory.

[ColinB]

Chassis looks really good!

[Oz singer]

Thanks Phillip, I hope that this '36 head will turn up in good condition I just need to clean it once more and it should be ok to look at it more closely.
I started to dismantle the rusty '36 engine but went not too far after that I opened the sump !!

[Oz singer]

This view is even more Titanic style !!

Maybe I should leave it in molasse for a month ?

Anyway, I'm after the '34 motor now, trying to remove the gear box from it !

[jeans_old_man]

Although it looks bad at first glance don't write it off!. With luck the bearing journals will have retained some oil and be OK. You will need a rebore, new pistons and maybe a new back bearing but it looks like you have a useable crank and that is good news. The chances are that any block that you find will require the same amount of work.