SM Engine in a 39 Roadster Chassis

[Geoff Hale]

Hi. Has anyone fitted a SM 1500 engine in to a 39 Roadster Chassis? Being new to the Singer marque I would appreciate any advice on problems and pitfalls
Geoff Hale

[mikeyr]

I planned on doing that for my 1.5 if the motor was bad.

But I am not sure it would fit in a 4 cyl very well. It may fit I think but it will be heavier than the original motor. I can do some measuring over the weekend between a 4AD motor into my 34 chassis

*** EDIT ***

Ok, I was on my phone with the first reply and I hate typing on that. So, I was thinking that if my 1.5L motor was bad, I would put in a 4AD motor in since it is also 1.5 and the car would stay Singer powered. I think that would have worked since the 1.5 was a 6cylinder motor.

The issues as I see it for a 39 Roadster, is that a 4AD motor is larger than earlier motors and will be quite heavy, I have no way of measuring it but I am going to guess the motor/gearbox is double the weight of a 9hp/LM motor/gearbox in the LM since the early 9'hp's were very lightly built. I can only compare the LM to the 4AD as that is the motors/gearboxes I have handy to physically measure. I have never seen a Bantam motor that I read is where the main parts came from for the Nine Roadster. I know that motor has an extra main bearing and more power, so that motor may be closer to a 4AD motor but never seen one. Even if you can make it fit, the weight over the front wheels would be my concern as it would make the car hard to steer. Again, never having seen a Nine, I am only guessing based on the 2 models I have seen, 1934 and 1953.

[Geoff Hale]

Hi Mike
Thanks for your message,
The chassis I have is the J prefix Under slung chassis with the beam front axle (not the later independent) I was under the impression that the chassis were basically the same but with a strengthening x member in the centre which I will need to add. Looking at the weight specs for the roadster and the SM Roadster are the same 15 1/2 cwt but I don’t know the weight distribution across the car.
The one good thing in my favour is that chassis is stripped so I can move the engine position back as far as the steering box will allow
I planned to check the chassis alignment to day and will try to rest the engine in position

Does anyone have any information on the weight distribution preferably with out the body

[Phillip]

Hi Geoff,

NASOC member Gene Abbondello (also our Club Librarian) successfully fitted a 1500 engine in his 4A, but that car has a stronger chassis based on the 1940 Light Ten saloon that was never produced. This chassis design carried on throughout Roadster production from 1946 to 1955, being heavily modified in 1951 when the 4AB was introduced with IFS.

Your '39 has what is basically the Bantam chassis that was also used in modified form for the last version of the Nine Le Mans and Nine Sports.

I have driven - and been driven in- Gene's converted 4A and would say that the weight does affect the handling and suspension a bit and the engine is a tighter fit. The 4A frame is bigger than the Bantam frame, so it might be tighter still - but - that said, both took the 1074 engine OK.

Hope that helps...

[Geoff Hale]

Hi Phillip
That’s good to know it has been done
Many thanks
Geoff