The Marston Sunbeam Club & Register Forum

General Category => Technical Discussion Forum => Topic started by: Alex on November 08, 2020, 07:19:56 PM

Title: Inlet Camshaft M9/90
Post by: Alex on November 08, 2020, 07:19:56 PM
Hello!

1. Could anyone tell me the reason for the design of the inlet camshaft of my 1929 ohv? It is two pcs and has something like a preload spring? I have never seen this before and was wondering what the reason for that is?

2. Does anyone use sparkplugs NGK BxES and has either good or bad experience with it? Which sparkplug do you recommend using with this modell?

Best Regards
Alex
Title: Re: Inlet Camshaft M9/90
Post by: singleminded on November 08, 2020, 10:07:51 PM
I thought that those 'silent' cams were much later than 1929. The idea was that the 2 halves of the cam wheel tensioned against each other and took up any clearance between the half time gear and cam gear...john
Title: Re: Inlet Camshaft M9/90
Post by: klaudius on November 09, 2020, 12:15:28 PM
Hello. These are not 1929 camshafts. They were available later from 1935 onwards. The springs were used to reduce noise. The whole thing didn't catch on. Greetings from Claudius
Title: Re: Inlet Camshaft M9/90
Post by: phutton on November 09, 2020, 10:59:22 PM
I believe we have some suitable cams in the used parts stock. Paul Knight will be able to help you if you want to go back to the original pattern.
Title: Re: Inlet Camshaft M9/90
Post by: Alex on November 10, 2020, 06:58:49 PM
Hi all!

ok that does make sence, I just never seen it before. Thanks for your quick answers!
I understand that that should be a improvment rather then not so I think I will keep them in since they are also in good condition.

Now I just wondering about the spark plugs, what do you guys use or recommend?

2. Does anyone use sparkplugs NGK BxES and has either good or bad experience with it? Which sparkplug do you recommend using with this modell?
Title: Re: Inlet Camshaft M9/90
Post by: Thomas on January 12, 2021, 06:18:06 PM
Today I've found this design in my 1937 Model 9. As Alex I wonder about this design. How does it work if it is for noise reduction? There is some play for the inside finger adjustment (four teeth). Is there a preferred position for the internal finger?
Title: Re: Inlet Camshaft M9/90
Post by: Alex on January 12, 2021, 07:25:07 PM
I think the only way that you can mount those two parts that would make sence is with the internal finger preloading on the spring. That's how I mounted it finally. So you have to twist it a bit when you assamble the cam onto the shaft sprocket so it has some preload.
Title: Re: Inlet Camshaft M9/90
Post by: Thomas on January 12, 2021, 08:01:36 PM
Yes, Alex, that makes sense.

And I can see a respective trace on the spring where the finger touches it. What puzzles me, though, that I can also see a trace on the surface as if the finger can move (which is impossible, of course). Anyway, I will check it again.

Thanks a lot, Thomas