Cam - which to choose

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Steve Payne
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Re: Cam - which to choose

Post by Steve Payne »

That's interesting Basil.

I had the same problem so I rung them and I was told that I didn't need to replace the distributor drive gear.

The technical guy I spoke to asked me for the part number so maybe some do?

The other thought is when did you purchase yours? I bought mine last year so maybe it is a new thing?

Steve
Last edited by Steve Payne on Sat Jun 19, 2021 8:45 am, edited 1 time in total.
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johnw
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Re: Cam - which to choose

Post by johnw »

Steve Payne wrote: Fri Jun 18, 2021 2:50 pm
RockyUSA wrote: Fri Jun 18, 2021 2:32 pm Why is it called “The Purple Cam”?
The purple shaft was just a name for mopars after market brand cams. they were made by crane.
"Purple Shaft" is named after the colour of dye on the shaft, ie, the shaft as in the shaft with cams on it. The colour indicates the intended use, yellow might be street, white, red etc. The purple one got really popular!

In the 60s, Ducati also daubed dye or paint on the shafts to indicate which grind the cam was. Green White is a really cool one for street use. Even after 50 years some parts keep their old paint!

The drive gear material needs to match the material of the cam. Cast Iron camshafts vs Cast Steel, different hardening processes, etc. Get it wrong and your engine will be full of filings. Joerg had a problem like this that he reported on the forum. I think his Bronze gear got eaten up.

(Edit: Having read all these posts and charts, it turns out so many things I thought I "knew" were not true! For example, I thought the Purple Shaft was the SP cam, but the SP had two different cams according to the year of production, neither being a Purple Shaft!)
Have you seen our stolen Jensen FF 119/011 https://twitter.com/jensenffdotcom
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Steve Payne
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Re: Cam - which to choose

Post by Steve Payne »

Basil McKinley wrote: Sat Jun 19, 2021 1:34 am Hi Steve,

Some years ago I purchased the same Lunati hydraulic roller cam I as you. I recall thinking at the time that their information on whether a bronze oil pump/distributor drive gear was required was ambiguous so I rang their tech support to check and they advised me to use a bronze gear. It would be interesting if you have got more information on this,

Regards,
Basil
After reading various articles and forums on this subject it appears if you are running a Lunati Hydraulic roller cam a standard gear is not a problem, on the other hand a Lunati solid roller cam must have an upgraded gear, there are also available now toughened gears like this http://www.hughesengines.com/Index/prod ... rtid=28107 as the bronze gears have a relatively short life, I have heard they can need replacing in as little as 3k miles in some applications.

I have already done over 2k on my cam so I might pull the oil pump drive out in the near future to how it is looking. At least with these Hughes pump drives we have options.

Steve
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Re: Cam - which to choose

Post by Basil McKinley »

Hi Steve,

I purchased my cam around 10 years ago but it seems that the part no. has not changed according to Lunati's website. It's often hard to get definitive advice on this type of issue. I have also read that toughened distributor/oil pump gears for use with billet steel camshafts have to be mated to a new cam. Anyway it would be interesting to hear of your observations if you end up inspecting your cam gear after running with the original distributor/oil pump drive gear. Hopefully you find all is well,

Best regards,
Basil
1970 Interceptor MkII 123/3798
1973 JH MkI 1141/12698
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