Author Topic: Valve springs for high lift cam  (Read 845 times)

Offline whittakers

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Valve springs for high lift cam
« on: 02.03. 2012 19:29 »
I am fitting a higher lift cam (higher than a 357 Spitfire cam) and am looking for alternative valve springs. The standard Rocket springs have gone coil bound at full lift so rather than the trouble of having different spring caps made up, does anyone know of any off the shelf springs that would be suitable? I have heard that some Porsche 911 springs or Gold Star ones may be suitable but have no way of confirming this.
(Aiming to give the Triumphs a run for their money this season!!!!)

Mark
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Offline andy2565

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Re: Valve springs for high lift cam
« Reply #1 on: 02.03. 2012 20:30 »
i use porsch 911,from the early 2 valve engines,theyre a progressive spring i use them imy J.A.P ENGINES and use to use them in my bsa single scrambler engines,only drawback is you have to buy a full set,which isnt cheep,but if you change them frequently,thats ok.
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near wolves uk,will keep riding as long as can stay upright,tribsa,tt500,2xJAP grasstrackers+jawa.gold flash.triumph metisse,and others.

Offline chaterlea25

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Re: Valve springs for high lift cam
« Reply #2 on: 02.03. 2012 23:14 »
Hi Mark,
Fitting "Gold Star" valve springs and caps is featured in the "Eddy Dow" tuning literature
The valve caps are different from the A10 engines,  fitting the Goldie caps keeps the proper spring pressure
They also come in Alloy

HTH
John O R
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1961 Super Rocket
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Offline Rocket Racer

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Re: Valve springs for high lift cam
« Reply #3 on: 03.03. 2012 07:22 »
As a fellow charioteer, I'd be interested to know what your mixing the higher lift cam with in the engine...I'm currently running a 357 but also have a 358 for the next motor... which has more lift on inlet but less duration than a 357 on the exhaust. Whats the story re your cam profile?
More pictures of the chair please!  *clap*
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A good rider periodically checks all nuts and bolts with a spanner to see that they are tight - Instruction Manual for BSA B series, p46, para 2.
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Offline whittakers

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Re: Valve springs for high lift cam
« Reply #4 on: 04.03. 2012 10:02 »
Thanks for the responses, I shall start sourcing parts this week and see how it assembles. I will of course keep you all posted as to the results when the motor is up and running. (I don't want to post the cam spec in public yet - don't want the competition to know what I am doing but if Rocket Racer sends me a PM I will provide).
Last season the engine was in essence just a Road Rocket motor, 9:1 pistons, 357 cam, A7SS head with a pair of 1 5/32 monoblocs. Plenty of grunt and good go (especially for an A10 on petrol). Would have been very ridable on the road, it even ticked over! The twin carbs gave the same power on the dyno up to 5500 rpm as a single carb. The twins though allowed it to rev beyond that (used 6500 as my limit) where as the single carb was struggling to get passed that 5500 spot - you could see the dyno trace collapse and go stupid. I don't think a GP or TT carb would have improved that as by instinct tells me it was the manifold that was restricting the flow.
More to come as it unfolds...
Mark
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