Prepping head for high lift cam - springs? Stem seals?

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turbodave
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Prepping head for high lift cam - springs? Stem seals?

Post by turbodave »

Donor heads: standard 3.9 issue, standard valves (for now). Have a set of early SD1 heads with the machined (pre-sintered) valve caps I'll be using to get rid of the sintered stuff.

I'm going to be using a Crane 901171 F-248/3334-8, so need .533" lift at the valve per this: http://powermechanics.com/download/CraneMasterList.pdf (bottom of page 9)

I'm looking at my spring options. Stock spring pocket is measuring up at 1.236" OD x .843" ID and a installed height of around 1.55 at the moment.
Crane has suggested these springs as the only close option http://www.cranecams.com/product/cart.p ... il&p=26305, but even these have an ID that is 1mm larger than the Rover spring pocket, and would need me to carve a much deeper pocket into the head (1/4" deeper). I'm also concerned about the extra radial movement of the spring at the cap.

I'm also looking at the stem seals. What do folks normally do here? it's not going to be that big of a deal to machine the stem seal location further down and knock the same amount off the top - I'm almost done making an angle-plate to put the valve guides vertical so i can machine the spring pockets (and guides) on the mill. It'll be a little time-consuming to do 16, but not difficult at all.

I of course am tempted to just jump on the piper springs; the VTSV8 - but would appreciate feedback on the longevity and reliability of these when used with a mechanical cam profile like the 248

Thanks!



JP.
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Re: Prepping head for high lift cam - springs? Stem seals?

Post by JP. »

Just fitted these valve springs myself http://www.v8tuner.co.uk/product.php?id=995.
Nice chap and quick responce on the mail.
Can not say that of our forum sponsor as they never responded.......

I machined about 2mm from the top of the valvestem

I used the OEM type washer type flappy rubber stem seals

Building a SD1 11A engine myself
'73 Ford Capri. 3.5 RV8, Magnacharger 110 Supercharger, Merlin F85 Heads, Water/Methanol Injected
'73 Ford F250, 6.7ltr V8
Building a GT40 mk2

turbodave
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Re: Prepping head for high lift cam - springs? Stem seals?

Post by turbodave »

Machined the top of the valve stem? Do you mean you machined the groove that the collets sit in?

JP.
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Re: Prepping head for high lift cam - springs? Stem seals?

Post by JP. »

Sorry, valve guide
'73 Ford Capri. 3.5 RV8, Magnacharger 110 Supercharger, Merlin F85 Heads, Water/Methanol Injected
'73 Ford F250, 6.7ltr V8
Building a GT40 mk2

minorv8
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Re: Prepping head for high lift cam - springs? Stem seals?

Post by minorv8 »

I think I used Euro Ford V6 springs on my first heads that were of early Range Rover origin. Can´t really say how much lift they could take.

I bought a Comp Cams cutter for valve guides and have used SB Chevy seals. https://www.summitracing.com/int/search ... ner=SREPD1

turbodave
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Re: Prepping head for high lift cam - springs? Stem seals?

Post by turbodave »

That is great info Jukka!
I didn't know that these cutters existed, that the SBC stems were the same dia, or that the SBC seal loation dia was smaller and hence could be cut into the rover guide!
If only they made one of their cool spring seat cutters for the 1.23" OD of the standard rover spring pocket! I guess I'll revert to my original plan of using a boring head and ground HSS tool for doing that particular job... Certainly the SBC seal cutter will make things much easier as OD boring on a mill is something i'm not overly enthusiastic about!

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