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jabe1807
Norway
192 Posts |
 Posted - 01 Dec 2013 : 21:37:04
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Hello to you. It has been a long time since I have been on the forum.
My prosject is still in my garage, I have done just a little work on the car during the summer. No painting yet.
Hope any can help to find out my camshafts.
I have bought 2 camshafts on ebay.
Nr 1 lifts 7.1 mm (0,275)
Nr 2 lifts 7,7 mm (0,303)
Are any of these Holbay cam?
I know this is answered on the forum before, but I was not able to find the answer.
Best regards Jan, Norway |
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1922
United Kingdom
549 Posts |
Posted - 02 Dec 2013 : 21:12:25
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Hi Jan,
Camshafts were
.255 1500
.260 1725 alloy head single carb (early cars)
.298 1725 alloy head twin carb (early cars)
.295 1725 allow head twin carb & single carb
.320 1725 Holbay
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jabe1807
Norway
192 Posts |
Posted - 03 Dec 2013 : 19:03:02
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Thanks.
Have to check out nr 2, maybe it is Holbay.
Jan |
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arrocuda
United Kingdom
501 Posts |
Posted - 03 Dec 2013 : 21:43:42
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The camshaft should be marked up with an identifier between the 5th and 6th lobe. (counting from the driven end of the shaft). Here's a pic of the one I have here.
I also have a standard Holbay camshaft but is not here to photograph, but you can easily identify the mark as it says 'HOLBAY' hand written using an engraver.
Building the 'Mark II' fastback Rapier ('Arrocuda'). |
Edited by - arrocuda on 03 Dec 2013 21:49:25 |
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jabe1807
Norway
192 Posts |
Posted - 03 Dec 2013 : 22:04:40
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Hi Arrocuda
My cam (nr 2, lift 7,7 mm) has no mark. It is Kent produced.
Can you measure the lift on your cams?
Jan |
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arrocuda
United Kingdom
501 Posts |
Posted - 03 Dec 2013 : 22:43:40
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Not sure as I don't think my micrometer is large enough to measure the lobes. Didn't seem to be any point in measuring them once I'd identified them from the marks, but will give it a shot next time I'm down there.
You should be able to get an approximate performance specification from Derek's (1922) post in the earlier thread. I'll cut and paste it here....
"But measuring the lift is a sure way to identify it - if you have something to measure it with.
Just measure a lobe at it's narrowest and widest point (does that make sense?) and work out the difference.
In thousands of an inch:
320 = H120/GLS
298 = early 1725
295 = later 1725
260 = very slow 1725
255 = 1500 (even slower)
In metric, er, 8.128, 7.5692, 7.493, 6.604 and 6.477."
TBH 7.7mm is only marginally bigger than the earlier standard Rapier shaft and is probably designed to give better torque at low revs by holding the valve open for longer. Not sure about the 7.1mm as that would be somewhere between Alpine and the later Rapier spec'.
Tim.
Building the 'Mark II' fastback Rapier ('Arrocuda'). |
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Holbay camshaft
