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Ron Grant
United Kingdom
160 Posts |
 Posted - 17/09/2008 : 18:23:06
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Having asked an electrical question,(re coil change over switches) a couple of months ago, and did not get one reply, I will try my luck again with a different question.
Does any body know of the merits of a Sintilla vertex mag. as against a BTH vertex mag.
Possibly answering my own question, is it because there are spare parts around for the Sintilla and very little for the BTH.
The next question, regarding the BTH , does any body know how to change the direction of rotation and how to lock the advance for a blown engine. Just for interest, the configuration of the points for both directions would appear to be the same.
What is the argument for locking the advance as opposed to running it with advance? |
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Bob Stringfield
United Kingdom
854 Posts |
Posted - 17/09/2008 : 20:38:35
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The Scintilla 'Vertex' has been fitted to any number of competition cars with great success.
The right rotation is, as usual, crucial.
The main disadvantage for many MMM cars is the need for a 'bulge' to enable the bonnet to close. |
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arjen
Netherlands
32 Posts |
Posted - 19/09/2008 : 11:20:22
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Ron,
With a scintilla the timing would be more precise as the drive is more direct. Also the drag will be lower. Henk de Vries sported a Scintilla in his K3R when he owned it. He did have issues with spark plugs creating misfiring and needed to change them regularly, besides this the engine performed beautifully with it. His Scintilla did have a working advance system. I personnally do not see the reason why blocking the device. Modern fuels are more critical to self ingnition so you better have all the technology working in your favor. I do not know the engineering rational to block the advance in combination with supercharging.
My KN K3R runs beautifully with coil and distributor with centrifugal advance. I have never problems with plugs like on Henk's former car. My volumex delivers 10 Pounds of boost and revs to 7.500 rpm without hesitation in any range.
Hope this answers a part of your question.
Arjen
arjen |
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etlanpa
United Kingdom
560 Posts |
Posted - 19/09/2008 : 12:12:21
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| The Scintilla is still widely used in light aircraft.....hence the favourable spares situation! |
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Richard Hardy
United Kingdom
2159 Posts |
Posted - 19/09/2008 : 16:58:42
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Ron
I originally looked at fitting a BTH and have a couple, one of each rotation I recall but the spares were difficult to locate. Also, Vertex spares are now easily obtainable from the States instead of relying on some of the new old stock left in the UK whereby the resin coats are breaking down and the old annode was fragile and if bent, would break. Modern replacements are far better and me new old stock coil I fitted 6 years ago failed a few weeks ago. The new replacement produces an amazing spark.
In response to Bob's comment, you can fit a Vertex on a J type withoug needing a bulge in the bonnet. I run one and there is about 0.25 inch clearange.
Regarding the use of a 009 and coil, the spark is far stronger with the mag and strong enough to leap 1 inch on my car. Not for the faint hearted!!
Can't comment on the locking of the advance. I use a Scintilla with a hairy 18 degree advance unit on my car and it runs very well indeed throughout the rev range but a difficult unit now to source. This is top end of the scale I believe though.
Rich H |
Edited by - Richard Hardy on 19/09/2008 17:05:32 |
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McEvoy
United Kingdom
252 Posts |
Posted - 19/09/2008 : 23:45:37
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| Contact info for Vertex spares from the States much appreciated as I have three NV4s all in need of some attention, one no auto advance, one with auto advance and one with cut out feature at ? revs. Don't know which I will use as yet depens on spares availability I am aware of some parts that can be sourced in the UK e.g. caps and rotor arms and have contacted various American aero suppliers but without any joy. Thanks in advance - Bob |
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