John,
You are probably on the right track. I would think that 5 and 7 firing
together and being far away from the cam drive gear would impart more of a
twist to the crank than would 4 and 2. If this is the case, then the rear
cylinders could be closer to the correct valve timing with the new firing
order. Dyno tests say it gives a little more power....more is better??!! and
runs smoother....smoother would imply less interference from harmful
harmonics. Small improvements sometimes result from subjective
analysis.......I needed to chage cams anyway......
Skip
----- Original Message -----
From: "John Burk" <joyseydevil@comcast.net>
To: "LandSpeed List" <Land-speed@autox.team.net>
Sent: Thursday, June 02, 2011 22:28
Subject: Re: [Land-speed] BBC Firing Order .
> Skip
>
> The altered firing order cam would trade 5-7 interference for 4-2
> interference wouldn't it ? Maybe it would reduce crankshaft harmonics by
> eliminating the normal 7,2 sequence crank twisting .
>
> John
>
>
>
>> My new cam will change the firing order of my BBC to 18736542....this
>> looks
>> good to me due to getting adjacent cylinders away from firing together.
>>
>> What are the pros and cons?
>>
>> Pros: Smoother running, few more Hp from not having 5 take the charge
>> away
>> from 7.....?
>>
>> Cons: ?
>>
>> Now I'll have to put the same nozzles in all cylinders...........
>>
>> Skip
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