RE: [alfa] single-row timing chains

["Brian Shorey" <bshorey@xxxxxxxxx>]

> I'm not sure why one would want to go to a single-row timing 
> chain on a four-cylinder Alfa.  There might be a tiny 
> reduction in friction, but at a loss of reliability, and I 
> would guess at a huge cost in parts and labor.
> There are two chains, and a total of six sprockets, if you 
> include the two on the idler.  I'd guess you'd need to change 
> all those.  Or can you get by putting a single-row chain on 
> the double-row sprockets?
>  
> I believe when Mercedes went to single-row chains on the V8s 
> in the 70s/80s they had a lot of trouble, and eventually went 
> back to double-row.  I recall they even offered a conversion 
> to retrofit single-row chains on older engines to double-row. 
>  I believe one of the reasons BMW went to a single-row chain 
> was to save a bit of length in the design of the engine, not 
> something you could benefit from on an existing Alfa engine.
>  
> What's the motivation?

Well, given that it was I that started this thread a while back..

The motivation is a not-insignificant gain in power, measurable on a dyno.
I think it was in the range of 5-10 hp on a 1600 motor.  And the associated
comment was that there was no drop in reliability.

The source was a letter from Dr Tenney to Pat Braden, quoted in Pats last
book.  Dr Tenney's comments were to the effect of looking for ways to reduce
losses in the motor, as opposed to ways to increase HP.  He mentioned three
things in particular, removal of the mechanical fan, single row timing
chain, and removal or modifications to the alternator.

Fwiw,

bs

bs
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