Hi All ,
I've been reading this thread with great interest . I will be building a
1275 cc for my Bugeye .
The car will be a weekend toy for "SPRIGHTLY" driving on the mountain roads
around home .
I will not be commuting or sitting around in traffic . (Read : I'm looking
for lots of street performance)
I am planning on using a Kent MD 286 S cam . $$$ is not a problem (this
time) My only experience
is with twin SU's . Do I want a side draft Weber or an HIF6 SU ??? Who
makes the best manifold(s) ?
I don't want to cut up the engine bay or modify the stock bonnet . Also I
see that there are many
makers of LCB exhaust manifolds , which one do you folks think would be best
suited in this application ?
TIA ,
Mark Hanna
AN5L/13731
> -----Original Message-----
> From: Mike Gigante [SMTP:mikeg@vicnet.net.au]
> Sent: Wednesday, November 11, 1998 10:28 AM
> To: Geoff Branch; Daniel1312@aol.com; ridleymj@bis.on.ca;
> spridgets@Autox.Team.Net
> Subject: Re: 1.5" SUs
>
> You might like to compare jetting for Webers on the following URL
>
> http://yallara.cs.rmit.edu.au/~mg/cars/goblins/tech/webers.htm
>
> Mike
>
> -----Original Message-----
> From: Geoff Branch <branch@valinet.com>
> To: Daniel1312@aol.com <Daniel1312@aol.com>; ridleymj@bis.on.ca
> <ridleymj@bis.on.ca>; spridgets@autox.team.net <spridgets@autox.team.net>
> Date: Tuesday, November 10, 1998 5:36 AM
> Subject: Re: 1.5" SUs
>
>
> >Were the comments re: Weber 45 DCOE for a 1500?? I'd love to hear what
> >anyboy else is running in a 45 on a 1275. I have 34 Main venturi, 35 aux
> >vent., 125-F2 main jets, 50-F9 idle jets. Any comments?? Geoff Branch
> >'74 Midget
> >-----Original Message-----
> >From: Daniel1312@aol.com <Daniel1312@aol.com>
> >To: ridleymj@bis.on.ca <ridleymj@bis.on.ca>; spridgets@autox.team.net
> ><spridgets@autox.team.net>
> >Date: Sunday, November 08, 1998 4:50 PM
> >Subject: Re: 1.5" SUs
> >
> >
> >>Hi Martyn,
> >>
> >>I do not agree that twins are better than singles. What matters is the
> >amount
> >>of airflow the engine receives (and requires) and with carbs the amount
> of
> >air
> >>the carb can flow be it a large single carb or two smaller carbs.
> Although
> >a
> >>twin 1.5 SU set up will flow a total of more air, on many A Series
> engines
> >you
> >>will get a better result with a single 1.75 (or maybe a single 2.0?).
> The
> >>only usual advantage of a twin SU setup over a single is better fuel
> >economy
> >>(gas mileage).
> >>
> >>Also, when talking about SU carbs it is perhaps worth clarifying which
> SU.
> >I
> >>mention this because the later HIF carbs flow more air than earlier HS
> >types.
> >>
> >>I am very acquainted with David Vizard's books, as well as Haynes SU
> manual
> >>and another book on SUs. I also have a library of other tuning books.
> >>Perhaps I can refer you to page 75 of the yellow edition of Vizard's A
> >series
> >>book where a table idicates airflow in cfm for a 1.5 SU H4 carb is 133,
> it
> >>being a reasonable assumption that two of these carbs make 266 cfm. The
> >same
> >>table indicates a SU HIF6 carb making 240cfm - only 26 cfm less than
> the
> >twin
> >>setup and I would suggest that the small gain of the twins might well
> >easily
> >>be lost on the manifolds.
> >>
> >>For myself I haven't run SU carbs in a decade but as I said before, from
> >what
> >>I have heard (some comments originating very close to Mr Vizard) the
> single
> >SU
> >>1.75 takes some beating.
> >>
> >>Further comment welcomed, especially when supported with dyno figures.
> >>
> >>Daniel 1312
> >>
> >>45 DCOE, 40mm main venturi (smaller sizes to prove it needed the 40mm
> >>venturis) 185 main jets, 55 pumps, 65 F9 idles - and the mixture bang
> on,
> >and
> >>engine taking full throttle in 4th at 2,500rpm if not lower with a MD286
> >>scatter cam (K&N air filter used to make sure small children are not
> sucked
> >>into the intake tracts)
> >>
> >
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