[Fot] 1300 Crankshaft

[Rick Parent]

Hi Bud,

We have been running SU's for years but have run the dual Webers in the past
with great success. I Dynoed our last race motor with both, there was zero
differance in HP. The Webers are much easier to tune than the SU's though. I
have Dynoed a single 45 set up but it was on a motor that only made 100hp so
its not really a fair assesment. I will try it on the next good race motor
which should be in the next couple of months. I can't say if the dual 45's are
better than the dual 40's as of yet either, my experiance says 45's are better
but the Dyno always tells the truth. If the carbs are tuned correctly I don't
think there is an advantage to changing the chokes for differant courses. When
choosing a choke size I do the math to see how much air flow is needed at the
max RPM / HP I want to run and start there. All the jetting including the
chokes work as a team. If you change say from a 36 choke to a 30 choke you
will be increasing the signal to the main circuit which will draw more fuel
sooner. It is necessary to Dyno tune race motors if you want max power and
reliability. I know they are not available everywhere and can be costly but,
its well worth the time and effort. A highly tuned Spit race motor is very
sensitive to jetting changes so in my opinion, (which is worth exactly what
you are paying for it) , you are asking for trouble changing a choke size at
the track. Changing the main jets and or air corrector jets because of weather
conditions yes, chokes never. If you can't Dyno your motor and are forced to
tune at the track get yourself a cheap data logger that can record an O2
sensor and RPM signal, like Innovate or Daytona Sensors Wego. Then a least you
will have a fighting chance, just try not to get frustrated. I will post the
results of the next motor with all the differant carb combo's if you would
like.

Side note;
The Dyno says our motors like 36-40 degrees total timing! no one likes to
believe me when I tell them that. I just get the look like man, you are full
of it! The Dyno says thats what the motor likes so that is how we show up at
the track.

Hope this helps, Rick


----- Original Message -----
  From: Bud R
  To: Rick Parent
  Sent: Monday, January 27, 2014 5:45 PM
  Subject: Re: [Fot] 1300 Crankshaft


  Hi Rick,


  Welcome to the FOT.



  Those are hard to find. I bought my 69 Spit Mk III for that very reason,
that it has the small journal crank. Hopefully it's like insurance that I
won't need it now that I have it. My race car came with the large journal
crank 1300 so I could always swap it out with the 69 Mk III FE engine if I
ever blown up the FE engine I have in the race car now. I got really lucky and
bought my 70 MK III parts car last summer for $150 and it had a small journal
crank plus it was only 40 miles from me here in Denver.  That rebuilt engine
is in the car now.


  I saw you run dual weber carbs and was wondering if I'm going to want to go
that route at some point. I'm running a single 40 DCOE 18 that a friend lent
me and in working through some charts on the web for flow for the 1300 engine
it seems like it should provide enough flow and power but then I see quite a
few folks running dual 40 or 45 webers so I'm curious as to what the benefits
are and if there's such a thing a a point of diminishing return.


  I just rebuilt that FE small journal engine this last summer/fall so I
haven't really had a race yet with the single 40 and can't say I'm happy or
not with it but I like to try to think ahead of the curve and have been
looking at some 40 DCOEs on eBay and also looking for the cannon intake for
them. Any tips or thought on this thread would be appreciated. Where did you
pick up your webers and intake?


  One more question. Do you change the chokes according to the track. E.g. a
smaller choke for shorter tracks where the straights aren't long? And bigger
chokes for longer straight tracks?


  Thanks for any help.
  Bud Rolofson


  Extreme Parts Racing (more than just a haircut)
  71 Spitfire MK IV Race Car #3
  69 Spitfire MK III (back up FE engine and dinghy car for RV)
  70 Spitfire MK III (parts car, FE engine donated to race car)
  71TR6 CC57365 (Good 6)
  93 Minnie Winnie Race Support Vehicle
  77 Z-50A Hardly Davidson Honda Mini-Trail Bike (Triumph Pit Bike)




















  On Jan 27, 2014, at 8:13 AM, Rick Parent wrote:


    Does anyone have any small journal 1300 standard / standard crankshafts?
    Russ??

    Thanks, Rick
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