Bill's got the answer as far as the driveshaft is concerned. You can't do
it yourself for or as well as the pros do and it's generally peretty cheap.
Frankly I've never had any problem and .020" dosen't sound like a lot to me
, depending on length of the driveshaft. As Bill has already stated the
demand at full song in top is REALLY high and you must make certain all the
electrics are putting out their fair share and a little more. We did have
this kind of thing with the TR-6 when the alternator (Lucas) would die but
when we fitted the Motorola that all went away forever. Another thing of
course is the fuel demand. Is the needle and seat big enough to supply the
demand at the speed? Most stock carbs do NOT have a big enough needle and
seata when the engine is highly modified and you'll run out in top when
running hard. Sometimes you can shut the engine down clean when at the high
revs and the missing going on , then check to see if the float chambers are
at the proper height. ( of course pull the lid and check the fuel height
before you start this manuver) If the engine is hot from several runs the
S.U.'s will perk over a bit and this won't work but the Webers should give
you a clue. At the same time I've had fuel pumps that just did not deliver
enoguh fuel for the power requirment and you need at least 15 gals per hour.
Test with a quart can and a stop watch. I don't know anything about the
engine you are talking about so without some more detail I guess my guess is
just another guess.(hah!).
----- Original Message -----
From: "Bill Babcock" <BillB@bnj.com>
To: <BillDentin@aol.com>; <Kaskas@earthlink.net>
Cc: <fot@autox.team.net>
Sent: Monday, February 04, 2002 3:37 PM
Subject: RE: tolerable DRIVE SHAFT run out?
> There are lots of driveshaft shops that will check and dynamically balance
> your driveshaft.
> I've had several made from bits and pieces. When the pros finish with them
> they are pretty, straight, and perfectly balanced. Don't even mess with
> measurements, it's cheap to get it done.
>
>
> By the way, unless you have true overdrive, I doubt your driveshaft is
> getting to 13K.
>
> In my humble experience, high end miss is usually caused by the familiar
> old bugaboos--fuel or spark, most likely spark. Even if it doesn't happen
> in the lower gears. High gear, high RPM is the highest load your engine
> sees, which means highest combustion chamber pressure and highest voltage
> required for the spark. It's also frequently caused by too lean a
> mixture--same root cause. I'd try closing the plug gap to .010" and see if
> that has any effect. If it does, it's your sparks--and it doesn't matter
> what kind of system you have, you can have something truly bodacious and a
> weak coil at high RPM will let you down.
>
> The second thing to try is going up big on the main jet. I don't know
> whether you have SUs or Webers. If it's webers, go up four or five steps,
> and see what happens. It won't be optimal, but it'll tell you what's going
> on.
>
>
> -----Original Message-----
> From: BillDentin@aol.com [mailto:BillDentin@aol.com]
> Sent: Monday, February 04, 2002 3:15 PM
> To: Kaskas@earthlink.net
> Cc: fot@autox.team.net
> Subject: tolerable DRIVE SHAFT run out?
>
>
> Hi Kas:
>
> Hope you are well!
>
> We are still working on 'high end break up', and John Reimer, a very
> successful local ROAD/ROUNDY ROUND/DRAG racer friend (from the old days)
> something to the effect of, "If you don't have similar symptoms in other
> gears (at top RPMs)", he would be looking at something spinning that is
> out
> of round, and at top speed perhaps we have past the tolerable limits. He
> said he would look first at the drive shaft. the Thunder Bolt has a one
> off
> drive shaft. Using less than laboratory equipment in our own shop, we
> suspect we have 20,000ths out of round at one end. Is that too much when
> we
> get to 13,000 rpms (read 6,500 actual)? Any idea what tolerable limits
> might be?
>
> Appreciate any thoughts.
>
> Bill Dentinger
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