i don't think is .472" Jim that is almost a half inch. I think you forgot
the "0" .
*Never be beaten by equipment.*
On Thu, Aug 24, 2017 at 11:49 AM, Jim Gray via Fot <fot at autox.team.net>
wrote:
> Chris,
> I finding it interesting you saw best power at .472. How much change in
> compression ratio did you get from
> .023 to .047. Im assuming you tried different ignition timing and at what
> Compression ratio did you start with?
> Jim g
>
>
> Sent from my iPhone
>
> On Aug 23, 2017, at 4:07 PM, Chris Marx via Fot <fot at autox.team.net>
> wrote:
>
> On dyno test we found a disturbing issue that lowers the power if the
> piston to head clearance is less than 0.039?.
>
> We didn?t find a cause for this but tested thoroughly clearances from
> 0.0236? upwards.
>
> Best power reading was with 0.0472?.
>
>
>
> Cheers
>
> Chris
>
>
>
> *Von:* Fot [mailto:fot-bounces at autox.team.net <fot-bounces at
> autox.team.net>]
> *Im Auftrag von *fubog1 via Fot
> *Gesendet:* Mittwoch, 23. August 2017 23:52
> *An:* timmmurphh at gmail.com; fot at autox.team.net
> *Betreff:* Re: [Fot] FW: Grattan VSCDA next weekend? piston/head clearance
>
>
>
> With the good rods and reasonable rpm you have plenty of clearance.
> You don't want too much clearance either cuz then it lessens the "squish"
> effect.
> The idea is to have enough clearance for all running conditions, plus a
> few thou safety margin, and no more.
> Glen
>
>
>
>
>
>
>
> -----Original Message-----
> From: timmmurphh <timmmurphh at gmail.com>
> To: 'fubog1' <fubog1 at aol.com>; fot <fot at autox.team.net>
> Sent: Wed, Aug 23, 2017 3:38 pm
> Subject: RE: [Fot] FW: Grattan VSCDA next weekend? piston/head clearance
>
> The Payen head gasket last used was compressed to 0.055 at the fire ring.
> So, with the 0.010 pop-up that I have from the all efforts to deck the
> block, I will have 0.045 clearance. I have Carrillo rods and we try to
> stay to under 6000 RPM for engine ?longevity?. (Not sure ?longevity? is a
> term that can be used with a race engine!) At the most we?ll hit 6200 or
> 6300 RPM briefly before upshifting. Therefore, I should be within the
> 0.030 clearance that you recommended. It will be interesting to see what
> the top of the pistons looks like on the next rebuild with regard to carbon
> build up in the squish area.
>
>
>
> Thanks for the advice and all the other comments on this subject. All
> much appreciated. Still a lot to learn?
>
>
>
> Tim
>
>
>
> P.S. Finally got everything together on the engine and about ready to mate
> up to the transmission and put back in the car. Looking forward to ELVF
> next month. That will be the test.
>
>
>
> *From:* fubog1 [mailto:fubog1 at aol.com <fubog1 at aol.com>]
> *Sent:* Wednesday, August 16, 2017 5:27 PM
> *To:* timmmurphh at gmail.com; fot at autox.team.net
> *Subject:* Re: [Fot] FW: Grattan VSCDA next weekend?
>
>
>
> Check the gasket thickness, it depends on what piston/wall clearance,
> rods, and RPM you use.
> You generally need around .030 piston/head with stock rods, so add that to
> your pop-up of .010 for minimum gasket thickness.
> If you run good rods you can run a little less before the pistons smack
> the head.
> It's perfect when there isn't any carbon build up on the piston tops under
> the squish area.
> When it's not right, it goes BRRRRRRRRRRRRR...
> HTH
> Glen
>
>
>
> After all the machining to get the stick out
> right I now have the pistons sticking up about 0.010 above the tops of the
> liners. No problem with the composite Payen head gasket.
>
>
>
>
>
>
>
> -----Original Message-----
> From: timmmurphh--- via Fot <fot at autox.team.net>
> To: fot <fot at autox.team.net>
> Sent: Wed, Aug 16, 2017 5:48 pm
> Subject: [Fot] FW: Grattan VSCDA next weekend?
>
>
>
> -----Original Message-----
> From: timmmurphh at gmail.com [mailto:timmmurphh at gmail.com
> <timmmurphh at gmail.com>]
> Sent: Monday, August 14, 2017 12:20 PM
> To: 'Tony Drews' <tony at tonydrews.com>
> Cc: ryan.murphy at fdlco.wi.gov; Steve Yott <tr4 at wi.rr.com>
> Subject: RE: [Fot] Grattan VSCDA next weekend?
>
> Sadly, we won't be able to make it.
>
> I just got the block back from the machine shop last Tuesday. Not enough
> time to get everything together and in the car and ready to go by Thursday.
> The good news is the liner stick out is the 0.004 the machine shop said
> they
> machined the liner seats and deck to. It's still a bitch to measure, as the
> liners "wobble" on the seats and when you're looking for 0.004 it's a
> problem. I finally have a decent dial indicator gage setup to at least give
> repeatable readings. The figure 8's used was a set of copper ones I had
> that measured 0.016. The machining was done on a single setup on a Rottler
> floor type vertical 4-inch spindle milling/boring machine. These are
> special purpose machine tools built specifically to machine engine parts,
> such as blocks and heads. After all the machining to get the stick out
> right I now have the pistons sticking up about 0.010 above the tops of the
> liners. No problem with the composite Payen head gasket.
>
> Thanks for all the responses to the Figure 8 gasket question. I did
> eventually hear back from Moss UK. They said their steel fig. 8's are 0.016
> and their copper fig. 8's were 0.018. No explanation regarding the
> different thickness other that they have not had reported problems with the
> gaskets. I'm not sure where the 0.020 thick copper ones that I measured
> came from or for that matter, the 0.016 thick copper ones I'm using.
>
> Tim & Ryan Murphy
> 1961 ('61, it is Comm. No. 511 and was built in 1961 per British Heritage)
> TR4 #317 BRG
>
> -----Original Message-----
> From: Fot [mailto:fot-bounces at autox.team.net <fot-bounces at
> autox.team.net>]
> On Behalf Of Tony Drews via
> Fot
> Sent: Saturday, August 12, 2017 6:21 PM
> To: fot at autox.team.net
> Subject: [Fot] Grattan VSCDA next weekend?
>
> Anyone else going to Grattan next weekend?
>
> Vroom, vroom, Tony Drews
>
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