[Fot] Engine going flat at 4500 rpm

[Tony Drews]

Are you running a fuel pressure regulator?  Any gunk in the fuel 
filter(s)?  Kinda sounds like problems we had long ago due to not 
enough fuel flow - in our case taking out the fuel pressure regulator 
solved it.  We also seemed to have an occasional problem where we 
think we were setting up a vibration in the float bowls of the carbs, 
but that was at more like 5500 RPM.

I'd try new pumps, check fuel filter, remove pressure regulator 
(those Facets don't put out much pressure anyway), look at what kind 
of diameter fuel line (I run 3/16" ID / -6 Aeroquip).  Double check 
float level, make sure the needles aren't sticking, look for junk in 
the bottom of the float bowls (probably need to take carbs apart to 
blow everything out).  If backing off of the gas seems to get you 
more RPM's, I strongly suspect a fuel delivery problem - that's how 
the regulator restriction acted.

Starting point, anyway...

Tony Drews

At 08:15 PM 3/3/2011, Greg & Alison Blake wrote:
>I ran at TWS this past weekend and had some trouble with the TR3.  On Friday
>and Saturday I could not get the engine to pull above 5500 RPM in 4th on the
>front straight at TWS.  Coming out of the corners in 3rd, I was getting
>6000rpm without issue.  I checked the timing and it was rock solid at
>32degrees at 3000-5000rpm.  I run H6 carbs with RC needles and 0.100 jets.
>I run twin facet cube pumps pushing fuel from the cell at the back.
>
>
>
>On Sunday, we noticed that my cross shaft (at the firewall) had lots of
>slop.  It turns out that the cross shaft was rotating about 10 degrees
>before it was pulling the little lever back that actuates throttle shaft.  I
>had been checking the butter flies by moving the carb linkage at the carbs,
>bad mistake.  My butter flies were not fully opening.  So we corrected that
>problem (thanks Walt) and at the same time I replaced the Grosse Jets with
>Viton tipped float needle valves.  Strange thing was I could not get the car
>to run over 4500 rpm on the front straight or pulling out of the corners
>after those two changes.  I tried going a bit then a lot richer (to the
>point the car would hardly start) thinking that I had just introduced a lot
>more airflow at full throttle, but that did not help.
>
>
>
>Any ideas?  I'd like to solve this one at home but I can't replicate the
>full load and this problem does not manifest until under full load.
>
>Thanks,
>
>
>
>Greg
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