Bernie ..... I forwarded your email to my friend Dave Zappetini, out there
in the SF bay area( Marin County ),
and he has run an unblown fuel digger for some years now, and my youngest
son Darrell spends a lot of time working on the dragster( while his own Black
Radon Eng altered is not yet ready to return to the Salt ...... )
Here is what Dave sent back to me regarding your injectors :
You might bring up the idle rpm so the transition is not as great so you
can burn the fuel, but with my car we installed a bdk valve to adjust the
volume of fuel. The idle jets could be squeezed down to raise the egt temps .
You could put a thinner head gasket to raise the compression and burn the
fuel.
The fuel pump bypass is installed so when you idle fuel goes back to the
tank, then you have a pump saver bypass that works when you get off the
throttle
so you do no hydraulic the pump.
This is what we do, but we have 160lbs. of idle fuel pressure and that is
not where you are at.
The problem sounds like the barrel valve is dumping too much fuel and the
motor can not take it.
Maybe you could adjust the barrel valve to react slower, by moving the
linkage or lenghtening a linkage arm.
We calculate the total area of the jets that feed the motor so we can adjust
the fuel volume but with a carb you have less of an adjustment which makes
it easier to run.
Maybe you need to put an under drive on the fuel pump.
When they changed the pill how much of a change was made?
How much fuel pressure were they using?
What is the jet size in the bypass?
What spring pressue is in the bypass?
Check the bypass for a blockage.
What is the fuel percentage?
Do you have a Don Jackson fuel book?
Dave Z.
( Please send any questions that you might have directly to Dave at
: _zappsintro@msn.com_ (mailto:zappsintro@msn.com) )
Good Luck with your Rat Motor ! ..... our cast iron one ran well( 259 +
)on the Salt; the following year the aluminum block Merlin one blew( on 20%
)part way down the course .....as someone( JD ? ) wrote here recently, the
Salt
can be a real 'humbler' of many of our best building/racing efforts ! )
Bruce F. on the CT shoreline ~
PS : Good Luck to Glen Barrett on his new ball-joint(s) installation, and,
Thanks, again, to him : he was one of the first on the scene when that Merlin
self-destructed into many worthless piece$$$$$ .......
~ SPEED COSTS MONEY ~ HOW FAST DO YOU WANT TO GO ??? ~
( that sign was over the door to Banjo Matthews' speed shop many, many years
ago )
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