289 R.P.M.

I want to know why my motor 289 isn't keeping the r.p.m.?  

we need a better description than it isn't keeping the RPM...


there are so many things..

you might also want to clear up.. year.. make and model... since you posted here.. its probably a ford mustang.. so that narrows it down to about 49 year models..  

OK, your are right. My car is a Mustang 1.967, 289 cid, 4 speed (Top Loader) Coupe and my carb is a Holey 600 cfm. with a Pertronix Ignition and dual exhaust with Magnaflow mufflers.  I think may be is the carb, gas filter or fuel pump.
Thank you  

lets test the fuel system...

disable the distributer or coil.. so NO SPARKS can be created while you crank the engine...

disconnect the fuel line as close to the carb as you can..


extend the fuel line into a clean clear plastic 2 or 3 liter soda bottle....

while you control the bottle and the hose into the bottle...  have a friend crank the engine for 15 seconds...

each pulse from the fuel pump should be equal and full...  not diminishing...

you will also want to dead head a fuel pressure gauge on the hose...  the fuel pump should hold pressure...


i have had terrible issues with mid 60s fords... where the Red dUST gets from various sources...  gas tank.. fuel lines.. gas station..   this gets into the fuel pump as there is usually not a good fuel filter to protect it... the debris holds the check valves open.. reducing the amount of fuel pumped... i have found some that i could blow into the fuel line at the carb.. and make bubbling noises in the gas tank...   not a good day.. those cars also required 15 to 20 seconds of cranking to get fuel from the end of the hose..

i have also found these with fuel lines that were CRUSHED by jack stands and floor jacks...   leaking hose sections.. kinked hose sections..  others that were blocked with sediment..  these also failed the full flow cranking test..

you should get close to a pint in 15 seconds...  thats half a quart..

this test only takes a few minutes.. proves the fuel system can keep up with the carb needs..

a good fuel injection type of fuel filter installed in a loop of hose between the fuel line and the fuel pump inlet will cure a lot of issues..

start with this test...

you might want to take a magnet to the bottom of the bottle when you have performed this test.. see if it attracts sediment..

i have been sticking magnets to the bottom of fuel tanks to attract the sediment moving around inside them to one spot..
i also when i have the sending unit out.. drop in a super magnet into the inside. this also keeps the sediment out of the fuel lines, pumps, and carb... even keeps it out of the fuel filters...  

one more thing...  all cars need the ground wires hooked up properly...

do you own a digital volt meter...




run this test..


if you have a ground issue.. you may not have enough electrons to operate the various systems... like the ignition system


 

OK... thanks a lot. I will try next week end.  

I'm still confused as to what "not keeping RPM" means.
Can you please narrow it down a little bit more?
like:
doesn't idle with the right RPM, doesn't go over some rpm value,
doesn't accelerate, doesn't keep a constant RPM at idle or speed, etc....