DanielSlocum
Well-Known Member
Some may open farther/flow more than others i suppose.
My Six Pack seems odd
- Thread starter 440beep
- Start date
DanielSlocum
Well-Known Member
Regarding fuel pressure: A long time ago.....i was shocked to learn the hard way that......fuel pressure drops off some as under hood temps go up. Thus setting ones fuel pressure with the hood open can be very deceiving indeed.
Texas97
Well-Known Member
mechanical pump or electric pump or doesnt matter?
DanielSlocum
Well-Known Member
Doesnt matter the pump. Its all about the temp increase as the hood closes and the engine makes power. Might only drop of 1-2-3 psi,which can make all the difference[especially with NOS as was my case] .
What’s the ideal pressure? I’m going from EFI to the A12 setup, with electric pump, that I’ll regulate down.
I’ve heard 6.5-7 lbs
I’ve heard 6.5-7 lbs
Pulled #1, 2 and 8 plugs and definitely doesn’t look rich.
Texas97
Well-Known Member
i agree, doesnt look rich
Six Eight
Member
I have pretty much the same setup as you. Once I accepted the fact that the outboard carburetors contribute air/ fuel at idle, the engine became quite a bit more simple to tune.
cj's mopar
Well-Known Member
Question are these carbs original rebuilds
Or new replacement style from Holley?
Reason I ask is the main meter block on the center carb could be warped cause it to run rich . Or leak in the vacuum side of the power valve area
Or new replacement style from Holley?
Reason I ask is the main meter block on the center carb could be warped cause it to run rich . Or leak in the vacuum side of the power valve area
Mopar Miki
Well-Known Member
Plugs show tuning issues.
Those that think a six pak engine does not require a 195 t stat are not understanding the principles of 6 paks and proper tuning.
Those that think a six pak engine does not require a 195 t stat are not understanding the principles of 6 paks and proper tuning.
Texas97
Well-Known Member
id like to know the science behind a 195 degree and 185 degree thermostat for a 6 pack.
regardless of the thermostat temperature, underhood temperature that is affecting a carb wont be much different because of manifolds/headers, etc. So why does the engine thermostat need to be 195?
Mopar Miki
Well-Known Member
Free help is now closed
Today's gasoline is formulated to run in engines that operate with a min operating temperature of 195 degrees. A lower min operating temperature of 180 degrees or worse 160 degrees; allows raw fuel to collect on the intake surfaces and engine oil that never gets to the proper operating temperature. That unburned fuel slowly burns off in the cruise mode causing the air-fuel mixture to eventually go lean creating a ping-pong effect with the AF. Reformulated and/or oxygenated unleaded gasoline with or without ethanol creates different tuning parameters.
AF Ratios are set different between ethanol/non-ethanol gas/race gas!!
For gasoline engines, the ideal or stoichiometric A/F ratio is 14.7,which is 14.7 parts of fuel by weight to one part fuel.
ForE10 gasoline (90 percent gasoline with 10 percent ethanol alcohol),the stoichiometric ratio is 14.08:1.
Engines don't create the most peak power or best fuel curves at a predetermined A/F ratio. The A/F ratio is merely a number you should take into consideration when tuning to keep out of the danger zone. At the end of the day, you are looking for the best performance, not a specific reading on the A/F meter. Ha!
Overjetting of the center carb will not ever allow idle mixture control as the jet size does contribute to the amount of fuel sent to the idle circuit. At idle fuel flows from the float chamber thru the main jet then into a the small angular but horizontal passage that leads across to a vertical passage and onto the idle feed restriction where it is mixed with the air coming in from the idle bleed. Remember this. Do not over jet!
The baseline settings affects the AF thru the entire rpm operating range and the AF ratios at WOT. Remember - at very light throttle openings the engine is running in the idle circuit rather than in the main metering circuit.
A very normal operating temp is 195-220
230 is warm
240 is HOT
250 is very hot
260 is overheating
Beware of high under-hood temperatures. Measure it at the base of the ctr carb! Check after a heat soak. Lowering the minimum operating temperature of the engine to 180 or 160 degrees F does not correct this problem. Lean engines and or improperly tuned/timed engines create lots of under the hood heat. Power steering pumps and automatic transmissions create heat so an external cooler should be installed.
Today's gasoline is formulated to run in engines that operate with a min operating temperature of 195 degrees. A lower min operating temperature of 180 degrees or worse 160 degrees; allows raw fuel to collect on the intake surfaces and engine oil that never gets to the proper operating temperature. That unburned fuel slowly burns off in the cruise mode causing the air-fuel mixture to eventually go lean creating a ping-pong effect with the AF. Reformulated and/or oxygenated unleaded gasoline with or without ethanol creates different tuning parameters.
AF Ratios are set different between ethanol/non-ethanol gas/race gas!!
For gasoline engines, the ideal or stoichiometric A/F ratio is 14.7,which is 14.7 parts of fuel by weight to one part fuel.
ForE10 gasoline (90 percent gasoline with 10 percent ethanol alcohol),the stoichiometric ratio is 14.08:1.
Engines don't create the most peak power or best fuel curves at a predetermined A/F ratio. The A/F ratio is merely a number you should take into consideration when tuning to keep out of the danger zone. At the end of the day, you are looking for the best performance, not a specific reading on the A/F meter. Ha!
Overjetting of the center carb will not ever allow idle mixture control as the jet size does contribute to the amount of fuel sent to the idle circuit. At idle fuel flows from the float chamber thru the main jet then into a the small angular but horizontal passage that leads across to a vertical passage and onto the idle feed restriction where it is mixed with the air coming in from the idle bleed. Remember this. Do not over jet!
The baseline settings affects the AF thru the entire rpm operating range and the AF ratios at WOT. Remember - at very light throttle openings the engine is running in the idle circuit rather than in the main metering circuit.
A very normal operating temp is 195-220
230 is warm
240 is HOT
250 is very hot
260 is overheating
Beware of high under-hood temperatures. Measure it at the base of the ctr carb! Check after a heat soak. Lowering the minimum operating temperature of the engine to 180 or 160 degrees F does not correct this problem. Lean engines and or improperly tuned/timed engines create lots of under the hood heat. Power steering pumps and automatic transmissions create heat so an external cooler should be installed.
cj's mopar
Well-Known Member
Thank you for posting this .
However we have to remember
This is related to street driven vehicles .
This may not apply to someone who is drag racing the car at track on Saturday night. Keep this in mind I never have run the fastest ET with my engine at 220 deg.at.a track .
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