318 idle rpm
- Thread starter Phil21502
- Start date
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I've been able to get them up to about 800...
Set the idle, then have a helper get inside and put the car in gear and make sure that the ammeter is not discharging... If it is when you have your foot on the brake in gear, bump it up a bit...
Make sure to adjust the accelerator pump on the carb also to help it come off the line... Shorter stroke = less gas, longer stroke - more gas... Try different positions of the linkage to the different holes on the arm to see where it runs the best...
Wyrmrider
Well-Known Member
and check your advance
now that you are out of smog you could move to say 68-70 specs fir a first try
as said above check your accelerator pump
600 is about stock so you should be able to get it to work
while you are at it run a compression check and check for oil *valve stem seals could be old) on the plugs
do the on it, off it , on it again puff of smoke test
you can run long reach plugs which run cleaner RFN14LY, RN12LYC (old numbers from memory LOL) look for AMC 6 plugs they can really clean up an idle in a low comp motor
those are OEM Champion numbers BTW
now that you are out of smog you could move to say 68-70 specs fir a first try
as said above check your accelerator pump
600 is about stock so you should be able to get it to work
while you are at it run a compression check and check for oil *valve stem seals could be old) on the plugs
do the on it, off it , on it again puff of smoke test
you can run long reach plugs which run cleaner RFN14LY, RN12LYC (old numbers from memory LOL) look for AMC 6 plugs they can really clean up an idle in a low comp motor
those are OEM Champion numbers BTW
Check the timing, it sounds like it could use advanced.
nm9stheham
Well-Known Member
Timing is what I would look at.... ignition AND cam. Being that old, the chances that the chain is worn and retarding the cam timing 3-5 degrees is pretty high. That will make any low compression engine doggy off-idle and mid-range.
OL DODGE
Well-Known Member
I could never get the carb set up correctly on Dad"s 318 even after it was rebuilt . Years later i found out why-the heat cross over was 100% blocked on the intake . It was maddening-you'd set it all up per the specs .fire it up and it'd all go to crap. My point is that there's a whole lot to take into consideration sometimes.
AJ/FormS
68 Formua-S fastback clone 367/A833/GVod/3.55s
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If it's sluggish, do a compression test.
And check the slack in the timing chain.
The cylinder pressure on these teeners was pretty low to begin with, and a retarded cam is like a hole in the drinking bucket, as is poor ring seal, huge ring gaps and sunk and/or leaking valves . A teener just can'afford to lose much pressure before the low-rpm performance goes straight into " a bit doggie in off-idle acceleration"
But ti answer your quwstion
Mine liked 500/550 in gear. But it had a 2.74 low, and 3.55s, and a 2800TC,so it would fly when I nailed it.
Your results may vary.
The trick is to get the throttle valves open far enough so that when you tip them in slowly, hesitation is all but eliminated. Then you set the pump-shot to fine tune it.
But the throttle valves have to be closed far enough so that the mixture screws can fine-tune the idle quality.
Find the sweet-spot and then give her advance, until the Rs climb high enough that it bangs into gear from neutral. Then back it up some. Your Rpm-drop into gear should not be more than about 100.
BTW, that heat crossover and the EGR baggage that comes with it, can be blocked off completely for the summer, even up here at the 50th latitude. Yeah you might have to tweak the carb a bit, but it is possible to pick up a little performance by doing that. If you drive your car 4-seasons, then it will be far,far, better to make sure it is functioning BEFORE it gets cold. Then you would also want to keep your carburetor preheat system as well. This is backwards for performance tho. Up here that device is designed to maintain an inlet-air temp of 85*F and all the carb circuits are designed to work on that except at WOT. At WOT the vacuum falls, the flapper opens, and the carb gets fresh cold air, or is supposed to, from in front of the core support..
At WOT, the EGR is supposed to be inoperative, and the X-over is supposed be stagnant or nearly so. What I'm saying is at WOT.
Now at normal throttle openings that passage and EGR are doing all kinds of dumbchit that may or may not be doing anything good for your engine, lo these many decades later.
Back to the Top
And check the slack in the timing chain.
The cylinder pressure on these teeners was pretty low to begin with, and a retarded cam is like a hole in the drinking bucket, as is poor ring seal, huge ring gaps and sunk and/or leaking valves . A teener just can'afford to lose much pressure before the low-rpm performance goes straight into " a bit doggie in off-idle acceleration"
But ti answer your quwstion
Mine liked 500/550 in gear. But it had a 2.74 low, and 3.55s, and a 2800TC,so it would fly when I nailed it.
Your results may vary.
The trick is to get the throttle valves open far enough so that when you tip them in slowly, hesitation is all but eliminated. Then you set the pump-shot to fine tune it.
But the throttle valves have to be closed far enough so that the mixture screws can fine-tune the idle quality.
Find the sweet-spot and then give her advance, until the Rs climb high enough that it bangs into gear from neutral. Then back it up some. Your Rpm-drop into gear should not be more than about 100.
BTW, that heat crossover and the EGR baggage that comes with it, can be blocked off completely for the summer, even up here at the 50th latitude. Yeah you might have to tweak the carb a bit, but it is possible to pick up a little performance by doing that. If you drive your car 4-seasons, then it will be far,far, better to make sure it is functioning BEFORE it gets cold. Then you would also want to keep your carburetor preheat system as well. This is backwards for performance tho. Up here that device is designed to maintain an inlet-air temp of 85*F and all the carb circuits are designed to work on that except at WOT. At WOT the vacuum falls, the flapper opens, and the carb gets fresh cold air, or is supposed to, from in front of the core support..
At WOT, the EGR is supposed to be inoperative, and the X-over is supposed be stagnant or nearly so. What I'm saying is at WOT.
Now at normal throttle openings that passage and EGR are doing all kinds of dumbchit that may or may not be doing anything good for your engine, lo these many decades later.
Back to the Top
Last edited:
BigBlockMopar
BigBlockMember
Idle RPM has little to do with off-line acceleration.
Proper ignition timing is imo one of the most neglected, but important things on an engine, next to proper air/fuel mixture.
If you're new to carbs (never thought/expected I would hear anyone say that), some good reading on how they work can be off great help. Especially if you like the technology behind it and want to get educated on the subject.
Proper ignition timing is imo one of the most neglected, but important things on an engine, next to proper air/fuel mixture.
If you're new to carbs (never thought/expected I would hear anyone say that), some good reading on how they work can be off great help. Especially if you like the technology behind it and want to get educated on the subject.
Wyrmrider
Well-Known Member
When NOT at WOT warm fuel/air stays in suspension better, washes down the cylinder walls less, better gas mileage cus you can run leaner (up to a point)
keep us posted
get a chance go TQ (like late OEM 318 4bbl) and learn how to adjust one- next best choice AVS
keep us posted
get a chance go TQ (like late OEM 318 4bbl) and learn how to adjust one- next best choice AVS
Wyrmrider
Well-Known Member
That's so retarded
so shorten up he timing to pre smog specs
do you not have a selonid that energizes with the ac on? (damn spell check)
so shorten up he timing to pre smog specs
do you not have a selonid that energizes with the ac on? (damn spell check)
BigBlockMopar
BigBlockMember
"0" advance is all about having late ignition to increase exhaust temperature to burn off any left over fuel particles after the initial burn. This is purely done for emissions to clean up and pass legislation at the time.
Most stock(ish) engines will like ignition advance to be well upto 25° (vacuumadv. included) at idle with transmission in drive.
Most stock(ish) engines will like ignition advance to be well upto 25° (vacuumadv. included) at idle with transmission in drive.
No solenoid on 73.
I have a couple I'm going to try fabricating a bracket for, but might wait until I put a 4 barrel on it so I don't have to do it twice.
As I said, any mechanical advance more than 0 at idle and it pings under load.
Car runs real good and will spin the tire for about 75 feet from a standing start with the 2.76 gear.
Could stand a bit better MPG. Getting about 14 average. Expected about 17.
I have a couple I'm going to try fabricating a bracket for, but might wait until I put a 4 barrel on it so I don't have to do it twice.
As I said, any mechanical advance more than 0 at idle and it pings under load.
Car runs real good and will spin the tire for about 75 feet from a standing start with the 2.76 gear.
Could stand a bit better MPG. Getting about 14 average. Expected about 17.
nm9stheham
Well-Known Member
I'm confused: Mechanical advance in the distributor weights, or in the initial setting? The 0 in the book is the initial setting. I suspect a lean carb.....or vacuum advance that is messed up or hooked up wrong.
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