440 still idles with screws turned in
- Thread starter Moparnocar
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Wietse
Well-Known Member
My blood was boiling when it broke...you can imagen where it went.
It might still be in orbit somewhere, perhaps it has left our solar system already. lol
Later on I will check the part numbers you left here and see if I they would fit my distributor, I want to get that vac can working if I can after the other modifications.
It might still be in orbit somewhere, perhaps it has left our solar system already. lol
Later on I will check the part numbers you left here and see if I they would fit my distributor, I want to get that vac can working if I can after the other modifications.
Geoff 2
Well-Known Member
The Rhoads lifters will make a difference & improve idle vacuum. So that will help with dialling in MVA. Engine may not want as much timing at idle with Rhoads but would think it would be 30+*.
Moparnocar
Well-Known Member
Well, so far so good. Jumped timing up to 25, and was able to back idle down. Better vac , 11ish, but still sounds like it's missing at idle, not loping. Power is WAY better. Gonna install the FBO kit, and 1 light spring.
Moparnocar
Well-Known Member
Sorry for late response, yes, 6.5 psi, new pump
Regulate it to 4# and see what happens.
Moparnocar
Well-Known Member
What's the reason for that? Flooding out the performer @ idle? I was able to get it to run on the idle circuit finally but upping timing like everyone said, how ever, can't get it to " lope " nicely. Plugs look good, good power, no bog. I put 5 lb springs in the metering rods, and tried #3s too
Geoff 2
Well-Known Member
[1] These carbs can easily withstand 8 psi f/pressure. In fact Carter recommended 7.5-8.5 for performance engines.
[2] You upped the initial timing, but is it enough? Here is how to check: engine warmed up, idling, in gear if auto, loosen dist clamp & slowly turn dist to advance timing. Advance dist until you have the highest rpm. Toggle the dist back & forth to make sure you have the highest rpm. Now check what the timing is....
You will never have the best possible idle & tip in response until you do this. The best way to get the extra timing at idle is to use an adj vac adv connected to manifold vacuum; most adj units can add up to 30* of timing. Even if you have to buy a new dist with adj VA, freely available. You might have to fabricate a stop to limit total VA applied; turn the Allen Key fully CW. Yes, it is a lot of messing around but once done, you never have to touch it again & the results will be well worth it.
[3] Once idle timing is sorted, you can adjust the carb. You may need to add bypass air, but this is only done AFTER step 2 above, NEVER before.
[4] To select the correct met rod piston springs. After above is completed, engine idling, in gear if auto, loosen piston covers & swivel slightly so that you can see the pistons but they are still retained; tighten cover screws. Pistons should be down, not moving. Swap springs & recheck. Ideal is strongest spring that keeps pistons down at idle.
[2] You upped the initial timing, but is it enough? Here is how to check: engine warmed up, idling, in gear if auto, loosen dist clamp & slowly turn dist to advance timing. Advance dist until you have the highest rpm. Toggle the dist back & forth to make sure you have the highest rpm. Now check what the timing is....
You will never have the best possible idle & tip in response until you do this. The best way to get the extra timing at idle is to use an adj vac adv connected to manifold vacuum; most adj units can add up to 30* of timing. Even if you have to buy a new dist with adj VA, freely available. You might have to fabricate a stop to limit total VA applied; turn the Allen Key fully CW. Yes, it is a lot of messing around but once done, you never have to touch it again & the results will be well worth it.
[3] Once idle timing is sorted, you can adjust the carb. You may need to add bypass air, but this is only done AFTER step 2 above, NEVER before.
[4] To select the correct met rod piston springs. After above is completed, engine idling, in gear if auto, loosen piston covers & swivel slightly so that you can see the pistons but they are still retained; tighten cover screws. Pistons should be down, not moving. Swap springs & recheck. Ideal is strongest spring that keeps pistons down at idle.
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8.5 psi is way to much for any carb out there.
What fuel pressure should I run with my new carb?
Carburetor Fuel Pressure by Manufacturer
Each style of carburetor has a fuel pressure range where they perform the best. The owners manual that came with your carb will give you set-up and tuning instructions. However, you can use the table below as a basic guideline.
Carburetor Style Recommended Fuel Pressure
Summit Racing 5 - 7 psi
Autolite 4.5 - 6.5 psi
Holley 5.5 - 7.5 psi
Edelbrock 6.5 psi (max)
Demon 5 - 6 psi (at idle)
Quadrajet (street engines) 4 - 5 psi
Quadrajet (performance engines) 6 - 7 psi
How do I adjust the pressure?
To adjust and maintain consistent fuel pressure to your carburetor, use a Fuel Pressure Regulator.
Why does it matter?
If your fuel pressure is too low, you run the risk of running the fuel bowls dry. If the pressure is too high, it can force too much fuel into the engine. That can cause fouled spark plugs, among other issues.
I disagree with what they say for Holley, more like 6.5 max, but this is good info.
Mark
What fuel pressure should I run with my new carb?
Carburetor Fuel Pressure by Manufacturer
Each style of carburetor has a fuel pressure range where they perform the best. The owners manual that came with your carb will give you set-up and tuning instructions. However, you can use the table below as a basic guideline.
Carburetor Style Recommended Fuel Pressure
Summit Racing 5 - 7 psi
Autolite 4.5 - 6.5 psi
Holley 5.5 - 7.5 psi
Edelbrock 6.5 psi (max)
Demon 5 - 6 psi (at idle)
Quadrajet (street engines) 4 - 5 psi
Quadrajet (performance engines) 6 - 7 psi
How do I adjust the pressure?
To adjust and maintain consistent fuel pressure to your carburetor, use a Fuel Pressure Regulator.
Why does it matter?
If your fuel pressure is too low, you run the risk of running the fuel bowls dry. If the pressure is too high, it can force too much fuel into the engine. That can cause fouled spark plugs, among other issues.
I disagree with what they say for Holley, more like 6.5 max, but this is good info.
Mark
4406bbl
Well-Known Member
It all depends on the needle and seats and the floats. You can run 8 maybe more on a Carter, but not with stock float settings. The holley does not seem to like that much, 7psi runs you out of adjustment with .110 seats, but I have no doubt you could do it with trial and error, just never had a need for it.
Geoff 2
Well-Known Member
8.5 psi is NOT too much when the manufacturer recommends it, which Carter did.
My Motors Manual covers 1959 to 1966 year models. The quoted specs come from the car manufacturers.
The quoted pressure for the 426 Ramcharger is 6-8 psi & the same for the Hemi.
Some 273 engines are listed at 6- 7.5 psi.
If the FP is changed from the recommended FP, the float level should be adjusted [ for any carb ]. Carter provides a chart for that & guess what? It goes up to 10 psi.
My Motors Manual covers 1959 to 1966 year models. The quoted specs come from the car manufacturers.
The quoted pressure for the 426 Ramcharger is 6-8 psi & the same for the Hemi.
Some 273 engines are listed at 6- 7.5 psi.
If the FP is changed from the recommended FP, the float level should be adjusted [ for any carb ]. Carter provides a chart for that & guess what? It goes up to 10 psi.
Moparnocar
Well-Known Member
The timing seemed to fix most issues, However, if I cant get it to idle nice , I'll try that.
4406bbl
Well-Known Member
Good to hear, with 11" of vacuum you have options. What idle rpm gets you the 11" reading? It should idle nice at 6 psi fuel pressure no problem. You say you are running on the idle circuit, so this means the mixture screws are 1-2 turns out, and the engine will die with one fully closed?
Moparnocar
Well-Known Member
Not sure on rpm, no tach, but I'd guess 700 ish. Yes, about 2 turns on screws. It will die now with one turned in
RM23M9A
Well-Known Member
Did you have the AIR CLEANER on or off of the CARBS while tuning? Having the FILTER & LID OFF, will LEAN it out. Filter installed causes a "restriction" making carbs PULL harder on idle A/F mix. Always tune carbs with Air Cleaner ON carbs.
RM23M9A
Well-Known Member
This an AVS you're working with?
That would be pretty near impossible on my 66 Hemi and possibly also on my air conditioned 67 GTX. Those big air filter cans and the upward angled idle mixture screws on AFBs pretty much restrict idle mixture adjustments to air cleaner off only. Just my observation.
Moparnocar
Well-Known Member
Yes, Edelbrock performer, timing was the biggest issue, needed to bump it up
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If you have enough restriction while idling to change the mixture, you have a problem with the air filter.
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