JDMopar
Well-Known Member
That thing is cool ! You should rig up a swivel crane with a boat trailer winch in one corner of the bed. If for nothing else, it would make it easy to get the floor jack that weighs more than you do in and out of the bed.
What causes "dieseling"
- Thread starter Princess Valiant
- Start date
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Screw that. That's too much like work! Get an electric winch. lolThat thing is cool ! You should rig up a swivel crane with a boat trailer winch in one corner of the bed. If for nothing else, it would make it easy to get the floor jack that weighs more than you do in and out of the bed.
AJ/FormS
68 Formua-S fastback clone 367/A833/GVod/3.55s
- Joined
- Jan 19, 2014
- Messages
- 25,587
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Principally, as has been said; as to engine run-on, this is caused by
the throttle blades being too far open, at engine shut-down.
This allows the inertia of the spinning crank to allow the atmosphere to keep on bullying it's way into the engine, past the throttle blades, where it picks up fuel;
and to continue into the chambers, where, anything glowing-hot can ignite it, including hot sparkplugs.
BTW-1
You can idle that engine at any rpm you want to. That sticker provides the baseline to pass emissions in the year it was manufactured. It has nothing to do with best performance, nor with best fuel-economy, nor with best anything.
Nor is the engine, with stock timing and carburetion, going to be the best that it can ever be; no matter how you set it.
But
those factory parts can be modified, to get reasonably close.
as to fueling;
most of those emission carbs have what is commonly called, a "throttle-kicker"; which is like an electric fast-idle device. When everything is working right, you probably will never know it's there.
It's job is to reduce the idle rpm to near stalling, as soon as you shut the key off.
It is called a kicker, cuz as soon as the engine runs, it kicks the idle UP, to prevent that stalling.
What this means to you is that if you have a kicker, you now have TWO idle-speeds to set; the first is the base throttle opening, aka the curb-idle speed, and the second is the running idle speed, with the kicker engaged.
The first is set with the curb-idle screw, to just above stalling, and the second is set by turning the plunger shaft, that is sticking out of the kicker, but before you do that,
1) verify that the kicker still works and
2) those kickers rarely have enough power to actually kick the throttle open, so you gotta open the throttle just a crack, manually, and then you can work that shaft, which usually has a hex head.
3) That said; if you change the timing AFTER these two idles have been set, you will need to reset the idles again. So do the timing thing FIRST.
As to ignition timing;
Every internal combustion gasoline engine, installed in a passenger car, has FOUR basic timing requirements. In order of importance, IMO, they are;
1) maximum Power-Timing
2) Power-timing at stall-speed, for automatics, obviously
3) Cruize-Timing
4) Idle-Timing
As to Power-Timing;
ALMOST all SBMs will want at least 34 degrees of Power Timing, which is the total of;
1) the max that the distributor can supply, added to,
2) whatever you set the IDLE-Timing to.
However, different configurations of engines will determine how soon or how late, this Power-Timing number will be accepted by the engine. Some engines will not detonate at 36* at 3800, but will detonate at 3600. Some will accept 36* at 3000. More is not necessarily better.
A reasonably safe target number is 34* at 3400rpm.
You will need a tachometer and a timing light. If your balancer is not scribed out to some 40 degrees, then you will need a Dial-type of timing light. Alternatively you can install a Timing-Tape on your clean balancer, and use a regular timing light.
If yur not into modifying distributors, do this.
1) With the vacuum advance disconnected; check and record your current idle timing
2) rev the engine up until the distributor stops advancing. Record the amount of advance, and the rpm at which this occurs.
3) subtract the little number from the bigger number. This is the amount of advance that this particular distributor is "programmed" to supply. This is usually called the Mechanical Advance.
4) Whatever the number is, subtract it from 34 and set your Idle Timing to that smaller number.
Example, if you get 24* of Mechanical advance then;
34 less 24 equals 10, so set your idle timing to 10 degrees.
Then go tune your curb-idle, down to just above stall. Then set your running idle rpm. then tune your mixture screws to best lean idle. Then
Hook your Vcan back up, and roadtest it.
As to Cruize-timing,
If yur not into taking apart and modifying the guts of your distributor, just drive it, as above. Just know that there may be gains to be had, in those modifications, but the realization of those gains can be a lotta lotta work.
Just drive it.
As to Idle-Timing
Again, to change it, after the Power-Timing has been discovered and set, requires the distributor to be disassembled and modified, and honestly your particular engine hardly cares what the Idle timing is, just set the power timing, and drive it.
As to stall-timing
In your application, the first time the engine really cares about timing, will be at Convertor stall-rpm; and one more time, you cannot easily change that ............ just drive it....... unless she gets into detonation,
now you gotta make wholesale distributor changes.
the throttle blades being too far open, at engine shut-down.
This allows the inertia of the spinning crank to allow the atmosphere to keep on bullying it's way into the engine, past the throttle blades, where it picks up fuel;
and to continue into the chambers, where, anything glowing-hot can ignite it, including hot sparkplugs.
BTW-1
You can idle that engine at any rpm you want to. That sticker provides the baseline to pass emissions in the year it was manufactured. It has nothing to do with best performance, nor with best fuel-economy, nor with best anything.
Nor is the engine, with stock timing and carburetion, going to be the best that it can ever be; no matter how you set it.
But
those factory parts can be modified, to get reasonably close.
as to fueling;
most of those emission carbs have what is commonly called, a "throttle-kicker"; which is like an electric fast-idle device. When everything is working right, you probably will never know it's there.
It's job is to reduce the idle rpm to near stalling, as soon as you shut the key off.
It is called a kicker, cuz as soon as the engine runs, it kicks the idle UP, to prevent that stalling.
What this means to you is that if you have a kicker, you now have TWO idle-speeds to set; the first is the base throttle opening, aka the curb-idle speed, and the second is the running idle speed, with the kicker engaged.
The first is set with the curb-idle screw, to just above stalling, and the second is set by turning the plunger shaft, that is sticking out of the kicker, but before you do that,
1) verify that the kicker still works and
2) those kickers rarely have enough power to actually kick the throttle open, so you gotta open the throttle just a crack, manually, and then you can work that shaft, which usually has a hex head.
3) That said; if you change the timing AFTER these two idles have been set, you will need to reset the idles again. So do the timing thing FIRST.
As to ignition timing;
Every internal combustion gasoline engine, installed in a passenger car, has FOUR basic timing requirements. In order of importance, IMO, they are;
1) maximum Power-Timing
2) Power-timing at stall-speed, for automatics, obviously
3) Cruize-Timing
4) Idle-Timing
As to Power-Timing;
ALMOST all SBMs will want at least 34 degrees of Power Timing, which is the total of;
1) the max that the distributor can supply, added to,
2) whatever you set the IDLE-Timing to.
However, different configurations of engines will determine how soon or how late, this Power-Timing number will be accepted by the engine. Some engines will not detonate at 36* at 3800, but will detonate at 3600. Some will accept 36* at 3000. More is not necessarily better.
A reasonably safe target number is 34* at 3400rpm.
You will need a tachometer and a timing light. If your balancer is not scribed out to some 40 degrees, then you will need a Dial-type of timing light. Alternatively you can install a Timing-Tape on your clean balancer, and use a regular timing light.
If yur not into modifying distributors, do this.
1) With the vacuum advance disconnected; check and record your current idle timing
2) rev the engine up until the distributor stops advancing. Record the amount of advance, and the rpm at which this occurs.
3) subtract the little number from the bigger number. This is the amount of advance that this particular distributor is "programmed" to supply. This is usually called the Mechanical Advance.
4) Whatever the number is, subtract it from 34 and set your Idle Timing to that smaller number.
Example, if you get 24* of Mechanical advance then;
34 less 24 equals 10, so set your idle timing to 10 degrees.
Then go tune your curb-idle, down to just above stall. Then set your running idle rpm. then tune your mixture screws to best lean idle. Then
Hook your Vcan back up, and roadtest it.
As to Cruize-timing,
If yur not into taking apart and modifying the guts of your distributor, just drive it, as above. Just know that there may be gains to be had, in those modifications, but the realization of those gains can be a lotta lotta work.
Just drive it.
As to Idle-Timing
Again, to change it, after the Power-Timing has been discovered and set, requires the distributor to be disassembled and modified, and honestly your particular engine hardly cares what the Idle timing is, just set the power timing, and drive it.
As to stall-timing
In your application, the first time the engine really cares about timing, will be at Convertor stall-rpm; and one more time, you cannot easily change that ............ just drive it....... unless she gets into detonation,
now you gotta make wholesale distributor changes.
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ESP47
Well-Known Member
I remember when I had a vacuum leak back in the day and my engine was idling higher than normal, I'd slam it into park and shut the key off as quick as I could before the rpms would rise. That would keep people in the parking lot from looking at me like I was some sort of hillbilly.
@Princess Valiant any updates?
Ran out of weekend and have not had time to mess with it more because of overtime at my office job.
I have a 3 day weekend coming so I'm planning to work on it more. I'm going to lower the idle and then I'm going to take the time and find TDC and mark the balancer and try timing it again.
Also I have some more tune up parts on order.... Shame you cain't just walk into a local parts store and get slant six parts over the counter anymore.
sorcerer
Active Member
Do like me since you have a manual transmission ; when you turn ignition off engage the engine releasing the clutch as it comes to a stop. I do that with a 417 stroker for many years; you will get used to it when you consider benefits it does.
Dale Davies
Well-Known Member
Lots of those emissions era engines had an idle solenoid. When you turned the key on they were generally not strong enough to open the throttle a bit, but a small tap on the throttle and they would hold. The bolt that pushed on the throttle linkage was used to adjust the idle speed. When you turned the key off, the solenoid snapped back, closing the throttle a bit. If you disconnected the wire to the solenoid, you could set the idle to say 600 RPM. You should be able to get a new solenoid from a parts store. Uses power supplied from key on engine run ignition switch terminal. The other way is to just set the idle to 700 to 750 RPM.
Yep, that will shut down the motor immediately.
Dale Davies
Well-Known Member
Lots of emission era engines had this problem. Timing at or close to TDC and the throttle opened more for a higher idle. An idle solenoid can fix it to comply with emissions. If an emissions test is not an issue, take 5° to 10° out of the mechanical advance and set initial to 8° to 10°BTDC. Reset the idle speed and mixture.
I think it likes 10* Btdc
Really hard to see on video but it's at 10 Btdc
I need to mark the balancer to be seen on video better.
I played with the idle and it kinda told me where it wants.
Really hard to see on video but it's at 10 Btdc
I need to mark the balancer to be seen on video better.
I played with the idle and it kinda told me where it wants.
I began having a dieseling-upon-shutdown on my stroked Hemi. This was low on the list of tuning issues but it didn't start occuring until the move to FL. I initially thought excess fuel was puddling on the floor of the cross ram, causing the issue. Long story short, I was using the 93 octane at various stations with price per gallon in mind. I recently switched to Top Tier only fuel and the issue is gone. I do the water trickle procedure about every 3 to 6 months as well. Hope this helps.
This kind of add-on is just what I need on one of my carbs on a 2.2 with run on issues. Does someone make a retro fit piece that closes the carb tight when you shut off the switch?
AJ/FormS
68 Formua-S fastback clone 367/A833/GVod/3.55s
- Joined
- Jan 19, 2014
- Messages
- 25,587
- Reaction score
- 12,870
IDK
But you can make your own bracket, and it doesn't have to be physically mounted where Carter put theirs. It doesn't have to be electric. And in fact, the Idle-Air doesn't even have to come past the throttle plates.
But you can make your own bracket, and it doesn't have to be physically mounted where Carter put theirs. It doesn't have to be electric. And in fact, the Idle-Air doesn't even have to come past the throttle plates.
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Dale Davies
Well-Known Member
I do not know if there are retro fit kits. Look at auto parts for a replacement for a 70's car. The throttle does not need to be closed tight when the solenoid is de energized, just say 150RPM less should do it. Your energized idle is set with the push rod on the solenoid.
Summit has some. I saw one listed for a Camaro, so probably a V8.
Amazon also has a bunch listed.
Some the body had a thread that screwed through the mount bracket and locked with a jam nut. Just find one that looks like you can make it work.
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