[hal101]

Originally Posted by Formulajones

I didn't say you definitely have nozzle drip, but you do definitely have carb tuning issues and some form of fuel remaining to create your run on. I'd be willing to bet you have the transition slot uncovered, so instead of fuel coming from the idle circuit "under" the throttle blade, it's going to come from the booster up above. Good recipe for run on. It may be as simple for you, and help to some degree, if you opened the rear blades slightly so you can close the front blades a little more.

I have 2 high compression engines here, with iron heads, one that is 11:1 that runs on pump. They don't have "run on" issues with straight 91 octane. Just trying to help as are others so you aren't spending unnecessary money.

im sure you are trying to help but my carb is in a great state of tune it idles great
the transition slot is not uncovered
there will always be fuel being drawn into the eng as long as it is turning
the key dose not turn off the fuel
just because you saw another car that had the prob that you are describing
that dosent mean my car has the same prob more than one thing can cause running on in my case it is low octane

[Schurkey]

Originally Posted by Schurkey

The typical cause of run-on is that the idle speed is too high.

Drop the idle speed, see what happens.

Originally Posted by hal101

600 to 800 cold when it is fully warmed up it dose creep up to maby 1000 in neutral 800 in gear

i can turn the idle down slower but with this cam it gets prity chopy

i like it just the way it is and it has never ran on with high octane fuel

Originally Posted by Formulajones

you do definitely have carb tuning issues .

A "Thousand RPM Idle" with an automatic transmission is just silly.

Fix the fuel curve so it idles decently, turn down the idle speed, and "POOF" the problem is solved.

This is not a detonation problem. This is not an octane problem. This is a "throttle blades are open too far" problem.

[hal101]

ok im done nobody wants to listen to what i say you think you know everything so please do not post to this thread anymore

[Cliff R]

My 12:1 428 did the same thing on lower octane gas. Did not diesel with good gas.

My current 455 will do the same thing. It is 11 to 1 compression and 236/245/112 HR cam. It is tuned to the brink of extinction, timing an fuel curves are spot on, and I race the car in addition to street driving it. The engine idles fine at 700rpm's in and out of gear, so idling too fast is not the issue.

I run it on a pretty steady diet of 87 octane and it does NOT even think about pinging under any conditions. Race days only I'll mix in half a tank of 92-93 octane on the way to the track just to give me a "warm and fuzzy".

What I do see in the hottest summer months when it's fully heat soaked is that it will run on once in a while when shut-down. If I use 89-93 octane it doesn't do this. If it's in the cooler time of the year of Winter it doesn't do it either.

It also "bucks" the starter ever so slightly when it's hot enough outside and engine hot enough to "run-on" after shut down. The easy cure is to run 89 or higher octane in in July and August and it never has an issue........Cliff

[hal101]

thanks cliff
im mixing fuel with a new additive and i got the octane to low on the first batch

[Schurkey]

Originally Posted by hal101

ok im done nobody wants to listen to what i say you think you know everything so please do not post to this thread anymore

We're all listening to what you have to say. YOU aren't listening to us.

Originally Posted by Cliff R

My 12:1 428 did the same thing on lower octane gas. Did not diesel with good gas.

My current 455 will do the same thing. It is 11 to 1 compression and 236/245/112 HR cam. It is tuned to the brink of extinction, timing an fuel curves are spot on, and I race the car in addition to street driving it. The engine idles fine at 700rpm's in and out of gear, so idling too fast is not the issue.

I run it on a pretty steady diet of 87 octane and it does NOT even think about pinging under any conditions. Race days only I'll mix in half a tank of 92-93 octane on the way to the track just to give me a "warm and fuzzy".

What I do see in the hottest summer months when it's fully heat soaked is that it will run on once in a while when shut-down. If I use 89-93 octane it doesn't do this. If it's in the cooler time of the year of Winter it doesn't do it either.

It also "bucks" the starter ever so slightly when it's hot enough outside and engine hot enough to "run-on" after shut down. The easy cure is to run 89 or higher octane in in July and August and it never has an issue........Cliff

Originally Posted by hal101

thanks cliff
im mixing fuel with a new additive and i got the octane to low on the first batch

So there we have it.

Proper tuning, 87 octane, no detonation, 700 rpm idle.

or,

Schitty tuning, Octane to the moon, Thousand RPM Idle, and it runs on.

I know which car I'd rather drive.

[hal101]

nobody is asking you

you couldnt answer the question so you made up a prob you thought you could fix

[steve25]

Two things to note here, one was rolled into Cliffs reply to you being that the temp of the air injested into the Carb on a hot day can make for run on, and number 2 different Brand / blend fuels will react different to a given air temp.
In light of this you might try a few different brands of the same octane to see if one or another helps out.
Just make a strong mental note that when a given let's say 89 octane fuel is found that's better then another 89 octane fuel in regards to your run on issue it will have less anti knock qualitys to it under full throttle load!

[hal101]

the question was never how to cure run on

the only question was is run on an indication of detonation that i cant hear

i know what caused the run on it happened when i dropped the octane

im just trying to find the lowest octane that i can safely run

[Formulajones]

Okay look, you were on here a couple months back asking questions about your compression, wanting to drive the car across country and needed solutions to your problem then. A lot of great advice was given by several members here and it appeared you didn't want to hear it then.

Now here we are.

To answer that first question of run on being an indication of detonation. The answer to that is NO.

You're getting run on because you have fuel remaining in the chamber, and it's igniting from the heat, throttle blades are most likely open too far. The low octane ignites when the key is shut off because of the extreme chamber heat, high compression, high heat range plugs, etc etc...

The only reason it goes away with more octane is because of the simple fact that higher octane is harder to ignite, it's slow burning. I explained this in post 20, and others have mentioned it as well. It doesn't mean your problem is fixed, it's just a bandaid to a larger issue. It doesn't necessarily mean your engine is detonating while you're driving it, but there is a pretty good chance you're causing damage trying to run 87 octane in a 11:1 motor with iron heads. But again we need more details on your state of tune. An engine like this is going to need spot on timing curves and close control of engine temps, as well as perfect AFR's if you are going to attempt to run this on pump gas, especially in the summer heat.
I have plenty of success doing this, my wife is daily driving an 11:1 engine on pump gas with iron heads and experiences absolutely NONE of these issues you're having. But I have close control over the parameters.

If your fine with spending $300 on additives to try and cure the issue, and don't mind dumping stuff in the tank every time you fill up, and happy with the results, then have at it. It's your car.
Seems to me it would be cheaper for you to just fill up with 91 or 93 instead of that cat pee 87, and tune the car accordingly for best all around drivability, and quit fooling with it. Better yet, for more piece of mind if you aren't confident in keeping control of the tune, I'd start looking at ways to lower dynamic compression with a cam change, or go straight for a set of aluminum heads that are more tolerable to octane levels so you can quit worrying about it. All things that were suggested in earlier threads.
Hope that helps.

[bryany]

I'm just reading the thread to see the new ways to spell common words.

Bryan

[hal101]

Originally Posted by Formulajones

Okay look, you were on here a couple months back asking questions about your compression, wanting to drive the car across country and needed solutions to your problem then. A lot of great advice was given by several members here and it appeared you didn't want to hear it then.

Now here we are.

To answer that first question of run on being an indication of detonation. The answer to that is NO.

You're getting run on because you have fuel remaining in the chamber, and it's igniting from the heat, throttle blades are most likely open too far. The low octane ignites when the key is shut off because of the extreme chamber heat, high compression, high heat range plugs, etc etc...

The only reason it goes away with more octane is because of the simple fact that higher octane is harder to ignite, it's slow burning. I explained this in post 20, and others have mentioned it as well. It doesn't mean your problem is fixed, it's just a bandaid to a larger issue. It doesn't necessarily mean your engine is detonating while you're driving it, but there is a pretty good chance you're causing damage trying to run 87 octane in a 11:1 motor with iron heads. But again we need more details on your state of tune. An engine like this is going to need spot on timing curves and close control of engine temps, as well as perfect AFR's if you are going to attempt to run this on pump gas, especially in the summer heat.
I have plenty of success doing this, my wife is daily driving an 11:1 engine on pump gas with iron heads and experiences absolutely NONE of these issues you're having. But I have close control over the parameters.

If your fine with spending $300 on additives to try and cure the issue, and don't mind dumping stuff in the tank every time you fill up, and happy with the results, then have at it. It's your car.
Seems to me it would be cheaper for you to just fill up with 91 or 93 instead of that cat pee 87, and tune the car accordingly for best all around drivability, and quit fooling with it. Better yet, for more piece of mind if you aren't confident in keeping control of the tune, I'd start looking at ways to lower dynamic compression with a cam change, or go straight for a set of aluminum heads that are more tolerable to octane levels so you can quit worrying about it. All things that were suggested in earlier threads.
Hope that helps.

you dont read what im saying so why should i respond

[STEELCITYFIREBIRD]

Originally Posted by bryany

I'm just reading the thread to see the new ways to spell common words.

Bryan

Thread that's best to just walk away from.

[70 bird]

Shut it off in drive under load, then put it in park.

[hal101]

Originally Posted by 70 bird

Shut it off in drive under load, then put it in park.

yes i do thank you

[tooski]

[QUOTE=hal101;5842376
but when i turned it off it ran on for about 3 or 4 sec
is that a sign of detonation that i cant hear or nothing to worried about?[/QUOTE]

If there is run on without spark (ignition turned off), I would call that detonation. (Just enough to keep the engine turning, maybe without hammering the bearings)
As Paul stated, if it was pre-ignition, the engine would cease to run.

When I had it I worried about it as the engine was more like bucking than running at 1-300 rpm. I don't know what the minimum rpm an oil pump requires to pump oil, but that was my concern. Did not have the presence of mind to look at oil pressure.

[wbnapier]

I am curious to know how your additive works for you. I have a 455, with #48 heads, and using California 91, it pings and diesels. I have been running 100 octane for some time, but I drive the car so much, the cost is unbearable. I have purchased https://boostane.com., which I plane to mix with 91 pump gas. The savings is marginal though as it is $20+ a bottle.

[tom s]

Your lucky you can get by with the 100,you have to be way over 11-1 if the block has been decked and any over bore.Tom

[Formulajones]

We ran a .030 455 with #12's, flat tops and zero decked on the street, and used a solid flat tappet ultradyne cam. In Ohio 94 octane was available at that time with no ethanol and that's what it was run with.

Had to be sharp on the tune, AFR, and keep engine temps under control but it was manageable. It didn't run on or diesel or any of those issues and was street driven for about 4 years. However when we raced it at the track it got several gallons of 115 octane race gas mixed with the pump gas to be safe.

It got to the point even that became a nuisance racing it 4-5 times a year so aluminum heads came into the picture.

I wouldn't even attempt that anymore living out here in AZ, same crappy 91 gas you guys have in California, lol.

[hal101]

Originally Posted by wbnapier

I am curious to know how your additive works for you. I have a 455, with #48 heads, and using California 91, it pings and diesels. I have been running 100 octane for some time, but I drive the car so much, the cost is unbearable. I have purchased https://boostane.com., which I plane to mix with 91 pump gas. The savings is marginal though as it is $20+ a bottle.

im not happy mixing it with 87 octane

so next mix will be with 93 octane ill let you know how it goes