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Stumble @WOT

Hey guys I'm finally back in action. From my busted collarbone.
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So I've been tinkering and adjusting but nothing could get the bog to go away.. I decided to put the demon back on to see how the car ran.. I put the old demon back on and no bog at all. Once the quickfuel recovers it seams to pull a littler harder, but the demon has no stumble.. What the heck??

Here is the Demon Video


Here is the Quickfuel with the bog


I'm going to open up the quickfuel and see if I find anything suspicious and maybe try changing the power valve? But the demon has a 6.5 power valve? Does this give you guys any other ideas??
 

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I am back to wondering about the vacuum secondary spring. I saw that you changed it to a stiffer spring. Why not experiment and put in the stiffest spring and see how it runs, and then take it from there.
 
I am back to wondering about the vacuum secondary spring. I saw that you changed it to a stiffer spring. Why not experiment and put in the stiffest spring and see how it runs, and then take it from there.
I'd thought that but when I did my paper clip test. The bog was occurring before the secondaries opened?
 
I remember that point now that you remind me. I think what is needed is another test that points to the problem being with the primaries. Have you tried wiring the secondaries shut?
 
I remember that point now that you remind me. I think what is needed is another test that points to the problem being with the primaries. Have you tried wiring the secondaries shut?

I have not yet ill try that this week see if it has any effect
 
So bringing this tread back to life. Since the problem still exists. I put the demon back on the car for a bit. It wanted to bog (lean out) right out of an idle and would die if the engine was still a little cold. Swapped back to the Quick Fuel. And the lean bog after is still there when accelerating. The engine will start to rev up then fall on its face.
Any ideas guys?? Im wondering timing or vacuum leak? since its happening with both carbs? Different bog spots on accerleration but both are a lean bog.
 
I really need help, I'm so lost. I checked for a vacuum leak with propane, couldn't find any leaks, pulled all my plugs no oil on them appear to be burning clean so i dont think i have a leak in the valley. That leaves me with.. timing? Im going to put an old extra distributor in tomorrow and see if there is a change. Any other ideas of things I should check?
The car falls fall on its face off the line under moderate-hard acceleration (then recovers and pulls hard), still leans out under easy accel but doesnt really sputter like harder acceleration. If I'm driving slow with throttle just barely cracked the engine runs lean and it's much worse when the car is cold. Cant even drive it till engine idles up to temp, otherwise the the minute you step on the gas the engine leans out and dies. Its also backfired through the carb on me a few times when trying to accelerate from a stop while cold, but only ever backfired while under normal operating temp. I really need help guys. Any ideas are appreciated!! Thank you.
 
Is ur choke operable? What is timing at 3000 rpm or so with vac adv plugged? You may just have to go back on carb settings to ur original. Maybe ur off the mark from so many changes? Engine sounds healthy though.
 
I really need help, I'm so lost. I checked for a vacuum leak with propane, couldn't find any leaks, pulled all my plugs no oil on them appear to be burning clean so i dont think i have a leak in the valley. That leaves me with.. timing? Im going to put an old extra distributor in tomorrow and see if there is a change. Any other ideas of things I should check?
The car falls fall on its face off the line under moderate-hard acceleration (then recovers and pulls hard), still leans out under easy accel but doesnt really sputter like harder acceleration. If I'm driving slow with throttle just barely cracked the engine runs lean and it's much worse when the car is cold. Cant even drive it till engine idles up to temp, otherwise the the minute you step on the gas the engine leans out and dies. Its also backfired through the carb on me a few times when trying to accelerate from a stop while cold, but only ever backfired while under normal operating temp. I really need help guys. Any ideas are appreciated!! Thank you.

I didn’t read through all the pages. Did you try a different pump cam? Pink cam is pretty lazy. Also timing?
 
Is ur choke operable? What is timing at 3000 rpm or so with vac adv plugged? You may just have to go back on carb settings to ur original. Maybe ur off the mark from so many changes? Engine sounds healthy though.
yes choke is operational. I think my total advance was I believe my total advance was 36 degrees, i was shooting for 34. But ive backed my initial timing down a bit from 18 to 10 degrees. Ill double check the advance tonight. My other plan for tonight is too put the carb back to stock out of the box.

Once it gets over the sputter the engine is super healthy and pulls strong but its the off the line that is killing me. It doesnt make sense to me.

I didn’t read through all the pages. Did you try a different pump cam? Pink cam is pretty lazy. Also timing?

Yes I've tried different cams with no real effect, and different squirters nozzles.
 
This probably is way way off the wall, but could the carb(s)not be seeing enuf air flow quick enuf to get the main circuit flowing? Think "lewtot" or others need to chime in, way above my paygrade. Does hooking up the vac adv alleviate any of the problem?(it should help)
 
Okay so i returned the carb to stock. and removed all the spacers/adaptor, now its just a square metal plate adaptor. I set the transfer slot to a square but had turn the screw up a bit to get the car to idle. Timing is at 10 degrees BTDC. Car runs a bit better but the bog is still there and the engine back fired through the 2 or 3 times on my test drive when I first stepped on the gas. Is this a timing issue?

Here are some videos of the the test drive.

you can see the RPMs actually drop in this video





 
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You probably should be hooked to manifold vacuum. Try it w/o though, it might help diagnosis.
 
Sounds to me like a tight converter and high (highway) gears... Don't think that qualifies as a stumble. Your engine actually sounds pretty good.
 
What port on the carb do you have your vacuum advance hooked up to?
It should be in the front, second tube from the left that gets connected to vac advance with all the others plugged. That will give you full manifold vac.
Your video shows you running rich, not lean. The backfire through the carb suggest lean but with the wrong vac line hooked up it will backfire. All the back firing may also destroy the power valve.
 
What port on the carb do you have your vacuum advance hooked up to?
It should be in the front, second tube from the left that gets connected to vac advance with all the others plugged. That will give you full manifold vac.
Your video shows you running rich, not lean. The backfire through the carb suggest lean but with the wrong vac line hooked up it will backfire. All the back firing may also destroy the power valve.

Currently on the timed/ported vacuum. I had it on the manifold vacuum but was trying it on ported vacuum to see if i was pulling in too much timing at idle? The back fire is occurring when the lean spike happened on the engine. The lean spike is the when my gauge goes to 17 Air to Fuel then the engine richens up as it recovers. While accelerating running rich, about 12.2 A/F then cruising at highway speed is between 14.3-15.0 A/F. The The lean spike corresponds to that RPM drop in the other video.

Where do you think my timing needs to be for a moderately built 318?
 
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