Stumble under quick wot

[Ricko1966]

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[Ricko1966]

move your vac adv to full manifold vac and try and put your acc pump rod in the top hole for a quicker pump shot , timing is very important on sbc they like around 34 to 36 degrees of total timing

He's been told this 3 times. Let's see how many more it takes. With yours he's been told 4. Do I hear 5 ?who will give us 5?

 

[iamtherealJayy]

Give it some more timing see what it does. Since you can't read your timing marks try.its not real scientific without being able to accurately check timing.but take off hard check top speed in 2nd gear,give it a little more timing check it again repeat until top starts drop speed or you get detonation then bring it back a little. I would tell go up and down in 2 degree increments but I guess we are going to have to be happy with up a little down a little.
Just reread your post in more detail,move your vacuum advance to ported then readjust your carb to get the idle speed down.If you are idling on the transition circuit it will stumble.

Actually @Ricko1966, in post 5 you said “move vacuum advance to ported” I followed what you said the first time. No reason to make it out like I can’t follow directions if you can’t give them. My only thing with the ported vs manifold is vacuum drops out and pulls timing with you get into throttle correct? Doesn’t a rich mixture need more timing to burn efficiently? I’ll change it back to manifold where it was originally before changing the distributor since you know, apparently I’ve been told 4 times to do so. I’ve also been told to move the accelerator pump down and up so I haven’t moved it I’m only changing one thing at a time. Sorry I’m too incompetent for you.

 

[iamtherealJayy]

If you want to see more of what it’s doing,

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This was the drive home from work, if you lay into the throttle around 2000 rpms it’ll stumble a little and if you stay in it it does calm down or if you let out a little and get back on it it smooths out.
And here’s a pull in the rain

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I don’t have an accurate speedometer so it’s third gear around 2200 rpms so around 55-58mph

 

[Ricko1966]

I apologize if I wrote that backwards. If you hook to manifold vacuum not ported you are going to pull in more timing at idle. Idles going to speed up now you can back the throttle stop screw down so you aren't idling on the transition circuit. You aren't worried about the vacuum advance except for at cruise and idle. You are worried about total which I told you because you can't read your timing tab and don't know if it's correct up aittle up a little then back down go read my first post. I do wish you had said I am on ported,so I wouldn't have thought you weren't listening and caught my mistake immediately. So did you give more timing or not? Never got feedback
either. I thought you were just another ask for help and then ignore it kinda guy. Did what Rich said? Did you do what potent rodent said? First thing I told you was it needed more timing,did you try it?

 

[iamtherealJayy]

I understand saying things backwards but make sure you know what you said before saying I can’t follow directions. I used to have one of those nicer timing lights with the knob to adjust timing. It’s somewhere between work and home in the ditch. My current setup does not have the adjustment so 12° Is the highest I can read and it seems to be accurate as far as tdc within a couple degrees minimum. And the total timing at around 3000 rpm does have the timing mark moved way over I’d guess above thirty but I don’t guess I have a way to truly measure unless I get another fancy timing light. I’ll change the advance back to manifold but then I’d have to richen my mixture screws correct? And for the accelerator pump, I don’t know if it’s rich or lean with the wot so just change it to up one see if it’s better or worse then down one so on?

 

[Ricko1966]

Now everything else I told you on post 5 is correct,yes I knew what I was talking about when I posted just wrote the wrong type of vacuum so did you time it like I said? Never heard back from you.30 is not enough for total.

 

[Rusty Nail]

Hey look, it's @rich weyand ! I knew you never quit lurkin ol boy..

Hey op.
Rich really like fixing Carter carburetors with edelbrock stickers on them.

Makes me wonder why you don't got it fixed yet if they got all this help in here.
How's that afr gage install coming? Got any pix?

 

[iamtherealJayy]

Change vac advance to manifold and adjust mix screws and I’ll have to update tomorrow at lunchtime after driving. I cannot verify timing I explained I don’t have an adjustable timing light so thirty is just a guess. I don’t know how to tell what it’s at after it’s off the tab.
Edit: is the transfer circuit you mention the “transfer slots” you hear people mention? Needing to be a square size. I can start with the vac advance to full manifold and changing mixture screws. Would I still have to advance it some if I changed the vac advance? I don’t want so much advance that it gives an issue cranking. With changing the vac advance to manifold I’d have to richen the mixture correct? I’ll bump the timing up, change advance, and add a little in the mix and update the drive to work tomorrow.

 

[iamtherealJayy]

@Rusty Nail I want to get an afr gauge but with my current exhaust there isn’t much point. That would be a later on item. The manifold flange to the down pipe is leaking on both sides. Would need new manifolds and exhaust to fix it, it’s beyond a gasket or donut fixing it.

 

[Ricko1966]

I know you can't read the timing that's why I told bump it a little from a dead stop check top speed in 2nd bump it a little more,try again, repeat until top speed starts dropping or it pings then bring it back a little. You are trying to use base timing with a different carb and a mystery distributor. You need to give the engine what it wants to run with you've got and let base fall where it falls.If you end up with a hard start problem we'll cross that bridge when we come to it. The more closed you have the throttle plates the more you are out of the transition circuit,yes the transfer slots. That is to cover the transition from closed throttle to open throttle. If you are using the transition circuit to idle, you aren't going to have the fuel you need to cover the stumble.

 

[iamtherealJayy]

I bumped timing up and I’m letting it idle and warm up right now to mess with idle mix. It’s currently at 20inhg it’s steady but not like frozen steady. It’s a small gauge and you can see it jitter just a tiny amount less than half 1inhg. Idle is currently at about 850, I’ll have to bring that down a little. There’s a little engine noise currently going on almost a rattle. Is that concerning? Engine only makes around 30psi oil pressure at idle to begin with(15w40)

 

[Ricko1966]

30 at idle is more than enough and as for the rattle I can't tell you, I'm not there to hear it.

 

[Snoots]

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[iamtherealJayy]

Here’s with advanced timing a bump, manifold vacuum, lowered idle to 700/750ish and mixture screws adjusted.

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You can hear the tapping sort of sound in this video. Also what the hell is the flutter sound after I rev it? It’s been doing it for forever and I’ve never thought to ask but you can hear it in the video.
And here’s a video of retarding the timing back a bump to where it was previously, manifold vacuum etc etc.

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You can hear the tap went away so I’m thinking the advance is around about where it needs to be. The engine still runs very smoothly I could balance a nickel on it if I wasn’t parked on a hill.