Engine sputtering at about 65

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Well you can keep throwing parts at it 'til next November;
or you can put a new, earlier opening PV, in the carb.

exactly this.
try a 7.5 or 8.5 PV.
make sure your accel pump linkage is tight against the pump arm. it should squirt as soon as the throttle moves.

if it's surging at a steady rate down the hwy, then either you have a vacuum leak or your jets are too lean.

if it's surging when you gradually ease into the throttle, then look at the PV.

if it's backfiring through the carb, then it's lean.

set idle mix when the motor is fully warmed up. lean each corner out gradually for the highest RPM. then idle it back down where you want it to idle...
 
This happens with a moderate acceleration, if I slowly try and increase it, there's pretty much no response, I have to ask for it moderately to get a response and the response is the sputtering.
Sounds like this is having problems when the power valve on the primary side is trying to open or when the vacuum secondaries are supposed to be opening. Since we don't know if you have a vacuum or manual secondary carb, it is a bit hard to diagnose. Can you post a pix of both sides of the carb? Or find the Holley list number on the carb and post that?

One very informative way to help diagnose this with the vacuum gauge is to just run a long vacuum line into the passenger compartment and observe the vacuum readings at various problem stages. If you are running on flat land at about 55-60 mph I would expect a vacuum reading of 11-13 inches with that type of idle vacuum reading. Then a moderate acceleration would give a vacuum reading of 5-8 inches, where the power valve would be opening. Pushing further open will drop you down lower in vacuum reading. Having the vacuum levels at various operating conditions tells us what the carb is trying to do.

If you have not set up the timing, you need to do that first. Get it up to around 10 degrees initial advance for starters. (Vacuum line disconnected from the distributor end and plugged.) Once this is observed, then reve up the engine slowly to about 3000 RPM and watch the timing, it ought to advance as you rev it up to the mlow-mid 30's range if the initial timing is at 10 degrees. That may not be the ultimate best point but it will get you to where the timing is not an issue and not so advance as to where you need to mess inside the distributor; at this point, you're just getting it in a happy range to make sure that is not messing with things.
 
Ok so an update. Spent the last day messing with the fuel system. Replaced the fuel pump, all hoses from the steel supply line coming forward from the tank all the way to the carb and the filter. It now will not idle for ****. I’ve taken the idle set screws all the way in and back out almost 3 turns and it still hasn’t leveled out. I’m not wanting to go any further than that because I’m not sure what that’s actually doing to the fuel delivery. I’ve looked at vacuum and now I’m at 16-17 and jumping all over instead of the smooth 20 I had before installing a brand new fuel pump.

I’m very new to carbs and timing so that’s why I had the carb professionally rebuilt a while back.

I will try and get the model number later today.
 
Try increasing engine speed slowly in neutral, and if it starts to miss at the same RPM as 65 mph it may be too much vacuum advance. I had that issue with a slight surge on the highway with mine.
Much easier to diagnose if you can duplicate the conditions

I did the timing by vacuum and it’s normally just right at 20 psi. I actually don’t have a tach in the car yet, definitely on my list but just haven’t done it yet, primarily because of all the electrical still to be done. I won’t be able to check the RPM that way is what I mean
If you don't have a tach and don't know what rpm it acts up at you won't be able to duplicate the condition. We're done here.

So, is this when you are just cruising or just trying to slowly accelerate, or when you are at 65 MPH and then punch it? If this is happening under cruise conditions then it won't be the secondaries; the engine will be running on the primaries at the point if cruising on flat land. And this is not the accelerator pump if this is at steady speeds.

Cruising at 60 doesn't use as much fuel as accelerating to 60 with your foot to the floor. I have a hard time believing it is a fuel delivery problem.

HaH I got you beat,I ran a 340 to valve float on a Carter 2bbl.
Got a chuckle out of that one.
Ok so an update. Spent the last day messing with the fuel system. Replaced the fuel pump, all hoses from the steel supply line coming forward from the tank all the way to the carb and the filter. It now will not idle for ****. I’ve taken the idle set screws all the way in and back out almost 3 turns and it still hasn’t leveled out. I’m not wanting to go any further than that because I’m not sure what that’s actually doing to the fuel delivery. I’ve looked at vacuum and now I’m at 16-17 and jumping all over instead of the smooth 20 I had before installing a brand new fuel pump.

I’m very new to carbs and timing so that’s why I had the carb professionally rebuilt a while back.

I will try and get the model number later today.

Dave, you said you had a 650. A 650 what? Although carbs all work basically the same, a 650 Holley and a 650 Carter/Edelbrock are way different.
Now that you changed something and got a negative result you need to go back to where you were or there is another issue to diagnose. If I were a betting man, I would say your new fuel pump is putting out too much pressure. You can either plumb in a temporary pressure gauge to diagnose or just throw a regulator at it and dial it to 4 or 5 pounds. Is there fuel dribbling out of the boost venturies onto the top of the closed throttle plates? It doesn't take much to cause what you are experiencing.
 
Unless the tank has been cleaned out, checked the pickup, blew air thru the steel line from tank to front,... first place to start unless already done. Them look at carb if fuel related.
 
Ok, so an update. Timing is still not perfect, but passable and driveable, although I haven't road tested upper speeds, I'm confident that I at least got myself back where I was before the fuel pump R & R, and motor wise, I'm ok.

So, not being 100 percent if it was fuel or spark that was screwing up my idle and poor performance after the new fuel pump was installed and all new plumbing was done, I went and bought a timing gun to be safe. Timing by vacuum was a recommendation from an old timer and he seemed like he was right on the money, at least before the new fuel pump. The old timer said that if the harmonic balancer has slipped or the timing chain has stretched, the gauges won't be accurate, thus their affinity for timing by vacuum (I'm sure that's a debate being had all over the place). After the new fuel pump, however, I was lost.

Anyway, back to the timing, it was badly retarded and way off, but I now have it set at 18-20 initial advance (on the gun) and it seems to run way better (this block is really hard to judge as all the marks say are -10, 0 and 10 and then the edge of the block drops off, so you literally have to guess at anything over 10 - see attached photo).

I then set about making sure electrical was not an issue, reseated every plug and the coil wire. The coil wire didn't seem to be fully seated when I took it off so I spent extra time putting it back on and it seemed like this time it really seated well. I feel like this was possibly a contributing factor although not the whole solution.

Timing Marks -10 0 10.jpg
 
Just be aware that at 18-20 initial timing and a stock distributor, your total timing when the mechanical advance is full in at 2500-3000 RPM will be around 40 degrees, and you will be flirting with detonation and piston damage if that happens. That is why I advised starting at 10 degrees advance or thereabouts... to keep you out of trouble. It may idle nicely with a lot of initial timing advance, but you have to look at all aspects of what is going on.

Yes, is can be a bit frustrating going back and forth between systems, but it will pay off in the long run to go through them all, sounds like this car has been neglected for a long time.

And, I agree with the statements on the fuel tanks... until you pull it a clean it out, you may continue to have fuel related issues and crud showing up in the carb. That type of tank clean is SOP for these cars.
 
Check the mechanical advance in the distributor they bind up a lot and can give you that symptom. Just pull the cap and see if the rotor will move a few degrees and return, easy check.
 
Just be aware that at 18-20 initial timing and a stock distributor, your total timing when the mechanical advance is full in at 2500-3000 RPM will be around 40 degrees, and you will be flirting with detonation and piston damage if that happens. That is why I advised starting at 10 degrees advance or thereabouts... to keep you out of trouble. It may idle nicely with a lot of initial timing advance, but you have to look at all aspects of what is going on.

Yes, is can be a bit frustrating going back and forth between systems, but it will pay off in the long run to go through them all, sounds like this car has been neglected for a long time.

And, I agree with the statements on the fuel tanks... until you pull it a clean it out, you may continue to have fuel related issues and crud showing up in the carb. That type of tank clean is SOP for these cars.

Fuel tank is actually something I had already put on the list to purchase. Not sure when it will actually get purchased, but I agree for a 50 plus year old car, that's definitely an automatic, I may be placing more stock in a fuel filter to stop the garbage from getting to the carb than I should but hopefully it saves me until the tank job is ready. I'll be back under the car today with more suspension issues so I'll follow the fuel line back to the tank and inspect all that line. I'll replace that if I'm going through the effort of swapping the tank also.

My priorities right now have been sorting out this fuel/spark issue and the electric in this gar is a total disaster so I wanted to tackle that next, at the moment, I have an oil pressure gauge working which is an aftermarket one under the dash and the original alternator gauge in the dash shows movement but I'm not sure it's accurate. Apart from that I have no dashboard, no lights, no warning lights, nothing. The aftermarket radio has power so my guess is that they robbed something for power instead of running proper power for the radio. Actually check that I also have turn signal indicators in the dash, but that's about it unfortunately.

The suspension is a priority also, its about 80 percent done, did the upper control arms, need to do the lowers and the front end will be buttoned up. The fuel is a priority but I need electrical and suspension also.

To address the original part though, I'll back it down to 12 to 14 initial and go from there.
 
The sock in the tank is getting covered with trash debris from the suction of the fuel pump after driving it for awhile... then you smash on the gas and it starts sputtering.... for lack of fuel because of blockage. Shut the car off the debris falls from the sock until you start driving it again... then the vicious cycle starts all over again.
 
The sock in the tank is getting covered with trash debris from the suction of the fuel pump after driving it for awhile... then you smash on the gas and it starts sputtering.... for lack of fuel because of blockage. Shut the car off the debris falls from the sock until you start driving it again... then the vicious cycle starts all over again.

That's the weird thing, I've been babying this thing, I haven't been smashing on it, at all, even on lower speeds, when I asked for a little more at 65 it was very gradual and basically that did nothing at all, when I used a little more pressure, that's when it'd start sputtering. I literally had no trouble with it at slow speeds, at all. It was like 65 was some weird barrier where that was all I was going to get out of it.

By the way, I'm not doubting that the fuel tank has a bunch of debris in it and that it's sucking up crap off the bottom, it just doesn't seem to fit here, primarily because at lower speeds and acceleration I didn't have the same behavior. Either way, the fuel tank is on the list of things to do, along with new lines front to back to go with the new rubber plumbing from the fuel pump up to the carb.

Currently I'm looking for a complete wiring harness install and new dashboard wiring to boot. Fuel pump won't be far behind.
 
Have the car warmed up and take a air hose and blow the sock out or off from the fuel pump supply hose then get in the car and drive hard to see if it clears up also leave fuel cap loose so it vents !
 
LOL... I initially read that last line as "perfect for gas tank explosion"...

Just keep in mind that as your speeds increases, the fuel consumption increases as the wind resistance increases. So low speed is less load and less fuel flow than at cruising speed, even at the same RPM's with a different gear. And sometimes the plugging up takes some time to show itself; the crud can fall off the sock when you stop and then build up again. It really does happen this way... and the best filter in the world won't change what is going on in the tank.

If you're gonna do the tank anyway, I'd do it now to get this out of the way. Then look into the carb again to see if things were plugged, and check the fule pressure at idle.

Fuel pump crapping out is certainly a possibility too.
 
LOL... I initially read that last line as "perfect for gas tank explosion"...

Just keep in mind that as your speeds increases, the fuel consumption increases as the wind resistance increases. So low speed is less load and less fuel flow than at cruising speed, even at the same RPM's with a different gear. And sometimes the plugging up takes some time to show itself; the crud can fall off the sock when you stop and then build up again. It really does happen this way... and the best filter in the world won't change what is going on in the tank.

If you're gonna do the tank anyway, I'd do it now to get this out of the way. Then look into the carb again to see if things were plugged, and check the fule pressure at idle.

Fuel pump crapping out is certainly a possibility too.

I hope the fuel tank explosion holds off LOL. So this morning before heading to work, I cranked the initial timing down to about 12 ish degrees initial advance. It drove well at cruising speeds but did start to want to stall in traffic when slowing down to a stop, so I think it may require a little more than 12 degrees initial. I'm not sure of the total timing because there's just no way to gauge it with the way the block is setup, and it disappearing pretty much after 10 degrees of advance timing.

I'm pricing the fuel tanks now just to be safe. I do think the hose before the inlet of the fuel pump being so brittle and cracking so easily had something to do with the original problem and replacing the fuel pump, although it was painful was something that shouldn't harm anything, so I'm actually ok with having had to do that.

Something else that came to me is that maybe the fuel pedal travel isn't enough. I had to hack together a new cable for this to fit the lokar TPV cable that I had to install because when the original owner yanked the /6 out of this, they tossed the kick down linkage that was there originally. I'll have a look at that maybe tonight.

Here's a photo of the 2 cable installs.

carb linkage.jpg
 
Timing is not causing the stalling in traffic.... it will run fine if all else is good. The extra timing is just masking something else going on. Check your idle timing once the engine is hot, to make sure it is staying consistently where you set it.

Have your vacuum levels come back up to around 20"? Are the float levels set so that the fuel is just at the bottom of the sight plugs in the bowls?
 
Timing is not causing the stalling in traffic.... it will run fine if all else is good. The extra timing is just masking something else going on. Check your idle timing once the engine is hot, to make sure it is staying consistently where you set it.

Have your vacuum levels come back up to around 20"? Are the float levels set so that the fuel is just at the bottom of the sight plugs in the bowls?

I'm at about 19 on the vacuum. Haven't checked the sight plugs on the bowls. I'll have a look at that tonight when I'm checking the pedal travel on the accelerator cable.
 
Had the exact problem with that exact same carb... hit around 60 and it began sputtering like it wasn’t getting enough fuel... did all the timing and vacuum leak check only to find out it was my power valve. Someone put in a 7.5 when what was needed was a 6.5
 
Look at your fuel line routing around your header collectors. You might try a heat sheath on the hardline. (cheap!) Could be partial or wide open throttle vapor lock.
 
also, does your car have part throttle kickdown?
looks like you might could do an adjustment on the wire on the lokar that adjusts your trans pressure, the "kickdown linkage"...
 
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