Holley 390 anyone running one?
- Thread starter Keeper
- Start date
Keeper
Active Member
I swapped the power valve for a 8.5 I am pulling 17 or so vacuum in gear. Same issue.
Today I am going to swap the squirter for the one off the 600 to see if there is any change. The stock one on the 390 is a 25. If that does not solve it, I will start swapping springs for the secondaries. I may need to go to a stronger spring as I am pulling a lot of vacuum.
Today I am going to swap the squirter for the one off the 600 to see if there is any change. The stock one on the 390 is a 25. If that does not solve it, I will start swapping springs for the secondaries. I may need to go to a stronger spring as I am pulling a lot of vacuum.
Keeper
Active Member
Some quick findings:
31 squirter from the 600 made a small difference.
The 8.5 PV is to high I think as the idle is making my eyes water!
The secondaries are not opening when the hesitation happens, you can sit in the car and watch the secondaries, you blip the throttle, is stumbles and the arm does not move.
I am going to move back to a 7.5 pv and the stock squirter and see what happens.
When I pick up the new pv I will grab a 28 squirter to try at a later date.
If I am at a dead stop and idling at 700 and stomp it, no hesitation at all. Only at part throttle.
31 squirter from the 600 made a small difference.
The 8.5 PV is to high I think as the idle is making my eyes water!
The secondaries are not opening when the hesitation happens, you can sit in the car and watch the secondaries, you blip the throttle, is stumbles and the arm does not move.
I am going to move back to a 7.5 pv and the stock squirter and see what happens.
When I pick up the new pv I will grab a 28 squirter to try at a later date.
If I am at a dead stop and idling at 700 and stomp it, no hesitation at all. Only at part throttle.
Although, I agree with items you are addressing, but I think you need to give each function a little more adjustment before jumping to something else. If you are just trying parts you have on hand, I understand that.
I would try the squirters for an immediate bog. If the bog occurs after the pedal stab, but before the secondaries open, I would consider power valve. Lastly, would be the secondary opening. NOTE, the secondaries will not open with the engine NOT under load, ie blipping the throttle. The reason I said, your passenger might be able to watch the secondary linkage. I probably should not have included this aspect of tuning as a suggestion.
As described your issues sound more like accel pump and power valve related. On burning your eyes at idle, the power valve may be the problem, but sounds more like the idle mixture screws.
I would try the squirters for an immediate bog. If the bog occurs after the pedal stab, but before the secondaries open, I would consider power valve. Lastly, would be the secondary opening. NOTE, the secondaries will not open with the engine NOT under load, ie blipping the throttle. The reason I said, your passenger might be able to watch the secondary linkage. I probably should not have included this aspect of tuning as a suggestion.
As described your issues sound more like accel pump and power valve related. On burning your eyes at idle, the power valve may be the problem, but sounds more like the idle mixture screws.
Bob is dead on, by your description, with his advise. Google Holley tuning. I know all this seems simple and so easy to get right, but all functions of these babies overlap. The tuning site can educate you so much, you will say, I never knew that, I did and I thought I knew Holleys inside out. Be sure you understand adjusting the pump arm and the recommended clearance is with the pump at full squirt, not at closed throttle. That one adjustment may be the cure with all the original parts.
Keeper
Active Member
Thanks.
Yes I am trying stuff I had on hand.
As I try things, if I see no change in the way it is running/behaving. I am going back to the stock setting.
Why I mentioned the secondaries not moving, was that it will hesitate, being in park. If you blip the throttle it will give you that little hiccup hesitation. I understand that the secondaries will not open without any load.
I have adjusted that accel pump arm so that any little touch of the throttle will shoot fuel out of the nozzles. I backed it off until there was some play, then snuck up on the setting.
Idle screws were adjusted with a vaccum gauge, I adjusted until I got the highest vacuum I could.
On the PV comments, let me clarify a bit. If I am cruising, then come to a light, when I stop and the exhaust rolls into the car, my eyes water.
I plan on making a video later to see if I can capture what is happening and hopefully it will help explain a bit more.
Yes I am trying stuff I had on hand.
As I try things, if I see no change in the way it is running/behaving. I am going back to the stock setting.
Why I mentioned the secondaries not moving, was that it will hesitate, being in park. If you blip the throttle it will give you that little hiccup hesitation. I understand that the secondaries will not open without any load.
I have adjusted that accel pump arm so that any little touch of the throttle will shoot fuel out of the nozzles. I backed it off until there was some play, then snuck up on the setting.
Idle screws were adjusted with a vaccum gauge, I adjusted until I got the highest vacuum I could.
On the PV comments, let me clarify a bit. If I am cruising, then come to a light, when I stop and the exhaust rolls into the car, my eyes water.
I plan on making a video later to see if I can capture what is happening and hopefully it will help explain a bit more.
Mike
Well-Known Member
If you have 17 inches of vacuum, an 8.5 power valve should not be sneaking open, leaving you with a rich exhaust. That valve shouldn't open until vacuum drops to 8.5 inches (which may be late enough to cause a slight hesitation, but this sounds as if you may have bigger fish to fry).
Is it a new power valve, or one you've pulled out of another carb? Could it have been blown in the other carb? Have you experienced an intake backfire, since installing that power valve? Are you sure you had the power valve gasket properly seated, when you installed it?
Is it a new power valve, or one you've pulled out of another carb? Could it have been blown in the other carb? Have you experienced an intake backfire, since installing that power valve? Are you sure you had the power valve gasket properly seated, when you installed it?
Keeper
Active Member
Let me see if this will work:
Vacuum gauge hooked up, car in gear:
http://www.netquickposse.org/photos/index.php?album=bucket3&image=19aug04.mp4
I have more coming. 18 was a bit high as you will see.
Vacuum gauge hooked up, car in gear:
http://www.netquickposse.org/photos/index.php?album=bucket3&image=19aug04.mp4
I have more coming. 18 was a bit high as you will see.
Keeper
Active Member
Okay here is the vacuum gauge hooked up car in park:
http://www.netquickposse.org/photos/index.php?album=bucket3&image=19aug02.mp4
As you can see, I am not sure if its my gauge, or something else going on.
Here is me running the engine through some quick ups and downs. Of course in this vid, it is not hesitating like it was before. This is with orange cam in #1 and 7.5 PV.
http://www.netquickposse.org/photos/index.php?album=bucket3&image=19aug01.mp4
http://www.netquickposse.org/photos/index.php?album=bucket3&image=19aug02.mp4
As you can see, I am not sure if its my gauge, or something else going on.
Here is me running the engine through some quick ups and downs. Of course in this vid, it is not hesitating like it was before. This is with orange cam in #1 and 7.5 PV.
http://www.netquickposse.org/photos/index.php?album=bucket3&image=19aug01.mp4
Mike
Well-Known Member
Hmmm... Curious.
Keeper
Active Member
Now comes the "I am an idiot" type post.
So I had switched the orange cam to #1 position, which made things worse, did not like that change at all. So I swapped it back to the stock #2 setting and went for a ride to get things good and hot.
This is where the "I am an idiot" part comes in. Apparently the floats like to be set once things are hot, I had set them when I first installed the carb, thinking that would be fine. Apparently not. So I readjusted the floats that were very low. Of course me pulling the bowl off a few times may have upset things.
Once the floats were set again, I got the vacuum gauge out and went at the idle screws again. This time I paid more attention to the vacuum signal and not the RPM's. I was at 1 3/8's and now they are set at 1.
Then I took it for a cruise around the block. If I blip the throttle when cruising, it does not hiccup near as bad as it was.
Imagine that, setting things correctly in the first place, will fix a lot of crap.......
Tomorrow I will take it back out for some more testing and see if I can pick up another vac gauge from a buddy to test mine.
So I had switched the orange cam to #1 position, which made things worse, did not like that change at all. So I swapped it back to the stock #2 setting and went for a ride to get things good and hot.
This is where the "I am an idiot" part comes in. Apparently the floats like to be set once things are hot, I had set them when I first installed the carb, thinking that would be fine. Apparently not. So I readjusted the floats that were very low. Of course me pulling the bowl off a few times may have upset things.
Once the floats were set again, I got the vacuum gauge out and went at the idle screws again. This time I paid more attention to the vacuum signal and not the RPM's. I was at 1 3/8's and now they are set at 1.
Then I took it for a cruise around the block. If I blip the throttle when cruising, it does not hiccup near as bad as it was.
Imagine that, setting things correctly in the first place, will fix a lot of crap.......
Tomorrow I will take it back out for some more testing and see if I can pick up another vac gauge from a buddy to test mine.
When people report, they set the float levels, adj the idle mixture, etc, etc. You can only hope they are doing it right. Holley specifically states the float level on the primary bowl is just below the site plug. Key word there is below. When shooting for perfection, these things matter. Blipping the throttle in neutral doesn't tell me much. I have never been able gain anything by pushing the clutch in, blipping the throttle. I would not worry or pursue that as an issue. Difficult to tell, but your idle sounds high. pv vacuum reading would be done idling in gear for an auto trans. I would call that 15-16 inches, 7.5 ideal. Your discovery of a better idle mixture adj relating to less hesitation, is discussed in the Holley tuning site, you read earlier, supporting how all the systems overlap to get a smooth transition from one level to the next. I'll bet that carb won't be far off stock when you get it right. Seems we asked earlier on the 600 carb, what fuel pressure are you running?
Keeper
Active Member
Okay more fun for today. Weather cleared a bit so I went for a short trip. Still had the hesitation.
So to eliminate the secondaries I wired them closed so they could not open. Hesitation still there.
Got out the timing light to see what we have been running. It was around 16 advanced without the vacuum. Strange as I do not remember setting it that high. I backed it off to 10.
Went for a cruise, seemed a bit happier but still had a shorter hesitation.
Popped in the 28 squirter and that seems to have sorted things out. Weather turned so I could not go for a longer ride, but the hesitation seems to be gone.
Will know more once the weather clears up.
So to eliminate the secondaries I wired them closed so they could not open. Hesitation still there.
Got out the timing light to see what we have been running. It was around 16 advanced without the vacuum. Strange as I do not remember setting it that high. I backed it off to 10.
Went for a cruise, seemed a bit happier but still had a shorter hesitation.
Popped in the 28 squirter and that seems to have sorted things out. Weather turned so I could not go for a longer ride, but the hesitation seems to be gone.
Will know more once the weather clears up.
Mike
Well-Known Member
I know it seems like a lot of effort, but when you think of how many different applications people purchase that one carb part number for, you can easily see how some fine-tuning is necessary to make things right. Remember, now that you've changed nozzles, you might want to juggle the pump cam to the other position.
Probably not an issue, but check your float level after setting the fuel pressure. Sounds like you are narrowing it down. You need to verify, I think it was Bob's advise, the squirter needs to shoot immediatley with any movement of the throttle. I have adjusted the arm to be into the stroke a little with closed throttle. Anytime you move the cam this will need to checked. ...., and this hesitation is a part throttle, while cruising and you stab it? And which vacuum source are you using on the distributor?
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