Vacuum signal

[jrvariel48]

Originally Posted by Bored&Stroked

You cannot trust the AFR meter if you don't have a correctly installed and sealed O2 sensor in the exhaust system. It should be at least 18" back from the third (rear) exhaust port, should be installed at an angle (to keep water off of it) and there needs to be enough pipe AFTER it to not let oxygen from the outside mess with the readings. There cannot be any leaks in the system before the O2 sensor - or you'll get too lean of readings.

It's in the right spot and at the right angle now if I just had time to get to the shop to get the flex pipe out! I think I'll stop testing until I nail that down so I can tell what's really happening. Thank, Joe

[Pete F]

Have you checked the power valve yet to see if it's blown out or what vacuum reading it's for.
A blown power valve richens the mixture unbelievable !!
And if you can read boost I'm sure you can read vacuum to verify thAt you have the proper one in!


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[jrvariel48]

Originally Posted by Pete F

Have you checked the power valve yet to see if it's blown out or what vacuum reading it's for.
A blown power valve richens the mixture unbelievable !!
And if you can read boost I'm sure you can read vacuum to verify thAt you have the proper one in!


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Pete, I checked and I had 18 in's of vacuum at the manifold at 800 rpm. I was going to try an 8.5 PV in there because right now I have a 4.5 PV. I didn't check the PV that's in there presently to see if it's NG. Is there a way to check it with the motor running? At this point, I think I'll wait to get the exhaust sealed up before I do anymore testing so I know what's going on.
Thanks, Joe

[Pete F]

Originally Posted by jrvariel48

Pete, I checked and I had 18 in's of vacuum at the manifold at 800 rpm. I was going to try an 8.5 PV in there because right now I have a 4.5 PV. I didn't check the PV that's in there presently to see if it's NG. Is there a way to check it with the motor running? At this point, I think I'll wait to get the exhaust sealed up before I do anymore testing so I know what's going on.

Thanks, Joe

Joe if you have 18" of vacuum you can put a 10.5 valve in and jet down the main jets if it's rich.
Also what color spring is in the secondary's since you have a stock engine and ignition you can't get to aggressive with the secondary's .
Have you checked the float levels
I set the primary just below the hole and the secondary just above the hole. And Holley carbs should run 7 psi fuel pressure they are not like Holley 94's or Strombergs they will take the fuel pressure!!


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[jrvariel48]

Originally Posted by Pete F

Joe if you have 18" of vacuum you can put a 10.5 valve in and jet down the main jets if it's rich.
Also what color spring is in the secondary's since you have a stock engine and ignition you can't get to aggressive with the secondary's .
Have you checked the float levels
I set the primary just below the hole and the secondary just above the hole. And Holley carbs should run 7 psi fuel pressure they are not like Holley 94's or Strombergs they will take the fuel pressure!!


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Right now I have both float levels set at the hole. I'm not sure on the spring. I haven't got that far yet! I'll have to open it up. I can adjust the fuel pressure up, I'm at 6 now.
Thanks!

[Pete F]

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Originally Posted by jrvariel48

Right now I have both float levels set at the hole. I'm not sure on the spring. I haven't got that far yet! I'll have to open it up. I can adjust the fuel pressure up, I'm at 6 now.

Thanks!

5-7 is fine for fuel pressure but the primary fuel level you want just below the hole.
If you want to try an easy test wire the secondary's closed and try the car at least you can tell if the primaries are rich or lean than after that go to the secondary's


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[jrvariel48]

Originally Posted by Pete F

5-7 is fine for fuel pressure but the primary fuel level you want just below the hole.
If you want to try an easy test wire the secondary's closed and try the car at least you can tell if the primaries are rich or lean than after that go to the secondary's


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Thanks will do!

[jrvariel48]

I was able to get some work done the last couple of weeks. I got rid of the flex pipe and welded in hard pipe and installed a new O2 sensor. When I pulled out the old sensor, I saw the threads were damaged. Here's what I have so far for my timing with the help of Charlie sending me a bag of assorted springs! Thanks Charlie! I went with the advise of Joe Abbin on my intial advance of 4 degrees for now. I also went with RonnieRoadster's advice and installed a Pertronix set-up including wires. I went with PeteF's advise on the power valve. Right now I started with an 8.5 and jetted down the primary's from 68 to 66 for a starting point. I also found the secondary float was stuck so that may have explained the lean condition at WOT. I installed a quick change vacuum secondary spring set up and found a natural spring in there. I purchased the spring kit so I can tune accordingly. At idle, my A/F reading was 11.0. As I drove, I noticed it richen up when the power valve kicked in. I didn't get a lot of good info at cruise as the streets here are short and I didn't want to go too far from home in case something went wrong. When I mashed the pedal, the lean condition was gone and the A/F was around 12.5. I didn't look at the boost, but the motor pulled very nicely! I think I have a good starting point now with the help of everyone here. Let me know what you think of the numbers and I'll try to get some more info as soon as I can. Thanks to all that helped!
RPM DEGREES
750 4
1000 7
1200 9
1400 11
1550 12
1700 13
1900 14
2000 15
2200 16

[Ronnieroadster]

Very nice Joe now that you have the motor pulling nicely all that's left is a little fine tuning which im sure you can now handle. The advance cure looks good and safe. If you discover she runs a touch warm on the open road I would look into getting the total as close to 20 as possible but for now drive the car and see how the temps are. The secondary float issue was certainly a major cause of all your troubles. With everyone helping with ideas and the various changes you were able to accomplish now you can feel good about tuning and moving forward on your combination. Very Very Good.

[jrvariel48]

Originally Posted by Ronnieroadster

Very nice Joe now that you have the motor pulling nicely all that's left is a little fine tuning which im sure you can now handle. The advance cure looks good and safe. If you discover she runs a touch warm on the open road I would look into getting the total as close to 20 as possible but for now drive the car and see how the temps are. The secondary float issue was certainly a major cause of all your troubles. With everyone helping with ideas and the various changes you were able to accomplish now you can feel good about tuning and moving forward on your combination. Very Very Good.

Thanks Ronnie, couldn't have done this without your help and the help of others!
This post isn't dead yet. Hopefully I could get some pointers on what to do with the carb and the A/F numbers I come up with.
Thanks, Joe

[Bored&Stroked]

Great news! Sounds like you found the big source of it going lean and stumbling as a result. I'm with Ron - once you get a little more seat time in it, you might advance it about 2 degrees at a time, just to see how she performs.

Keep driving it and watching your AFR readings - so you get a really good feel for where they are at under different conditions. Given that you're not running much boost, you'll probably be able to lean it out a bit in the secondaries . . . getting the AFR closer to 13.1 to one (or a bit more). I wouldn't go much leaner than that.

You'll need to take it on some longer routes to see what the AFR is at in different cruise and load conditions - to see whether or not you need to go leaner in the primaries as well. Just don't move too many jet sizes at a time - in any direction! I don't remember if you have one, but a vacuum gauge is a pretty handy tool to have as well.

[jrvariel48]

Originally Posted by Bored&Stroked

Great news! Sounds like you found the big source of it going lean and stumbling as a result. I'm with Ron - once you get a little more seat time in it, you might advance it about 2 degrees at a time, just to see how she performs.

Keep driving it and watching your AFR readings - so you get a really good feel for where they are at under different conditions. Given that you're not running much boost, you'll probably be able to lean it out a bit in the secondaries . . . getting the AFR closer to 13.1 to one (or a bit more). I wouldn't go much leaner than that.

You'll need to take it on some longer routes to see what the AFR is at in different cruise and load conditions - to see whether or not you need to go leaner in the primaries as well. Just don't move too many jet sizes at a time - in any direction! I don't remember if you have one, but a vacuum gauge is a pretty handy tool to have as well.

Thanks for your help B&S! I do have a vacuum gauge right next to the A/F gauge. I should be able to get some driving time this weekend and I'll report my findings. Thanks Joe

[jrvariel48]

I was able to do a little more fine tuning on the timing last night. I should be able to get out tomorrow for some better A/F readings.
Here's what I have after last night.
RPM'S Degrees
750 4
920 5
1000 6
1080 7
1120 8
1240 9
1270 10
1360 11
1520 12
1780 13
1950 14
2110 15
2340 16
2580 17

The rpm numbers are very close. I took my time and checked it twice using a digit timing light where I could dial in the degrees and then carefully rpm the motor up to my 0 timing mark. It's the best I could do with what I have.
Please comment on what you see. I know every motor is different, but I'd like to know what others may have if it's been recorded.
Thanks, Joe

[jrvariel48]

I got a little drive time today.
So cruising on a flat road at 60 mph in 5th gear at 1800 rpm's, the A/F gauge seems to vary from 12.1 to 13.0 with a steady 10 inches of vacuum.
When I put it to the floor and up to 4 lbs of boost the A/F was 14.4
Going up a big hill and maintaining 60 mph, A/F was from 12.8 to 13.4, vacuum was at 3 inches so I had my foot in it but the secondaries weren't open.
I did a video while holding my phone. Next time out, I'll have my Gopro on the A/F and vacuum gauges, while I try to record the rpm and boost.

Please comment! Thanks, Joe

[Charlie ny]

Joe,
You are what this hobby is all about.
Did you down shift or was the hill in 5th. Keep in mind modern cars unblown
or blown with automatic trans probably drop down 2 or 3 gears to clear a big hill. 221
cubes is low on the omph scale. Keep in mind your brain is the computer controlling
your motor.
Charlie ny

[jrvariel48]

Originally Posted by Charlie ny

Joe,
You are what this hobby is all about.
Did you down shift or was the hill in 5th. Keep in mind modern cars unblown
or blown with automatic trans probably drop down 2 or 3 gears to clear a big hill. 221
cubes is low on the omph scale. Keep in mind your brain is the computer controlling
your motor.
Charlie ny

Thanks Charlie! Couldn't have done it without your unwavering assistance! Much appreciated!
I did not downshift. The car just climbed right up the hill with a little throttle. I can tell you before the blower was installed, I had to downshift to 4th gear and keep the pedal to the floor to make it up that hill. I was very surprised at how nicely it pulled itself up!

[Bored&Stroked]

I think your primaries are fine - in that you were in the 12 to 13.5 range. The only part that I don't like is that when you were under full throttle, that you were are 14.4 with boost (did you stay in it a bit to see if that held? Were you in a higher gear - 4th or 5th?). That is a bit too lean in my mind - even for a NA car.

What did the vacuum do under full throttle? Were you low enough to open the power valves? If so, then I would richer up the secondaries a bit - to get down to no more that 13.5 under boost. If the power valves aren't opening, then you'd go UP in the vacuum number so they open sooner . . . if they are opening, then you'd probably want to change the secondary jets one number and then see where the AFR goes too. Good work on everybody's part!

[jrvariel48]

Thanks B&S. I didn't stay in it. I put the pedal to the floor in fifth gear going about 50 mph until I reached 4lbs and then released the pedal. I can certainly do it again! The vacuum gauge shows the vacuum completely dropping out at WOT. The power valve is an 8.5 and I can say it's opening because when I'm cruising and push the pedal down to drop vacuum, the A/F definitely shows it richen up. I'm assuming that's what I'm seeing
Thanks, Joe

[jrvariel48]

Also, I ordered a Holley conversion kit to get rid of the secondary jet plates which were equal to 67 jets. I have 68, 69 & 70 jets to try.
Should I start with the 68?
Thanks, Joe

[V8COOPMAN]

I will say that everything in that engine compartment is mighty tidy looking! DD