Restarting My '70 Nova Project

[BravoXray]

I wish I had the '69 SS396 L78 375HP Nova I had beck in the early 70s. I had to sell it and buy a more family friendly car when I got married.

 

[BleedingOrange]

Glad to see you are getting a chance to enjoy your beautiful Nova. I was at a car show last week-end and was wondering how your summer was going with it on the road.

 

[Alan46]

Been putting some miles on the Nova, and the small tach I installed in the cluster is difficult to read and not accurate. I have an Autometer pod tach, like the venerable Sun Super Tach of days gone by, so I decided to mount that on the right side of the steering column. Fortunately, I connected the in-dash tach to the wire harness with a three pin Deutsch connector, just in case this situation arose. So I installed a connector on the Autometer tach wires disconnected the old tach, and connected the new one. I had to take the steering column loose to be able to get to the connectors, but I was able to switch the connection and put it back together pretty easily. I connected the internal light to the power wire, so it's on all the time, rather than pull the cluster out and run another wire just for that.
Started it up, and it agrees with the digital readout on the EFI hand set as closely as you can determine on an analog scale.
It was a nice day, so I went for a 50 mile cruise around the area, burning up some of that Speedway 93 octane gas. Next tank, I think I might try running the mid-grade gas in it, as long as it doesn't ping under a load.
I've been fussing with the EFI for a couple of weeks, as it developed a low RPM bog that was getting worse, it was leaning it out, and you had to feed it throttle really slow, and would then take off. It was really annoying taking off from a stop. Tried adjusting AFRs, accelerator shot, power valve setting, ignition timing and checking for vacuum leaks, all to no avail. I finally reset it back to factory defaults, and it's much better now. I think it just needs to be kept above 1500 RPM due to the fairly aggressive cam, it doesn't like being lugged down.
With the overdrive transmission, I can cruise 60 MPH at 1900 RPM, which is really nice, witch cuts down on noise and fuel consumption, so I'm really glad I went with the TKX with the .68:1 fifth gear.
I still have to put the new upper A-arms on and get it realigned, but I've been procrastinating about doing it for no good reason. Should be pretty easy, I just need to knuckle down and get 'er done.

View attachment 4035674

View attachment 4035680

Great to hear you’re enjoying your ride! What kind of compression are you running? As far as your issue, I personally don’t like that it was getting worse, I would call the tech support and pick there brain ! I think what you did was good, but just a band aid in my opinion, no disrespect!!! I think you are extremely detailed oriented

 

[BravoXray]

Great to hear you’re enjoying your ride! What kind of compression are you running? As far as your issue, I personally don’t like that it was getting worse, I would call the tech support and pick there brain ! I think what you did was good, but just a band aid in my opinion, no disrespect!!! I think you are extremely detailed oriented

The 434 is running 10.5 to 1 compression.
Yes, I'm going to call tech support next week, about the problem, and also a couple of other questions. One of the problems is that I bought the EFI system in 2012, and they only ever put out one update for the software several years ago. They have since been acquired by Holley, and they push their EFI systems rather than any real updates to the MSD products.

 

[arrow]

Been putting some miles on the Nova, and the small tach I installed in the cluster is difficult to read and not accurate. I have an Autometer pod tach, like the venerable Sun Super Tach of days gone by, so I decided to mount that on the right side of the steering column. Fortunately, I connected the in-dash tach to the wire harness with a three pin Deutsch connector, just in case this situation arose. So I installed a connector on the Autometer tach wires disconnected the old tach, and connected the new one. I had to take the steering column loose to be able to get to the connectors, but I was able to switch the connection and put it back together pretty easily. I connected the internal light to the power wire, so it's on all the time, rather than pull the cluster out and run another wire just for that.
Started it up, and it agrees with the digital readout on the EFI hand set as closely as you can determine on an analog scale.
It was a nice day, so I went for a 50 mile cruise around the area, burning up some of that Speedway 93 octane gas. Next tank, I think I might try running the mid-grade gas in it, as long as it doesn't ping under a load.
I've been fussing with the EFI for a couple of weeks, as it developed a low RPM bog that was getting worse, it was leaning it out, and you had to feed it throttle really slow, and would then take off. It was really annoying taking off from a stop. Tried adjusting AFRs, accelerator shot, power valve setting, ignition timing and checking for vacuum leaks, all to no avail. I finally reset it back to factory defaults, and it's much better now. I think it just needs to be kept above 1500 RPM due to the fairly aggressive cam, it doesn't like being lugged down.
With the overdrive transmission, I can cruise 60 MPH at 1900 RPM, which is really nice, witch cuts down on noise and fuel consumption, so I'm really glad I went with the TKX with the .68:1 fifth gear.
I still have to put the new upper A-arms on and get it realigned, but I've been procrastinating about doing it for no good reason. Should be pretty easy, I just need to knuckle down and get 'er done.

View attachment 4035674

View attachment 4035680

Do you have a self contained efi system such as a Sniper?
Your cam size should have little to do with it.
I agree to you having a low end bog caused by lack of low rpm fuel.

The self contained Edelbrock or Sniper have fuel table adjustments at any rpm.
Something is impeding your fuel flow at low rpm so I assume fuel pressure is ok?

 

[BravoXray]

Do you have a self contained efi system such as a Sniper?
Your cam size should have little to do with it.
I agree to you having a low end bog caused by lack of low rpm fuel.

The self contained Edelbrock or Sniper have fuel table adjustments at any rpm.
Something is impeding your fuel flow at low rpm so I assume fuel pressure is ok?

There is a setting for the cam type, Stock, Medium or large and I have it set on large, as it has over 230° of duration.
The fuel pressure fluctuates a lot. It's not a problem with the pump, as I can change the setting so that the pump runs constantly, as when set up as a system with a pressure regulator and return line, and it will develop well over 100 PSI.
Tomorrow I'm going to plug my laptop into the handset and see what that shows. I can't find any info on what program to use to access the tables or look at the data logs, everything I can find is for the more recent Holley Sniper systems. That's one of the questions I have for tech support.

 

[arrow]

There is a setting for the cam type, Stock, Medium or large and I have it set on large, as it has over 230° of duration.
The fuel pressure fluctuates a lot. It's not a problem with the pump, as I can change the setting so that the pump runs constantly, as when set up as a system with a pressure regulator and return line, and it will develop well over 100 PSI.
Tomorrow I'm going to plug my laptop into the handset and see what that shows. I can't find any info on what program to use to access the tables or look at the data logs, everything I can find is for the more recent Holley Sniper systems. That's one of the questions I have for tech support.

If you’re at .50 with 230 duration with your engine cubes, whether intake or exhaust, I would consider that a medium cam.
I have 236-242 in a 408at .50 and would consider that medium.
Lsa at 112.

 

[BravoXray]

If you’re at .50 with 230 duration with your engine cubes, whether intake or exhaust, I would consider that a medium cam.
I have 236-242 in a 408at .50 and would consider that medium.
Lsa at 112.

That's pretty much the same as the cam I have in the 434. The instructions for the EFI say that over 230° to use the large setting, but I have tried it on both settings with the same result.
The cam card says 239° IN and 246° EX with 112° LSA.

 

[arrow]

That's pretty much the same as the cam I have in the 434.

View attachment 4036192

Our cams are almost identical.
Mine has a bit higher lift but that valve event should not be impeding your fuel atomization at lower rpm’s.
Did you try the medium cam setting?
My stall converter is 2800 with 3.91’s out back but yours is a stick right?
As I recall, you measured vacuum and you’re producing sufficient amounts.
I wonder if the electronic position sensor may be wonky on your unit? Your idle would be getting higher if it was creeping.
Should be at zero.
Before we jump to that conclusion, try the mid cam setting.

 

[Alan46]

The 434 is running 10.5 to 1 compression.
Yes, I'm going to call tech support next week, about the problem, and also a couple of other questions. One of the problems is that I bought the EFI system in 2012, and they only ever put out one update for the software several years ago. They have since been acquired by Holley, and they push their EFI systems rather than any real updates to the MSD products.

Well that sucks!!! May they still have someone on staff who can help you. I had a 351W 10 to one in my first race motor I ran premium 4(gl) to one gl 100 octane no pinging and got 2,500 passes before going to a 408W. Let me know about the phone call!!!