Restarting My '70 Nova Project

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My little Yamaha RD400 with a 25 cubic inch engine and my little 135# body would pull 11.92 pretty consistently. It only weighed about 450# with me on it.

I recall some car magazine article back in the 80s that focused on weight and wind, where they took a stock engine out of a car of that year and put it in a dragster frame and it ran pretty close to 10s.

The fastest car I owned was a 68 Cobra jet Mustang that ran in SS/E It went 11.28. That car with me in it weighed 3400 lbs and had to be well north of 450 hp.
What would be so comical to me was for your RD400 to pull up to my Mustang and pretty much stick with it through the quarter where I would be playing catch up from the hole.
Now just to put this all in tractor perspective. A tractor with 14 hp weighing 4000 lbs, would outwork my Mustang.

 

[goeduck]

The fastest car I owned was a 68 Cobra jet Mustang that ran in SS/E It went 11.28. That car with me in it weighed 3400 lbs and had to be well north of 450 hp.
What would be so comical to me was for your RD400 to pull up to my Mustang and pretty much stick with it through the quarter where I would be playing catch up from the hole.
Now just to put this all in tractor perspective. A tractor with 14 hp weighing 4000 lbs, would outwork my Mustang.

Reminds me of when I worked road construction. One day the road-grader operator and a flagger got into an argument. The flagger had a ~400 HP corvette and said he could out-pull the road-grader which was about 40 Hp. So one Friday night they hitched up a chain in the equipment yard and went at it. I left after about a half hour of the grader pulling that corvette backwards over the all over the yard. I don't know how long they went at it, but the flagger probably left with an appreciation of weight, gearing and traction over HP.

 

[BravoXray]

I got the hard fuel lines out of the car and the braided hose in on Thursday afternoon. I reset the EFI to factory settings and went through the setup process. Took it for a drive and it's no better than before so that was wasted time and hose.
I spent over an hour on the phone with MSD tech support, including about 45 minutes on Friday with the "MSD EFI guru". Seems like he is stumped too, the only thing he recommended was to change the IAC, the idle air control, which was acting strange sometimes. So I ordered one from NAPA, picked it up yesterday, and installed it this afternoon. It didn't make any difference at all as far as I can tell, so I'm going to call him back on Monday. If you rev it up over 2,000 RPM or more and then let it back to idle, it will almost and sometimes die for a few seconds before it recovers and goes back to idle speed. While at a steady speed with the engine turning 1,800 to 2,000 RPM, sometimes it surges like you are giving it more then less throttle. It has also started backfiring, mostly when shifting from 1st to 2nd and sometimes on the 2nd to 3rd shift. It never did that before, and is a sign of a lean mixture, or possible an exhaust leak. When I had it up in the air, after I got the fuel line installed, I started it up and checked the entire exhaust system for a leak and didn't find one.
If I can't get this sorted out, I'm just going to pull it off and get either a FiTech or Holley unit and put that on. I'm tired of messing around with this unit and want it running right so I can drive it without fighting it all the time.
I guess if I ran a return line to the tank, I could install a pressure regulator and slap on one of the Holley cabs I have setting on the shelf, it couldn't possibly be any worse.

 

[MossRoad]

Leaves are starting to change. Another year passes. But as you know, a car like this is never finished, so something to occupy your time and skills. Keeps your brain sharp, too.

 

[dodge man]

I’m not any kind of an expert on aftermarket Efi systems but it seems you have a limited ability to play with the fuel and ignition curves. I watched the guy tune my Challenger on an dyno and there are three settings for rpm bands for both ignition and fuel curves. He put a wide band 02 sensor in the tail pipe and the fuel curve is amazingly flat, nearly perfect. I think a newer system will let you fix your problem but then I’m spending your money.

 

[George2615]

Have you pulled the distributor lately? A friend of mine had similar problems of bogging and backfiring. I also thought it was too lean. Upon further checking I found he installed the distributor off one tooth. Moving the distributor one tooth eliminated all the problems.

 

[Alan46]

I got the hard fuel lines out of the car and the braided hose in on Thursday afternoon. I reset the EFI to factory settings and went through the setup process. Took it for a drive and it's no better than before so that was wasted time and hose.
I spent over an hour on the phone with MSD tech support, including about 45 minutes on Friday with the "MSD EFI guru". Seems like he is stumped too, the only thing he recommended was to change the IAC, the idle air control, which was acting strange sometimes. So I ordered one from NAPA, picked it up yesterday, and installed it this afternoon. It didn't make any difference at all as far as I can tell, so I'm going to call him back on Monday. If you rev it up over 2,000 RPM or more and then let it back to idle, it will almost and sometimes die for a few seconds before it recovers and goes back to idle speed. While at a steady speed with the engine turning 1,800 to 2,000 RPM, sometimes it surges like you are giving it more then less throttle. It has also started backfiring, mostly when shifting from 1st to 2nd and sometimes on the 2nd to 3rd shift. It never did that before, and is a sign of a lean mixture, or possible an exhaust leak. When I had it up in the air, after I got the fuel line installed, I started it up and checked the entire exhaust system for a leak and didn't find one.
If I can't get this sorted out, I'm just going to pull it off and get either a FiTech or Holley unit and put that on. I'm tired of messing around with this unit and want it running right so I can drive it without fighting it all the time.
I guess if I ran a return line to the tank, I could install a pressure regulator and slap on one of the Holley cabs I have setting on the shelf, it couldn't possibly be any worse.

I like your idea of swapping out to a Carburetor, that will tell you if it’s the EFI or not!!! Best of luck bro.

 

[BravoXray]

Have you pulled the distributor lately? A friend of mine had similar problems of bogging and backfiring. I also thought it was too lean. Upon further checking I found he installed the distributor off one tooth. Moving the distributor one tooth eliminated all the problems.

I set the distributor just as I have for the last 50 years, with the pointer on the rotor pointing at #1 cylinder, with #1 at TDC on the compression stroke.
I have checked the timing a couple of times lately wondering if that was the or part of the problem. It's right at 12°BTDC where I set it.
I spent another half hour this afternoon with the tech support guy changing every possible parameter that might contribute to the problem, all to no avail. After I got off the phone, I played around with it some more, and by running the idle up to ~1000 RPM the problem with it nearly dying, then going down to 3-400RPM if you rev it up and let it come back to idle, helped, but that's just a bandaid, not a fix. Somehow the system isn't turning the fuel back on until the RPM drops too low. It doesn't try to recover soon enough. If I can just get it driveable for a couple of months, this winter I'll convert it to another brand of EFI.

 

[BravoXray]

I’m not any kind of an expert on aftermarket Efi systems but it seems you have a limited ability to play with the fuel and ignition curves. I watched the guy tune my Challenger on an dyno and there are three settings for rpm bands for both ignition and fuel curves. He put a wide band 02 sensor in the tail pipe and the fuel curve is amazingly flat, nearly perfect. I think a newer system will let you fix your problem but then I’m spending your money.

Yes, the newer EFI systems give you a lot more ways to tweak the system, unfortunately, mine is an early system that doesn't have that capability.
That said, I don't think that type of tuning would solve my problem. As I said previously, for some reason the unit isn't bringing the fuel delivery back to idle volume until the RPM has fallen well below the desired idle RPM. I don't have an aluminum flywheel, so the RPMs don't fall off all that quickly, certainly no differently that it did previously.

Color me frustrated.

 

[arrow]

Yes, the newer EFI systems give you a lot more ways to tweak the system, unfortunately, mine is an early system that doesn't have that capability.
That said, I don't think that type of tuning would solve my problem. As I said previously, for some reason the unit isn't bringing the fuel delivery back to idle volume until the RPM has fallen well below the desired idle RPM. I don't have an aluminum flywheel, so the RPMs don't fall off all that quickly, certainly no differently that it did

I got the hard fuel lines out of the car and the braided hose in on Thursday afternoon. I reset the EFI to factory settings and went through the setup process. Took it for a drive and it's no better than before so that was wasted time and hose.
I spent over an hour on the phone with MSD tech support, including about 45 minutes on Friday with the "MSD EFI guru". Seems like he is stumped too, the only thing he recommended was to change the IAC, the idle air control, which was acting strange sometimes. So I ordered one from NAPA, picked it up yesterday, and installed it this afternoon. It didn't make any difference at all as far as I can tell, so I'm going to call him back on Monday. If you rev it up over 2,000 RPM or more and then let it back to idle, it will almost and sometimes die for a few seconds before it recovers and goes back to idle speed. While at a steady speed with the engine turning 1,800 to 2,000 RPM, sometimes it surges like you are giving it more then less throttle. It has also started backfiring, mostly when shifting from 1st to 2nd and sometimes on the 2nd to 3rd shift. It never did that before, and is a sign of a lean mixture, or possible an exhaust leak. When I had it up in the air, after I got the fuel line installed, I started it up and checked the entire exhaust system for a leak and didn't find one.
If I can't get this sorted out, I'm just going to pull it off and get either a FiTech or Holley unit and put that on. I'm tired of messing around with this unit and want it running right so I can drive it without fighting it all the time.
I guess if I ran a return line to the tank, I could install a pressure regulator and slap on one of the Holley cabs I have setting on the shelf, it couldn't possibly be any worse.

As long as the Holley is at least 750 cfm you can certainly go that route. Too bad for not having a mechanical pump or else you could have eliminated the return.