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Non-FE Discussion Forum / One problem after another! Need help, please.
« on: January 04, 2021, 04:29:18 AM »
So I've posted on here before about issues my nephew has had with his '66 Ranchero. I talked with him a little while ago, as he just got back to port after a few months away. I'm hoping that some of you guys will take the time to read through this story and offer some good suggestions, because I'm about out of ideas! Sorry that this will be long-winded, but I thought it important that you have all the info if I'm going to ask for your opinions/help.
He's got a completely rebuilt 289 (<500 miles), a good built C4 (3,000 RPM stall converter), and a 4.00 9" posi. The engine has about 9.6:1 c.r., with KB pistons, Pro Comp 175cc cylinder heads, Tri-Y headers, a Lunati Voodoo hydraulic (non-roller) with 227/233 @ .050", .522"/.538" Lift, and a 110 LSA, a Weiand Stealth intake, with a Speed Demon 650 VS carb. Until recently it had a HP289 distributor with a Pertronix III module, and their matching super-low ohm coil, Accel 8.8mm spiral wound plug wires, and Autolite racing 3924's gapped at .035".
In general driving, it seems to run great. Off-idle, mid-range and full power are everything he could want! From a standing start it will boil his 235/60's all the way through low gear until the speed catches up to the engine RPM around 5,000, then it continues to pull hard out past 6,000 RPM. I've never felt or heard a stumble or any hesitation while out driving with him. But there are problems. Gas mileage is dismal, around 8 mpg he said on the last tankful, and the engine refuses to idle properly, despite trying several things to improve a persistent 'roll' in speed.
Thinking that the virtually new BG carb could be at fault, I took it apart for him and looked everything over. I didn't find anything to point a finger at, but re-set the transition slot exposure to the recommended 'square' (.020") on all four throttle blades, and set the 4-corner idle mixture screws to 1.0 turn out for starters. I also dropped Pri & Sec jet sizes by 2 numbers (now 68/76, from the factory 70/78), installed a new 6.5 power valve, and re-checked the float levels to be at half on the sight windows.
Back on the car, things continued pretty much as before. After adjusting the idle speed and mixture screws, the engine idled with a maximum of about 12 inches of vacuum (though often at 10), dropping down to about maybe 8 for a second or so as the idle speed rolled. If I tried to reduce the idle speed much below 1,000 RPM, it would roll worse. It would stay running like that for 5+ minutes in Park, but in gear (at about 800 RPM) it would die after no more than a couple minutes. If I watched the tach while idling, what I would see wasn't a 'flutter' (like a misfire), but rather a quick, sharp drop down to about the 500 RPM range for a half-second or so as the engine rolled, then it would rebound.
I checked the fuel pressure, and it was about 6.5 PSI. If I 'deadheaded' the gauge, by disconnecting the carb from the gas line and plugging just the gauge in, pressure would slowly climb to an indicated 10+ PSI. So I got him to buy and install a pressure regulator, and we set it at 6 PSI, then again set the float levels.
If we pulled the cap off of the manifold vacuum port on the carb at idle, it would speed-up and smooth out somewhat. This suggested that the engine was running rich. In an attempt to get the idle speed down and smoother, I closed the secondary throttle blades so that the transition slots were no longer exposed. This did virtually nothing, so I tried turning the secondary idle mixture screws right in, and adjusting the idle on the primary ones only. This produced a little better idle, but you had to 'put your foot further into the gas pedal' to accelerate while cruising.
This carb has Demon's 'Idle-Eze' adjustment under the air cleaner stud, but it didn't seem to do anything for either idle speed or smoothness. So, frustrated with all this work but no real improvement, I removed the BG carb and installed a new 600 cfm Holley that a friend had. To my dismay, after checking/making all the usual adjustments, the idle still rolled with this carb!
So I'm thinking 'fuel & spark' are the two important things, and decided to look at the ignition. But before doing that, I pulled the plugs (sooty black, as from running rich, not oil fouled, etc.) I did a compression test, and got 160 readings from all eight cylinders. I then verified the 14-degrees initial timing, and the 32 total with 18 in the distributor. Not seeing anything there to indicate a problem, I went back to the carburetor.
He had a 600 cfm Edelbrock carb that was on the car when he got it. Although it had now sat for years, I gave it a try. At first the accelerator pump wasn't working, but once I got the engine running for a few moments, it came around. I found that I could drop the idle speed down to about 800 RPM, and adjusted the idle mixture screws. It seemed to be a little better than the BG carb, but still had that roll to it. Aaarrggghh!
I decided to try bumping the initial timing up a little, to 18-degrees. It was while doing this that I saw something unusual. I now had 14 & 18-degree marks on the dampener, and you could clearly see them under the timing light. But frequently they seemed to 'dance around' a bit, and would then go back to what you expected to see. The #5 cylinder plug boot came close enough to its header tube that it had started to melt, so I'd suggested he install a 6" length of that thermal protective sleeving. I decided we should check that cylinder, to ensure that there wasn't any misfiring going on with it. Simple enough to do, just put the timing light's inductive pickup on the #5 wire and watch the light flash...nice and steady. But then I saw something unexpected. When I turned the light back towards the dampener, I could sometimes see those same two 14 & 18-degree marks (for #1 cylinder) showing up under the light! How could that be, as the two are spaced well apart in the 1-3-7-2-6-5-4-8 firing order?? I checked the #6 plug wire, and saw the same thing. Then I went to the other bank of the engine, and checked cylinder #4, only to again see those same 14 & 18-degree marks under the light sometimes...
?
So we then removed the distributor and Pertronix ignition components, going right back to 'dirt simple', with an Accel dual-point distributor, Taylor plug wires, and a 'no-name' aftermarket coil. The car started instantly, and I set the timing up to 18-degrees initial, but that was not before noticing something else. As the engine idled, you could visibly see current jumping from the coil's hi-tension tower over to either of the coil '+' & '-' terminals?? This was despite the thick boot on the hi-tension lead. I had never seen this happen before, but wanted to see if I could get it to stop. So I cut a couple 1" pieces of 1/4" rubber gas line, slit the lower end, and pressed them over the coil terminals. Despite this additional insulation, the shorting continued, but then stopped after a minute or two. How could a points-based ignition have so much current at the coil that it had to find a way to dissipate by shorting to a ground?? The one good thing was that you were no longer seeing those #1 cylinder timing marks show up on any of the other cylinders!
After being thoroughly warmed up, the engine would idle at 800+ RPM, but still had a roll to it. Again, thoroughly frustrated with a lack of progress, and one inexplicable issue after another, we replaced that points distributor with a new Duraspark distributor and an MSD 6A box and coil. I re-installed the Speed Demon carburetor, having decided that if it wasn't doing anything the other two weren't, it wasn't likely the problem. I set the initial timing back at 18 degrees, brought the engine up to 180 degrees, and tried adjusting the idle. This time, I could get it to idle as low as about 600 RPM, but not with the kind of regularity and smoothness that you'd expect from an engine with good compression and a 'fairly' mild cam in it. I could only get a decent idle in gear with all four of the mixture screws set at about 3/4 of a turn out. Any less, and the speed would falter; any more and the roll would be worse. Engine vacuum and fuel pressure readings are the same as before.
Since it'd only been driven a few hundred miles for break-in and trying to resolve some issues, like this idling thing, he wasn't that worried about what appeared to be dismal gas mileage, writing much of it off to prolonged idling periods and trips around the block. But when our recent torrential rains finally stopped for a while the other day, we decided to take it for a longer drive, both to see how everything behaved, and to actually check the mileage. I'm not liking what we came up with!
We topped up the tank with 94-octane premium, and went straight out on the highway to a nearby town. 3,000 RPM with his 25.25" rear tires gets 56 MPH, which is where we cruised. After getting there, he did about a two mile lap up and down the main street of the town at about 30 MPH, then it was back on the highway again. Once back in our city, we refilled the gas tank again. It took 5.64 gallons to do that. Then we get to the confusing part, and the real problem.
I know his speedometer reads low. Where it should be indicating that 56 MPH on the highway, it only shows about 51, suggesting that it's off by about 10%. I reasoned that if the speedo was under-reading, the odometer probably was too. When we had refilled the tank, it was indicating that we'd gone 48 miles since starting out. But his Garmin GPS unit only showed 38.5 miles? So first off, this suggests the odometer was actually over-reading??
If we divide the 48 miles that the odometer showed, by the 5.64 gallons, it comes out to a whopping 8.5 MPG!?!? Even more pathetic, if we use the GPS figure of only 38.5 miles, and divide that by the same 5.64 gallons, it comes to only 6.82 MPG... How could a mechanically good 289, with moderate performance improvements, get that dismal mileage while under light cruising loads??
We checked thoroughly for any gas leaks, right from the tank forward, including gas somehow dumping into the engine/oil, and we see nothing. There is no smell of gas, either when the car is under way, or when it's sitting. There is a bit of a stronger odour when the car is idling, but it's not 'eye watering'. The power and acceleration while driving are great, with no bogs, surging, or any other problems above idle. There's no obvious drag, such as brakes not releasing, and the C4 is working great, shifting up and down just as it should. Has anyone else experienced anything like this? Anybody have a guess as to what is wrong here?
As I mentioned initially, I'm frustrated and stymied here. I have no idea what the problem really is, nor how to fix it. Sorry for such a long-winded post, but I thought it was important you have all this information. If anyone has dealt with this kind of an issue before, or has a good suggestion to offer, I'd be glad to hear it!
He's got a completely rebuilt 289 (<500 miles), a good built C4 (3,000 RPM stall converter), and a 4.00 9" posi. The engine has about 9.6:1 c.r., with KB pistons, Pro Comp 175cc cylinder heads, Tri-Y headers, a Lunati Voodoo hydraulic (non-roller) with 227/233 @ .050", .522"/.538" Lift, and a 110 LSA, a Weiand Stealth intake, with a Speed Demon 650 VS carb. Until recently it had a HP289 distributor with a Pertronix III module, and their matching super-low ohm coil, Accel 8.8mm spiral wound plug wires, and Autolite racing 3924's gapped at .035".
In general driving, it seems to run great. Off-idle, mid-range and full power are everything he could want! From a standing start it will boil his 235/60's all the way through low gear until the speed catches up to the engine RPM around 5,000, then it continues to pull hard out past 6,000 RPM. I've never felt or heard a stumble or any hesitation while out driving with him. But there are problems. Gas mileage is dismal, around 8 mpg he said on the last tankful, and the engine refuses to idle properly, despite trying several things to improve a persistent 'roll' in speed.
Thinking that the virtually new BG carb could be at fault, I took it apart for him and looked everything over. I didn't find anything to point a finger at, but re-set the transition slot exposure to the recommended 'square' (.020") on all four throttle blades, and set the 4-corner idle mixture screws to 1.0 turn out for starters. I also dropped Pri & Sec jet sizes by 2 numbers (now 68/76, from the factory 70/78), installed a new 6.5 power valve, and re-checked the float levels to be at half on the sight windows.
Back on the car, things continued pretty much as before. After adjusting the idle speed and mixture screws, the engine idled with a maximum of about 12 inches of vacuum (though often at 10), dropping down to about maybe 8 for a second or so as the idle speed rolled. If I tried to reduce the idle speed much below 1,000 RPM, it would roll worse. It would stay running like that for 5+ minutes in Park, but in gear (at about 800 RPM) it would die after no more than a couple minutes. If I watched the tach while idling, what I would see wasn't a 'flutter' (like a misfire), but rather a quick, sharp drop down to about the 500 RPM range for a half-second or so as the engine rolled, then it would rebound.
I checked the fuel pressure, and it was about 6.5 PSI. If I 'deadheaded' the gauge, by disconnecting the carb from the gas line and plugging just the gauge in, pressure would slowly climb to an indicated 10+ PSI. So I got him to buy and install a pressure regulator, and we set it at 6 PSI, then again set the float levels.
If we pulled the cap off of the manifold vacuum port on the carb at idle, it would speed-up and smooth out somewhat. This suggested that the engine was running rich. In an attempt to get the idle speed down and smoother, I closed the secondary throttle blades so that the transition slots were no longer exposed. This did virtually nothing, so I tried turning the secondary idle mixture screws right in, and adjusting the idle on the primary ones only. This produced a little better idle, but you had to 'put your foot further into the gas pedal' to accelerate while cruising.
This carb has Demon's 'Idle-Eze' adjustment under the air cleaner stud, but it didn't seem to do anything for either idle speed or smoothness. So, frustrated with all this work but no real improvement, I removed the BG carb and installed a new 600 cfm Holley that a friend had. To my dismay, after checking/making all the usual adjustments, the idle still rolled with this carb!
So I'm thinking 'fuel & spark' are the two important things, and decided to look at the ignition. But before doing that, I pulled the plugs (sooty black, as from running rich, not oil fouled, etc.) I did a compression test, and got 160 readings from all eight cylinders. I then verified the 14-degrees initial timing, and the 32 total with 18 in the distributor. Not seeing anything there to indicate a problem, I went back to the carburetor.
He had a 600 cfm Edelbrock carb that was on the car when he got it. Although it had now sat for years, I gave it a try. At first the accelerator pump wasn't working, but once I got the engine running for a few moments, it came around. I found that I could drop the idle speed down to about 800 RPM, and adjusted the idle mixture screws. It seemed to be a little better than the BG carb, but still had that roll to it. Aaarrggghh!
I decided to try bumping the initial timing up a little, to 18-degrees. It was while doing this that I saw something unusual. I now had 14 & 18-degree marks on the dampener, and you could clearly see them under the timing light. But frequently they seemed to 'dance around' a bit, and would then go back to what you expected to see. The #5 cylinder plug boot came close enough to its header tube that it had started to melt, so I'd suggested he install a 6" length of that thermal protective sleeving. I decided we should check that cylinder, to ensure that there wasn't any misfiring going on with it. Simple enough to do, just put the timing light's inductive pickup on the #5 wire and watch the light flash...nice and steady. But then I saw something unexpected. When I turned the light back towards the dampener, I could sometimes see those same two 14 & 18-degree marks (for #1 cylinder) showing up under the light! How could that be, as the two are spaced well apart in the 1-3-7-2-6-5-4-8 firing order?? I checked the #6 plug wire, and saw the same thing. Then I went to the other bank of the engine, and checked cylinder #4, only to again see those same 14 & 18-degree marks under the light sometimes...
?So we then removed the distributor and Pertronix ignition components, going right back to 'dirt simple', with an Accel dual-point distributor, Taylor plug wires, and a 'no-name' aftermarket coil. The car started instantly, and I set the timing up to 18-degrees initial, but that was not before noticing something else. As the engine idled, you could visibly see current jumping from the coil's hi-tension tower over to either of the coil '+' & '-' terminals?? This was despite the thick boot on the hi-tension lead. I had never seen this happen before, but wanted to see if I could get it to stop. So I cut a couple 1" pieces of 1/4" rubber gas line, slit the lower end, and pressed them over the coil terminals. Despite this additional insulation, the shorting continued, but then stopped after a minute or two. How could a points-based ignition have so much current at the coil that it had to find a way to dissipate by shorting to a ground?? The one good thing was that you were no longer seeing those #1 cylinder timing marks show up on any of the other cylinders!
After being thoroughly warmed up, the engine would idle at 800+ RPM, but still had a roll to it. Again, thoroughly frustrated with a lack of progress, and one inexplicable issue after another, we replaced that points distributor with a new Duraspark distributor and an MSD 6A box and coil. I re-installed the Speed Demon carburetor, having decided that if it wasn't doing anything the other two weren't, it wasn't likely the problem. I set the initial timing back at 18 degrees, brought the engine up to 180 degrees, and tried adjusting the idle. This time, I could get it to idle as low as about 600 RPM, but not with the kind of regularity and smoothness that you'd expect from an engine with good compression and a 'fairly' mild cam in it. I could only get a decent idle in gear with all four of the mixture screws set at about 3/4 of a turn out. Any less, and the speed would falter; any more and the roll would be worse. Engine vacuum and fuel pressure readings are the same as before.
Since it'd only been driven a few hundred miles for break-in and trying to resolve some issues, like this idling thing, he wasn't that worried about what appeared to be dismal gas mileage, writing much of it off to prolonged idling periods and trips around the block. But when our recent torrential rains finally stopped for a while the other day, we decided to take it for a longer drive, both to see how everything behaved, and to actually check the mileage. I'm not liking what we came up with!
We topped up the tank with 94-octane premium, and went straight out on the highway to a nearby town. 3,000 RPM with his 25.25" rear tires gets 56 MPH, which is where we cruised. After getting there, he did about a two mile lap up and down the main street of the town at about 30 MPH, then it was back on the highway again. Once back in our city, we refilled the gas tank again. It took 5.64 gallons to do that. Then we get to the confusing part, and the real problem.
I know his speedometer reads low. Where it should be indicating that 56 MPH on the highway, it only shows about 51, suggesting that it's off by about 10%. I reasoned that if the speedo was under-reading, the odometer probably was too. When we had refilled the tank, it was indicating that we'd gone 48 miles since starting out. But his Garmin GPS unit only showed 38.5 miles? So first off, this suggests the odometer was actually over-reading??
If we divide the 48 miles that the odometer showed, by the 5.64 gallons, it comes out to a whopping 8.5 MPG!?!? Even more pathetic, if we use the GPS figure of only 38.5 miles, and divide that by the same 5.64 gallons, it comes to only 6.82 MPG...
How could a mechanically good 289, with moderate performance improvements, get that dismal mileage while under light cruising loads??We checked thoroughly for any gas leaks, right from the tank forward, including gas somehow dumping into the engine/oil, and we see nothing. There is no smell of gas, either when the car is under way, or when it's sitting. There is a bit of a stronger odour when the car is idling, but it's not 'eye watering'. The power and acceleration while driving are great, with no bogs, surging, or any other problems above idle. There's no obvious drag, such as brakes not releasing, and the C4 is working great, shifting up and down just as it should. Has anyone else experienced anything like this? Anybody have a guess as to what is wrong here?
As I mentioned initially, I'm frustrated and stymied here. I have no idea what the problem really is, nor how to fix it. Sorry for such a long-winded post, but I thought it was important you have all this information. If anyone has dealt with this kind of an issue before, or has a good suggestion to offer, I'd be glad to hear it!