Gumball
06-24-2015, 11:23 AM
Just a little reminder to everyone on this simple little step when doing your initial drives and as part of the debugging process.
My car was running fairly well, but I had a few issues... some of which I just chalked up to the nature of these things. In hindsight, I noticed that some of these were becoming more pronounced as I drove the car more - especially a couple of longish trips (120 - 150 miles) using fifth gear quite a bit and running at 1500 rpm / 55 mph for most of the time.
1) The exhaust was loud and had quite a "bark" to it.
2) Fuel consumption seemed higher than I thought.
3) An occasional stumble on returning to idle when stopping.
4) Flat spot and a feeling of a "miss" when dipping into the throttle in second and third.
The other day, at the end of a 100+ mile drive, the flat spot really seemed pronounced. But, it would idle fine and would chug along at lower rpm in first - fourth with no problem.
I pulled a couple of the spark plugs and they didn't look quite right - sort of glazed and some ash deposits. When I built the engine, I used Autolite Platinum plugs - the type with the very fine electrode tip. I figured that was a bad choice for the 110 leaded fuel I'm using, so I changed them to a more traditional plug design. That helped somewhat, and the car was back to running like it had when I did the first start and go-kart.
Next was a quick check of the float levels on my Holley 650 double pumper. Both were fairly low, so I reset it appropriately. But, when doing that, I was reminded (by my fuel pressure gauge on the feed rail) that it always was a bit low on fuel pressure - somewhere around 2 psi. I'm using a Carter OEM-style mechanical fuel pump with an in-line replaceable cartridge filter between the pump and carb. As an experiment, I pulled the sintered bronze filter element from the housing and the pressure went up to 3 - 3 1/2. A quick drive showed that it was again better, but not noticeably better than first start and go-kart. Further experimentation with other in-line filters resulted in a 5 - 6 psi reading, so no more cool replaceable cartridge filter - just an inexpensive, but quality, filter.
While I was at it, I decided to check the timing. As expected, it was right on the mark. Only I noticed something I hadn't seen before - something hidden by the pointer. When I built my engine, it was under the guidance of a friend who has a shop that builds vintage race cars and he marked the crank damper for me. But, I thought he market it at 10* advance for the static setting. Well, turns out he marked it a TDC - oops... my bad! All this time, I was running the car with absolutely no static advance - relying only on the centrifugal advance of the OEM Ford dual-point distributor (with a Pertronix II module).
Well, as you'd expect, that really made a difference. After a few tests an a check of total advance, I'm now running the car with 16* static and all of the issues mentioned above have been cured. In fact, it's even quieter and more mellow - an added benefit!
The biggest difference is that I thought it was fast before, but now it's scary fast.
Moral of the story is to not take anything for granted and check, double check, and trust your instincts if you sense something is wrong. I convinced myself that the issues had to be something else as I thought all along that the timing was right... lesson learned.
My car was running fairly well, but I had a few issues... some of which I just chalked up to the nature of these things. In hindsight, I noticed that some of these were becoming more pronounced as I drove the car more - especially a couple of longish trips (120 - 150 miles) using fifth gear quite a bit and running at 1500 rpm / 55 mph for most of the time.
1) The exhaust was loud and had quite a "bark" to it.
2) Fuel consumption seemed higher than I thought.
3) An occasional stumble on returning to idle when stopping.
4) Flat spot and a feeling of a "miss" when dipping into the throttle in second and third.
The other day, at the end of a 100+ mile drive, the flat spot really seemed pronounced. But, it would idle fine and would chug along at lower rpm in first - fourth with no problem.
I pulled a couple of the spark plugs and they didn't look quite right - sort of glazed and some ash deposits. When I built the engine, I used Autolite Platinum plugs - the type with the very fine electrode tip. I figured that was a bad choice for the 110 leaded fuel I'm using, so I changed them to a more traditional plug design. That helped somewhat, and the car was back to running like it had when I did the first start and go-kart.
Next was a quick check of the float levels on my Holley 650 double pumper. Both were fairly low, so I reset it appropriately. But, when doing that, I was reminded (by my fuel pressure gauge on the feed rail) that it always was a bit low on fuel pressure - somewhere around 2 psi. I'm using a Carter OEM-style mechanical fuel pump with an in-line replaceable cartridge filter between the pump and carb. As an experiment, I pulled the sintered bronze filter element from the housing and the pressure went up to 3 - 3 1/2. A quick drive showed that it was again better, but not noticeably better than first start and go-kart. Further experimentation with other in-line filters resulted in a 5 - 6 psi reading, so no more cool replaceable cartridge filter - just an inexpensive, but quality, filter.
While I was at it, I decided to check the timing. As expected, it was right on the mark. Only I noticed something I hadn't seen before - something hidden by the pointer. When I built my engine, it was under the guidance of a friend who has a shop that builds vintage race cars and he marked the crank damper for me. But, I thought he market it at 10* advance for the static setting. Well, turns out he marked it a TDC - oops... my bad! All this time, I was running the car with absolutely no static advance - relying only on the centrifugal advance of the OEM Ford dual-point distributor (with a Pertronix II module).
Well, as you'd expect, that really made a difference. After a few tests an a check of total advance, I'm now running the car with 16* static and all of the issues mentioned above have been cured. In fact, it's even quieter and more mellow - an added benefit!
The biggest difference is that I thought it was fast before, but now it's scary fast.
Moral of the story is to not take anything for granted and check, double check, and trust your instincts if you sense something is wrong. I convinced myself that the issues had to be something else as I thought all along that the timing was right... lesson learned.