A
Anonymous
Guest
I discovered something interesting today - after rebuilding my head, raising the CR, opening up the ports, etc., etc., it ran faster, no question. But, it was rough. It almost seemed like "half a miss" was happening on cylinders #3 or #5, I couldn't quite pin it down, even by pulling plug wires, etc. Changed plugs, no difference.
Then I remembered that I also had changed the rotor and cap on the distributor, so I got another one, put it ont, and it smoothed right out.
Upon close examination, I found that the tower contacts for the cylinders #3, #6 and #2 were all clocked about 2 degrees late! Someone either messed up on the molding operation or made a bad fixture to assemble this cap at the factory. The evidence was very clear in the 'burn' pattern on the contacts: only 2/3 of contacts 3,6 & 2 were burned across, as opposed to the whole face on contacts 1,4 & 5. So, the spark was coming about 2 degrees late on 3,6 and 2. (I run 10 degrees static advance.) As final proof, after changing the cap and rotor, the engine starts at a touch (instead of cranking like it has been) and it idles almost 150 RPM faster, so I'll have to slow it down a bit. I'll bet my MPG just got better, too....
So, if yours seems rough and you bought a new cap recently, take a good look. The molds they use to make these caps get used several thousand times before replacement, so there are a LOT of bad caps out there!
By the way, this was a Niehoff set. In reality, though, there are only a couple of manufacturers of these 'generic' parts out there, and they get private-labelled for anyone with the $$, so look carefully.
Then I remembered that I also had changed the rotor and cap on the distributor, so I got another one, put it ont, and it smoothed right out.
Upon close examination, I found that the tower contacts for the cylinders #3, #6 and #2 were all clocked about 2 degrees late! Someone either messed up on the molding operation or made a bad fixture to assemble this cap at the factory. The evidence was very clear in the 'burn' pattern on the contacts: only 2/3 of contacts 3,6 & 2 were burned across, as opposed to the whole face on contacts 1,4 & 5. So, the spark was coming about 2 degrees late on 3,6 and 2. (I run 10 degrees static advance.) As final proof, after changing the cap and rotor, the engine starts at a touch (instead of cranking like it has been) and it idles almost 150 RPM faster, so I'll have to slow it down a bit. I'll bet my MPG just got better, too....
So, if yours seems rough and you bought a new cap recently, take a good look. The molds they use to make these caps get used several thousand times before replacement, so there are a LOT of bad caps out there!
By the way, this was a Niehoff set. In reality, though, there are only a couple of manufacturers of these 'generic' parts out there, and they get private-labelled for anyone with the $$, so look carefully.
