WarNose
Full Access Member
I just learned that 6.9 injection lines are very slightly shorter than 7.3 lines. Are they different enough to cause any trouble if they are mixed?
I.D. seems to be the same at .007", as best as I can tell with my dial calipers.Maybe it was the I.D. of the lines?
Good idea. The only wire that I could fit in is very skinny so there's no way of keeping it perfectly centered in the tubes. Twisting two together was too fat. But it seem that the 7.3 lines are roughly .010" shorter than the 6.9 lines.@WarNose if you have small copper wire (like network cable) you could feed that threw the inside of each line then measure the wire instead.
Interesting. I think that folks like Mel and Wes try to get all the injectors within 50PSI or so of the same pop pressure? I wonder how +/-25PSI pop pressure compares to +/-0.010" line length?But it seem that the 7.3 lines are roughly .010" shorter than the 6.9 lines.
Interesting. I think that folks like Mel and Wes try to get all the injectors within 50PSI or so of the same pop pressure? I wonder how +/-25PSI pop pressure compares to +/-0.010" line length?
The infallible internet tells me that the speed of sound in #1 diesel at 20MPa is 1400 m/s. Figuring 39"/m, that's 1400m/s*39"/m=54600"/s, so sound travels 0.010" in 0.010"/(54600"/s)=183 nanoseconds. 2000rpm means 360*2000 degrees/minute, 6*2000 degrees/second, so that hundredth of an inch translates to .002 degrees? When we're setting timing, we try to get it to the nearest degree, right? So that hundredth of an inch means nothing if I did the arithmetic right.
Wow, I can't follow all of that math but I ran some tests today. The longer 6.9 line on my #4 cylinder showed 1.5 to 2 degrees more advance than the 7.3 line. It's opposite of what I expected. I thought the shorter line would advance the timing more.
This would prove the theory that the 6.9 line would have a smaller diameter, and achieving the injector pop pressure sooner but who knows. How were you able to test timing on a different cylinder other then #1 with a timing meter? I suspect that my #6 line is different then all the rest and probably should test it first before hunting down a #6 line. Thanks