Dial back inaccurate

C

Corley

Senior Member
I've modified a Honda distributor to fit Elvira, and in playing around with the timing, I noticed that my almost new HF dial back timing light reads about 40 degrees advance, when the Nurex timing tab shows 30 degrees (when dial back set to 0.) I then tried an old Chraftsman dial back, and it shows about 34 degrees when I see 30 degrees on the Nurex timing tab.

After finding 4 different tachometers all read different rpms, I'm becoming very skeptical about the accuracy of these electronic tools. Any thoughts on what I should trust?

(Honda distributor has both centrifugal and vacuum advances. I wanted to experiment with the vacuum advance.)
 
what model Honda ?? Recently had timing light problem with MSD ignition on my engine . new light (expensive ) same 4 flashes per revolution , called msd , OH you need our t/light , Mutter mutter , & yes there,s worked , course had to freight from USA.
 
quickchange said:
what model Honda ?? Recently had timing light problem with MSD ignition on my engine . new light (expensive ) same 4 flashes per revolution , called msd , OH you need our t/light , Mutter mutter , & yes there,s worked , course had to freight from USA.
Click to expand...

This is the '78-'81 Honda distributor. It is $24.99 on eBay rebuilt right now, and is self contained electronic, with both centrifugal and vacuum advances. (Can you say CAMO?) I did the machining, and installed it yesterday, and was checking out it's advance curves when I found the dial back issues. By the way, I found about 21 degrees of centrifugal advance, and 10 degrees of vacuum advance in this one. (Had to change the advance springs to get it all in by 2k rpm.)

So, if I set initial timing at about 5 degrees BTDC, it should give me around 36 degrees at cruise, and drop back to about 26 degrees when I put my foot in it. Today I'll give it a run and see how that feels, it might be a bit much. It will also give me about 15 degrees advance at idle, so no over heating in parades and such like with my FSI. So far, Elvira loves it.

PS CAMO - Cheap *** Model A Owner
 
quickchange said:
what model Honda ?? Recently had timing light problem with MSD ignition on my engine . new light (expensive ) same 4 flashes per revolution , called msd , OH you need our t/light , Mutter mutter , & yes there,s worked , course had to freight from USA.
Click to expand...
"MUTTER-MUTTER"---You crack me up!!!---In the end, He wants to sell you HIS STUFF! EVERYBODY'S out to make a BUCK!---ME TOO! Want to buy a VINTAGE Dog Bone Wrench?
Bill Suspicious
 
Maybe the random readings are due to all the ignition noise from Model A when running?

My experience even with Fluke meters is that they go wacky near copper spark plug wires.

This was 45 years with the company Fluke 77 meter. I wonder if radio suppression wires would help? Found literature on meter says it was an 8020A

Saw same thing when using Textronics 454 and 465 B Oscilloscope near the running engine.

I will have to dig out one of the Tex 2235's or a 454 or 465Bs from "The Legacy Lagoon" as my brother calls my basement storage area and try it again with RS wires
 
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Benson said:
Maybe the random readings are due to all the ignition noise from Model A when running?

My experience even with Fluke meters is that they go wacky near copper spark plug wires.

This was 45 years with the company Fluke 77 meter. I wonder if radio suppression wires would help?

Saw same thing when using Textronics 454 and 465 B Oscilloscope near the running engine.

I will have to dig out one of the Tex 2235's or a 454 or 465Bs from "The Legacy Lagoon" as my brother calls my basement storage area and try it again with RS wires
Click to expand...


Could be the wires, but these seem to be pretty stable, just a wrong reading. Didn't consider using my 465 Tek scope, as it takes higher math to interpolate into RPM, and I'm too old for higher math! HA! You are probably correct that there is tremendous noise all over that thing...
 
john in illinois said:
I found a suppressed coil wire worked to cut noise.

John
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John, Minerva ran on ALL suppressor wires, I did it because "everyone" sed, "IT WON'T EVEN RUN ON THEM"!! She ran perfect on her Autolite plugs, for over 12,000 MILES & I never even LOOKED at a PLUG!
Chief always sed, "Put it together RIGHT & if it runs GOOD, don't DIDDLE with it"!!!---I was BLESSED to have him for a DAD!!
Chiefs' Studentandhelper
 
Randle, pictures are not really required, just make the bottom half of the Honda distributor look like the bottom half of a model A distributor, and connect the two wires to the coil and viola, you are Bob's uncle. It's really just that easy. Use full vacuum on the advance chamber, and while you have it apart to do the machining, swap out the centrifugal advance springs for some light ones so full advance will come in around 2k rpm.

Set intial timing at 0 if you plan to ever crank it, or 3-5 btdc if not. It gives you 21 degrees of cetrifugal advance, and 10 degrees of vacuum advance, so a total of 31 degrees when starting at 0, or more if you start with some initial advance. Works a treat on Elvira.

NOTE: You really need a metal lathe and milling machine to turn the base outside diameter down by 0.060", and mill a Tang on to the shaft. Cost to have that done is???, as I did my own.
 
Thanks for this info....
I do have a small mill and lathe..i'd like to do this after my other engine issues are sorted out.

Randall
 
Just a note , the Model A distributor is a counterclock wise rotation and the Honda is clockwise. Spinning it the wrong way hampers the advance, the electronics (polaritys) as well as the rotor phasing with the cap.???:eek:
 
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