Inductive tach

Tom-MI

Tom-MI

Member
Amazon has a Runleader inductive tach for $13. The hook up seems easy especially for a flathead. Has anyone had any experience with one?

Thanks

Tom
 
Used a similar one on a lawn tractor. It just had a wire that wrapped around a plug wire for the signal.
Unless you can determine it will work on an 8 cyl. engine, I would be suspect of it's capability to do so.
 
I had a Cirello magneto on the hemi in my race car. It wouldn't run a regular tach, so got one of those inductive senders and a very cheap digital tach from J.C. Whitney. I don't think the whole setup was even $50. It worked fine. I later got a magneto-specific sending unit from Autometer and hooked up a regular "4-wire" Mallory tachometer. The units read very close to each other.

The hemi, of course, had eight cylinders. These things will work on any 4-cycle engine from 1 to 28 cylinders because each individual cylinder only fires once every two revolutions. Well, their are some engines with "wasted spark" ignition systems, but I think we can ignore them here. And there goes my 6 volt tach driver business.:mad:
 
51 MERC-CT said:
Used a similar one on a lawn tractor. It just had a wire that wrapped around a plug wire for the signal.
Unless you can determine it will work on an 8 cyl. engine, I would be suspect of it's capability to do so.
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If it is just connecting to one wire the number of cylinders shouldn't matter. It is just counting the number of times per unit of time a current passes through a wire. 2-cycle vs 4-cycle would make a difference.

Nope, looks like they even take care of the number of cycles.

Runleader is proud to present the new RL-HM035LT LED Digital Multifunction Temp meter Tach/Hour meter. It can work on any 2 or 4 stroke gas engine up to 16 cylinders, 9 engine type setting. It has a powerful Temp system, RPM measuring system,timing system, as well as some other unique function design.
 

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Well, gave one a try and ended up finessing it to get close to accurate reading.
Set it up for 8cyl 4 stroke reading as directed and got about half the RPM reading I should have compared to the reading on my timing light. Played with the settings till I got close to what the timing light was reading for idle RPM and ended up on 4cyl 4 stroke setting. Reasonably accurate through several throttle settings. This, on a 59AB with crab dual point dizzy 1947 vintage.
Any speculation as to why the 4cyl setting vs the 8cyl was more accurate??
 
WBrown said:
Well, gave one a try and ended up finessing it to get close to accurate reading.
Set it up for 8cyl 4 stroke reading as directed and got about half the RPM reading I should have compared to the reading on my timing light. Played with the settings till I got close to what the timing light was reading for idle RPM and ended up on 4cyl 4 stroke setting. Reasonably accurate through several throttle settings. This, on a 59AB with crab dual point dizzy 1947 vintage.
Any speculation as to why the 4cyl setting vs the 8cyl was more accurate??
Click to expand...
What is the source of the inductive pulse?
 
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Hi; My British vehicles had tachs that used a single coil of wire on the back of the tach. Found those in MGB and some British military vehicles. the tach sensed ign pulses or current in that single loop of wire. Newc
 
WBrown said:
Well, gave one a try and ended up finessing it to get close to accurate reading.
Set it up for 8cyl 4 stroke reading as directed and got about half the RPM reading I should have compared to the reading on my timing light. Played with the settings till I got close to what the timing light was reading for idle RPM and ended up on 4cyl 4 stroke setting. Reasonably accurate through several throttle settings. This, on a 59AB with crab dual point dizzy 1947 vintage.
Any speculation as to why the 4cyl setting vs the 8cyl was more accurate??
Click to expand...
Possibly having 2 sets of points
 
So I am curious, how accurate is “reasonably accurate”. Were you able to verify your readings with another source? Do you think attaching the sensor on the #1 cylinder would make a difference? They sound like a good option for those who just want to monitor the RPMs going down the road.
 
banjoQ said:
So I am curious, how accurate is “reasonably accurate”. Were you able to verify your readings with another source? Do you think attaching the sensor on the #1 cylinder would make a difference? They sound like a good option for those who just want to monitor the RPMs going down the road.
Click to expand...

Within 50-75 RPM. Used my timing light tach (which is accurate) as the benchmark. As mentioned, just looking for a guideline as to RPMs vs road speed.
 
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