I have a 73 4 speed L48, and tach (and speedo) don't work. I saw online you can remove the tach cable and spin it to see if problem is in distributor or at cable/gauge itself. I'm slowly learning more about my car (thanks to everyone here and all the recommended books).

I found in engine bay my tach cable was disconnected at distributor. I turned it by hand and it was free, so then I hooked it up to drill going CCW, and saw movement in my tach gauge! My issue is, I can't find any connection for the tach cable at the distributor. I looked at my first post on this forum and someone pointed out I have an HEI distributor.

So my question is: where do I hook up the tach cable (if anywhere)? I saw some HEI distributors still support tach drive but I can't find the location on mine. Do I have to remove the distributor to access the hookup location?

Or, if it isn't driven by tach cable, how do I hook up wires/connector to the tach? I can't seem to find any matching tach wires that go to my tach. I'm guessing it should be connected to the yellow wire in my pictures below.

I dont know anything about distributors, figured I would ask here while I research it on the side. Thanks


View of distributor

Distributor with top plastic cover removed. Theres a black wire connected to the red wire, but nothing connected to the yellow one. You can see this in omage below

Yellow terminal (left side) empty, no connection

 

They make HEI distributors with a gear driven tach output. It looks like your car didn't get that, nor did it get an electric tach conversion. Don't hold me to this, but I think the change from gear-driven (mechanical) tach to electronic occured in 1975.

Either is a solution for your current situation, but it sounds like you will have to choose one or the other.

Can you get a picture behind your dash?

 

I haven't taken apart the dash with the tach and speedo yet. Will be doing that soon since I need to troubleshoot the headlight switch and grounding.

I tried looking under the plastic cover for tach drive location, but couldn't find one. I'm now fairly certain this distributor does not have a tach cable input anywhere, see below pic


Picture of current distributor on car. No tach drive visible. Was able to identify it as delco remy 1103375.




Any recommendations on which path to choose? I am leaning more towards electric conversion of tach since not sure how much more life the tach cable has... but open to either option. Will look at prices and options from the vendors tomorrow

 

If it were my car, I'd keep the HEI and convert the tach. But I haven't been faced with the challenge that you have. Getting the dash cluster out of a 78-82 is a lot easier than what you may have to do.

And before you decide, does that distributor have a vacuum advance? Is your timing (and perceived performance) what you expect?

 

Bonus question:

Why is the engine blue in your 73? Is it possible you have a swapped engine from a late 70s Corvette (or other vehicle)?

What does the engine stamp pad say? It should be on the block just in front of the passenger side head, perhaps under the AC compressor (if equipped).

If it is a Corvette engine, you can decode it here:
http://corvettec3.ca/engines.htm

Otherwise, here:
https://nastyz28.com/chevy-engine-code-stampings.php

 

73' had points distributor still. It was and still is very common for people to convert the distributor to HEI because they do not understand points.
If this were my car.....I would put the original points distributor back in it.......for two reasons.
1) They are smaller in diameter and easier to work around....
2) It really is the cheapest option for something reliable.....
OR....you can convert the tach to electronic...which is more stable and accurate...and is a $200 bill.....you have to crack the dash open anyway...

Whatever you do...make sure your distributor and timing is set to performance specs and the vacuum advance only pulls 12 degrees and is hooked to full manifold vacuum. Contact member Lars (V8fastcars@msn.com) for his tuning papers.....

You really would be surprised at how reliable and smooth a properly set points setup is.....

Jebby

 

Here is a link on just the electronic tachometer conversion, does not include pulling the dash.
With some bla,bla,bla...
I suggest getting the correct HEI tachometer wire connector, not a F/M crimp connector like video shows.
https://www.ebay.com/itm/28360953563...QAAOSwBgFdcbWi
Looks like the conversion kit does NOT have a inline tachometer filter like 75-82 use?

 

To pull the complete driver-side gauge panel out, which you'd have to do to access the tach gauge, is a huge undertaking. You can trouble shoot the headlight switch without pulling the dash, so the tach gauge adds a level of complication above what you've already got planned. If you do go with pulling the gauge panel, remove the upper dash first to make it easier to gain access to hookups.

If'n it were my car, I'd look at solving this issue by replacing the distributor with either the stock points version or look for an HEI version if I really liked HEI. (Both my cars have the factory points distributors and they perform just fine.) You've already got a functioning cable and the appropriate tach gauge - the cables are quite robust, IMO - and changing out those parts are the worst of the options.

 

as Jebby said the 71 had points. sounds like orig points dist did not come with the car. somebody replaced the dist with HEI and didn't get this one.one. https://www.ebay.com/itm/16458440438...3ABFBMjp3CseBf

 

a 71 should have a correct-looking smaller distributor. but nobody is gonna laugh at the HEI setup unless you are getting it judged. and they don't laugh. they just deduct points...

 

Distributor does have have vacuum advance. Performance seems fine (I am no expert), I had a friend come over to check timing and it was 10 degrees.



Forum members pointed out my engine color in the past, it is the numbers matching engine, some PO painted it blue. See post 23 here:

https://www.corvetteforum.com/forums...te-help-2.html

 

Has anyone installed this distributor? $50 for a new distributor seems like a great deal. Reviews look good on ebay too.

 

Thanks Jebby and others for your advice. I do need to remove driver dash anyways to diagnose speedo issues too, and ensure I have good grounds. So we can assume I will tearing all that apart anyway. I also want to inspection bubba wiring under driver area with the aftermarket alarm..

Currently in my car, I already have the center cluster out and passenger dash out


Current state of affairs

 

Tough decision which way to go...back to points or upgrade the mech tach with an electronic assembly on the back. If you go with points again you might want to replace the cable at the same time in case it is damaged. I have the same problem...PO put what I believe is a replacement mid seventies 350 in with an electronic HEI. Car goes like a banshee but I don't know how high I am reving it.

Please let us know what and how you solved your issue.

Edit update: I see that there is a HEI distributor with a mechanical output available also as an option.

 

I installed a similar one scored from KMJ performance on ebay, it was $56.
I have over 1,000 trouble-free miles on it this past summer.
I spent a few minutes with it before install making sure the rotor tip-to-cap clearance was good, but other than that, dropped it in and go. It fit nice and snug in the original intake on my '71.

 

Thanks everyone for replies. I'm leaning more towards electric conversion, since price is actually closer to $150 w/ free shipping at Top Flight and I won't have to worry about the cable going bad in the future. I want to keep HEI for performance reasons. Will pull the trigger in a few days, after I troubleshoot tach & light switch, and see if I need to buy any other parts while I'm at it.

 

https://m.facebook.com/groups/1209119532534591/

You could pick up a used 75-up electronic tach, seems like you’d spend about the same as a conversion.
Edit: sorry my link didn’t work.

 

he already has a 75-up HEI. that is the problem. i still vote for tach drive HEI. whether you spend 60 on ebay or 320 for the DUI version.

 

In the long run, the more Bubba changes you can reverse the better off you will be. I vote for a stock distributor. If you want electronic ignition, put a pertronic kit in the original distributor and hook up your tach. Easy peasy.

 

Be aware that those electric tach conversions that the vendors sell need calibrated. I installed one and didn't know this and buttoned up my dash only to find out it wasn't even close to reading correctly. Otherwise I love the electric tach.