HEI Tach Upgrade Question?
Thread Starter
Racer
Joined: Jun 2006
Posts: 316
Likes: 1
From: Southern California
HEI Tach Upgrade Question?
I have a 73 that was upgraded with an OEM AC Delco (from a 75 Vette I believe) HEI distributor. It has been working fine since the install years ago. The distributor does not have the mechanical cabel drive for the tachometer so of course the 73 tach on the dash does not work.
Instead of swapping out the distributor for an HEI that supports cable drive for the tach, what all would be required to upgrade the tachometer to an electronic version and maybe use my old face plate for looks?
Not a number one priority but one of those "While I'm in there I might as well fix that too". When your heading for the poor house due to the " While your at its" what's an extra couple of hundred buck, right?
Thanks
Instead of swapping out the distributor for an HEI that supports cable drive for the tach, what all would be required to upgrade the tachometer to an electronic version and maybe use my old face plate for looks?
Not a number one priority but one of those "While I'm in there I might as well fix that too". When your heading for the poor house due to the " While your at its" what's an extra couple of hundred buck, right?
Thanks
Thread Starter
Racer
Joined: Jun 2006
Posts: 316
Likes: 1
From: Southern California
Okay, I should know this by now, but the search button is your friend!
Looks of great info to questions that have already been asked and answered.
So who has a 75 tach that they would not mind parting with? Even not working is fime.
Looks of great info to questions that have already been asked and answered.
So who has a 75 tach that they would not mind parting with? Even not working is fime.
Intermediate
Joined: Jul 2006
Posts: 43
Likes: 0
From: Claremont Ca
I just did the tach conversion a few months ago. I had the same situation where someone had put a HEI unit in so i bought a tach off ebay for $40 from a 1975 vette. The faceplate is exactly the same except the rivets are a little wider on one of them. It was a direct install. You can only tell the diffrence if you look very close at both of them.
Dan
Dan
Team Owner
Joined: Jul 1999
Posts: 65,492
Likes: 230
From: Orange Park Florida
Dan is correct, that is what I did some 12 years ago, in fact I swapped my old dist/gears/cables/crap, tach too with a vette shop for the '75-77? tach head....still in the car, working fine....
NO WAY in hell I would ever have a mechanical tach again....
NO WAY in hell I would ever have a mechanical tach again....
Melting Slicks
Joined: May 2007
Posts: 3,246
Likes: 4
From: Bay Area CA
I have a '73 and recently did the swap to an HEI as well. When you swaped yours over, you did bypass the original black with pink lettering resistance wire right? If you don't that will cause serious lack of performance / voltage drop at dist.
Thread Starter
Racer
Joined: Jun 2006
Posts: 316
Likes: 1
From: Southern California
At the time my swap was done, I did not have the foresight to do my own work. Now I'm a little more maticulous about how things are done and you know the old saying "If you want something done right ....."
Performance wise I have no complaints so the wires must be correct. I'll check it out when I go out to remove the control valve.
I'm installing a Hot Rod Air system and it came down to that infamous " While I'm in there" that lead me to think about fixing my non working tach. I'm also cleaning up the engine bay and am tired of looking at the tach cable hanging there on top of the intake. One thing keeps leading to another not to mention the complete poly suspension kit I just ordered, seat covers and foam, carpet, Reflectix lining throught the cab, chrome bumpers, weather striping, power steering components, restored ralley wheels and new rings and caps and I'm sure you all know it doesn't stop here
My biggest problem is finding where to stop and finish what I've started. Logic keeps getting in the way with that old "While I'm in there". How do you turn that thing off?
Melting Slicks
Joined: May 2007
Posts: 3,246
Likes: 4
From: Bay Area CA
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Instructor
Joined: Oct 2006
Posts: 219
Likes: 0
From: Jupiter FL
Probably would not hurt to install it. It may avoid spikes that may damage your tach board. I'm sure GM put them there for a reason.
Melting Slicks
Joined: Jun 2005
Posts: 2,239
Likes: 74
From: Palatine, Peoples Republic of Illinois
St. Jude Donor '09-'10-'11-12-'13-'14-'15-'16-'17-‘18
NCM Sinkhole Donor
From what I understand, the filter only filters out radio noise. I did the swap about a year ago - no filter - no problems!
Thread Starter
Racer
Joined: Jun 2006
Posts: 316
Likes: 1
From: Southern California
Ther is an OEM barrel type with a wire at each end. Then there is a replacementtypes with two wires at one end and a single wire on teh other. I think what I need is a really good diagram that shows how I shoudl wire this tach and filter up.
I'm going with the old school Custom Autosound radio and plan on hooking up XM. Would hate to not have the best sound possible with that set up.
Anyone got a quick sketch of this wiring for the tach upgrade?
I'm going with the old school Custom Autosound radio and plan on hooking up XM. Would hate to not have the best sound possible with that set up.
Anyone got a quick sketch of this wiring for the tach upgrade?
Drifting
Joined: Nov 2003
Posts: 1,634
Likes: 4
From: Northern NJ
St. Jude Donor '04 & '05
Here's a schematic of the tach filter. It's just two resistors and two capacitors. Easy to assemble w/Radio Shack parts.
Here's a pic of one of the ones I've built for several forum members.
Good Luck!
Here's a pic of one of the ones I've built for several forum members.
Good Luck!
Cruising
Joined: Jul 2009
Posts: 10
Likes: 0
HEI Installation in 1970 Corvette
I see from postings it is recommended not to hook up HEI to Black/with Pink Lettering Resistance wire.
If I use alternative wired connected directly to Fuse Box / Ignition connector, do I need to install an auxilliary resistor to protect HEI electronics?
Pete
1970
If I use alternative wired connected directly to Fuse Box / Ignition connector, do I need to install an auxilliary resistor to protect HEI electronics?
Pete
1970
Le Mans Master
Joined: Dec 2007
Posts: 6,422
Likes: 591
From: McHenry Illinois
Just a 12 ga wire from the ign terminal in the fuse box to the HEI is all that's needed.
2nd Gear
Joined: Nov 2010
Posts: 2
Likes: 0
I recently replaced my points distrubitor and had an HEI put in my 74 (by someone else). After reading this post i looked at my distributor and I have what looks like the original wires hooked up to my HEI. There is one orange colored wire and one wire with a fiber sleeve around it coming from my firewall going to the distributor. I don't see a black wire with pink letters at all. How can I tell if I need to run a new wire? If I run a new wire where should it come from?
Melting Slicks
Joined: May 2007
Posts: 3,246
Likes: 4
From: Bay Area CA
I recently replaced my points distrubitor and had an HEI put in my 74 (by someone else). After reading this post i looked at my distributor and I have what looks like the original wires hooked up to my HEI. There is one orange colored wire and one wire with a fiber sleeve around it coming from my firewall going to the distributor. I don't see a black wire with pink letters at all. How can I tell if I need to run a new wire? If I run a new wire where should it come from?
Burning Brakes
Joined: May 2006
Posts: 865
Likes: 53
HEI Tach
I purchased from star performance , an HEI dist with mechanical tach drive that blew up in 3 days . They wanted to see it , sent me a new one (looked different)and it and my tach have been working fine for 3 years .