Looking at adding the sniper efi and was wondering what folks have done to keep the mechanical tach drive, while having a distributor that will link to the ecu for timing control. Car is a 1970 small block with a 4 speed.
Thanks for any help !

 

dunno squat about sniper efi ... but, if it requires an ignition signal, perhaps an electronic points eliminator OR a tach-drive HEI would work? dunno?

For that matter, points ignition also supplies a signal ... the tach signal output.

 

Might be easier to convert the tach to electronic. Not sure about your '70 but the previous owner of my '73 converted to electronic tach by sourcing a later model tach and re-using the face from the existing tach. I've since upgraded to AutoMeter gauges so I didn't have this issue when I added EFI.

DC

 

I used an MSD pro billet with the tach drive and used the MSD 6AL digital fir timiing control. IT may be worth it to convert your tach gauge over to electric and run the tach off the MSD, then you can just buy one of the Holley plug and ply distributors

 

You just use a MSD tach drive distributor and phase it per the instructions......but you will have to hardwire it to the Hyperspark box for timing control.
If it were me....I would just convert to electric tach as I did in my 72'......to me, the cable drive unit is a PITA. That way you just use the whole Hyperspark kit for timing control.
The electric tach conversion is more accurate and doesn't bounce around.

Jebby

 

If it were mine, I would just convert it and get on with my day. You paint yourself into a corner using a cable drive TACH.

 

Is there a particular model year tach that would work best / match the 1970 gauge faces ? I plan to go with the Holley ignition system so converting to an electronic tach makes the most sense.
I appreciate the help!

 

You keep your stock tach
The conversion kit attaches to it.
Or you can have the guts of your current tach changed out.

for example
https://www.corvettecentral.com/c3-6...version-391000

 

If you swap the guts try not to put your fingers on the face. You may smudge the numbers

 

Did some searching and found quite a few options!
Thank you for the help !

 

I spoke to soon, is there a specific year that works best to visually match the rest of the gauges and can accommodate the signal from the Holley distributor ?

 

What tach is in there now?
The original?
If so that is the one to use

 

I have a "all" MSD Ignition system on my C3 and I have been using a Billet Drive Distributor with mechanical tach output since the early 1990's. Yes The Tach Cables and all their maintenance doesn't make them a good deal.

Holley Sniper Stealth was installed on my 427 and I still use the same ignition parts until I switch it over to the EFI system. I will continue with my MSD CD Ignition with the Sniper controlling the timing and the MSD only making a BIG spark. You remove the vacuum advance unit and the centrifugal advance and lock the rotor base plate. Like Jebby suggested above when he mentions Following the instructions and complete the "Phasing" of your distributor. I drilled a hole in an old distributor cap between the center and the terminal and made one of the tools myself. Then you buy the MSD Adjustable Rotor and get it "Phased In". What they want is to be sure that when the distributor rotor is accurately pointing the energy at the correct terminal in the distributor cap when firing that plug. You want the closest gap between the rotor and the terminal inside the distributor cap. It is really not that hard to do.

After the MSD is locked in you set the timing to 15* and tighten it down. At that point the EFI will be able to control the timing. All the distributor is doing now is sending the trigger signal to the MSD box which fires when the Holley EFI Software tells it to.

I have been messing with making a way of mounting a Holley EFI 7" screen over the gauge panel in the center console. The sensors are available to monitor oil pressure, fuel pressure and cool gadgets. The data available on the screens that Holley Software has is great and easy to set up and customize.

The Holley Sniper Installation is well documented and the support I get is incredible from the folks who sold me the EFI system and OEM Tank Module.

 

The Holley hyperspark will supply an electric tach signal, the original tach is a mechanical cable driven gauge. I need a tach that works with the hyperspark system. I understand later year C3’s 72- 74 ? are electronic I just am not sure what years are best to use.
I have also read about redline gauges, apparently they can convert the original gauge to use an electrical signal but not much info on their site.

 

I am sounding like a broken record, but you can buy an adapter to convert your current cable driven tach
to an electronic tach that will work with a sniper system.
Your call.


see post #8

 

I have seen the conversion kits but for pretty much the same cost you can get a new tach from a later year that is already electronic. That way I have the unmodded original if ever wanting to return to stock. So what I am looking to find out is when did they go to the electronic tachometer, what year ?

 

1975, 1976, and 1977.
I converted my 68 to electronic ages ago (had to go look...egad! it was 2003!). Got it from a fellow on the forum here (had to replace tach board but I was not surprised). My 68's gauges were already white lettered so made it easier. Eyeball the 75, 76, and 77 tachs and see which will match yours the best.
If your 70 has the "greenish" digits you might be better off using a conversion kit just to keep matching the other gauges.

I've had a MSD corvette tach drive distributor & a MSD-6 box for decades. I first converted to electronic tach so I could use it with the Ram Jet 350 more modernish distributor and MEFI controller. When I started using the GM 730 ECM and burning my own chips it kept working flawlessly. I then got the EZ-EFI 2.0 to control the Ram Jet 350 so I went back to the MSD tach drive and MSD box.... I locked-out the distributor and removed the tach drive and vacuum advance mechanism to let the EZ-EFI 2.0 control the timing--- it's been working great and having the Electric Tach made everything a lot simpler. I know it's a long story but I think it's what you are asking about.
some info:

 

If I was starting today I would go to an electric tach and a standalone electronic distributor. I cannot bitch too much about my MSD setup, other than that distributor corrodes terribly under the cap (I've totally cleaned it and painted it with POR-15 a couple of times), but it's always worked.

 

I am going to continue useing the mechanical tach as I have it hooked up and it still works. Weren't the instruments lettering Green on the 1968 Corvette's? I might convert the original tach to get rid of the cable when problems occur. Currently it has a grease-able 90* connector on the distributor's tach drive to reduce the binding at the entry to the tach drive on the distributor. I lubricate the tach cable with motorcycle cable lubricant and that keeps it quiet for the most part.

On the 1968 Corvette we have it came with the factory Transistorized Ignition, I pulled that distributor and had it rebuilt along with the other components. At that time I installed the MSD Tach drive Distributor and it has worked great. The MSD system is able to send a tach signal if you need it as well as the Holley Sniper. I bagged and Tagged the distributor and the other T.I. parts for the future owner of the C3.

Hello carriljc
My MSD tach is the same Pro Billet with mechanical tach drive and I have never seen any rust inside the distributor base. The one I have is as clean as the day I bought it. It has over 10k worth of use on it and still looks and works great. I wonder what happened. The guys who sold me the EFI system suggested that the Holley Dual Sync Distributor would make the installation a bit easier. Why spend another $240 for another distributor if I can make the MSD work.

 

I cannot bitch about the MSD tach drive distributor performance and I have some pics on post about the corrosion. It lives inside a garage and has no reason to corrode. It is really quite bad. I mention it so the individual is aware. Lemme find the pics....