1984 C4 Tach buffer location

[Swang]

Can anyone tell me where the tach buffer indicated on the electrical system diagrams for the 84 vett is located? My tach operates only after I run the vehicle until warm, shut it off and restart it. I have checked my grounds and connections at the distributor. I have moved the wires around under the dash just in case it could be a loose wire there. Could it be the tach buffer?
Speedometer and all other cluster read-outs work. Coil has been replaced.

 

[Daryllawman]

Welcome to CAC........I don't have your answer, but there are several in here that will..........VIG?

 

[Eagle85C4]

The tach buffer or filter is attached to the rear or the drivers side head. With the attached connectors it is possible to reconnect them and bypass the filter. Then you can send it to me and I will repair it for you for 20.00 plus shipping. Gm does not make them any more. The problem is one of 2 things.....water gets into the wires and causes the contacts at either end to corrode causing it to quit or at least become intermittent or the capacitors inside are going bad which causes it not to work until it gets warm. send me email or PM and I will give you address to send to.

 

[oldace84]

I've had the same problem......but after it runs awhile it correctds itself..
Do you know of a fix?????
Please let me know....
thanks
tony

 

[oldace84]

Forgive my spelling....
thanks
tony

 

[JoBy]

You don't even need it. I had problms with nu tach too and I just removed it. The cable going to the filter will connect directly to the distributor. My tach works great without it.

 

[kmcewan]

Tach Filter

Mine was bolded to the intake, on the drivers side.

One of the leads broke off the filter and I removed the filter entirely. Like the others said, the tach still works but I found that acts flakey from time to time.

Found a replacement on Ebay for less than $20.00

Ken

 

[Eagle85C4]

The filter is there to keep spikes generated at the distributor from entering the digital display. Sure you can run without it, but for how long? I personally do not wish to replace the cluster because I was too lazy to replace the filter. Check the cost of cluster replacement and or repair. Better to spend 20.00 and get the filter replaced....like the oil filter guy...you can pay me now.....or later. The tach filter is not just an arbitrary part they added for the heck of it....it has a reason for being there and could save you 1500.00 for a replacement digital cluster.
GM does not make the part anymore, and if you buy a used one you are playing on time. I rebuild the filters with better rated parts and water proof it as I have found that to be one of the major problems with the filter as well as heat from the head.

 

[Eagle85C4]

received filter

Steve,

received your filter today. Problem was somehow the case got a big ding in it that caused the capacitor inside to go to ground shorting it out. I am replacing the guts with new parts. Should be mailed out tomorrow.

 

[Swang]

Tach Buffer fixed

Thanks Ray

Got my tach buffer back from you in the mail and installed it. Digital tach works again. Thanks for the help. Great to see the RMPs again.

Steve

Heres what Ray did if anyone out there has a similar problem.

Rebuilt a part no longer made and any available used would suffer the same consequence as the one I sent him.

To top all this off the design He sent tach buffer back with larger, 1/2 watt resistors versus the 1/4 chevy used, the capacitors are 250 and 400 volt version versus the 135 chevy used, the caps are also rated at 150°C versus the 105°C chevy used. This was encapsulated with high temp hot glue then capped off with high temp RTV to prevent the return of moisture that ruined the original part.

If you need to contact him he can be found at:
Rb2153@AOL.COM

 

[Eagle85C4]

Thanks for the kind words Steve...but I am still not going to increase your commission...





Now that the design has been tested and found to be working I will rebuild any tach filter for 25.00 plus shipping. Email me for address. FYI the money is for parts only...CAC members get labor free...