Tach filter for 1227747?

[babywag]

I'm building a fuel only system and would like to build/install a tach filter.
Tried both Howell & AFI, neither are willing to sell me one.

Plan is to use an MSD 6A box, but would like to use a tach filter.

Been searching, found some references, but no schematic.
Anybody out there have something I could use to build a tach filter?

It has to be a fuel only system, in order to get it through smog in CA.

[EagleMark]

Unless something has changed in CA from when I sold EFI systems it won't pass. Any aftermarket part used needs a CARB number or will fail visable inspection, does not matter if emissions pass or are improved.

I've seen the filters sold by AFI and Howell and had some picturtes years ago, small board with some circuts. For the $50 to $75 they used to sell for you can do ignition. Can also build one with LM1815 (?) chip I've read. But never tried as MSD 6 works fine but for the cost you can go ignition as well.

The MSD6 and others do the same thing as the EST/ICM module, cleans up signal to square wave for ECM to fire injectors. Without it the ECM will fry (let out magic smoke). They never run right after the smoke is let out!

Sorry I couldn't help. Go ignition. Still not sure how to pass inspection in CA?

[EagleMark]

Tach Filter picture.

[1project2many]

Many years ago I needed a square wave from a points ignition but had no idea how to design one. I bought a cheapie induction timing light and stole the circuitry out of that. Worked ok.

[EagleMark]

Would an EST/ICM module work without ignition? It does filter the signal.

[babywag]

Unless something has changed in CA from when I sold EFI systems it won't pass. Any aftermarket part used needs a CARB number or will fail visable inspection, does not matter if emissions pass or are improved.

I've seen the filters sold by AFI and Howell and had some picturtes years ago, small board with some circuts. For the $50 to $75 they used to sell for you can do ignition. Can also build one with LM1815 (?) chip I've read. But never tried as MSD 6 works fine but for the cost you can go ignition as well.

The MSD6 and others do the same thing as the EST/ICM module, cleans up signal to square wave for ECM to fire injectors. Without it the ECM will fry (let out magic smoke). They never run right after the smoke is let out!

Sorry I couldn't help. Go ignition. Still not sure how to pass inspection in CA?

A new MSD box is pretty expensive these days, luckily I had one sitting on the shelf in the garage.
@ least they have a CARB EO#

To get TBI through CA smog, you need to deal directly with a smog referee.
After talking with him, and telling him what I wanted to do he agreed to let me proceed.
The system will need to mimic the Howell CA legal system;
VSS, heated O2, No EST, No ESC.
This means I have to retain the stock distributor for timing.
He's done several CJ's with Howell systems and it's his way or don't waste his time kind of a deal.
Seems like a cool guy so far though, he could have easily just said no.

[EagleMark]

Condsider yourself a lucky man! They have actual human beings working there now.

I dealt with a referee in about 1989. 70s Vw bug had a defective decel valve on carb, to slow return. Part was no longer available, car was sweet and clean but first was told it was worthless, junk it. Or sell to mexico... can't pass inspection, several months later I had enough paperwork to get past... also went through at least a dozen JY decel valves, all bad. What a nighmare! Then moved back to AZ...