While I was out scrounging parts for my HEI upgrade, I grabbed the wiring harness out of a GM V8 HEI distributor. There is a capacitor wired to to the B terminal of the 4-pin module. I couldn't find its rating but (never having used this feature before) my Klein CL2000 clamp meter shows a capacitance of about 0.431 µF of the salvaged condenser. This measurement seems to be a bit different every time I check it.

I read Joshua's recommendation as adding a 1000 µF capacitor in the feed line to the #30 terminal of the relay although it should be electrically the same as connecting to the #87.

_________________
1965 Plymouth Barracuda,
225 engine, Quadrajet, HEI, Dutra Duals, 904 Torqueflite, 2.76:1 axle, Addco front bar
Rods & Relics - Fort Erie, ON / Collector Car Tech

Ok, here is some info that i found on the hei capacitor when troubleshooting a no start condition. Which isn't related to this topic but may not be bad info to have
Here's a pic of how i think Joshua is talking about wiring it...like the above quote states "It is wired in parallel with the pink wire going to the HEI module and goes to ground."



Here's a pic of the 1000uF 35WVDC that radio shack sells for $1.99 they also sell a 1000uF 50WVDC for $2.99

_________________


1984' Dodge D150 Utiline Bed
Slant 6 225, Holley 1920 Carb
A833 4 Speed O/D Transmission

1000uf is probably gross overkill, but it won't hurt anything. I can't see photos here at work. The most important factor here is that you chose something that you can mount securely. I'd use a nylon or rubber covered cable clamp screwed to the module mounting bracket if you have room.

_________________
Joshua

I noticed on the axial leads capacitor that one end is a shiny metal and the other is black...Does it matter which end goes to ground?

_________________


1984' Dodge D150 Utiline Bed
Slant 6 225, Holley 1920 Carb
A833 4 Speed O/D Transmission

Shiny metal can part is usually the negative side of the cap. This should also be indicated by the - sign with an arrow pointing toward said shiny end.
This end must go to ground.

_________________
Mattelderca
78 NYB (gone now), two S series, three old Snow Cruisers and a Doo.

Thanks for your response...i can see the - arrow pointing to the shiny metal end of the cap

_________________


1984' Dodge D150 Utiline Bed
Slant 6 225, Holley 1920 Carb
A833 4 Speed O/D Transmission

I've been through this, and yes the alternator and other things under the hood will disrupt the HEI signal.I think the filtering concern is not as important with a carbureted engine. With EFI the fueling is based in large part by the RPM read, which outside interference effecting the HEI will sabotage.

That being said, I have a separate fuse block on the fender for all switched voltage devices turned on by a toggle on the dash. There is a minute amount of theft protection in this switch as the car will not start and run without the switch on. The ECU, HEI and fan relays come off that block. The fan power comes from another source.

I put ferrite chokes, and capacitors on the power leads. I also put ferrite chokes on the starter motor lead, and on the alternator feed. These are cheap devices found at Radio Shack for about $3 each. If you look at the power cord to your computer, or printer you will see one clamped around the cord. However I would reserve this addition until it seems needed.

When I gounded my HEI module to the block it picked up noise from the starter, through ground when cranking. That might not be a problem with your carbureted car. The noise on the EFI application made the ECU think the engine was cranking at 6K, and flooded it. If it fails to start, check the grounding point. Just some more thoughts. Let us know how it goes.

Oh yeah, I forgot to say, the switched fuse block is powered by a single large relay. The toggle turns it on. The toggle gets its power from B+ unswitched power under the dash.

Sam

_________________