Hi Chevy Guys.

Hope you can help a jeep guy with a quandry. My tow/work rig spun a rod bearing and got a new healthy 350. I swapped the HEI from the old engine, which was working fine, to the new engine. I cannot get enough voltage to charge the HEI coil while cranking unless I wire directly from the battery terminal to the BAT on the dist. While in the run position I have 12.xx volts, but when I crank the normal BAT wire drops to around 9.5 volts. I ran a new 10G wire all the back to the ignition switch, but that wire too drops to 9.5 volts. I even ran a relay so I can go directly from the batery to the dist with 12V when the ignition switches the relay, but the relay wont work on 9.5V.

Thinking that the starter was drawing too much, I replaced it (it was old with a tempermental solenoid anyway). I have replaced the coil, cap and rotor.

This is on a 1975 Chevy 3/4 ton. I desperately need to get this running this weekend as a I have job I need it for on monday. Can anybody suggest how to deal with this voltage drop?

Thanks

SeanP

try a different battery?????

did these years have the resistor for the 9 volt igntion system? but if you ran a new wire from the ignition switch it should have 12 volts all the time. If you only 9.5 cranking volts, I second it is time for a new battery

I am charging up the optima from my jeep tonight. I hope this is it, it's been a frustrating experience,.

thanks, :beer:

SeanP

'75 should have had HEI, and thus a 12v wire from the factory.

I'd check your ignition switch out.

I'd check your ignition switch out.

Exactly!

run a wire directly from the battery to the HEI....no relay. And then try and start her up.... That will tell you right away if the ignition switch is the problem.

run a wire directly from the battery to the HEI....no relay. And then try and start her up.... That will tell you right away if the ignition switch is the problem.

I did this and, yes, it starts right up. Are the ignition switches pretty easy to change? Is this something that Kragen or Napa would carry or a dealer only item?

SeanP

you can try those guys.....or these people:

http://www.lmctruck.com/

if you want a universal switch, just get a 10 dollar one at napa...you can look through their book and fine which one you want

UPDATE:

Well, it's not the battery that is causing the problems. I put my blue top Optima freshly charged to 1100 CCA's and it too will drop to ~9.5 V. Can anybory verify how many volts the HEI coil needs to fire? Would a bad ground be causing the voltage to drop when cranking?

Thansk
SeanP

UPDATE:

Well, it's not the battery that is causing the problems. I put my blue top Optima freshly charged to 1100 CCA's and it too will drop to ~9.5 V. Can anybory verify how many volts the HEI coil needs to fire? Would a bad ground be causing the voltage to drop when cranking?

Thansk
SeanP

It could be.....but you said it started right up when you ran the HEI directly to the batt. It sounds more and more like the ignition switch...

Sometimes HEI will run on lower voltage but it will eventually burn it up. Go get a new ignition switch from Napa/Vatozon/Kragen and swap it out. Not that difficult, its located at the base of the steering column, on top of the tube. It is adjustable so pay attention when changing it. It is also your neutral safety switch. If its out of adjustment you will know pretty quick.

HEI's will run on just about any voltage down to 6-7 volts. they wont run great , but will run.. my alternator belt fell off and i went 6 hours with no battery. the lights would hardly light up at all, but the truck drove all the way to the parts store. have you checked the fusible link right behind the distributor on the right (mounted to the firewall)? it supplies power to the ignition, and was the problem when mine did that.. that might not be quite right after a swap.

just ditch the HEI

just ditch the HEI

yeah, upgrade to points :rolleyes: :shaking:

just ditch the HEI

What kind of dumb advice is that? HEI is so much simpler than a point's type ignition.... :shaking: :confused:

just ditch the HEI


i guess you are the kind of guy who has his truck "worked on" huh?
and ya run xterrains that says it all... DUMBASS