MikeSammy

I am rebuilding my sbc and pulled an hei from a 78 chevy truck. It looks exactly the same as my stock one excpet for the vacumm cam. I would like to get rid of the comupter under the passenger side dash, so I need a non computer comtrolled hei. I already got a holley carb. Anyone know where I can buy one, got any pics so I can see what they look like. is the hei in the link non -computer controlled. heres the link: click here

t-top havoc

iTrader: (3)

That is a non-computer-controlled HEI.

MikeSammy

can someone post pics of both a non-computer controlled hei, and computer controlled hei so I can see the difference thanks

Apeiron

There are no external differences, aside from the vacuum advance can.

MikeSammy

Would I have to hook up the two wires from my car into the distributor, or can I just drop it in and the car will run? I think one wire is for the rpm tach and the other is for the computer

vetteoz

iTrader: (13)

CC one has a large flat plug with 4 wires from the base as well as the 3 wire plug to HEI cap
Non CC only has the 3 wires to cap

Of course you have to hook it up to something otherwise dist will have no power.
Wires connect exactly the same as on CC unit .Pink wire is power , white is Tacho
The computer connects on the 4 wire plug which you won't have with a non CC dist

MikeSammy

how does the vacuum advance can work. Do I hook it up to the carburetor

vetteoz

iTrader: (13)

The vac can changes the dist advance as engine load changes because engine vac changes in relation to load
Low load ( cruise / idle ) = hi vac ; lots of advance.
Hi load (WOT )= low vac ; so less advance

There is a port on the carb for the vac line to dist

MikeSammy

Can I hook this up to any vacuum port on the carb or is there a specific one?

vetteoz

iTrader: (13)

Bottom of page
http://www.gofastforless.com/ignition/advance.htm

rgarcia63

Distributor vacuum should be taken from from the intake itself.
My '86 Silverado 305 takes it from a T-port on the manifold directly behind the Brake booster vacuum connection.

If you have to get it from the carburetor be sure the port is below the throttle plates.

Apeiron

No difference taking it from a full-time vacuum port on the carb, or from the manifold.

Ported vacuum is fine, but cars with larger cams will idle better with full-time.

rgarcia63

My understanding of ported vs manifold vacuum is that ported vacuum increases as manifold vacuum decreases this is why ported vacuum is used for EGR control, manifold vacuum is weak at the rpm required for EGR, which is opposite of how the distributor works.
Having said that, I only stated it for emissions/economy purposes.

Apeiron

That's a common misconception, but they don't work like that. Ported vacuum is drawn from a port above the throttle blades, so there'a no vacuum on it until the throttle is opened past that point. After that, it behaves the same as manifold vacuum.