SBC/8BA distributor specs

[Charlie ny]

removing the cap noe removing the rotorI have had lots of interest in the SBC/8BA distributor conversions.......


























Here's what I offer.....with the vac adv can $300 incl shipping w/o the can
$275 incl shipping. The can seems to be suffering from a lack of interest.

Any 8BA timing cover can be used.
An allen set screw adjuster is provided to adjust max adv, in place of the offset bushing. Adjustment is made by removing the cap, the set screw is
accessed without removing the rotor....very intricate adjustment are
easily made
A full size clamping pad is provided just the like the loadamatic
The upper area of the post has a bushing installed to provide full register
into the top bore of the timing cover
OEM or better points, condenser, cap and rotor are installed.
Full advance as supplied is 20 degrees all in at 2000 rpm
The gear is installed
If you have a nice core I'll allow $10 to $20......depending on it's niceness.
Thanks,
Charlie ny
Be sure to use my e [email protected]

[KiWinUS]

Originally Posted by Charlie ny

removing the cap noe removing the rotorI have had lots of interest in the SBC/8BA distributor conversions.......
Here's what I offer.....with the vac adv can $300 incl shipping w/o the can
$275 incl shipping. The can seems to be suffering from a lack of interest.

Any 8BA timing cover can be used.
An allen set screw adjuster is provided to adjust max adv, in place of the offset bushing. Adjustment is made by removing the cap, the set screw is
accessed without removing the rotor....very intricate adjustment are
easily made
A full size clamping pad is provided just the like the loadamatic
The upper area of the post has a bushing installed to provide full register
into the top bore of the timing cover
OEM or better points, condenser, cap and rotor are installed.
Full advance as supplied is 20 degrees all in at 2000 rpm
The gear is installed
If you have a nice core I'll allow $10 to $20......depending on it's niceness.
Thanks,
Charlie ny

Charlie can you have can but not hook to vacume or remove if you choose

[Charlie ny]

The internals in the can will hold the breaker plate in place just fine if you for any
reason do not hook the vac to it. The vac adv can be removed from the dist but it is a slight pita . Initially everybody wanted the can, the last batch only 4 out of 12 requested
it.
Charlie ny

[Tinker]

I thought the sbc conversion was to go all mechanical. Get rid of the vacuum? I'm I wrong?

[40cpe]

It works great using the vacuum can as it was designed to do.

[Tinker]

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for a non-sbc conversion. sbc getting rid of the vacuum was to run 97's and duals. Let alone the advantage of getting rid of the vacuum dizzy. in my opinion? Installed a few bubbas with great success and tire burns.

[Charlie ny]

The sbc conversion brings mech adv into the picture but if the purchaser wishes he
can also add vac adv which comes into action at low load high vac situations.......such
as freeway driving. THIS vac adv compliments the distributor's mech adv.

Charlie ny

[Tinker]

Don't over think it. Vacuum advance is less then good. The standard ford dizzy has both already, mechanical and vacuum. Sbc takes it out of vacuum. Not my perchance, but do what works.. not sure how you can run a 97 on it.

[40cpe]

Originally Posted by Tinker

The standard ford dizzy has both already, mechanical and vacuum.
.

The Ford distributor in the 8BA did not have mechanical advance. Distributors prior to electronic engine management had vacuum, it works.

[flatheadmurre]

If you are going wide open down a track at a steady rpm you don´t need advance at all...you can have a fixed ignition.
If you want performance at a wider rpm range you need mechanical advance.
Vacuum advance gives you a better fuel economy and not running the engine rich makes it last longer without maintenance.
Fords 8BA venturi vacuum advance was a cost effective solution that looked good from a manufacturing point of view...

[flatjack9]

Originally Posted by Tinker

Don't over think it. Vacuum advance is less then good. The standard ford dizzy has both already, mechanical and vacuum. Sbc takes it out of vacuum. Not my perchance, but do what works.. not sure how you can run a 97 on it.

I don't think you understand the vacuum advance on these distributors. It uses manifold vacuum and increase spark advance at lighter load conditions. I would not run one of these distributors without the can. There are no negatives to be concerned about.

[Ol' Ron]

Most of you drive yor cars on the street and about 90% of the time at part throttle. It is during this period of time that the vacuum advance does it work by regulating the timing during different engine load conditions. Now after spending many thousands if$$$$ on the engine, why not take advantage of an inexpensive way of improving performance and economy. While extending the life of the engine.

[rotorwrench]

I never could figure out why all the systems were referred to as vacuum advance. This is kind of a misnomer. The Load-O-Matic is truly a vacuum advance system with load retard as a benifit but there is NO centrifugal system in there. It uses a tuned venturi porting from the carburetor to get the vacuum and not manifold vacuum. The springs what work against the vacuum inside the distributor could be adjusted to get the correct amount of advance for a given vacuum signal.

The SBC and later non-LOM Ford systems have centrifugal advance with vacuum load retard system. It is generally referred to as automatic spark control but somewhere in there, any unit with a vacuum can was referred to have vacuum advance. The flyweights give the advance and the vacuum can will override that and provide a bit of retard of the spark for pulling a load such as going up a long hill.

The old Model A vehicles had manual spark control. You had to retard the spark manually for starting the engine or just a little bit when you hit a long hill while driving.

[flatjack9]

The vacuum truly does advance the spark in modern distributors, it does not retard.

[BUBBAS IGNITION]

Just to add in here a little bit using a delco as an example .

Typically the vac can is 12 degrees distributor advance (24 engine) with full vac , then the weights are limited to another 12 degrees dist (24 engine) .

However you cant have full vacuum under full load (max rpm) SO the units must over lap each other , when one is high like coasting the other is low and vise versa.

So lets say the engine designer wanted the engine to have 24 degrees of engine spark advance .. 24 vac and 24 mech over lapped at 2500 would be a perfect world at 24 degrees , snap the throttle vac drops and mech picks it up 24 degrees , let off the throttle rpm drops off vac picks up 24 degrees .....

Ya think they wanted 24 degrees ??????

[flatjack9]

Not quite sure what your point is.

[BUBBAS IGNITION]

Originally Posted by flatjack9

Not quite sure what your point is.

No real
Point other trying to explain a very mid understood subject . It’s a little more complex than many think !!!

[Ol' Ron]

The way I use it is: Set the Mechanical adyat 18/20 @ 2000, depending on cak and compression. I then set the Vac canister to 6/8 degs. now when jetting the carb, I try to get 14.5/15.5 AF In cruise. THis requires 26/28 Degs adv. On cruse at 2500 @70 plus MPH I get over 20 mpg with L-100 cam. At WOT dist drops back to 18/20 for max acceleration and no PING. All this is hard to do with Multi carb setups, especially with Strombergs. The Edelbrock 500 works well, due to the selection of rods.

The development of engine management systems, probably started with this in mind

[rotorwrench]

What modern distributors? I haven't seen one in a while on a modern car. It's all computer controlled now through all the sensors.

The vacuum can pulls a bit of advance but not as much as the flyweights. It had to have something to back off to when the high load lowers the manifold pressure. Under full throttle, the vacuum is reduced to near atmospheric levels and then the vacuum builds back up as the load goes away. There isn't much pull on the can at full throttle under load. It's truly an "automatic spark control". The term "vacuum advance" just doesn't describe the system completely since it was designed to be a load balance system.

The helmet and crab distributors have only flyweight advance with vacuum operated retard through the brake system. The vacuum doesn't pull any advance at all on them it just pull the brake piston away from the advance ring.

[40 Deluxe]

Originally Posted by rotorwrench

I never could figure out why all the systems were referred to as vacuum advance. This is kind of a misnomer. The Load-O-Matic is truly a vacuum advance system with load retard as a benifit but there is NO centrifugal system in there. It uses a tuned venturi porting from the carburetor to get the vacuum and not manifold vacuum. The springs what work against the vacuum inside the distributor could be adjusted to get the correct amount of advance for a given vacuum signal.

The SBC and later non-LOM Ford systems have centrifugal advance with vacuum load retard system. It is generally referred to as automatic spark control but somewhere in there, any unit with a vacuum can was referred to have vacuum advance. The flyweights give the advance and the vacuum can will override that and provide a bit of retard of the spark for pulling a load such as going up a long hill.

The old Model A vehicles had manual spark control. You had to retard the spark manually for starting the engine or just a little bit when you hit a long hill while driving.

???"non-LOM Ford systems have centrifugal advance with vacuum load retard system."??? Uh, no. The vacuum unit actually further advanced the ignition timing under part throttle light load conditions (when the fuel mixture is leaner). A lean mixture burns slower (more space between fewer fuel molecules) so timing needs to be advanced to compensate. When the load increases, you open the throttle more to get more power. The resulting drop in vacuum causes the spring in the vacuum can to lessen or eliminate the additional advance.
The only partial exception to this is found on some '70's Fords for emissions purposes. A dual diaphragm vacuum unit had a second chamber that kicked in at idle, using manifold vacuum to retard the timing at idle only. With the timing retarded from base timing, more throttle opening was required to maintain correct idle speed. This greater throttle opening at idle allowed more air into the combustion chambers, which lowered emissions. Primitive, no??
I might add that with the addition of Exhaust Gas Recirculation even more vacuum advance was needed under light load conditions when the EGR valve opened and dumped inert exhaust gas into the combustion chambers. Guys who in their great wisdom plugged the EGR hose without changing the vacuum chamber often had pinging problems. With even greater wisdom they backed off the base timing or plugged the vacuum advance hose to eliminate the ping, resulting in negative gain!
Even worse, the state of California mandated disconnecting the vacuum advance hose on some models to reduce missions! Talk about a real hack job!!