Switching cam gear cover from 2-bolt to 3-bolt

[Ziggster]

I will likely use a helmet style distribute on my C69 block for a number of reasons, and just ordered a 3-bolt cover off of eBay. My 2-bolt cover has an oil feed port whereas the 3-bolt doesn't. I can't seem to find anything about this port other than a mention in my Ford Flathead V-8 Engine book, and even then there is no mention of what it connects to. Is there anything special about this port I should know about by "deleting" it when I install the 3-bolt cover?

My original 2-bolt cover and 3-bolt cover.

[flatheadmurre]

The port is vacuum for the distributor...not oil.
On the earlier style vacuum is bolted directly to distributor...

[Don]

Isn’t there a spacer,,,slug,, in there somewhere to make up space of shorter cam???

[Ziggster]

Interesting. I noticed the later style cover also doesn't have the port. From the book...

[Bored&Stroked]

It is important that you understand what cam you have in the engine - otherwise the distributor to cam snout-face depth may not be correct.

[Ziggster]

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Originally Posted by Bored&Stroked

It is important that you understand what cam you have in the engine - otherwise the distributor to cam snout-face depth may not be correct.

I'm using the original cam. I understand that I'll need the distributor drive spacer. Is that correct?

[rotorwrench]

Pre-42 cams are longer. You would need the drive button spacer to adapt the short cam nose to the early distributor.

Personally, I like the crab type a lot better for clearance issues on applications that interest me. It's easier to get on and off too.

[Ziggster]

Originally Posted by rotorwrench

Pre-42 cams are longer. You would need the drive button spacer to adapt the short cam nose to the early distributor.

Personally, I like the crab type a lot better for clearance issues on applications that interest me. It's easier to get on and off too.

Hopefully for me it won't be too much of an issue as I will have no fan and radiator to deal with as they will be located at the rear of the car.

[Ziggster]

Ok. I think I'm slowing figuring this out. So, the port on my original cam gear cover is for a vacuum signal to the dizzy. This makes sense as the helmet style distributor has what appears to be an external vacuum signal next to the vacuum brake. So, where does this this vacuum signal come from? Is it the port on the manifold just below the carb? Seems the whole topic of spark advance on these engines using the vacuum signal is either not well understood or avoided.

From an old thread...

https://www.fordbarn.com/forum/showthread.php?p=90803

Close-up of cam gear cover with matching port for dist body.

[Ziggster]

Same port on body of crab style dizzy.

[Ziggster]

Vacuum line on helmet style dizzy.

[Tinker]

Crab is a better distributor in my opinion. But if your changing to be more original?

[Ziggster]

Vacuum signal port on intake manifold?

[Tinker]

40's wiper if I remember right. Had a cast fitting that also had a small baffle. A hard or impossible fitting to find as they were easily broken and not repoped.


Your carb is also a later 8ab carb. to my limited knowledge. I know enough not to be certain here.

[JSeery]

Vacuum source is not critical, it's manifold vacuum. The distributor timing advance is mechanical, the vacuum operates a vacuum brake.

Some information on Bubba's site. http://www.bubbasignition.com/helmet--32-41-1.html

[Ziggster]

Originally Posted by Tinker

Crab is a better distributor in my opinion. But if your changing to be more original?

Original is in the eye of beholder I guess...

https://youtu.be/Ug7oyobYONk

[Tinker]

Originally Posted by Ziggster

Original is in the eye of beholder I guess...

https://youtu.be/Ug7oyobYONk

True so why change the dizzy?

[Tinker]

To add to JSeerys post.


http://www.bubbasignition.com/crab-42-48.html

[JSeery]

Originally Posted by Ziggster

Seems the whole topic of spark advance on these engines using the vacuum signal is either not well understood or avoided

How the advance works is well understood. The vacuum component is likewise well understood and not avoided. It is a very simple system, the vacuum operates a brake on the advance plate to hold back the mechanical advance at low manifold vacuum. With modern fuels the adjustment is normally backed-off to the point very little to no braking is used. If you did have a pinging situation you would add brake pressure to reduce it.

[Ziggster]

Originally Posted by Tinker

True so why change the dizzy?

I guess because I can. I like the fact that the engine seems older than it is with the helmet dizzy. Many will wonder what is that thing on the front of the engine. With no fan or rad to be seen, the mystery will deepen. The more that can be done to make it look unlike any engine most are accustomed to seeing is partly my goal. That is because the car I'm building is a recreation of another recreation using an air-cooled 5.0L engine from around 1910.