When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
I’ve installed an 800 CFM Edelbrock (Carter) carb on my 447 CID FE engine and I have a question about vacuum. Neither the brakes nor the distributor require vacuum. The only demand for vacuum I have is from the vacuum modulator on the TCI Super Street Fighter C6 automatic transmission. There are four vacuum ports to choose from.
This port on the back of the carb is normally used for vacuum assisted power brakes. Sometimes the fitting used here has one large barbed fitting for the brakes and one or more smaller barbs in a tree formation for other functions, including the AT vacuum modulator. I suppose I could source a single fitting with a very small barb connecting to the transmission. This would be the path of least resistance so I need to know if there might be a problem with this approach. There will be no power brake system taking the lion’s share of vacuum from this port.
The other three ports are at the front of the carb and these will all be plugged. Crankcase ventilation is handled by breathers on the valve covers.
So with only one source of demand for vacuum, what is the best practice in this particular case?
I think your approach is spot on. Typically you see the AT plugged into a tree on the rear of the intake, but it looks like your running a pretty clean setup and dont want to tap into the manifold just for the AT, so the rear port on your Eddy would supply to correct type of vacuum and be a straight shot out the back and down to the AT and will maintain the cleanliness of your setup.... , just gotta get a little barb adapter for that size hose, I want to say its 3/8 but its been awhile.... Are you still running one side of the valve covers as PCV ? just curious, I have a very similar setup on my FE390.... with one valve cover as a filtered breather the other PCV hosed to the front of my Eddy....
Are you still running one side of the valve covers as PCV ? just curious, I have a very similar setup on my FE390.... with one valve cover as a filtered breather the other PCV hosed to the front of my Eddy....
No PCV at all. I'm using these circle track type breathers:
Since this is a new, limited use power plant the amount of blow-by released into the atmosphere will be negligible. Oil mist should be well contained by the paper filters. Thus, with no need to compromise the air/fuel mixture, I will be plugging that big port on the front, This decision will always be easily reversed.
Nice setup.... I like those breathers also, and im diggin the coil mount, I need to move mine off the drivers fender and get it closer to the distributor, what is the coil clamp attached to ?
Nice setup.... I like those breathers also, and im diggin the coil mount, I need to move mine off the drivers fender and get it closer to the distributor, what is the coil clamp attached to ?
This was hand built and documented here beginning with post # 415.
I would definitely say use the rear port on the carb.
I plugged mine, only because the offenhauser intake has a nice 45 degree (upwards towards the windshield) port off the rear of the intake. It was a convenient spot for me to use.
If memory serves me right, that rear port on the edelbrock is a 3/8" NPT (pipe thread, not straight thread).
If needed, you could always invest in a two-piece elbow that makes a 90 degree bend (to the passenger side) to make your life easier for hose routing. The reason I mention a 90 degree bend is because a 180 degree thread/hose barb combo is going to make your life a living nightmare when trying to connect the factory vacuum (steel) line to the rear of the carb. I tried this on my build, and the hose would kink significantly when connected.
IMO it doesn't matter. Any manifold vacuum source will do. Just dont use a port above the throttle blades and you'll be fine.
I would always run PCV on a street rig, you need to pull a vacuum on crankcase to draw in fresh air through the breather. If you are worried about oil in the intake run an oil separator and drain it every oil change. I've made several on the cheap and they work great.
I would definitely say use the rear port on the carb.
I plugged mine, only because the offenhauser intake has a nice 45 degree (upwards towards the windshield) port off the rear of the intake. It was a convenient spot for me to use.
.
The Edelbrock Performer RPM intake manifold for FE engines has only one vacuum port and it's forward of the carb. I have that plugged as well, see:
Here are the three ports on the front of the carb. I have all three plugged.
The single rear port was designed with vacuum assisted power brakes in mind. This is a 1/4" NPT threaded port.
In order to repurpose this port for the AT vacuum modulator, I needed to source a 1/4" NPT X 5/16" replacement for the 1/4" X 3/8" fitting supplied by Edelbrock.
So here is the completed connection with the vacuum modulator line.
I was pleased with being able to minimize the number of potential vacuum leaks and a snake pit of hoses.
Did you have to rebend the vacuum modulator line (factory) to get it straight like that?
I recall mine having a lovely 130 degree bend from the firewall towards the passenger side exhaust manifold.... made for a pain to disconnect! Your's looks awesome
Did you have to rebend the vacuum modulator line (factory) to get it straight like that?
I recall mine having a lovely 130 degree bend from the firewall towards the passenger side exhaust manifold.... made for a pain to disconnect! Your's looks awesome
Thanks. I can take no credit though. This is the way it came to me. My other '76 FE/C6 looks the same so this is apparently normal for this particular configuration.
This Hennessey Takes the Expedition Tremor's Off-Roading Capability to the Next Level
Slideshow: The VelociRaptor Expedition gains a lift, upgraded suspension, Brembo brakes, and trail-ready equipment while retaining the stock 440-horsepower EcoBoost V6.
Rezvani's Latest Post-Apocalyptic Monster Is a Ford F-150 Raptor Underneath
Slideshow: Called the Fortress, the 850-horsepower pickup combines Raptor underpinnings with military-inspired features, survival equipment, and a starting price of $285,000.
