78fj40 emissions unit? (1 Viewer)

[fjc-man]

Do you still have the charcoal canister mounted on your truck? Do you have the distributor vacuum advance hooked up that way because the the plugged off diaphragm leaks? The one that’s hooked up is only good for 6 degrees advance. The other one is good for 16 degrees if still functional.

 

[1911]

Do you still have the charcoal canister mounted on your truck? Do you have the distributor vacuum advance hooked up that way because the the plugged off diaphragm leaks? The one that’s hooked up is only good for 6 degrees advance. The other one is good for 16 degrees if still functional.

@fjc-man is correct. To further clarify, the inner dizzy advance port (that is capped off in the photo) is the main vacuum advance, and should be connected to the advancer port at the base of the carb. The outer dizzy port is for the High Altitude Compensation system, and should be connected to the HAC valve (big round plastic thing) on the driver's side fender in the engine bay.

 

[woytovich]

Do you still have the charcoal canister mounted on your truck? Do you have the distributor vacuum advance hooked up that way because the the plugged off diaphragm leaks? The one that’s hooked up is only good for 6 degrees advance. The other one is good for 16 degrees if still functional.

No, it is not installed.
YEs, as per Jim Chenoweth.

 

[woytovich]

@fjc-man is correct. To further clarify, the inner dizzy advance port (that is capped off in the photo) is the main vacuum advance, and should be connected to the advancer port at the base of the carb. The outer dizzy port is for the High Altitude Compensation system, and should be connected to the HAC valve (big round plastic thing) on the driver's side fender in the engine bay.

Thanks. I do not have the HAC installed. I will double check with Jim C as to why this is set the way it is.

 

[dmaddox]

The larger High Altitude thing was an option in 78 and a permanent fixture in 79+, no? The high altitude stuff is included in the 1978 emissions manual, but not part of Federal or California. It is a separate diagram. Regular, federal routing showing the two distributor lines: (photo from my original 1978 air cleaner)

 

[Pighead]

Thank you!

So... I have a "large cap" distributor, no EGR, a '79 2F, unknown year carb and no charcoal canister. I am interested in getting this set-up "correctly" given the mish-mash of components.

I am running a Big Cap dizzy on an early 2F with a 10/73 carb. No EGR or nuthin'. Throttle positioner removed, fuel cutoff disabled, etc.
I replaced my non-functioning dizzy dual diaphragm vacuum advance module with a single diaphragm vacuum advance module that i got from @4Cruisers. That single diaphragm is hooked to the ported vacuum source at the base of the carb. Also did the "shadetree recurve" with the MSD spring kit.

 

[Engineer8000]

Since you removed the fuel cut off solenoid, do you have issues with dieseling? That FCS was originally just wired to the ignition switch before it was incorporated into the emissions strategy in 79.

 

[Pighead]

Since you removed the fuel cut off solenoid, do you have issues with dieseling? That FCS was originally just wired to the ignition switch before it was incorporated into the emissions strategy in 79.

No. None.

 

[4Cruisers]

Thanks. I do not have the HAC installed. I will double check with Jim C as to why this is set the way it is.

IIRC, Jim's point is that some amount of vacuum advance is better than none, even if it's limited by using only the outer port. Does the vacuum hose from the outer advancer port connect directly to a port near the carburetor base?