New 4180 Carb Rebuild, Low Vacuum, Need some help...

[tlmartin84]

For starters let me say that I have no clue what has been done to this motor. I'm trying to figure out what the PO installed.

It came with an aluminum "Ford" 4 barrel intake, 4180 Carb, E7 or E7TE heads.

I checked the lift at the pushrod, it measures .210", at the intake valve it measures .340". Seems to be a stock Cam, right?

Compression is even across all cylinders.

At 6 degrees timing, it is pulling 7 inHG. I advanced it to 12 degrees, and it is pulling 13 inHG.



Now Monday evening I advanced the timing to around 20 degrees, and had it tuned pretty decent. Still only pulling 13-14 inHG. Some guys reccomended I disconnect the PCV valve (it is aftermarket) and check readings at factory timing. This is where the issues started happening. I couldn't get the hose off of the pcv valve or off the nipple on the carb spacer. So I just pulled the PCV out of the valve cover...engine died immediately. tried to restart it, and nothing.

Pushed it back into the cover, and it starts and idles fine. So I think okay I will pull the hose off. Pulled the hose off the PCV and plugged it. Pulled the PCV out of the valve cover.

Engine starts, sputters surges really hard, starts knocking. I grab the test light, and put it on the balancer. The vacuum advance kicked in and timing is probably 40-50 degrees. At this time, I panic and grab the distributor and twist it back down...a little to fast and retard the timing below 0 degrees and cut the ignition. As this is going on I look up and fuel is pouring out of the accelerator pump.

I cleaned everything up, plugged the PCV back in, set everything back to where I had it the night before, fires right up. I now have a small leak at the accelerator pump, that sprays fuel when I hit it. But the engine runs....except now I think I have a permanent knock near cylinder 8.

What are your all's thoughts?

No vacuum leaks (that I can find). Would a small leak at the accelerator pump cause this? Or is there maybe an internal vacuum leak somewhere? I just put new intake manifold gaskets on, as well as the carb rebuild.

[erratic50]

Pcv is an air source for the engine. If you plug the line it requires more air if it was slow on idle to begin with

something sounds fishy to me with this whole thing

are there vacuum leaks or a burn valve or anything coming into play? Head gaskets ok?