351m VCV issues
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1st Gear
Joined: Jul 2024
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351m VCV issues
I'm working to get a 1979 F150 custom with the original 351m engine in it started up again. It sat for about 5 or 6 years.
It will start and run for a minute or two before puttering out. I just got a vacuum gauge on it and there's definitely leaks. If the the VCVs near the front of the vehicle, a 3 port had one port open, another 3 port had nothing plugged in to it, and the two port had hoses on both ports, but the valve broken where the plastic joined the metal.
I have no idea how these VCVs work. Do the open ports or the cracked plastic leak vacuum? Can I simplify the vacuum lines and delete some of these,
It will start and run for a minute or two before puttering out. I just got a vacuum gauge on it and there's definitely leaks. If the the VCVs near the front of the vehicle, a 3 port had one port open, another 3 port had nothing plugged in to it, and the two port had hoses on both ports, but the valve broken where the plastic joined the metal.
I have no idea how these VCVs work. Do the open ports or the cracked plastic leak vacuum? Can I simplify the vacuum lines and delete some of these,
Lead Driver
Joined: Oct 2018
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To get it running just plug EVERY vacuum port except the vacuum advance, and you can plug that too if you want. then start hooking up hoses and find your leak.
An engine should have, but doesn't require a PCV. if you have power brakes you need that. you need your vacuum advance hooked to ported vacuum. and your A/C controls if you have it, and transmission line if you have an auto. . other than that you're better off to delete the rest of the garbage.
An engine should have, but doesn't require a PCV. if you have power brakes you need that. you need your vacuum advance hooked to ported vacuum. and your A/C controls if you have it, and transmission line if you have an auto. . other than that you're better off to delete the rest of the garbage.
Mountain Pass
Joined: Jul 2024
Posts: 189
Likes: 19
From: Saskatoon
To get it running just plug EVERY vacuum port except the vacuum advance, and you can plug that too if you want. then start hooking up hoses and find your leak.
An engine should have, but doesn't require a PCV. if you have power brakes you need that. you need your vacuum advance hooked to ported vacuum. and your A/C controls if you have it, and transmission line if you have an auto. . other than that you're better off to delete the rest of the garbage.
An engine should have, but doesn't require a PCV. if you have power brakes you need that. you need your vacuum advance hooked to ported vacuum. and your A/C controls if you have it, and transmission line if you have an auto. . other than that you're better off to delete the rest of the garbage.
plug everything, inc vac advance , brake booster, pcv.
then get it running good
if theres stil vac leaks , inspect carb and intake gaskets, spray with carb cleaner or some flammable aerosol while its running to see if idle changes.
once its running good and you wanna drive down the road, you can add dist vac advance, brake booster back in after carefuully inspecting each hose, if not replacing.
on my engine the brake booster hose was so cracked it was falling apart, but from the front you couldnt see that back of the sharp bend where this leak was.
Also my pcv hose was so loose it wouldnt stay connected
fixing both those helped alot!
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yankeerebel
1973 - 1979 F-100 & Larger F-Series Trucks
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Jul 12, 2013 02:07 AM
