Sep 21, 2026 at 8:48 AM
purchased Ranchero with a 351W that has vacuum lines unhooked and all over the place...... no diagram sticker left under the hood. Could someone point to where I can find one... Would much appreciate!
Vintage
1979 Ford Ranchero vacuum line mess
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Oct 22, 2026 at 8:41 PM
Sorry this sat a month. Short version: there's no single correct 1979 diagram. Ford built several calibrations of the 351 that year and the hose routing changes between them, so the number you need is the calibration code. Look for a small engine label, usually on the front of the valve cover (sometimes the door edge), with a code like 9-xxA-Rxx. If it's gone, the engine family on any remaining emissions label helps too.
Until then, the basics on a 351W 2V are the same on almost every version. Manifold vacuum (the carb base or the manifold itself) feeds the brake booster, the PCV, the transmission modulator, and the line to the heater/AC controls. Ported vacuum (the carb port that has no vacuum at idle) feeds the distributor advance and the EGR valve, usually through temperature switches screwed into the thermostat housing. If you have an air pump, its bypass valve takes a vacuum line too, and the charcoal canister has a purge line back to the carb.
Hook up the booster, PCV and modulator first and plug everything else, and it will run and be safe to drive while you sort the rest.
Our 1977-1979 Ranchero vacuum page has Ford's factory A/C and heater vacuum routing page for the 1978-79 Ranchero, T-Bird, Cougar and LTD II, which covers the dash-side lines. It also has one engine diagram, but that one is for a 351M, not your 351W, so use it for the general layout only, not hose for hose:
https://www.supermotors.net/reference/ford/ranchero/1977-1979/vacuum-routing
Ford's 1979 Electrical and Vacuum Troubleshooting Manual for these cars has the engine routing for each calibration. Post the code and a photo or two of the carb and the thermostat housing here and we can help match it.
Dana
Until then, the basics on a 351W 2V are the same on almost every version. Manifold vacuum (the carb base or the manifold itself) feeds the brake booster, the PCV, the transmission modulator, and the line to the heater/AC controls. Ported vacuum (the carb port that has no vacuum at idle) feeds the distributor advance and the EGR valve, usually through temperature switches screwed into the thermostat housing. If you have an air pump, its bypass valve takes a vacuum line too, and the charcoal canister has a purge line back to the carb.
Hook up the booster, PCV and modulator first and plug everything else, and it will run and be safe to drive while you sort the rest.
Our 1977-1979 Ranchero vacuum page has Ford's factory A/C and heater vacuum routing page for the 1978-79 Ranchero, T-Bird, Cougar and LTD II, which covers the dash-side lines. It also has one engine diagram, but that one is for a 351M, not your 351W, so use it for the general layout only, not hose for hose:
https://www.supermotors.net/reference/ford/ranchero/1977-1979/vacuum-routing
Ford's 1979 Electrical and Vacuum Troubleshooting Manual for these cars has the engine routing for each calibration. Post the code and a photo or two of the carb and the thermostat housing here and we can help match it.
Dana
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