Vacuum Reading on 1973 351C
Printed From: The Ford Torino Page
Category: Powertrain Specific Forum
Forum Name: 335 Series Engine Forum
Forum Description: 351C, 351M and 400 engines
URL: https://forum.grantorinosport.org/forum_posts.asp?TID=21034
Printed Date: 26-March-2026 at 2:22PM
Software Version: Web Wiz Forums 12.06 - https://www.webwizforums.com
Topic: Vacuum Reading on 1973 351C
Posted By: 73grantorinoB
Subject: Vacuum Reading on 1973 351C
Date Posted: 07-December-2023 at 4:55PM
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Hi everyone, new to the forum. I recently got a 1973 gran torino base with a 2bbl 351C that has been running a little rough. I've put a link to a youtube video with a vacuum gauge plugged into the intake manifold. It's getting around 11-13" on the vacuum gauge. Any tips on what I could start looking for/tweaking first? I have not touched the carb or the timing yet. Thanks everyone! youtube link: https://youtube.com/shorts/78uqvQwnRrk?si=HtXvsPZZc21ucsOp" rel="nofollow - https://youtube.com/shorts/78uqvQwnRrk?si=HtXvsPZZc21ucsOp |
Replies:
Posted By: 72FordGTS
Date Posted: 11-December-2023 at 11:50AM
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Welcome to the forum. I'd start by looking for vacuum leaks. Once you are sure there are none, set the timing and adjust the idle mixture and report back. ------------- Vince 1972 Ford GTS Sportsroof - Survivor, One Family car GTS.org Admin |
Posted By: Rockatansky
Date Posted: 11-December-2023 at 12:54PM
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i would investigate everything between the carb base and the intake manifold. i'm guessing there should've been stock from the factory an aluminum EGR plate? that has a gasket on either side, the top gasket is a std carb gasket but the lower gasket is kind of special, heavy duty rated for exhaust temps. after all these years it'd be no surprise to me that the gaskets are failed not to mention the alloy plate itself. they either carbon up solid, burn through or both. if it turns out you need a plate you can still find NOS and used plates but be aware there are several different styles. you need the right one to match your manifold. also check the EGR valve itself for function by applying vacuum to the connection and see if the valve operates. if the valve is stuck mid-stroke IDK what effect that would have on your manifold vac reading but i suspect it wouldn't help any here's your EGR gasket, https://www.rockauto.com/en/catalog/ford,1973,gran+torino,5.8l+351cid+v8,1129159,exhaust+&+emission,egr+gasket,4972" rel="nofollow - https://www.rockauto.com/en/catalog/ford,1973,gran+torino,5.8l+351cid+v8,1129159,exhaust+&+emission,egr+gasket,4972 EGR valve, https://www.rockauto.com/en/catalog/ford,1973,gran+torino,5.8l+351cid+v8,1129159,exhaust+&+emission,egr+valve,4968" rel="nofollow - https://www.rockauto.com/en/catalog/ford,1973,gran+torino,5.8l+351cid+v8,1129159,exhaust+&+emission,egr+valve,4968 and from this window, https://www.rockauto.com/en/catalog/ford,1973,gran+torino,5.8l+351cid+v8,1129159,fuel+&+air,carburetor+mounting+gasket,10024" rel="nofollow - https://www.rockauto.com/en/catalog/ford,1973,gran+torino,5.8l+351cid+v8,1129159,fuel+&+air,carburetor+mounting+gasket,10024 you'll need the FEL-PRO 60185 (lower) and upper gasket of your choice, these are all basically the same. besides the gaskets between the carb and intake, then i'd check all the usual suspects like all the hoses tapping vacuum off the intake manifold and whatever they're connected to. even the interior climate control valve and the 'soup can' reservoir
------------- 72 GT Ute |
Posted By: 73grantorinoB
Date Posted: 13-December-2023 at 2:41PM
Thanks for all the tips. I've gone ahead and ordered the gaskets as they will likely need to be replaced, and ill inspect for a cracked plate. I adjusted the idle air mixture screws out to 3 full turns after they bottomed out and the vacuum reading went up to 15". I checked the timing and it seems like initial timing is reading somewhere around than 3-5 degrees BTDC. I suspect the balancer might've slipped, so I'll be making new marks and getting the timing back up to around 8-10 degrees. No obvious vacuum leaks after plugging off different hoses, but ill use some carb cleaner around the carb/intake to check for any there. Unfortunately, after starting up the car a few days ago I started hearing what I believe was a collapsed lifter, but it went away after about 10 minutes and hasn't come back since. Any thoughts on it? Thanks  Youtube video for tick: https://youtube.com/shorts/GZj_fOEaG6A?si=ScCZSewkpUpHpK1b |