351w intake manifold4/7/2023 The pre- '77 heads have larger intake ports, and some gasket brands have small port openings that are only large enough for the later heads.Īlong with the RTV tip from above, that ought to get your intake sealed up. Just make sure the openings for the ports are big enough that they aren't a restriction. ![]() The extra holes will prevent the carb spacer from sealing to the intake.Īs far as sealing the intake to the head, with a 12-bolt intake, use '77-up Windsor gaskets rather than the '69 - '76 style. Likewise, the universal gaskets typically have two holes for each carb stud. Universal 4V gaskets don't have enough material to seal up this area, which will cause a leak. There's a protrusion on the back of the carb pad on the '69 and '71 4V intakes that matches the vacuum-port "bump" on the back of the spacer. Unless blocked off, these will create a vacuum leak.Ĭarb gaskets are also important, especially if using a factory Ford spacer between the carb and intake. Flow wise, they're comparable to the original C9OE 4V, but have integral EGR passages cast in. The only FoMoCo produced 12-bolt 4V intake for the 351W was used on trucks during the Eighties. Anyway, the reason you must not use the cork- or rubber end seals is that it makes sealing the side intake gaskets that much tougher - very hard to get the proper torque on the bolts since that end seal keeps compressing, thereby reducing the clamping force on the intake bolts and possibly causing a water or vacuum leak later on.Īll the factory 351W intake manifolds, including the C9OX and D1JE 4V intakes, had 16 bolts until '77 or so, when Ford switched to using 302-style heads. Belive me, that Ultra-stuff seals good! You'll probably have to cut it with a razor blade to remove the intake later. Otherwise, the intake will want to kick out to the other side and cause leaks.Īlso, did you use the end seals on the intake gasket? If so, throw them away and use a bead of Permatex Ultra-Blue or Ultra-Black, not regular RTV silicone. Start with one inner bolt on the driver's side, then one on the passenger side, then the other inner on the driver's side and so on. Do this several times! As the gasket compresses, the other bolts will need to be re-tightened. You must follow the proper torquing sequence when bolting down the intake manifold - starting at the inner bolts and working to the outermost. Did you verify the cylinders with the alleged problem by pulling spark plug wires or checking exhaust temp? either a vacuum hose came off or the carb isn't tightened down. I seriously doubt that the intake cracked internally. DOKįord found that 12 bolts were sufficient, so the 16-bolt thing was only for the first year or so. (bolts were all tightened to spec 23 ' #s) Any ideas? And why would a 2V manifold use less bolts than a 4V? You would think it might be the other way around! Thanx for any help. When assembling to engine, it matched, and fit, but the 4V manifold used 12 bolts, where the 2V used 16! Now, I still have a massive vacuum leak at edges where intake, gaskets and heads meet. (no external cracks visible) No surfaces were machined on heads or intake, and looked flat when a straight-edge was placed across them. Since the gaskets looked to be ok, it was assumed that the manifold was cracked internally. It was determined that There was a vacuum leak, which caused the engine to run from 1 plane of the manifold, and would not fire on the other plane ,effecting cylinders 2 ,3, 5 & 8. The car ran fine for a short time, then ran poorly. The heads were replaced on engine, then 2v manifold and carb. The upper plenums and lower manifold are also available separately.I have a 69 Cougar, which the valves needed replacement. *Overall height to the lower manifold flange is 5.375 in. Manifolds for 351 Windsor engines with a 75mm throttle body inlet produce power in the 1500-5500 RPM range, and 90mm throttle body applications produce. *Overall height to the upper manifold flange is 11.500 in. 351C Ford Small Block V8 351M Ford Small Block V8 351W Ford Small Block V8. Manifolds for 351 Windsor engines with a 75mm throttle body inlet produce power in the 1,500-5,500 RPM range, and 90mm throttle body applications produce power in the 2,000-7,000 RPM range. H22 Blocks & Sleeves Intake manifold 5 20 It has 55mm mains Jan 12. Trick Flow® R-Series EFI Intake Manifolds are available in kits with a natural finish aluminum lower manifold and an A319 aluminum upper plenum in your choice of silver powdercoat, black powdercoat, and natural finishes. The manifolds have long, large cross-section runners to further improve flow velocity and performance. Trick Flow’s® R-Series EFI Intake Manifolds are computer-engineered to deliver ideal airflow distribution and velocity to increase low-end torque and provide superior high-rpm horsepower.
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