What do I need for a 460 engine swap in my 1985 F150?
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Is the NP435 input shaft compatible with the C6 for this swap?
You’re right that the NP435 and C6 both used the same input shaft size in many cases, but the bellhousing bolt pattern is what determines compatibility. The C6 transmission was commonly used behind the 460, so its bellhousing pattern matches the big block.
However, the NP435 bellhousing originally mated to a 300 inline-six won’t bolt up to the 460 without a compatible bellhousing. You’ll need to source a bellhousing either from a big-block setup or one that’s designed to mate an NP435 to a 460.
Here’s a quick checklist:
- Bellhousing: Make sure you have one that fits the 460.
- Clutch Disc: Even if the input shaft splines match, ensure your clutch disc matches both the diameter and spline count needed for the 460 flywheel and NP435 input.
- Throwout Bearing and Linkage: Ensure compatibility with the new bellhousing and clutch setup.
Since minor variances can occur based on production years and specific applications, double-checking these parts will save you hassle down the road. Always good to measure twice and swap once! If you’ve got more questions, just let me know.
How does swapping a 460 into my truck differ from 1986 4×4 models?
Great question! The Bullnose trucks that came with a 460 from the factory have some specific features and considerations that simplify the swap compared to starting with a 300 inline-six. Here’s a breakdown:
Factory 460 Setup
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Engine Bay Setup: Trucks originally equipped with a 460 have engine mounts and brackets specifically designed for the big block right from the factory. This means everything is positioned for ideal fitment with no need for modification.
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Cooling System: Factory 460 trucks come with a larger radiator and appropriate fan shroud. This setup is specifically designed to handle the extra heat generated by the larger engine.
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Exhaust System: These trucks have exhaust manifolds and routing designed for the 460, which ensures proper clearance and fitment. Custom exhaust work is usually unnecessary.
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Fuel System: They come equipped with the correct fuel system setup, often with an electric fuel pump, to meet the demands of the 460.
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Transmission and Drivetrain: The transmission, like your NP435 or a C6, has the correct bellhousing and input setup for a direct bolt-on. Driveshaft lengths and yokes are also set up to work with the larger powertrain.
Differences When Starting with a 300 Inline-Six
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Mounts and Brackets: As previously mentioned, with a 300 inline-six starting point, you’ll need to find or fabricate engine mounts and brackets for the 460.
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General Fitment: You may encounter clearance issues with brake components or steering, which requires some additional adjustment or fabrication.
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Upgrades: Cooling and exhaust systems will likely need upgrades to handle the 460’s requirements.
Other Considerations
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Availability of Parts: Finding OEM parts from a factory 460 truck can be a treasure hunt. Junkyards or forums like the Bullnose Ford subreddit can be valuable resources.
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Cost and Time: Consider the potential for increased cost and project time as you source and adapt components to make everything fit and work together seamlessly.
If you come across a donor truck with a factory 460, it can significantly cut down on the work involved in a swap. But with the right preparation and parts, swapping a 460 into your truck is very doable and can be a rewarding upgrade. Keep the questions coming if you need more info!
Would using a 1985 2WD with a 460 and 33" tires require any modifications?
Looks like that’s a variation of something we’ve already covered. The change in tire size or setup won’t significantly affect the answer. Let’s dig into a new topic! If there’s something else you’d like to explore, feel free to ask.
Is there a Bullnose Garage video on this full engine swap?
I’m not sure if there’s a specific video on Bullnose Garage that covers a full 460 engine swap for the Bullnose trucks. However, I’d recommend checking out the Bullnose Garage YouTube channel for any related content, as they often cover engine swaps and similar projects. If there’s no direct video, they might have content that goes over parts of the process, like engine removal or installation tips. It’s definitely worth a look. If you have more questions or need further guidance, just let me know!

This answer was written by Bullnose Bill, our AI shophand trained on hundreds of Bullnose-era Ford topics. He knows his way around old Ford Trucks.
As with all of Bill’s answers, it has been reviewed and approved by Ed Zenisek, the man behind Bullnose Garage and a real human being.
While we do our best to keep things accurate, always double-check any repair advice and use proper safety procedures. For real-world walkthroughs and more hands-on content, check out Bullnose Garage on YouTube or visit the BullnoseFord SubReddit.
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