75 highboy engine swap/clutch problems

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Oct 17, 2002 | 08:08 PM

short76

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75 highboy engine swap/clutch problems

Hi all,

I have installed a 400 engine in a 75 highboy that had previously had a 429 for power (bought the truck without an engine, had a spare 400). Truck has a 4 speed. I of course had to switch the towers to ones from a 78-79 with the 351M/400. Engine sets level and all lined up with transmission. I used the bellhousing, etc. from the 400. If I understand it right, the bellhousing would have been the same for the 429. Now the linkage for the clutch does not line up. The transmission was never out of the truck. There have been no modifications previously to the bracket on the frame. When I use the bellhousing bracket from the 400 the bar sets at an angle instead of straight. The bracket on the bellhousing is lower and too far back. Everything will hook up and the clutch works ok, but I'm concerned that with this angle, the adjusting rod may not stay in place, even with the spring in place. What have I done wrong? Is my only choice to modify the bracket on the frame to get it lined up?

Any advice would be appreciated.

Oct 18, 2002 | 04:06 AM

bad 78 f 250

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Joined: Mar 2002

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From: detroit, michigan

75 highboy engine swap/clutch problems

let me know how it goes any weld and fab
you will probley have to do
bad 78 f 250

Oct 18, 2002 | 08:22 AM

jalampi

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From: Michigan

75 highboy engine swap/clutch problems

Make a mark where it needs to be and then do some fabrication.

Oct 18, 2002 | 02:57 PM

Torque1st

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75 highboy engine swap/clutch problems

Check the other bell housing, was it different?

Oct 18, 2002 | 08:47 PM

Mike W

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Joined: Apr 2002

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From: Central Kali

75 highboy engine swap/clutch problems

I have made a bellhousing bracket. I did a 302 swap from a block that had the pivot screwed into the block to one that did not. It wasn't too hard to do.

Oct 18, 2002 | 11:58 PM

short76

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75 highboy engine swap/clutch problems

Thanks for the input. I didn't specify, but although the tranny was still in place, the previous owner removed the old bellhousing when they took the 429 out so I don't have it to compare to. It looks like fabrication will be my only option. I believe I will have to modify the bracket on the frame because the current bracket on the bellhousing perfectly aligns the adjusting rod with the throwout bearing lever. It looks to me like any modification to the bracket on the bellhousing side of the bar will still result in improper alignment.

Using this train of thought, is the piece that the ball attaches to pressed, welded, or screwed on the bracket? If I fab a new bracket, I will need this piece off of the old bracket.

Has anyone who installed a 429/460 in a highboy with a 4 speed experienced this kind of problem? I feel that all of these problems have arisen due to changing to 351/400 towers but this had to be done to keep the engine level in the truck.

Thanks again for helping me think this through.

Oct 21, 2002 | 11:48 PM

masterbeavis

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From: Eldorado Ca. USA

75 highboy engine swap/clutch problems

I had the problem you speak of when I installed a 460 into my lowboy. The motor sits about 2 inches lower than the 351M did. I took the frame bracket and cut about 5/8" out of the middle, welded it back together. If you need it longer, just cut it in half and add some steel to the middle. Problem solved.

Tony

'77 F250, 4X4 460 transplantee, "Flamer"