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Old 01-12-2018, 03:20 PM   #1
sick472
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'76 350 into an '85 3/4 ton 4x4

I have my old '76 2wd that has a GM 350 crate motor with 70K miles on it and my '85 3/4 ton 4x4 is burning a lot of oil (like a quart every 1000 miles. maybe more). The '76 is almost see-through due to rust. Both are automatics and AC trucks. Neither have any real power to speak of. The '85 has an edelbrock intake and Holley carb with unknown heads and is a 350 ci as well.

My questions...what should I be aware of if I chose to swap the motor from the '76 into the '85? Would it be straight forward or will I have to make mods?

I'd love for this to be a one weekend chore should I pull the trigger.

Thanks in advance!
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Old 01-12-2018, 03:25 PM   #2
natedogg
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Re: '76 350 into an '85 3/4 ton 4x4

This will be a easy swap. All the pulleys and brackets from your 85 will swap over to the 350 out of the 76. You and a buddy should be able to do this in a weekend.
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Old 01-12-2018, 07:40 PM   #3
MikeB
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Re: '76 350 into an '85 3/4 ton 4x4

Should be a piece of cake, especially if you're going to use the intake and carb off the 85's current engine. But there's always some little issues to iron out. Seems like 85 engines had passenger side dipstick, whereas 74 had drivers side. But that shouldn't be any big deal. I would transfer any parts like intake manifold, oil & temp senders, and kick-down cable bracket while both engines are out. And that's also the time to make sure the 74's starter will bolt to the 84's electrical connectors.
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Old 01-16-2018, 09:38 AM   #4
sick472
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Re: '76 350 into an '85 3/4 ton 4x4

Thanks for the encouragement folks!

I guess it's time to just wait for the old 85 engine to expire or use so much oil that I can't take it anymore. I think it is constantly leaking by the valve seals as I never see any oil smoke or leaks big enough to compare to the oil loss. The spark plugs need to be freshened-up/changed every year or so (5000 miles) because of oil fouling. Compression is from 170 to 200 psi and the pcv valve has been changed. There is no coolant loss either. Anyhow, this may be something for a different thread. Thanks again!
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Old 01-16-2018, 01:44 PM   #5
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Re: '76 350 into an '85 3/4 ton 4x4

If the dipstick is on a different side, you may have to swap out exhaust manifolds...which means your exhaust pipes will no longer fit -> trip (tow?) to muffler $hop. I think a lot of the crate engines had dipstick provisions on both sides though. You'll just have to check I guess.
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