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Old 01-11-2011, 08:52 PM   #1
Canyon Copper
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Replacing 305 in 1986 K10

Hello everyone:

I'm a newbie to this board, but not new to Chevy trucks. The truck you see pictured below I bought new in 1986 and I still drive it today. It has 175,000 miles on the clock and still runs pretty good, but the little 305 is finally showing its age and oil fouls the number eight cylinder.



I have done rebuild work before, and it is time-consuming, can be expensive, and you have no one to blame but yourself if the motor doesn't run. I could go with a machine shop rebuild, but those usually aren't cheap either.

From what I've read so far it sounds like the best option is to buy one of the GM 350 crate motors. The motor I'm thinking about is this one here (NAL-10067353) that generates 260 horse and 300 ft/lbs of torque. Torque is what I need to move the 2.73 gears that came with my truck.




As I did my reading, I learned that my truck is the ba$tard child of the Chevy V-8 world. This is because 1985 and earlier V-8's have a two-piece rear main seal, are carbureted, and have perimeter bolt valve covers. The 1987 and up engines have a one piece rear main seal, center bolt valve covers, and are fuel injected. My 1986 is a one-piece rear main, but it is carbureted and has the perimeter bolt valve covers.

This truck is a four speed.

So here are my questions:

What changes do I need to make in order to run the motor shown above in my truck? Is it as simple as swapping the flywheel to one that fits the two-piece rear main seal and everything will bolt up?

I assume the stock exhaust and all the front dress will just transfer over from the original motor to the crate motor -- is that correct?.

Will the EGR bolt up to the e-brock or Summit aluminum EGR manifolds as claimed?

Thanks guys for any advice you care to offer.
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Old 01-11-2011, 09:15 PM   #2
cableguy0
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Re: Replacing 305 in 1986 K10

Its pretty much a bolt in deal. Everything but the flywheel will interchange. All accessories will bolt right up. Motor mounts are the same.
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Old 01-12-2011, 12:07 PM   #3
Warrens69GMC
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Re: Replacing 305 in 1986 K10

This is a better replacement.
http://sdparts.com/details/gm-goodwr...gines/12520270

you just need to enlongate the intake manifolds center holes to match the 72* of the 87-95 heads, or source a carb intake for those years (yes there are stock ones)
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Old 01-12-2011, 05:21 PM   #4
Canyon Copper
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Re: Replacing 305 in 1986 K10

Quote:
Originally Posted by Warrens69GMC View Post
This is a better replacement.
http://sdparts.com/details/gm-goodwr...gines/12520270

you just need to enlongate the intake manifolds center holes to match the 72* of the 87-95 heads, or source a carb intake for those years (yes there are stock ones)
Why is it better?
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Old 01-12-2011, 06:46 PM   #5
jkade
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Re: Replacing 305 in 1986 K10

If you go to a 350 make sure you get a balancer for a 350 if you are using a 350 timing cover. I would get a new balancer anyways.

That gm 350 is a good motor, that is what was in my 86 when I bought it. It should be a 4 bolt main block. Mine had good power even with the 35's. If it were me I might would get a short block and some vortec heads and you would probably be a lot happier for about the same money. I just sold a good set of vortec heads and intake for $225 so you can find them cheap and they are good for about 30hp.

Last edited by jkade; 01-12-2011 at 06:49 PM.
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Old 01-12-2011, 11:20 PM   #6
Warrens69GMC
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Re: Replacing 305 in 1986 K10

Quote:
Originally Posted by Canyon Copper View Post
Why is it better?
This is just my opinion -
1. Has provision for roller cam & might have a roller cam (would ask before I bought it)
2. Better sealing heads (no valve gasket issues like those of the past).
3. 1 piece Rear main seal, has shown to seal better than 2pc RMS.
4. Introduces you to swirl port heads for your engine operating below 4K rpm.
5. You don't have to buy a new flywheel
6. if it has a roller cam, no cam wear like a flat tappet would without ZDDP
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Old 01-16-2011, 04:21 PM   #7
Canyon Copper
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Re: Replacing 305 in 1986 K10

Appreciate the help guys. I'll post up swap pics in the spring.
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Old 01-16-2011, 08:44 PM   #8
Mr. 250r
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Re: Replacing 305 in 1986 K10

what about an 5.3 or 6.0 ls truck motor with carb manifold? i know its not direct swap like a 350 though
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Old 01-20-2011, 04:55 PM   #9
Canyon Copper
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Re: Replacing 305 in 1986 K10

I'm going for dead-nuts simple and foolproof -- that means the 350 - got too many other projects to occupy my time
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