292 to 350 Swap

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deucecoupe

Junior Member
Joined
Jun 29, 2022
Posts
16
Reaction score
8
Location
Lake Oswego OR
First Name
Richard
Truck Year
1984
Truck Model
C10
Engine Size
350
I'm a little late to this thread. I'm doing a 250 to 327 swap right now into my '84 C10.

When I pulled off the old motor mounts on the front crossmember, there were two sets of holes - one set lower and one set slightly higher but neither forward or backward. The 250 lower sat in the lower set of holes.

I just mounted the new SBC motor mounts into the upper holes and everything is fine.

The pics from Bextreme04 were exactly what I used. The lower mounts are easy to find and purchase. I dug around on FB marketplace and craigslist to find a used set of the upper clamshells that worked perfectly. Just need paint.

This isn't a hard swap to do, but I've spent more time than I thought finding all the various brackets and pulleys.

Good luck
 

nvrenuf

Full Access Member
Joined
Jul 30, 2010
Posts
1,709
Reaction score
1,913
Location
Mobile, Al.
First Name
John
Truck Year
1991
Truck Model
K5
Engine Size
454
You should read the replies, it's not the same with a 292.
 

greyghost

Full Access Member
Joined
Jun 15, 2022
Posts
50
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15
Location
kansas
First Name
vic
Truck Year
1981
Truck Model
C10
Engine Size
250
I have a 1984 C30 crew cab with a tired 292 I6 and I am looking to swap in a small block 350. Will I need to change the motor mount perches (brackets that connect from the frame to the cross-member). If I need to change the perches will I need ones from a C30 or will C10/C20 ones work and what about years, will 73/87 work or do I need ones from 81/87? Any help would be appreciated.
curious to know if swap has occurred yet, n wat outcome was? my thots I'm swapping out my 250 I6 for LS. The only way i know to tell is use a straight edge across bellhousing mt surface n rear side of engine mts measure distance , f numbers match good to go, if not a diff location set of holes must be used. be sure to used exact set for both sides as engine angle pitch is critical, also affects tranny angle pitch n tranny mt position stress. I believe there are 3 diff sets of mounting positions already in Xmember, b sure to clean out with thread tap. 3/8 coarse i think 18 tpi, same size as existing. clamshells mt to engine n rubber mt on Xmember. good luck on first try, no fun in a second try cept more time. check all measurements b4 hand will b best outcome..
 

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  • Screenshot 2022-10-10 at 11-06-25 Engine Mount and Bracket.png
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  • Screenshot 2022-10-10 at 11-06-57 Engine Mount and Bracket.png
    Screenshot 2022-10-10 at 11-06-57 Engine Mount and Bracket.png
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