250Ci swap to a 355ci What needs to be changed

[Furno68C20]

I'm about to start removal of a i6 250 engine and swap for a sbc v8 355ci.

The truck is a 67 3 on tree.

My question is what can be used and what cant be used? Radiator? clutch? flywheel? pressure plate? starter? ect....

Need to make a part list to order for the job to run as planned.

for now going to use the 3 speed that in there until i find a 4 speed saginaw or t10.

[gmc684x4]

Depends on how much hp your new engine puts
I used my rad starter clutch etc you will need a v8 zbar for the clutch pedal

350 will drop right in place on the motor perches as well
Rubber mounts will bolt onto the block as well
I did this with 200 hp 70s square truck engine

[Furno68C20]

Originally Posted by gmc684x4

Depends on how much hp your new engine puts
I used my rad starter clutch etc you will need a v8 zbar for the clutch pedal

350 will drop right in place on the motor perches as well
Rubber mounts will bolt onto the block as well
I did this with 200 hp 70s square truck engine

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[Furno68C20]

Originally Posted by gmc684x4

Depends on how much hp your new engine puts
I used my rad starter clutch etc you will need a v8 zbar for the clutch pedal

350 will drop right in place on the motor perches as well
Rubber mounts will bolt onto the block as well
I did this with 200 hp 70s square truck engine

300-315 hp engine. Mild cam vortec heads. Nothing too crazy. The math spits out 10:1
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[gmc684x4]

New engine i look at a new rad used engine i am more willing to take a chance on an old rad an old rad in these gals can be well over 50 years old

I am getting a 2 core all aluminum rad for my 72 it will be pushing somwhere over 400 hp

Either way you will want to use a good fan shroud to help keep her cool

[67mater]

the Z bar I think is the same, it's the block side mount that is different. the inline 6 is wider to make up for the block being farther away.

the throttle linkage and pivot are 6 cylinder only, assuming you are running all stock.

if your clutch is the 11" one you could get way with reusing it. Would not recommend the 10" with a v8, but it ill all bolt up and work.

[tim_mc]

I left my SBC in the i6 position as well. The HEI is close to the firewall, but there's enough clearance to pull the distributor when needed. For the fan shroud you can use one for a 4x4 V8 as 4x4s had the V8 in the inline 6 position. I got mine from LMC and like it (p/n 32-2826).

[tim_mc]

Oh, you might also want to consider a newer throttle cable setup instead of the pushrod. There are a few threads on here that detail the changes and mods needed.

[Furno68C20]

Planning on keeping mostly stock. I’ll have to check the clutch diameter make sure it’s 11.

What about the radiator supports?

The oil pressure sensor? 6 cyl is wired to the cluster. The sensor fits next to the distributor on the sbc which usually is hard tubed the dash.
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