L6 250ci to 350ci SBC conversion- Stock Gas Pedal/carb linkage and radiator reusable?

[Yamariv]

I'm thinking about picking up a worn out 350ci to slowly rebuild over the next few years to put in my C10 and replace my L6 250ci.

I've read a bunch of old threads but couldn't find the answer to if the stock gas gas pedal/carb linkage would work for the 350ci and if I can keep the stock 250ci's radiator?

Cheers

[Palf70Step]

Since you'll probably mount it in the 6 cyl position so you can use same trans/ driveshaft. It sets it back closer to firewall but still will clear an HEI distributor. It will be tight. Radiator. Upgrade to a 3 or 4 core and good fan shroud. I stuck with a factory style clutch fan. But have known others go with electric ones. To stay with throttle rod is no issue, should easily adapt or make a new one out of 1/4 threaded rod.

[Palf70Step]

Even changing carbs on V8s require changing the rod length. Some prefer to adapt 71-87 throttle cables.

[Yamariv]

Originally Posted by Palf70Step

Even changing carbs on V8s require changing the rod length. Some prefer to adapt 71-87 throttle cables.

Sorry I should have clarified, mines a 71 and has the cable. So the cable would just bolt up to the V8 carb? There wouldn't be length issues or anything like that? (sorry probably a dumb question..)

[Yamariv]

Originally Posted by Palf70Step

Since you'll probably mount iti. 6 cyl position do you can use same trans/ driveshaft. It sets it back closer but still will clear an hei distributor. It will be tight. Radiator. Upgrade to a 3 or 4 core and good fan shroud. I stuck with a factory style vlutch fan. But have known others go with electric ones. To stay with throttle rod isno issue, shoul easily adapt or make a ne one out of 1/4 threaded rod.

I thought I read somewhere where the stock 250's radiator could cool the V-8's, is the rad a nice upgrade or more of a must? I guess I'm trying to figure out if I can do the swap on a budget lol.

Yup, definitely keeping the 3 Speed trans and the rest of the driveline stock. I think a 350 would probably do well with the 3.08 gear out back.

[Palf70Step]

The stock radiator would cool it, but question is would it be enuff. Also, a 6 does not have a fan shroud. IMO, you will want/need the shroud. Adding the shroud to ur radiator may be enough to keep it cool. Especially as far up north as you are. Down here, no way. And yes cable will work. It will be long but should be ok.

[Yamariv]

Originally Posted by Palf70Step

The stock radiator would cool it, but question is would it be enuff. Aldo, a 6 does not have a fan shroud. IMO, you will wNt/need the shroud. Adding the shroud to ur radiator ma be enough to keepitcool. Especially ss far up as you are. Down here, no way. And yes cable will work. It will be long but should be ok.

Makes sense, thanks! I always wondered why the 6's never had a shroud. So all V8's had shrouds? Do the stock shrouds fit most radiators that I would upgrade to or is fitting a shroud an issue?

[truckster]

Originally Posted by Yamariv

I thought I read somewhere where the stock 250's radiator could cool the V-8's, is the rad a nice upgrade or more of a must? I guess I'm trying to figure out if I can do the swap on a budget lol.

Yup, definitely keeping the 3 Speed trans and the rest of the driveline stock. I think a 350 would probably do well with the 3.08 gear out back.

Where you live does have something to do with it. The 250 radiator should handle Saskatchewan summers. After more than 50 years, I'd have the radiator professionally cleaned, though.

[72SB]

On the 350 motor positioned so the stock 6 cyl bellhousing/mounts remain...do the front mounts for the 350 need to be different than the 250 motor mounts?

I have been told the trans, saginaw 3 speed, needs a X member though, right?

so that would mean front 350 mounts, rear mounts are the same as 6 cyl but then also have a X member?

or??

[CAMAROBOY68SS]

The frame stands are the same for the motor mounts between a 250 and V8. My 68 C10 was a 292 I6 truck, they have one oddball stand on the passenger side that has to be swapped, but the driver side is the same. If you leave the stands in the I6/4WD location, you can reuse everything from the bellhousing back with the 3 speed.

As far as the fan shroud, use a 4wd small block shroud. That is how I have my truck setup and its never had a cooling issue.

[72SB]

I have a 72, 2WD 250 3 OTT...so just swap out the PS mount for the V8 and bellhousing/rear mount can remain with Saginaw hanging off the back?

or with a V8 I also need a X member??

I would add a fan shroud

[Palf70Step]

You don't need a xmember for the manual trans. The stock bell housing is how they did it from factory, 6 0r 8. The PS pump may work on the V8, you'll just need the brackets for the V8. I didn't have power steering originally on mine, so I got all the accessories for the V8, then added the pwr steering gear box. Just mount the V8 on the 6 cylinder stands and position and u'll be good. Use new rubber mounts though.

[72SB]

Thanks Bill, I will look up a PS V8 stand on LMC. Good to hear the bell housing/mounts work and the 3 speed hangs off the back. Will keep the 3 OTT. My 55 SB was the same with a 327/Muncie and my 57 Belair also. I had heard though C10 had X member with V8, thanks for clarifying.

I suspect the stock 6 cyl radiator would work OK but I would get a shroud. I have a 327 from my 67 Camaro that I may rebuild but more inclined to get an 85 or newer SBC with 1 piece RMS and full roller. Wish those GMPP new replacement 350's were still around back when they were around $1300

[cwcarpenter98]

72SB,
Since you have a 250, you do not need a different passenger side engine mount. The 292 has the different passenger side mount.

[pjmoreland]

Originally Posted by 72SB

I had heard though C10 had X member with V8

Just clarifying - there were two different manual crossmembers for V8 vs. I6 from the factory. The V8 version allowed the engine to be mounted farther forward. It isn't worth the trouble to switch crossmembers though since you can just mount your V8 farther back in the I6 position.

[72SB]

Originally Posted by cwcarpenter98

72SB,
Since you have a 250, you do not need a different passenger side engine mount. The 292 has the different passenger side mount.

This is what LMC shows for I6 to SBC swap for 67-72....different stands & mounts. (I had to enter year, make model to get the page to read the specific parts)

https://www.lmctruck.com/1967-72-che...and-components

So you saying my I 6 (250) stands and mounts are direct fit for V8 but only it will be rearward of a factory installed V8?

I am Ok if SBC is further back than factory as long as dizzy clears firewall (its very close in my 67 Camaro) but I suspect a fan spacer, even with long water pump, is needed to get the fan positioned 1/2 in/out of V8 fan shroud with motor further back??

[Palf70Step]

Originally Posted by 72SB

So you saying my I 6 (250) stands and mounts are direct fit for V8 but only it will be rearward of a factory installed V8?

Correct.

Originally Posted by 72SB

I am Ok if SBC is further back than factory as long as dizzy clears firewall (its very close in my 67 Camaro) but I suspect a fan spacer, even with long water pump, is needed to get the fan positioned 1/2 in/out of V8 fan shroud with motor further back??

When I went to a new radiator, 4 core versus stock 2 core, I did not need a space from what I remember. Now my engine had the short water pump, so whatever spacer was on it, is what I used without issue.