Technical 65’ C10 250 to 350 Swap

Hello so I have a Chevy 250 currently in my 65’ C10 and I’m waiting on putting a 350 into it. I’m wondering if I can reuse the alternator as well as the fan for the engine. If not where’s the best place to get those things other than Summit Racing

 

Alternator for sure. Your truck, of stock, will have a 10DN alternator, with an external regulator. If it came with a V8, it would have had that, too. GM moved to an internal regulator alternator later on, in most cases, up to 1986-ish, that is a 10SI. It is dimensionally matched to the 10DN, and they fit in each other's brackets.

The fan, probably. a 350 will have either a short or a long water pump setup. That depends on the year of the donor.

You may need to use a spacer between the water pump pulley, and the fan, to get it closer to the radiator.

Since this truck was also sold with a V8, there should be very little in the way of adaptation. Depending on what path you want to take it in, you can even reuse the transmission, in the same place that it is in now.

 

Yes, alternator, fan, maybe. Bolt pattern or pilot hub might be off.

 

A 10DN alternator has a two-wire plug that comes in from the back:


A 10SI alternator has a two-wire plug that comes in from the side/edge:


Either way, disconnect your battery, unbolt the alternator from the 6-cylinder, swap engines, and bolt it to the V8.

 

Good catch. I forgot about that.

A bunch of the new water pumps found at the auto parts stores are dual drilled, so they fit both patterns.

Here's a one:

 

@gimpyshotrods , I was typing mine, while you posted your first one. On the same wavelength!

 

Gonna be a Happy New Year

 

I did that swap 50+ years ago (230 to 327).

Un-bolt the front motor mounts from the brackets on sides of the 6 and bolt them onto the side of the 8. Drops the engine right onto the frame brackets.

Take the flywheel and clutch from the 6 and bolt it on the 8.

Drop it in.

The rest is just finding accessory brackets (Easy for me because the truck was less than 5 years old and only had an alt.) and extending or shortening wires.

If you are going to run exhaust manifolds you will probably need center dump ram horns. They make aftermarket 2 1/2" Corvette manifolds that should work

The starter also works.

The one thing you will need to work out is your radiator, fan and spacer combination. Mine pegged the gauge going around the block with the stock radiator.

If it still has the stock Muncie (318?) 3 spd. transmission, be gentle. I grenaded mine regularly, even with the tires available then. If you upgrade to a 4/5 speed you will need to use a bolt and nut on the bottom 2 mounting holes. For what ever reason GM ran the bottom 2 bolts from inside the bell housing into threaded holes in the trans.

 

If you're shopping a used 350 for this swap, try to find as complete an engine as possible. It's handy to have all the accessory mounting brackets on the front of the engine if possible, especially if you're swapping in a power steering pump or A/C compressor. Also look for an engine that used v-belts instead of a ribbed serpentine belt. You'll need exhaust manifolds as well, unless you plan on running headers.

 

X-Coupe gave you the correct info.

NOTE: THERE IS NOT ONE DAMNED PART THAT YOU NEED FOR THE SWAP THAT YOU HAVE TO GO TO SUMMIT FOR, EVERY PART CAN BE SOURCED AT A LOCAL PARTS HOUSE.
It's just a Chevy truck that you can still get motor mounts and other pieces from the parts house you go to all the time. With the right parts on hand this is an easy one day swap with only the exhaust being an issue that might take extra time.
Your alternator will bolt on the bracket on the 350 and work a long as the 350 has V belts. You most likely will have to make the wires to it a bit longer though. You can swap the pulley on the alternator if the engine has a serpertine belt though. It just means that you still have the older external regulator alternator rather than a newer internal regulatot one. That's all. Chevy trucks used internal regulators through 71. If you have had trouble with the alternator or doon't have one as the truck came in drag it home on a rope conditon we can give you a simple diagram to hook up a later 10 or 12 SI alternator but if it isn't broke don't get carried away fixing it. I have the directions for that saved if and when you need them.
The starter is the same as long as you use the flywheel off the 250.

It's simpler with ram horn manifolds as trucks up through 72 with V8 engines at least ran ram horns. 73 and later run the drop down like are on most 350's and the frames aren't that much different in that area.

The only actual hassles that I know of are hooking up the throttle linkage to the stock pedal and maybe extending the wires on the alternator.

You want to get upper and lower hoses for a V8 beforehand and I would get new heater hoses.

If it runs and drives with the six get some gunk or your favorite engine cleaner spray and take it to the spray wand car wash and clean up the engine compartment and under the front of the truck as good as you can. That ten bucks for cleaner and quarters for the car wash will pay off big time.

Unbolt the engine from the bellhousing or trans depending on stick or automatic. The mounts will hold the manual trans up but if it is automatic you will have to support the front of the trans. On and automatic unbolt the converter from the flex plate and push it back into the trans a tad.

Outside of a bit of cleanup and prep work you can very honestly pull the six, swap the mounts and flywheel/ flex plate and clutch (remember to install a pilot bushing if it is a stick.) and drop the V8 in.

 

Awesome thank you so much for the help. I started doing this stuff about 2 years ago when I was 15. This was my dads truck so I’m just trying to make it into a fun project car. Also let me send some reference photos of the 350

 

One thing that you might check, is that I am not sure that the pivot ball for the engine side end of the clutch cross shaft will unbolt from the bracket for the six and bolt into the block on the V8. You may need a new pivot ball. That's one of those little things that could slow you down.

With the manual trans you might want to stick a board across the bottom frame rails to hold up the back of the trans and block it up so the back of the trans doesn't drop. Just a little 5 minute or less project to cut an old 2x4 to length and stick it up there so the back of the transmisson doesn't drop and turn the bellhousing at an akward angle. That just makes lining up the cutch with the transmission input shaft easier. Another thing that will make life a lot easier is get two 3/8 course bolts about 5 or 6 inches long, just grade 2 out of the bulk buy them by the pound bin When you go to put the engine back in stick them in through the two bottom bolt holes in the bellhousing and line the engine up with them and screw them into the matching holes in the block a few turns. Those serve as guide pins so the engine and clutch will line up with the transmisison a lot easier. That way all you have to worry about is haivng the back of the block parallel with the front surface of the bellhousing. Then you can put some of the other bellhousing bolts in and swap those "guide pins" for the bellhousing bolts.

 

Do you have any of the accessory brackets or the water pump for that engine?

The only thing on it that denotes which water pump it had on it is the crank pulley. That one went with a short water pump.

Of you have nothing but that, you can build it either way now.

It has been mentioned, the clutch equalizer bar, also known as the z-bar, which gets you from the pedal pushrod, to the clutch fork pushrod, might need to be addressed.

I checked part numbers, and it appears that the same one fits the 6-cylinder and the V8.


I believe that you will need a ball-stud for the threaded hole in the V8 block.


Those are about $16.
https://www.usa1industries.com/1963-84-fullsize-chevy-gmc-truck-clutch-engine-stud-ball.html

If you're on that Amazon, it is $18.29, but the shipping is free: https://www.amazon.com/GM-Genuine-Parts-03866568-Clutch/dp/B09CW1ZHVD

It fits 1963-1984, and it it might be something you can get at NAPA.

If you are asking after it at the parts counter, it is NOT the one that goes in the bellhousing for the clutch fork.

That one looks like this:

Don't let them sell you that.

 

Also, if that replacement engine did not come from a vehicle with a manual transmission, then the hole for the engine block ball stud has paint in it, and on the threads.

If you can get your hands on a bottoming tap, you should run that down the threads to clean them out.

 

One wrinkle that you might find is this:

Later blocks only have the rearward ball stud hole. It is over the oil filter (block appearances vary).


Earlier blocks have two. One is where the later one is, and one is forward of that:

I believe that you will need to use the forward hole, so you need to make sure that you have one in your 350.

Somewhere in the middle of the life of the SBC, the boss for the forward hole was still there, but not tapped.

Also, that will probably prevent you from using the current headers.

This is the detail shot of the 6-cylinder:


It has both potential pivot locations, too, but uses the forward one in the truck.

They are in the same points in space on both the 6-cylinder, and the V8, for easy interchange.

 

I swapped my 64 a few years back, and had to move the frame mounts back. There were 2 sets of holes, and if I remember correctly, when I started sitting the small block in, it wouldn't reach the bellhousing lol. It's been a few years, but I do remember i had to move the frame mount.

 

Many years for me, and for some reason I'm thinking the V8 trucks used different motor mount stands than the sixxer, could be wrong.
When I "butchered" my 66 Suburban I hauled all that crap to the Portland Swap Meet.

 

Lol I just remember there being 2 sets of holes in the frame. And the panic that set in when I got the block against the bellhousing, and the mounts wouldn't line up! That's when I seen the light lol

 

If the V8 came from an automatic vehicle you will need a pilot bushing for the back of the crankshaft.

 

It's a good idea to install a new pilot bushing rather than use a used one though.

 

Yeah I have a new pilot bearing if that’s what you’re mentioning

 

Perfect thank you so much for the info

 

Yup, you lucked-out.

You have both ball-stud holes.

With the ball-stud in the forward hole, everything just goes right back into place on the V8.

Easy-peasey.

 

It's been 40+ years since I put a built 283 in place of a 230 six in my OT '68, so my memory could be a little fuzzy, but as I remember it the factory V8's had the motor mounts farther forward on the crossmember than the six and so the trans was farther forward too. I just put the 283 in the rear set of holes with the trans in the original place, but I had to source a longer fan shroud (I think from a 4WD) since the fan was so far from the radiator. Of course '67 & '68s were a different generation than your '65, and I could be dis-remembering it too.

 

Another thing that you will need to address.

The ignition coil on the side of the inline-6 is not a 12V device. It gets power through a resistor wire, that is fed by the ignition switch. If you look, that wire will not have a plastic jacket, but a white cloth cover.

If you put a voltmeter on the + terminal, with the ignition switch on, you will see somewhere near 6-9V. Old-school points-triggered ignition systems operate at a lower voltage.

The ignition coil on the top of the HEI distributor on your donor engine IS A 12V device.

You will need to tease that white cloth covered wire out of the harness, all the way back to the big plug on the firewall. That's where the resistor wire starts.

You will need to replace it with a conventional wire, of the same gauge.

Here's a good writeup: https://67-72chevytrucks.com/vboard/showthread.php?t=708975

You can pop the blade that the wire attaches to out of the plug, and solder on the replacement wire, or buy a replacement pre-made wire, for just $12.00: https://www.yearone.com/Product/SearchTarget/35089

Minor modifications to use this on a 1965 vehicle may be necessary.



This has the HEI plug on the other end, which locks-on to the coil, so the wire does not randomly fall out while driving. More than well worth the $12.00, if you ask me.

 

Tied in with all of this is the third wire on the starter.

There are three wires currently on your starter, which will bolt directly to the V8.

The first of the three wires is the big one that goes to the battery. That stays as-is.

The second is a small one, hooked to the S terminal on the solenoid. This is the trigger wire that makes the starter work when you turn the key. That stays as-is.

The third is another small one, hooked to the R terminal on the solenoid. This WAS used with the original points-triggered ignition system. It temporarily sent 12V to the + terminal on the coil, for hotter spark, when the starter was cranking.

That wire is not needed with the HEI distributor, and it should not be connected to the R terminal on the solenoid.

If you do leave it connected there, it will be live when you crank the starter. Since there will no longer be anywhere to connect the other end of the wire, it could create sparks. You don't want that.

Best to leave it off, or completely remove it.

 

Does anyone happen to know if the 230 or 250 water pump would install onto the 350? They look really similar but I can’t tell since the I6 is still in and running

 

Not even close. 2 different animal's.

 

A 1965 short water pump, new, at your average chain auto parts store is $45-55.

The brackets for the alternator you can raid from any self-service yard, or new, from various vendors.

I like these:. http://www.alangrovecomponents.com/Small_Block_Short_Pump.htm

The short water pump was used until 1968. The long one was used after that.

After that, you need a water pump pulley, for a short pump.