Going from I6 to V8, 3spd to 4spd

[stickshift_or_walk]

Much of the foundation for this thread is located here:

http://67-72chevytrucks.com/vboard/s....php3?t=104502

But, I wanted to get a clean one going that kinda wraps up a specific swap. For search purposes, I'll use full words here. 1969 C10, original 250 inline six cylinder, column-shift three-speed transmission, changed to a smallblock Chevy V8 with a SM465 granny-geared transmission.

Here's an update on my son's project, which I get to play with, too. We're converting his '69 C10 from I6/3spd to SB V8/SM465 4spd. Someone else is bound to try this sometime, and might use some of this information (as I know I've followed a lot of advice from this board), so I'd like to make a thread here that's useful to others. I've tried to do this swap as close to a factory setup as practical, although a lot of other options are out there. Here are the steps that got me to this point. Sorry if it's too long, but I wanted a thread like this when I started, and told myself I would make one when I could.

Progress to date (after pulling original drivetrain, radiator, linkages, etc.):

- Changed I6 engine stands to SB V8 stands, mounted in forward (factory) V8 position on frame. No new holes - they are there from the factory.

- New engine stands & position moved the engine assembly forward about 3.5", so the crossmember that the original I6 cast iron bellhousing mounted to had to go. I could have located the bellhousing crossmember for a V-8, but elected to use the rear tranny mount as the support point and use a crossmember from an automatic truck.

- We removed the rivets holding the bellhousing crossmember with an air chisel, safety goggles, and ear protection. It's noisy, throws little metal bits everywhere, and vibrates a lot of dirt & stuff loose, but it's pretty effective. Watch the angle so you don't dig into the frame. Once the rivets are out, just knock the thing out of the frame by beating the crap out of it with a small sledge, driving the ends in opposite directions.

- With the engine compartment empty and the crossmember out of the way, we scrubbed the engine bay and repainted everything metal. We used spray-can bedliner on the fenderwells and radiator support, and a Rustoleum hammered finish on the fenders and firewall, and it looks much, much better.

- Next, we cut the floor pan out for the high-hump tranny cover. We laid the new cover on and traced around it and marked the mounting holes (just to be sure), then removed it and cut through the factory impressions with a SawzAll. Have an extra blade on hand, and file the sharp edges down when finished for safety.

- Our V8 donor was an automatic, so we elected to use the I6 flywheel. Had this been a truck destined for lots of heavy loads and trailering, I would have moved up to a larger flywheel and clutch assembly. But since this will be my 16-year old son's daily driver, we decided to stick with the smaller setup for now, which also allowed us to use the I6 cast iron bellhousing and starter. We had the flywheel resurfaced and bought a new clutch kit with properly matched parts.

- I did this next step after the engine was installed, but wish I had known to do it while I had the engine compartment open to work in. It turns out that the clutch z-bar pivot on the V8 block is actually farther rearward than the bracket and pivot was on the I6. This surprised me some since we had moved the engine forward, but that's the way it worked out. So to prevent the z-bar from being at an angle that would cause all kinds of problems, we broke out the air chisel again for the clutch pivot bracket on the frame. With the two rivets out, we drilled two new holes in the frame 1.5" rearward and remounted the bracket with bolts. This puts the z-bar just about perpendicular to the frame, and it pivots freely, with room for the engine to move without binding. We did need to bend the clutch rod from the pedal slightly so it cleared the firewall hole through its travel, but that was pretty simple. Just put it in a vise and pull - it bends without heat.

- So next we dropped in the engine. I didn?t have an equalizer on my engine hoist, and was using the plate that mounts on the carb base to lift with, so I decided not to mount the transmission with the engine/bellhousing. We did put the pilot bushing, friction plate, and pressure plate on with the engine out, then put the bellhousing on with the clutch fork installed. We chose the method of putting the engine in with the mounts on the block, then stabbing the one 5/8 head bolt in through the engine tower. It went in surprisingly easy, then we worked a few more minutes with the hoist and stabbed the other one. We supported the back of the engine with jack stands under the bellhousing edges.

- Considering all the trouble we had mounting that heavy SM465, even using a floor jack, I'd like to try the equalizer next time and put the whole assembly in at once. I'll probably not use the carb base lifting plate, though - especially in an aluminum intake manifold.

- I remembered a slick trick from my Camaro days that flopped here, but will be useful with other 3&4-speeds. I took two 6' bolts that threaded into the top bellhousing-to-transmission mounting holes, cut the bolt heads off, and ground a slot in the end for a large screwdriver. The idea is that with these in the bellhousing, you can lift the transmission up, slip the mounting ear holes over these bolts, and slide it up with them supporting the weight while you stab the input shaft into the clutch splines and pilot bushing. Well, it doesn't work on the SM465 because the case is wider than the mounting ear holes and the thing won't slide on.

- Instead, after removing the cut-off bolts, we muscled the input shaft through the throwout bearing into the clutch splines (supported by the floor jack so we didn't bend anything), then wrapped a ratchet strap from the left side of the bellhousing around the rear tranny mount and back to the right side of the bellhousing. We used the ratchet to gently apply forward pressure while we adjusted the angle of attack with the help of the floor jack. With that big hole cut in the floor, there's actually enough room in the cab (especially with the seat out) for one person to work up top with another under the truck. Don't try it alone without more/better equipment. Soon we could start the top bolts and the rest is history. Just remember, if you're using the cast iron bellhousing, you'll need nuts inside the bellhousing and longer bottom mounting bolts, because those holes aren't threaded like the top ones. Make sure the bolts aren't long enough to hit any of the spinning assembly.

- With the floor jack still under the tranny, we slipped the rear transmission crossmember in and lined it up to the mount on the transmission. Check to make sure it's perpendicular to the frame by measuring from the next crossmember rearward. Naturally, when the thing was where it needed to be, none of the existing dozen or so holes in the frame were right, so we had to drill new ones. I'm a glutton for punishment, so we did both top and bottom sets, although the later model trucks didn't have the top mounts on the transmission crossmember at all. Some folks just drill the lower holes and go with it. The good news is that the holes in the crossmember matched the ones in the tranny mount, so no drilling there.

- So with everything tightened up, we have the engine/bellhousing/transmission assembly secured at three points - two motor mounts and one rear transmission support. Personally, I like the strength of the cast iron bellhousing holding that together, but I have the aluminum one in my '72 C20 with the same config, and it's holding up fine. That's also the factory solution for later-built trucks, but I don't think they're built as well as ours anyway.

- With all that back in place, we got the clutch linkage installed. The original push-rod that ran from the bottom z-bar mount to the clutch fork was way too long, and not threaded all the way, so we used one from a later model that was a few inches shorter and fully threaded. We did use the angled steel head from the I6 rod, since it matched the I6 clutch fork. Turn the pivot pin block around so it wears on the unworn side. Put some good grease on it as you assemble, and it'll be quiet longer than the clutch will last. Use the original GM C-clip pins on all such pivot pins, since they keep the joints nice & tight. They're pricey compared to cotter pins, but work better.

- Since we kept the cast iron bellhousing, we used the starter that came with the I6, and mounts to the bellhousing. It was a high-torque model anyway, and should handle the load. We've already tried it, and it works fine. If you're using the sheet metal pieces that close up the bottom of the bellhousing, you'll have to trim the top of the flat one where it contacts the V8 oil pan and block. Also, be sure when you get it mounted (the starter snout sticks through it, so it goes on first), that it doesn't stick out far enough for any part of it to hit the rear of the crankshaft, or you'll get a really nasty ticking noise when you start it up. Watch the bolt lengths and make sure the sheet metal is bent out of the way.

- On the front of the engine, our V8 came with the long water pump, so the fan is closer to the radiator, but OK. A board member tells me he just trimmed an inch off of the fan shroud and it works fine, but I haven't located one yet.

- So here?s the stuff I used from the original I6 setup:

o Flywheel
o Cast iron bellhousing
o Starter
o Bottom cover/plate for bellhousing (sheetmetal - had to trim plate)
o Clutch rod (from pedal lever to z-bar)
o Z-bar
o Clutch fork (w/angled steel fitting from end of push rod)

- And here are the items I had to find/purchase:

o V8 radiator
o Fan shroud (still looking)
o Small Block (SB) V8 with as many accessories, brackets, hardware as possible
o V8 engine stands
o V8 engine mounts (for '69 C10 SB V8)
o Clutch kit (pilot bushing, throwout bearing, pressure plate, friction plate, alignment tool)
o SM465 transmission & rear mounting pad
o High-hump transmission cover
o Rear transmission crossmember from a later model 4spd or automatic truck

- Some other details we?ve worked through:

o Rewired virtually entire engine compartment with the "full system" from M.A.D. Enterprises. Called Mark and he was really helpful and supportive. I can recommend his products and especially his documentation. First-class stuff, and really takes the time to tell explain the details and reasons. This includes:

 Changed from externally regulated alternator to new SI that came from donor car.
 Readied truck for HEI distributor
 Installed headlight relays for brighter and safer performance
 Fenderwell-mounted solenoid to improve starter performance and reduce heat problems
 Better power distribution throughout truck, better connection points and feeds for high-power accessories.

o Deep-cleaned interior, virtually stripped and new '92 bench seat, sound insulation, new paint, door panels, floor cover, seals, etc. going in.


And I'd be remiss if I didn?t give a BIG attaboy to my 16 year old son, Randy. He's done the bulk of the work here, and really wants this thing done right. He's run the air chisel, done the entire cleanup and most of the painting, and has spent dozens of hours on the wire wheel cleaning hardware and parts, to include all the bolts. Then he's prepped and painted them and everything else using mostly factory colors, and done most of the reassembly. It really looks tastefully done (no bias, of course). Anyway, he's proud of it and that's what counts. This has really given me a way to connect with him that I think a lot of Dads miss out on. Not to mention the value of what he's learning, with due credit, of course, to the fine folks on this board.

So the exterior is still plain-jane, primer and factory paint. But we've got a straight frame with no rust, solid rocker panels and cab corners & mounts, so it's a great foundation. We'll pretty it up after it's running solid and he's had time to get used to driving it.

That's about where we've gotten to, and have plenty things left to tackle. Next on the list is 10 more inches of driveshaft, since my rear tranny yoke is moved forward that far from the 3spd's position. I'll start another thread on that one.

Oh well, if it was easy, everyone would be doing it.

Keep it shiny side up . . . SSOW