Questions re- Switching a six to a V-8

[notmycity]

Hello,

I'm thinking about switching a (292?) six to a V-8 in a 1970 C-10. Some questions before proceeding....

Will the existing engine perches work with a V-8?

Aside from changing the radiator, what other parts will need changing to make a V-8 fit?

Also, how involved in switching from a manual tranny to an automatic?

Thanks.......

[dubie]

You need either 250 inline 6 towers or V8 towers to mount a small block. You will also need to install an auto cross member to support your tail shaft. If you go to and automatic, you need and auto column and shift linkages. No real need to change out the rad unless you live in some extreme heat either. I have done this swap in my 72, I went from a 250 to a 350 but placed the 350 in the inline 6 position . Which emans it sits 3 1/2" back from the stock V8 location. But all 4x4's of this year had the engine in the rear spot from the factory. If you search for this topic, I'm sure you will find a ton of info on it. It's been discussed many times around here.

[busterwivell]

The switch from manual to automatic is a lot easier that the reverse. You may need to change or relocate the tranny crossmember, you'll have to hook up linkage and you'll be ok.

[crazy longhorn]

I am running I 6 (250 position) with my sb. I think you will find that the drivers side stand is useable, but you will need to swap the pass side stand(292 stands were staggered ,due to fuel pump placement on the block). my setup runs the 73 -up long waterpump,steering pump, & all brackets/pulleys, to get the fan into the shroud without a bunch of spacer. i have also heard that a 4x4 sb rad shroud will fit the bill with the short waterpump & accessories that are used on the 67 -72 trucks. If you use the 73 up pcs, you will have a little rework on the underhood wires, as the alt sits on the pass side vs d side on the older sb trucks. the steering hoses are also different, but should not be a problem(use the73 to late 70's hoses with the samew ear pump). if you are swapping from a 4 spd truck, you will have driveline mods, as the truck 4 spd is much shorter than a 350T.....you will need the auto crossmember, as the guys have allready mentioned, & you will need to chop out the old bell mount crossmember. If you are running a 3 spd stick(saginaw/7 bolt side cover), a 6" tail 350 turbo is a direct fit for lenght....& spline on the slip yolk. I am sure that there are a few things that i havent covered.....but feel free to drop another post, or PM. Best of luck,crazyL

[Vince M]

Along with the auto tranny swap I am going to also swap out the pedal assembly to remove the clutch. Some just leave it in but I was able to find a auto tranny donor truck and I got everthing off of it including the wiring harness. That's probably the easiest way to go...or just ask on the Parts Board I'm sure somebody will have everything you need.

[crazy longhorn]

dont worry about swapping the peddle assy......just bolt the bracket off the rh side of the clutch arm & slide it out! the brake peddle will stay in place crazyL

[68jimmy]

I'm right in the middle of doing a swap in my 68 gmc from the original v6 to a v8. My biggest headache right now is the removal of the bell-housing cross-member. I used a grinder for most of the riverts and finally got my hands on a compressor wih an impact chisel, should go a bit quicker now... I completly rebuilt an auto column from a '72 and I will be using an aftermarket shift linkage instead of the factory setup. Good luck and let us know how it goes!

[Tx Firefighter]

The TxFirefighter method of pedal removal (TM).

Step 1- remove bolt
Step 2- pry lever off of shaft
Step 3- slide pedal out of bracket

Congratulations, you have just converted your truck to an auto pedal setup. They are the same. There is no difference between what is now left and a factory auto truck.

[Tx Firefighter]

let me clarify a little

TXFirefighter handy picture (TM)

[Rod]

A few years back I wrote a tech article on swapping ... from manual to auto. Here's the link.
http://67-72chevytrucks.com/tech/trannyswap.html

You will need different frame brackets for your swap... 292 and small block v 8 mounts are different. Not hard to find the sb v8 ones.

[notmycity]

Hey everyone,

Appreciate the feedback. Thanks...

[Kas68c10]

Need a home for that 292 ?

[stickshift_or_walk]

Well, here's another hardhead fighting this swap. My son turns 16 soon, so we're working hard to get his '69 C10 running with the SB and SM456 4 spd he's got his heart set on. The truck came with the I6, and the 3spd, so we have the bellhousing crossmember problem. Crazy Longhorn tells me the I6 stands match the I6 crossmember, so now that I've switched to V8 stands, I need the V8 crossmember.

I know this sounds like a lot of trouble, since ya'll are saying here that the V8 can be happy in the I6 position, but I've read elsewhere that there are distributor clearance problems there, especially with HEI's, and I'm a real fan of HEI's. Got a Summit blueprinted one on sale and can't wait to fire it up.

So, is this distributor problem for real? If so, what do you recommend? And where are all the other good threads on this topic?

SSOW...

[Tx Firefighter]

Stickshift.....

I've done this several times with HEIs. I refuse to run points in anything I own. Anyway, the distributor is close to the firewall. Like I said, close. It does not hit or do any untoward things, it just doesn't have gobs of room behind it like it does when the engine is in the V8 position. Just drop it right onto the I6 mounts and reuse all of your 6 cylinder bellhousing and riveted in crossmemember stuff. You'll save a lot of trouble by not having to chase around a diffferent crossmemember and deal with the nasty rivets holding it in.

As long as your engine is an earlier (pre 1 piece main seal) one, you can simply reuse your 6 cylinder flywheel and clutch on the V8. It bolts right on with the same bolts. Then, just reuse the same starter onto the bellhousing just like the 6 cylinder had.

[bigskiohio]

I did this swap i used parts off of a 1980 gmc still need to button it up but it was alot of work , not big stuff just alot of little stuff like tilt column,saftey switch, linkage,passing gear cable and bracket ,removing manual crossmemeber and finding a 72 crossmember because I didn't like the 1980 crossmember because it bolted on outside of frame on one side but it would have worked. The one piece driveshaft from 1980 was to long but the orignal two piece fit but i need to give it a final check to make sure it doesn't go in to far. I got lazy but hope to finish truck early summer because it is L.L. season now. Also had to rewire truck for new alt. and Hei , reroute and rewire to replace some old wires and neater look.

[stickshift_or_walk]

Ok, so I took this advice back out to the shop today, and have come up with another possible wrinkle with using the I6 mounts & crossmember for the V8. Seems like the 3.5" difference will put the clutch cross-shaft way off its normal axis. Any thoughts?

If I'm going to cut out the I6 bellhousing crossmember, I could use everyone's input on what rear tranny crossmember to use. I did the switch in my '72 C20 from TH350 to SM465, and used the same crossmember (new holes in frame), so I know that one will work. I checked the frame spacing on the two just to be sure. But, they may be scarce around here since most people switch to automatics. What was wrong with the '80 model that couldn't be fixed with a little metal work?

Let me know any rear tranny crossmembers that work in these trucks...thanks.

SSOW

[Tx Firefighter]

See that clutch pivot ball bracket bolted to the 6 cylinder block on the driver's side?

You need a V8 pivot ball that screws into the threaded hole in the driver's side of the V8 block. You reuse the same 6 cylinder Z-bar and frame bracket.

[crazy longhorn]

Lots of ways to "skin" a clutch linkage. I am I 6 position, have the v8 z bar & block bracket, custom frame bracket, & modified top arm on the z bar.....the hole in the firewall is moved to the left,& the top rod is straight with rod ends. the bottom rod also is wearing a rod end at the front. the complete "mess" works slicker than chit

[notmycity]

Well now....

I'm almost wondering if dropping another 6 cyl. in there would be better. I just found a supposedly rebuilt one @ 600.00 USD.......

Still appreciate the feedback...

[Fred T]

Nothing wrong with the six. The 292 should have the passenger side mount at the forward end with the oil filter aft of the distributor. The 250 has the center mount, filter at the front. To check casting number and see what you have, go to www.inliners.org Iirc, the casting numbers are on the passenger side, aft lower area. Under all the caked on gunk.

[Kas68c10]

I would jump on that if it were a 292,but I am patial to them anyway, if you don't buy it,let me know who has that engine so I can talk to him !
Thanks

[Rakort]

I'm preparing to do a similar swap. I just purchased a 69 GMC donor truck that I'm going to take the cross member, steering column, motor, tranny, linkage, radiator, etc out of an drop it into my 68 C10. I won't have to scrounge around for alternator brackets and the like either.

By the way I have available a 250 I6 with a documented rebuild just a few thousand miles ago that runs great.......I'll sell it for a fraction of the rebuild price.

[stickshift_or_walk]

Well, here's an update. Once we located the rear tranny crossmember to support the 4spd, we decided to commit. After a full day's work with the angle grinder and the air chisel, the 6 cyl bellhousing crossmember is out. So we've got the V8 mounts, rear crossmember, 4spd transmission hump (that was probably the hardest find), and the remaining 3spd clutch parts that I am hoping will fit up. We found the z-bar pivot ball for the V8 at O'Reilly's, they have a whole bunch of different ones they can order. Take your original in to match on. I got a 10 inch clutch kit while I was there, and plan to use the 6cyl bellhousing (I know about the bottom bolts needing the nuts), starter, etc.

In preparation for cleaning and painting the engine compartment, we've temporarily removed the new wiring harness (full kit from MAD Enterprises), and all remaining underhood accessories.

So the carcass is loaded on the trailer, headed for the car wash to remove all the years of grime and gook. When that's done, we'll open up the tranny tunnel for the new 4spd and start working on putting it back together.

So, after all, it looks like I've got a stovebolt 250 to part with. Has an HEI distributor, but most of the rest is original, including the alternator. I've also got the 6cyl bracketry for the power steering pump, but I never made that conversion.

Thanks for all the help and advice. Maybe I'll be able to help out the next guy.

Here's to rowing that stickshift....SSOW