HELP L6/3speed to V8/3speed Questions
 

So getting ready to do this swap in "Nasty Nadine" My 1969 SWB
http://67-72chevytrucks.com/vboard/s...d.php?t=588280

It's currently running a 250 inline 6 and the factory 3 speed shift on column config.

I'm about to remove the 6 and install a 350 from a 1971 Camaro Z28

So far from the searching I've done on the forum I've learned that:
1) the motor mounts need to be swapped to V8 mounts
2) the radiator needs to be swapped for a V8 unit
3) some kind of clutch pivot ball bracket needs to be fabbed (found here: http://67-72chevytrucks.com/vboard/s...d.php?t=125834)

My main question is...

Will the 3 speed that's currently bolted to my L6 direct fit to my new V8 without any mods. In other words are the 3 speed bellhousings the same from L6 to V8 transmissions.

I'm trying to remember what I saw while working on it today and it seemed right, but I'm really really tired. I might be overthinking this as well. I tried searching all over the forums and could find countless L6 to V8 swaps, but it seems most folks are using auto transmissions or 4/5 speed manuals. I've never had a problem with the 3 speeds, so might as well leave it and see what it does right?

Re: HELP L6/3speed to V8/3speed Questions
 

Bueller...

Beuller...

Beuller...

Anyone have any info on this swap?

Re: HELP L6/3speed to V8/3speed Questions
 

I think you should contact Tx Firefighter. He helped with a L6 3 speed swap to a V8 4 speed. As far as I'm concerned, he is the man!

Re: HELP L6/3speed to V8/3speed Questions
 

Thanks for the heads up. I'll do that. I'm pretty sure the 3 speed bellhousing is same from L6 to V8, would just help reasure me to hear it from someone else I guess. So I know if I need to find another bellhousing.
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Re: HELP L6/3speed to V8/3speed Questions
 

I guess I should also note that the truck is currently at our hot rod shop about 10 miles from the house and I haven't had time to actually go measure things there since I've thought of this possible issue.

Re: HELP L6/3speed to V8/3speed Questions
 

I did this on a 69 I once owned. The bellhousing from the l6 bolted right up to the v8. I changed motor mounts, radiator but if I remember right everything else worked.

Re: HELP L6/3speed to V8/3speed Questions
 

Sweet! Thanks for the quick response, Now I can quit worrying about looking for that part. I need to make up my mind on a couple other things like a new radiator or a used one and a new gas tank or a used one.

:metal:

Re: HELP L6/3speed to V8/3speed Questions
 

I did this many years ago to my shortbed, If you want to put the motor mounts in the right location for the V8's you will have to find a V8 3 speed truck and get the trans crossmember, the 6 cyl 3spd will not work. It will not just slide forward with everything else. Also will have to get a longer drive shaft. This is if you want it in the right spot. If you dont mind the valve covers close to the fire wall, then your GTG.

Smitty

Re: HELP L6/3speed to V8/3speed Questions
 

Ok, I know the 6 cylinder trans crossmember is different, was planning on building a tube member.

But, if I'm reading correctly you're saying V8 automatic trucks used a different motor mount that the V8 3 speed trucks? or just a different location.

I'm contemplating fabricating new mounts as well.

Re: HELP L6/3speed to V8/3speed Questions
 

I did this same swap back when I was in high school (1983). If I remember correctly I did not move the engine mounts so that trans, cross member, drive shaft all worked. 6 cyl bell bolted right up. I had headers and the clutch linkage gave me trouble. The Z bar would hit the header tube if you pushed the clutch in. Also tracking down the special stud/ball that screws into the engine block to support one end of the Z bar, was a challenge (Way before the internet). I ended up cutting one arm of the Z bar and re welding it on.
Other than that it worked well for many years. Wish I still had that 327.....

Re: HELP L6/3speed to V8/3speed Questions
 

Thanks for all the input guys. We should have most of the stuff I will need at the hot rod shop from parts trucks that have been stripped.

Anything else I might need like a driveshaft (I'll move the engine forward to keep proper clearance) I might be able to source in a local scrap yard.

I'm just anxious to get back to work on it.

I still haven't pulled the valve cover on the 250, so it's quite possible that it will be an easy fix and I might not end up doing the swap. In that case the Chevelle will be back on the road sooner than anticipated. :)
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Re: HELP L6/3speed to V8/3speed Questions
 

The mounts are ok, its the towers that the mounts bolt to that are different.

Smitty

Re: HELP L6/3speed to V8/3speed Questions
 

So we could just bypass that problem by fabricating all new towers from scratch. ;)

Gotcha, thanks.
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Re: HELP L6/3speed to V8/3speed Questions
 

I think you just unbolt them and the hole for the v8 motor mount is left.

Re: HELP L6/3speed to V8/3speed Questions
 

There's two way to approach this. The easy way and the hard way.

Easy way, drop the small block right in place of the six. Same mounts, same everything. It all bolts up. If your small block is one with a 2 piece rear main seal, even the flywheel and clutch all bolt up. Doing it this way means no mods to any crossmembers and shift linkage or any of that. You'll have to make a longer accelerator pedal rod and lengthen the wire to the temp sending unit. I can do one of these swaps in half a day.

Doing it the hard way means getting the small block engine frame stands. This means the engine moves forward a few inches. Now you have to redo the trans crossmember, shift linkage and driveshaft.

There are people on this board who will tell you the distributor is too close to the firewall if you install a small block in the inline 6 spot. They repeat the same old crap again and again. It's something that is oft repeated but only by guys who haven't personally done the swap. I have done it a lot of times and will tell you from first hand experience there is plenty of room. You can still remove the cap easily and even pull the distributor up and out without hitting the firewall in any way.
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Re: HELP L6/3speed to V8/3speed Questions
 

I forgot to add, you need a screw in pivot ball for the clutch. Classic Parts sells them for 12 bucks or so. Once you screw the pivot ball into the side of the small block, you'll notice the clutch z bar is now too wide to fit into the gap between the frame bracket and the new pivot ball. Just hacksaw about half an inch off the end of the z bar tube and install it. The recess is deep enough for the pivot ball to fit into even after shortening it.

If you can stand it, cast iron exhaust manifolds work best. You want ramshorn style. If not, Hooker Comp headers work too. You will need to slightly offset bend the lower arm of the clutch z bar so the linkage passes between the tubes of the header. Just use a crescent wrench or pry bar and tweak it sideways a little until the clutch pushrod doesn't rub the header tube. Just takes a second.
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Re: HELP L6/3speed to V8/3speed Questions
 

I gotta tell ya guys, the Tx Firefighter is the MAN. He got me squared away real quick!

Re: HELP L6/3speed to V8/3speed Questions
 

I wouldn't go that far, but that's the big pieces when it comes to the swap.

Remember, your 250 uses the same bell housing pattern, flywheel, starter, clutch etc of a 2 piece rear main seal 350 small block. You can also reuse the rubber engine mounts off of the six cylinder. They are held on by three bolts each. You'll notice the same 3 bolt pattern in your small block on each side.

Reuse your temperature sending unit and oil pressure line also.
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Re: HELP L6/3speed to V8/3speed Questions
 

Thanks for all the input Tx Firefighter. I thought those L6 mounts looked very similar to the small block mounts. Hmmm. Sound like this should be a pretty straight forward swap.
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Re: HELP L6/3speed to V8/3speed Questions
 

x2 on what firefighter said. I did this very swap about 3 years ago and still going strong.

Re: HELP L6/3speed to V8/3speed Questions
 

Boy do I feel silly. I was expecting worse case scenario with that loud knock and burning oil so badly. Went to the shop today finally and pulled the valve cover. One of the rocker studs had backed out quite a bit. So we tightened the stud down and it's running like a champ. Hopefully get a few more miles out of her after all. So the 250 inline six is staying in for a while and I'm keeping the 71 Camaro 350 in the Chevelle for now. Going to try to get the Chevelle back on the road soon too.

I guess I just wasn't prepared for all the crazy horsepower a Chevy inline six makes. So powerful it just throws internal parts everywhere! What a beast

Video of her running again. :metal: