BBC Swap

[argonaut]

Just another BBC swap...

Next week I'll be pulling the SBC 350 out of my 64 short fleet, in favor of a BBC 402. The 402 has been pulled complete out of a 71 C30 with mount brackets, and freshened up a bit by me.

I'm assuming that the 71 mount brackets will bolt onto my 64 frame/crossmember and will shift the motor/trans forward away from the firewall. Thus I'll have to shift the transmission crossmember for my TH400 forward and lengthen the driveshaft.

I'm open to advice of suggestions from anyone who has swapped a BBC in this way. Thanks!

[1963c-10]

The engine should bolt into the forward set of holes on the frame, but I dont think that you'll have to move the trans member forward. Im putting a 427 in my truck in the spring and my bellhousing has the frame mounts. The bellhousing will stay in the same position, so only the motor mounts will be placed forward from the L6 mounts. Maybe somebody else can give some info on it, there are some trucks w/big blocks here. Let me know how it goes though.

[protrash64]

I'm not sure of the placement as I did mine differently. But you will probably have to trim back the frame about 1/2'' to let the perches sit correctly. Test before swinging the engine over the front of the truck. You should be able to roughly figure placement by measuring from the back of the engine to the mount boss, and then using this figure, from the front of your trans in the engine bay to the rough location.

I used 73-87 1/2ton mounts and made it up as I went.

[Rich 5150 69]

Some where I read that if he`s keeping the stock valve covers he can use the rear mount holes just like the small block, the tall covers will hit the firewall.

['63GENIII]

Originally Posted by Rich 5150 69

Some where I read that if he`s keeping the stock valve covers he can use the rear mount holes just like the small block, the tall covers will hit the firewall.

I think you're right Rich. I have the short Moroso's and if they were any taller, they might be close to hitting when I get on it.

Hey Jason, the motor mounts that are in the '63 are the ones with 1 big bolt to the frame. Napa had them in stock. If I recall correctly, the parts guy said they were stock for 283?
I just read that you have a 350 in it already. I think that the mounts are already in the same place as the BB would be.

[Wrecker55]

When I switched to a bbc in my 64 I just redrilled the motor mounts to the frame using the front holes for the back of the mounts, this gives you plenty of room for the dist and valve covers, used a turbo 400 so I did move the trans cross brace and had to modify the drive shaft.

[argonaut]

Well I spent the last couple of days performing heart surgery, ie. wrenching on the motor and the pickup.

When I pulled the 402 apart it turns out it was recently rebuilt. That would explain the unusually good results that I got from the leakdown test a couple of weeks ago. Regardless I pressure washed it, threw in a roller timing chain, new oil and fuel filters and re-gasketed the whole thing. Didn't rebuild that carb yet but I'll probably get a kit from Cliff and pull it off later.

Today I pulled the small block out of the 64. Kind of a shame considering I just finished assembling it and putting it in a couple months ago... Never the less, as the sun went down, I had a big space waiting for the big block.

Now I took a look at the stock mount perches along side the mount perches I pulled off the 71 C30. The big block perches use the front holes on the frame, and the same rear hole on the cross member, and the mount pad is about 4 inches, give or take, further forward than the stock 64 small block perches.

On the one hand it looks like the 402 might go right in on the original mount perches. This would mean I don't have to redo radiator hoses and shroud, driveshaft length, trans mount, re-make trans cooler lines to the radiator, etc.

But on the other hand it seems like using the 71 big block mount brackets would be more in the vein of doing it correctly. it would give way better access to the rear of the motor, and it would get the whole assembly positioned better for using the column and auto shift linkage from the 71 like I'm planning to do.

I'm also pressed for time to get this in and done so I can shift focus to getting the K10 running. So maybe I'll just stick with the 64 perches for now and come back to it later when I have more time. Anybody have any other thoughts?

[protrash64]

Anything that saves work is good, IMO. When I put in the 454 it went in fairly easily; it was all the little crap that took all the time and trips to the parts store to figure out. If you can avoid this part you will be well on the way to getting it done and driving.

Using the original perches will work; it's one of three ways of doing the swap using factory parts. I believe it may set the engine up a little higher but I'm not sure about that. If it did, it would be easier to route exhaust out of the engine compartment. My headers are tight!!

[steverino66]

I got my 454 in place using the original mount towers for my truck, but the driver's side header said no way it was going in there (automatic, no clutch linkage, just not enough clearance); using the taller 71 towers on the forward set of frame holes solved the problem

[Chevy Fleetside]

This is how I solved my problem and you can use the rear holes. I am sure most of you have already seen this picture.

[198plus]

I used the rear holes and same perches as Chevy Fleetside it worked out great.

Originally Posted by Chevy Fleetside

This is how I solved my problem and you can use the rear holes. I am sure most of you have already seen this picture.

[Rich 5150 69]

Originally Posted by Chevy Fleetside

This is how I solved my problem and you can use the rear holes. I am sure most of you have already seen this picture.

Ok John so where are our update pics....? nothing like pressure from the peanut gallery...HUH..?

[Captainfab]

I would go with the '71 big block mounts. Given your 2 option's, that's what I would do. I'm one for doing it right the first time

[Chevy Fleetside]

Originally Posted by Rich 5150 69

Ok John so where are our update pics....? nothing like pressure from the peanut gallery...HUH..?

Nothing to update. Been busy but have some free time now so I am going to get that darn firewall painted.

[argonaut]

Well it is finally in. When I got the motor on the hoist this morning my intention was to set it on the original perches in the rear hole location. I had however prepped the frame by cutting it down 3/4" to suit the big block perches and the exhaust manifolds... and it turned out to be a good thing that I did.

I learned that people swap the the aftermarket tubular perches with the newer style mount because the exhaust manifolds/headers will hit the stock perches. So I went ahead and installed the motor on the big block perches in the forward holes, and pushed the TH400 about 3" forward. Nearly got all the small stuff buttoned up today, but I still have a few loose ends. Need to get a longer driveshaft. Need to decide on a new fan/shroud setup now that the flex fan is right up against the radiator; considering going to an electric fan. The stock power steering pump brackets are too wide for the engine compartment and locate the pump into the left side inner fender; so I either have to notch the inner fender or find a different bracket.

I must say that I'm glad I went ahead and installed it the right way on the big block mount perches. It is SO MUCH EASIER to work on than when I had the 350 crammed way back in there. now I've got easy access all the way around.

[argonaut]

Thought I'd throw up a few photos

Here is an old photo of the motor that came out. This will be put in the 66 K10 tomorrow afternoon.


And another one from earlier this year when i was putting the 4-wheel power disk brakes on. After years and years of manual drums this was money well spent.


A nice shot of the truck-of-many-colors


71 Big block motor mount perches versus 64 small block motor mount perches


And finally a couple of really bad shots of the 402 (296) motor. It was getting dark and my phone camera has no flash. I'll take some better ones tomorrow.

[tincan1966]

Question - Does anyone know wher to get the CORRECT BBC motor mounts? I am talking about the actual 2 piece rubber with the thru bolt and tube like the original?. All I can find are "HD Mounts" which turn out to be SBC and no lower rubber. it's not a huge concern, as it was easy to use the other style. Hint to those using the SBC mounts. use a minimum of 1/4" plate and make a 2 X 2" square plate to cover the large hole in the BBC frame perch. A flat washer isn't enough if you ever really load and torque the motor. JMO

[66farmer]

I used the tubular perches 70ish vette motor mounts and used the rear mounting holes. I wanted the motor as far back as I could because of the weight. I did massage the firewall a little.

[argonaut]

Just fired it up! Runs like a champ!

@ tincan1966
You can get the correct two piece big block mounts at the truck shop in Orange County, CA. www.truckandcarshop.com But they aren't cheap...

Still on my to-do list:

I only have about 3-1/2" from the back of the radiator to the front of the water pump pulley bolts... so I need a super slim type electric fan. I've got a big 4 core aluminum radiator in it so I'm not too worried.

Need the drive shaft to be lengthened by about 3". Anyone know of a good driveline shop in south LA county or north orange county???

I'll have to put a call in to Alan Grove tomorrow to get a power steering pump bracket that is tighter to the motor.

Then last but not least I need to buy some muffler and get the exhaust modified. I took the existing 2-1/2 diam h-pipe exhaust from the C30 but it hits the rear crossmember that holds the trailing arm pivots. Thinking of just buying a couple 40 series flowmasters and taking it to the local muffler shop to have it welded up.

[argonaut]

A few photos from early in the day today before it was running.

Exhaust clearance and trimmed frame on driver's side.


Exhaust clearance and trimmed frame on passenger's side.


3.5" between radiator and water pump pulley!


Engine in its final resting place.



PLENTY of room between the back of the motor and the firewall. It is actually a joy to work on it now!

[tincan1966]

Thnx argonaut for the link and info.

[argonaut]

Got a few things done on Monday.

Had a longer driveshaft made (boy was that ever not cheap), just to find out that my yoke was not bored at the end correctly to match up with the bolted tailshaft of my TH400. Thus it had never been fully seated all these years. So now I'm waiting for it to be bored and ready for me to pick up.

I converted to the cable throttle setup from the 71. Mounted it on the firewall and it looks like it belongs there. Need to swap the brake pedal pad to match the 71-72 horizontal line style otherwise it will bother the OCD side of my brain!

Chopped the exhaust down so I could at least bolt up the front half with the H-pipe. The big block sure sounds sweet with straight pipes... but LOUD! A local shop quoted my ~$550 to do a complete new 2-1/2" dual system with H-pipe and 40 series flowmasters.

I also ordered a 17", 2,400 cfm fan from summit (I hope that is enough flow), and a power steering pump bracket set from Alan Grove. Hopefully I'll have everything I need to button this up and get old Gerty back on the road this coming weekend.

[protrash64]

Nice work argonaut!!! I was going to mention that my BB ended up about 4'' away from the radiator IIRC so I went with 2 12'' fans and mounted them diagonally to avoid the water pump pulley.

Also want to mention that Flowmaster 40's are LOUD!!! I have them on my shortbed with sb 400 and the truck rattles my house and is extremely loud driving. My BB has 50's and is nice sound, typical Flowmaster, not too loud. Dont know what your plans are for the truck, so I thought I'd throw it out there for your consideration..

[argonaut]

@ protrash
Thanks for the heads up on the 40 series. I'd prefer it to be a modest rumble than all-out loud. I'll check into the 50 series.

['63GENIII]

Hey Jason, Nice looking work there! If you like the Flowmaster sound but want it fairly quiet, look into the "70 series" my muffler guy says they use them on alot of big blocks and motor homes. I've got em on my truck and they are pretty mild until you really wood it. I like them so far. 2-1/2" all the way out, no x pipe yet.