Advice for fitting a '73 454 into a factory SB '71 C10

[humbulay]

Any headaches I should anticipate fitting this BB in?
-W/AC will a 3 row aluminum radiator be sufficient or is a 4 row necessary
-Motor mount recommendations?
-Front spring recommendations for slightly lower than stock ride height?
-Fan clearance issues?

Any insight/experiences would be much appreciated!

[68Gold/white]

My experience is not great, BUT,
I have a 68 big block pickup. I bought it in 1980, it still had all it's original stuff (I still have it, although all in pieces).

68 was the first year for a big block. 68-71 uses a specific motor mount and frame bracket, that mine came with. 72 is different. I plan to use the 72 frame bracket and mounts on my 68 396, and may use same on my 67 small block settup (If it worksout, I'm sure it will).

If you already have a 3 row rad. I'd try it, to see. It may(?) be enough cooling. Big block and small block fan shrouds ARE different. I just don't know if a one could be modified and used fir the other type of engine.

I would also see how the stock springs react to the heavier engine, before you spend $$$...

NEXT!!!

[HO455]

I would step right up and get a 4 row factory copper radiator to start. Has the 454 been rebuilt? What is the compression ratio? Those questions refer back to how much cooling the engine will need.

I'd get the engine installed before making any front spring changes if it was my truck. Less guessing that way.

What transmission will you run?

[Steeveedee]

Agreed on the radiator, especially with a 454. Squarebodies came with a bigger radiator for a reason.

[humbulay]

**Mild rebuild/ 468 / 4L80E trans... end goal is not having to worry about sitting in summer traffic with windows up and AC on blast

[kwmech]

Does the 68 truck have the transmission in it already----never mind I reread. You'll have to move the cross member back for the 4l80 anyways, so you may have to get some drill bits out anyways to relocate. Try to procure some 72 big block stands. You'll need them for the 468. Then there is the early/late water pump pulleys and bracket debacle for the fan and shroud location

[Steeveedee]

Unless you are going to run electric fans, I'd advise getting a BBC fan shroud and have it available when you locate the engine. I don't know why, but the fan on my truck has the clutch about 1/2" from the stock radiator. That puts the engine about 2" forward of where it should be. By all appearances, it came from the assembly plant that way.

[ochremo]

With AC definitely electric fans. 100 degree day caught in traffic with a big block and AC on, save money and time by going ahead with fans. The new brushless fans pull very little amperage coming on and require no relays. I'd do a radiator/fan combo of your choice. I had great luck with my Dewitt combo.

['68OrangeSunshine]

I used to run a '67 K/10 Suburban that the PO had shoehorned a 454/TH350/NP205 into. Since there was no engine notation on the SPID, we'll assume it came with the V8 283 as stock. [And SM420/T221].
No attempt at upgrade to the front end springs. That beast's Doghouse would Rock'n'Roll like a miniskirted GoGoGirl in a cage at freeway speeds.
Fun truck. I miss it.

[un4gvn!]

Get the 69-71 frame perch"s and motor mounts. They are easier to find and a little cheaper. Make sure to bolt the perch"s useing the most forward holes on the frame rail. You might have to have a drive shaft made for your combination. I have a 540 in my truck and I enjoy the h#%l out of it. You will to.

[kwmech]

Originally Posted by ochremo

With AC definitely electric fans. 100 degree day caught in traffic with a big block and AC on, save money and time by going ahead with fans. The new brushless fans pull very little amperage coming on and require no relays. I'd do a radiator/fan combo of your choice. I had great luck with my Dewitt combo.

Personally, I have never had any luck with electric fans cooling a 454. I did just about everything I could with the big block in my wrecker and after spending a lot of wasted money I went back to the clutch fan and a shroud.... never overheated again.

[ochremo]

Originally Posted by kwmech

Personally, I have never had any luck with electric fans cooling a 454. I did just about everything I could with the big block in my wrecker and after spending a lot of wasted money I went back to the clutch fan and a shroud.... never overheated again.

Crazy how things happen. I did just the opposite) Lot's of money on fans, clutches, and water pumps using stock shroud. It cooled great going down the road and for about 15 minutes on a very hot day in stop and go traffic until it started creeping up. Plenty of timing, AFR, and new Dewitt radiator. Added Dewitt's fan kit never ever get's past 185 with a 180 thermostat.

[jumpsoffrock]

Originally Posted by ochremo

The new brushless fans pull very little amperage coming on and require no relays.\

just searched them, boy them things is C-H-E-A-P.

[weq92f]

.

If you go electric, research a bit about how much total CFM your setup will need, multiply that by a fudge factor to make up for CFM loss due to air flow resistance, something between 1.2 and 1.4 and then purchase either a single or two high quality fans that meet that rating. Fabricate or otherwise acquire a shroud separately.

The total amperage draw of your fans must not overstress your charging system as if this occurs, you'll not be getting the CFM you need.

Anything less than the above can easily lead to disappointment at the red light on a 100 degree day.

YMMV,

-Kevin

[Joyridin]

When I bought my 68, it had a 454 in it with a TH400. No A/C though. It had a 3 row and it got a bit hot. I am not sure the gauge was 100% accurate though.

As for springs, it had the stock springs from the original 327. No issues at all. It actually sat a bit lower and rode good.

[425HP409]

I installed a big block in my small block 68 last year. I will be glad to help you with what you need to do to get it installed properly, and correctly. I do have a set of BB engine stands and mounts and a BB fan shroud which I would be glad to sell you. With a stock GM 4 core copper radiator and fan shroud on my truck it runs cool in 100 degree days with the AC on.
Some items that will be needed:
1. Heat shield for the right floorboard
2. new engine stands and mounts, moving engine back 2 inches, necessitating moving transmission back and if using existing transmission shortening driveshaft.
3. recommended installing a heat shield over the starter
4. a good radiator and fan shroud
5. recommended a left valve cover with a slant to clear firewall
I can be reached by PM and would be glad to help off line. I also installed factory AC while the engine was out.

[Classic Bowties]

Originally Posted by humbulay

-Motor mount recommendations? Any insight/experiences would be much appreciated!

humbulay, once you have your big block conversion parts list needs/wants figured up, we have several OE 68-72 short water pump BBC conversion parts already pulled/ready to ship available in the below linked big block parts board f/s thread, see parts list items #3 and #10 for both styles of OE BBC engine mount towers, have a look and let us know. Mel


https://www.67-72chevytrucks.com/vbo...d.php?t=760308

.

[Classic Bowties]

More pics...

[Mike C]

The factory big block is mounted higher and further forward than a small block truck. This is to provide extra clearance at the firewall. Factory big block trucks were high hump floor IME as well because of the increased height and TH400 transmission.

You actually need a LONGER drive shaft when keeping the existing transmission when doing a big block swap. But since you are changing to a longer trans you will need to shorten or most likely get a new driveshaft.

I concur with several of the previous posters. Use the 68-71 big block mounts and get a 4 core radiator. The ‘73 would have come with a long water pump, but I am a fan of keeping the short pump setup and the driver side alternator. Replacement brackets can be expensive but the 66-68 Chevelle parts mostly interchange when you are shopping if you can’t find original truck stuff.

[Richard]

I am kind of confused here. FWIU there are two mounting points for the engine crossmember. Forward and back. The stock small block trucks all use the forward mount. 4WD uses the rearward mounts as well a some sixes which may use a staggered mount as well. Not making sense to me as some are saying to move engine forward. Thought the BB used the rearward mounts as well. Makes sense to me BB would be in rearward location and lower. Thinking maybe why the BB was never offered in a 4x4. Already in back position and lower engine would reduce axle clearance.

[Mike C]

The two wheel drive crossmember only bolts in one place. There are multiple holes for the engine stands on top of the frame. And there are (3) different engine stands. 6 cylinder, small block and big block. You can mount a SBC on the 6 cylinder mounts and it puts the motor in the rearward position ala a 4x4. I would do this if I was converting a 6 cylinder car to a small block. But the big block is too wide to fit in the small block position, much less the 6 cylinder. So the factory big block mounts move the engine up and forward. I don’t recall which hole in the top of the frame the big block uses, but the stands are a different shape and have the large hole in them as you see in Classic Bow ties post.

[70STOVEBOLT]

Originally Posted by Mike C

The factory big block is mounted higher and further forward than a small block truck. This is to provide extra clearance at the firewall. Factory big block trucks were high hump floor IME as well because of the increased height and TH400 transmission.

You actually need a LONGER drive shaft when keeping the existing transmission when doing a big block swap. But since you are changing to a longer trans you will need to shorten or most likely get a new driveshaft.

I concur with several of the previous posters. Use the 68-71 big block mounts and get a 4 core radiator. The ‘73 would have come with a long water pump, but I am a fan of keeping the short pump setup and the driver side alternator. Replacement brackets can be expensive but the 66-68 Chevelle parts mostly interchange when you are shopping if you can’t find original truck stuff.

I put a 402 in my 2WD 6-cyl truck and I had to shorten my driveshaft. I already had a TH400 in the truck, as I had converted it from 3OTT previously. I needed to have my driveshaft shortened slightly. I used the existing holes in the frame for the trans mount, so there must be at least two sets of holes.

[Mike C]

I think there are 3 sets of holes. What I am not sure about is which ones are needed for big block factory stands.

Your conversion makes no sense to me as the placement of the stands with the 3 different engine combinations moves the trans forward quite a bit each time from the 6 cylinder to SBC then the BBC positions.

If you use factory big block stands in factory big block holes they move engine and trans forward relative to a sbc. The location on top of frame is dictated by where bottom of the stand attaches to crossmember.

If you put a big block on sbc stands the trans doesnt move.