Sbc to bbc swap

[Sawlog]

I have 69 c10 with a 350 and th400 tranny.
What am I getting into if I go with a 454?
I'm assuming new motor mounts, headers.
Will it fit without issues?
Thanks

[Steeveedee]

Do you have all the brackets for the alternator, etc., and the power steering pump and remote power steering reservoir? That would make it a lot easier. Do you have AC?

[kwmech]

With the correct motor mount frame stands the engine will actually be moved rearward about 1-1/2''. This means the trans will be moved accordingly---not a problem as the frame is already drilled. Driveshaft shortening, all the correct pulleys and brackets needed and unless you already have a 4 core radiator, that will likely be needed also along with a matching shroud. My truck originally had a 396, when I went to a 454 the factory 3 core radiator would not keep up with the added cubes

[Sawlog]

I would have all the brackets, no a/c.
I still have a 2 piece drive shaft. Also have a th400 tranny. I don't think they came out with a 400 from the factory. So I'm not sure if the tranny cross member has been moved in the past or not.
I just don't want a big block to be so tight that it's a pain to mess with and work on later.

[Sawlog]

Originally Posted by Sawlog

I would have all the brackets, no a/c.
I still have a 2 piece drive shaft. Also have a th400 tranny. I don't think they came out with a 400 from the factory. So I'm not sure if the tranny cross member has been moved in the past or not.
I just don't want a big block to be so tight that it's a pain to mess with and work on later.

Bump

[Steeveedee]

You could get a THM400 behind almost any engine in the lineup. I've seen vans with a 250 CI six, a 400 trans and a 4.11 rear axle. You're going to have to measure and then drop the engine and transmission in. There are probably holes for the cross member already. Mine has holes all along the frame for different drive train combinations.

[un4gvn!]

It's not that hard. I helped my son put my original 396 in his truck which had a inline 250 with a 4 speed. I put a 454 in my truck. All the frames are drilled for different drive trains. Like mentioned above, finding all the little things help. Find a complete 454 with all the bells and whistles and you shouldn't have any problems. I race mine. Lots of fun!

[Mark Umfleet]

There is still plenty of room under the hood even with a big block. Just make sure you pick up the correct motor frame mounts and it will go in easy. I chose to run 2nd gen fbody headers for better ground clearance. I did have to drink about 1/4 inch off of the passenger side frame rail for fitment.
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[Mike C]

Originally Posted by kwmech

With the correct motor mount frame stands the engine will actually be moved rearward about 1-1/2''. This means the trans will be moved accordingly---not a problem as the frame is already drilled. Driveshaft shortening, all the correct pulleys and brackets needed and unless you already have a 4 core radiator, that will likely be needed also along with a matching shroud. My truck originally had a 396, when I went to a 454 the factory 3 core radiator would not keep up with the added cubes

I know Kwmech knows that it would be driveshaft LENGTHENING in this case since everything is moving forward.

Lots of big blocks swapped into these trucks and a LOT of them not done right/well. I’m gearing up to swap a 427 into my 69. I bought repro frame stands and mounts for a 68-71 and repro power steering brackets and short pump pulleys for an OEM looking swap. I plan on running a TH200 4R behind mine so will move the crossmember and have a 1 piece driveshaft fabbed.

[70STOVEBOLT]

I went from a 250 to a 402 and I used all factory parts. BB frame stands and mounts, stock TH400 trans crossmember. Frame mounts moved to front frame holes, used existing holes for trans crossmember. Had to shorten the driveshaft, that was the only mod that was needed. I had a one piece driveshaft. I am running an HEI and there is plenty of firewall clearance. Stock TH400 shift linkage will work unless you are running Chevelle headers, which are shorter than truck headers, but allow the exhaust to be tucked inside the frame rails, which is what I am running. I used an adjustable shift linkage from Speedway and modified the stock linkage bracket on the trans. You can buy a shift linkage kit from Lokar, but I made my own instead. I am running a stock 3 core radiator and thermal clutch with 7-blade 19” fan and it has never heated up past the normal range. I have since changed to tubular trans crossmember since I tucked the exhaust, the stock one would not allow it. I am running Pypes 2 1/2 stainless exhaust with electric cutouts.

[mkmc69]

Originally Posted by 70STOVEBOLT

I went from a 250 to a 402 and I used all factory parts. BB frame stands and mounts, stock TH400 trans crossmember. Frame mounts moved to front frame holes, used existing holes for trans crossmember. Had to shorten the driveshaft, that was the only mod that was needed. I had a one piece driveshaft. I am running an HEI and there is plenty of firewall clearance. Stock TH400 shift linkage will work unless you are running Chevelle headers, which are shorter than truck headers, but allow the exhaust to be tucked inside the frame rails, which is what I am running. I used an adjustable shift linkage from Speedway and modified the stock linkage bracket on the trans. You can buy a shift linkage kit from Lokar, but I made my own instead. I am running a stock 3 core radiator and thermal clutch with 7-blade 19” fan and it has never heated up past the normal range. I have since changed to tubular trans crossmember since I tucked the exhaust, the stock one would not allow it. I am running Pypes 2 1/2 stainless exhaust with electric cutouts.

What trans crossmember did you use?

[bigmac73]

Originally Posted by Sawlog

I have 69 c10 with a 350 and th400 tranny.
What am I getting into if I go with a 454?
I'm assuming new motor mounts, headers.
Will it fit without issues?
Thanks

is this the same Sawlog from hotrodders?

[70STOVEBOLT]

Originally Posted by mkmc69

What trans crossmember did you use?

It was a Trans-Dapt 4539 that I bought from a member here.

Here is a link to one on Amazon:

https://www.amazon.com/Trans-Dapt-45...25907759&psc=1

[kwmech]

Originally Posted by Mike C

I know Kwmech knows that it would be driveshaft LENGTHENING in this case since everything is moving forward.

I stand by what I said, if you are swapping in a big block where there was a small block with the factory parts, the engine gets moved rearward 1.5''. He already has a T400, so making the driveshaft longer would be counter productive. Putting in a big block and moving the engine forward will result with a water pump/radiator clearance issue. That is unless you are stuffing a big block into a 4wd---then all bets are off. I've done this 3 times.

[Mike C]

My understanding of a big block swap with factory parts is moving the engine up and forward with the big block mounts.

If swapping the big block onto the small block stands then why would the trans move at all?

In doing a big block swap in a C2/C3 Corvette, the trans moves not at all so not sure why would it in a truck? If you have any engine dollies knocking around the shop the distance between the engine mounts and the bellhousing face is the same small block or big block. So putting one on the others mounts does not move the transmission.

Once I get mine in I’ll say “yup, kwmech was right” or “hah, knew I was right.” LOL

I am completing my conversion using the OEM big block stands. I have a small block and big block truck at the house now if the weather holds I will check and see where the bellhousing face is relative to the firewall on both trucks.

[kwmech]

The big block and small block stands bolt into the same forward frame holes. BUT if you look at where the center of the mount ends up, you'll find that the big block stands move the center line towards the rear. Yes the center line is the same from the bell housing forward to the center of the mount being 16'' (I believe). The issue is the size of the big block overall. that gives the illusion of the engine moving forward. Factory stuffed it back somewhat to get it to fit---even with the short water pump---for fan clearance.

For the people that use the small block stands, they usually have to cut them for exhaust clearance and run electric fans