454 in a '79 K20

[zac]

As I do test drives as I work through all my problems, I'm noticing the 350 is not really cutting it. I can't imagine I will be happy when I'm pulling a trailer or have a heavy load in back. The truck originally had a 400 sb, but it's long gone. I have several 350 4-bolt blocks I could do a 383 kit in. And I have a good '74 454. So I could approach diesel torque, with half the mileage. But I think I will only put 3000-4000 miles a year on this thing, anyway. Did 73-87 4x4's come with big blocks? By the looks of it, you would have to do the dented firewall trick like on 67-72's. Anybody done this? My truck has a th400 and np203. Thanks

[DirtyLarry]

A big block slips into a ’73-’87 4wd like an oily noodle. No beating the hell out of the firewall required like the ’67-'72s.

[b454rat]

My 84 had a 305/700r from the factory. Had a 350/700r when I got it, swapped in a 454 4-speed. Fit like it was made to go in, even with Chevelle headers.

Only thing you need to worry bout is the power steering. Really need the big block power steering stuff to make it work. Somehow I made a small block one bolt on and work without leaking on 2 different vehicles, but can't remember how I did it.

[ghettoluxury]

What not every 73-87 4x4 has a big block

Do it, I put a big block in my 82 and would never go back to the 350. Sure fuel consumption was better but you cant beat the power and torque of that 454 BIG BLOCK CHEVY

[zac]

I was afraid it was going to come to this. It will be especially hard to resist since I can easily get away with rings/bearings/gaskets/cam kit on the BB. I also have a pile of axles I have scrounged in my shop now. At the rate I'm going, the only original drivetrain part that will be left on the truck I bought Aug. 24th will be the rear half of the front driveshaft....

[b454rat]

I changed the motor, tranny, t-case, front axle, rear axle, and both front and rear springs.

I think I get better mileage with the 454 over the 350, and have a TON more power, not to mention so much fun to drive. You can't really go fast with a 465 4-speed, quick shifts and these tranny's don't go together. The motor is stock far as I know, was rebuilt at some point. Has a stock intake, phenolic spacer, adapter for the Edelbrock carb, headers and 3" flexpipe (temp to I get some money for a real exhaust) and 2 1/2" fake Flo's with no dumps just behind the cab. (Sounds sweet....)

Can't beat a big block. Don't think I'd ever had a small block in a truck again...

[2tons of fun]

why would you need to bash the firewall?

ive even had a bbc in my 71 swb with th emotro pushed back 1-2" and didnt need to touch the firewall.

bbc, the second fastest way to turn $$$$ into noise!!!!

[Burt4x4]

BBFL = BigBlocksForLife!!!!
I too will never run a SBC again, 454 is an awesome lowend engine!


When I put a '74 454 in my 72K5 I had to "hammer" my firewall on the drivers side to keep the corner of the head from touching. And I even have a 3"body lift.
Go BBC!

[kwmech]

Originally Posted by DirtyLarry

A big block slips into a ’73-’87 4wd like an oily noodle. No beating the hell out of the firewall required like the ’67-'72s.

NEVER in 30 years of working on these trucks have I had to get a hammer even close to the firewall to make a big block fit

[DirtyLarry]

Originally Posted by kwmech

NEVER in 30 years of working on these trucks have I had to get a hammer even close to the firewall to make a big block fit

Me neither, but have seen pictures were people have done it to make a HEI dizzy fit on a big block in a 67-72 4x4

[mickman77]

I yanked the original 400 SBC out of my '77 k20 and slid a 454 in with no problems at all. Used the same mounts and everything. Did have 1 small issue with oilpan clearance on the front xmember (maybe not the right way to fix the problem but) I just wiggled a prybar tip between the two a little at a time till they cleared each other and have been running it for a year now with no problems.

[zac]

I'm glad somebody mentioned the oil pan. Mine disappeared during the custody battle over this engine with my dad (I won). I've had trouble with aftermarket pans sealing right, so I think I'll look for an original one. Any idea what years and vehicles fit and which don't? Truck pans work, I guess. Also, somebody mentioned Chevelle headers fit. What years? Do 2wd truck headers fit? Which exhaust manifolds? Anything else I should look for other than the power steering stuff?

[DirtyLarry]

You might consider getting yourself one of these nice HD engine cross members from Off-Road Design.

http://www.offroaddesign.com/catalog...rossmember.htm

ORD cross member with my old 7.4L. You can even see the little wear mark where the original cross member got pretty friendly with the oil pan.


ORD cross member with the 8.1L and the 8.1L oil pan is huge!

[2tons of fun]

i dont know wtf some of you guys manage to do but i have never hit the pan, 2wd or 4wd, broken motor mounts and the lot.

[cheepin]

I replaced the SB 400 in my old '79 Sub.It bolted right in.Same motor mounts.You need to use a short bowl fuelpump.I think I got one for a 70 Malibou.Also need to swap to the four core Rad.
And like said mileage went up when cruising the highway.

[Dooley]

I put a 454 in my 1979 K30 back in the day. No problems. The pan never hit anything either. The previous poster is correct about needing the shorter fuel filter bowl.

[DirtyLarry]

I think it all depends what size pan you are using. The pan that was on my 454HO was a 7 QT pan and the 8.1L has at least a 7 QT pan if not bigger. On the other hand, we have a 427 in a ’78 4x4 tow truck that does not rub the cross member at all.

With the ORD engine cross member you don't need a short fuel pump. In fact, if look you at my 454HO picture I have a Race Pumps high zoot piston pump mounted in it, which is pretty big. Check out www.racepumps.com sometime.