Opinions on swapping in a 454.

[toomany]

well i dont know that much but i do know i had to change my motor mounts, headers, radiator, ext. the alt was just old. but yea you will most likly have a th350 if its a half ton so you will need to get a th400 with a 32 spline t-case. atleast that was what i had to do. i just would swap in a 350 if i could start over.

The Th350 and Th400 have the same bolt pattern. How long will a Th350 live behind a 454 is another question. If you're really that fed up with swapping the 454 in, you can bring it to me an I'll swap you straight up for a 350 or 400 .

 

[Wasatch K5]

I did the swap into an '86.

I purchased a donor 454 Suburban so I could get virtually everything I would need. I recommend this route. You get all the accessories, all the brackets, the radiator, fan shroud, ac plumbing, etc, etc.

After you're done harvesting parts, you can part out what you don't want, though that's serious ass pain.

 

[Greg72]

Listen to Bigblock72 and Burt4X4......

Those guys both drive 1st Gens, and understand what's involved in the swap. I've got a wee-bit of experience with BBC fitment as well.

I've driven Burt's truck with the 454 and I can tell you that manually rowing it though the gears with all that power is FUN, FUN, FUN!!!

Remember, to move a heavy truck you don't want horsepower you want TORQUE....and the lower in the RPM you develop it, the better. That paints a fairly compelling story for a BBC (or I suppose a stroker 383). Though to be honest, the "built" 383's I've read about seem to cost every bit as much as an equally powerful BBC. The BBC will build power a lot more effortlessly, so reliability and maintenance should be a lot easier too.


Take a trip to the 1st Gen Forum and look around, we've got quite a few 1st Gen BBC guys in there and plenty of photos and helpful advice regardless of which way you decide to go.

 

[Madspeed]

Your Very Close

It's a pretty straight forward swap but there are a few problems with big blocks in first gens.

The biggest problem is firewall clearance. The solutions are move the engine forward 2 inches, 2-3 inch body lift, or cut the firewall for clearance or combination of all three. Be careful if you decide to move the engine foreward because you can run out of fan clearance in a big hurry especially if you're using a long water pump.

The second problem is oil pan clearance. Make sure you use a single step oil pan (pan is straight and drops down to sump) not a double step oil pan because it will not clear the crossmember.

Headers can be a pain, I really haven't found any headers that fit and don't get in the way of the front driveline, the shackles and everything else. I've found it helpful to install 1/2" spacers between the motor mounts and the crossmember so the header tubes don't hit the crossmember.

Move the engine forward and use the short water pump system.
I have it all and aint usin it anymore
Headers you run from a Chevelle (ask me how I know).
Use the th400 205 combo a Dana 60 and hell throw some N2o on it like I did You might see daylight under your 35's on launch Like me
Iff you want all the answers PM me Ive done It on 5 trucks 69 to 72 Blazers

They should Pay me to post here not the other way around

 

[Keitha]

I am a fan of SBC's. I built my 350 to a 383 in my Suburban and love it. Milage is 11 - 13mpg and power is good. Obviously it is easier to get good torque out of a BBC and probably the same money in the long run, but they just take up more room in the engine bay. I have nothing against rats, just like small blocks for these trucks.

 

[kgblazerfive]

I like the BBC I have in my Burb no complaints at all, going to get FI for it one day to hard to keep running when its cold.

 

[Madspeed]

Corrections

dude i wouldent do it.... i did do it and im still in the middle of the swap. going from a 350 to a 454. everything is diffrent man, motor mounts, trany, t-case. you cant use any of ur old stuff, youll need a new distributer, headers, alternator, radiator, most lilkley drivelines if you dont keep the same t-case... ah its a nightmare. just put in a newer, stronger 350. thats the easy way to go. i got one out of an 87 with 85k in it. motor trany and t-case

The 454 will bolt in with the EXACT same mounts,dist and trans, rad alternator I Beg you to FIND me a sbbc and BBC dist that will NOT interchange

 

[william_7900]

gas mileage

what kind of gas mileage differences are there between the 350 (maybe a built 383) and the 454?

Thanks again for your help.

William

 

[tacoma]

My 350's are getting 12-14mpg, the 454 got 9.5 at best.

It got the same mileage empty or fully loaded and hauling a 4k trailer, so.....

 

[dyeager535]

Last tank was 15MPG, towing my 500lb trailer loaded and unloaded, 50 miles in 4wd with the hubs unlocked. (whoops)

340 miles on 22.5 gallons of gas.