73-80 454ci spec questions.

Hey guys, just picked up another truck! We got here a 1979 GMC C25 Sierra with factory 454/TH400. I have not had the chance to own a factory 454 yet in the squares so looking for a little info. I can find all kinds of specs on 454's from 81-86, 87-95 but the 70's truck 454's are kinda tough to find info on. From what I gather the 79 was the worse year to have for the BBC with a HP rating of only 205hp/335tq while back in 1975 the same truck was 245hp/375tq. I also gather that from 1973 up to 1979 the HP rating changed alot due to emissions laws but was that the only thing they did to choke up the BBC's was bolt on factory emissions or was it lower compression, heads, valves, cams ect...??? Basically can I just clean up the engine and gain back a few more ponies?

O btw here is a few photos from the seller.

No idea on cam specs but just about all factory pick up truck 454's will be 7.9 comp and have small valves (2.08 / 1.72). Iirc, peanut port heads didn't start until the mid 80's so there's a chance you might have some decent oval port heads (casting#'s ending 781 or 049) but you'll have to pull a valve cover to verify.

Of course all of this is assuming it's an unmolested, original motor BUT the truck is almost 40 years old so odds are it's been touched at some point.

nvrenuf, thanks for that info. I actually cant wait to get my hand on this truck and give it a great spit shine and tune-up. Ill hopefully have it in my possession later this week and open the hood.

Mine is also a factory 454 engine.
Not all that much of the horsepower, but it has enough torque to pull 4th gear (4 speed) at 25 mph with no issues.

This is info from a search I did when trying to figure out the same things...
Horsepower
The 1979 Chevrolet 454 cubic-inch V8 produced 245 horsepower at 4,000 rpm, better than the 225 horsepower at 4,000 rpm for the 1979 Dodge V8 440-3 and the 212 horsepower at 4,000 rpm of the 1980 Ford V8 460.
Torque
The 1979 Chevrolet 454 V8 generated 380 lb.-feet of torque at 2,500 rpm, which was also more than the 1979 Dodge 440-3, which generated 330 lb.-feet at 2,400 rpm, and the 1980 Ford 460, which generated 339 lb.-feet at 2,400 rpm.
Other Specifications
The 1979 Chevrolet 454 V8 had a four-barrel carburetor, a compression ratio of 7.6-to-1, and a bore and stroke of 4.25 by 4 inches.

From what I have read they are the peanut port heads.
So not the bestest of flow numbers, but fine for a low rev truck engine.
I am going to replace the stock exhaust manifolds on mine with headers soon.
That is said to help quite a bit in uncorking breathing abilities of the engine.
The only other planned change is putting on an aluminum intake.
That will be plenty of extra for me as I don't need it to be a tire fryer at this point.

I'm in the process of installing a GM rebuilt 454 into my truck. The part # is GM 12339193. It varies on where you look, but the application is 1974-90, some just say 81-90. My original engine RPO code is LE8, but this engine also includes L19. This is a peanut port engine. 230 HP, 360 TQ, 7.9:1 compression.

Make sure to research your intake before purchasing one. I had an '80 C20 3+3 that had a 454 back in the mid 90's. I bought it with a broken crank and block. I had a spare 454 from a friend's '86 Suburban that I had rebuilt for my truck. I made the mistake of using the peanut port heads instead of the original oval port heads on my motor. I installed a Performer intake. That truck never really ran right, but I could never figure out why.

I never realized until this past year when I got my K30 and wanted to bump performance that the Edelbrock Performer was not compatible with peanut port heads.

I was reading that as well when I went looking at them.
This is the one that I will end up with...
It will be more than enough as I don't intend on changing the heads out anytime soon.

These are the headers that I am looking to use as well.

My '78 Burb has an original and untouched 454, it feels more ballsy than my old '86 Burb that was also bone stock. Both with th400 and 3.73 gearing. The '78 is especially more peppy off the line.

My other two trucks are not a good comparison, they are very different weights and are not entirely stock anymore.

bucket, thanks for that input as always! I have made a small side business out of buying nice squares and reselling them after a while but enjoying them in the mean time so this C25 is going to be a fun ride for a while! I just wanted to know if i'll get the 454 experience while owning the most "smog-choked" version ever lol!

Catbox said:

Mine is also a factory 454 engine.
Not all that much of the horsepower, but it has enough torque to pull 4th gear (4 speed) at 25 mph with no issues.

This is info from a search I did when trying to figure out the same things...
Horsepower
The 1979 Chevrolet 454 cubic-inch V8 produced 245 horsepower at 4,000 rpm, better than the 225 horsepower at 4,000 rpm for the 1979 Dodge V8 440-3 and the 212 horsepower at 4,000 rpm of the 1980 Ford V8 460.
Torque
The 1979 Chevrolet 454 V8 generated 380 lb.-feet of torque at 2,500 rpm, which was also more than the 1979 Dodge 440-3, which generated 330 lb.-feet at 2,400 rpm, and the 1980 Ford 460, which generated 339 lb.-feet at 2,400 rpm.
Other Specifications
The 1979 Chevrolet 454 V8 had a four-barrel carburetor, a compression ratio of 7.6-to-1, and a bore and stroke of 4.25 by 4 inches.

Click to expand...

My `79 GMC C2500 454 wooden longbed with manual SM465 has plenty of torque too... feels like I could dump the clutch in 4th and it would go through a mobile home with no throttle. Don`t wanna try that..

I believe the cam duration is around 192/202, don`t know the lobe separation angle but probably wide because it has a pretty broad torque band. My 2wd has final gear ratio of 3.23 or so, so it runs about 2500rpm@75mph.

I am tempted (and probably will) to do an Advanced Adapters Ranger Torque Splitter for a 27% overdrive, which would drop that 2500rpm down to about 1800, plus it would have a 2-speed reverse...
http://www.advanceadapters.com/prod...tter-overdrive-27-with-a-5125-retainer-index/

On your headers... do you want the noise? "fun around town, gets old on the highway after a couple of hours..." If your target market is a young guy who likes the sound... maybe OK. I plan on keeping mine and doing some serious miles, so for now cast-iron manifolds do the job. If I decide to get deeper into the motor and do a cam change or even a stroker, then Doug Thorely Tri-Y style makes best torque. At a big price. And ceramic coated to reduce under-hood temps.
http://shop.dougthorleyheaders.com/collections/tri-y-headers/products/tri-y-headers-thy-300yc

A couple more threads or links for your perusal:
engine thread: http://www.airforums.com/forums/f159/all-things-454-a-95118.html

Brian Harris Performance, LLC -He likes more compression and TBI.
www.harrishighperformance.com
www.tbichips.com

LMC trucks: most everything for your truck-
In this case, dual 2-1/4 exhaust with mufflers:
http://www.lmctruck.com/icatalog/cc/full.aspx?Page=173

For a towing setup, I keep comimg back here for engine ideas:
https://www.pirate4x4.com/forum/tow...-bbc-towing-cam-suggestions.html#post27972489

And flip over that air cleaner and hook up a 4" aluminum dryer hose so it sucks cool clean air from behind the right headlight like it did when stock. Colder air intake temps=denser=more power. And it is shiny when clean.

My 454 block is a 1977. It is now a 496. 60 over with a Skip White performance stroker kit. It has 781 heads. It is a mild build, but wow it is now ALIVE !!!