Anyone been able to nail down some specs for Mark IV 454 engines?

[Mr_Ryumaru]

Sorry if this isn't the correct area to post such a question, but I couldn't find a general question forum. Then again, I am a ridiculously stupid person, so odds are I am in fact in the wrong area. Again, my apologies.

Now, I know that the 454s that were in trucks were pretty disappointing in regards to how much power they made in relation to their displacement. But the issue I'm having is finding specific power specs for it. I've found wildly different claims, anywhere from 230 hp - 400hp. I have little doubt the truth lies somewhere pretty near the lower end of that spectrum, but I would really like to hear the knowledge that you guys have, because I know it damn sure is far more vast and complete than mine. And all the interactions I've had with you guys are simply awesome. You guys are some of the kindest, most helpful people around, so this is where I ask for your help.

How much power/torque does a factory Mark IV 454 make? I know that the heads can make a big difference, and I think these ones are "Large Oval" heads, but tbh its been a bit since I've seen the block as its in storage atm.

And if you'll tolerate some blasphemous bench racing, how much power gains would you typically expect with the mods I'll be doing? The mods are are: Headers and dual exhaust, 750cfm Quadrajet, MSD ignition system, Lunati barebones series cam (PN# 10110101LK), and an Edlebrock Performer intake manifold?

Thanks for any and all help!

EDIT: I just felt it was prudent to say I'm not a Horsepower/Torque guy. These figures should not, and will not define my build or how I enjoy it. This is just because I am curious, and kinda wonder how much difference the mods would make. Regardless of what answers may be given to me, this is the path I've chosen, and the path I will take.

 

[dvdswan]

Straight from Hot Rod Magazine...

https://www.hotrod.com/articles/0707phr-mark-iv-family-zl1-big-block-chevy-history/

 

[Mr_Ryumaru]

Straight from Hot Rod Magazine...

https://www.hotrod.com/articles/0707phr-mark-iv-family-zl1-big-block-chevy-history/

Thanks for the link, but I've already read that particular article. The issue lies in that the vehicle the 454 came out of was a 1973 K20 suburban. Typically, such options were not possible, but this specific suburban was purchased by The Montana Forest Service, who around here are quite well know to pull strings and get special ordered vehicles directly from manufacturers. As such, the chart is useless, and the article simply states "From 1965 until it was discontinued in 1974, the Mark IV big-block was produced in a variety of horsepower configurations". In addition, that article seems to only pertains to cars, not trucks.

So you see, I've hard a hard time finding anything concrete lol

 

[Craig 85]

Here's some specs for my '85 454 (LE8). It has peanut ports. I had an '80 3+3 with a 454 around 1995. I know that had oval port heads.

LE8 - 7.9 to 1 compression, 230 HP @ 3800 RPM, 360 TQ @ 2800 RPM

I'm in the process installing a rebuilt GM 454 in my truck. They no longer produce the LE8. The replacement listed is the L19. The specs given for that engine (1987-90) with a TBI set up is:

L19 - Unknown compression, 230 HP @ 3600 RPM, 385 TQ @ 1600 RPM

I would guess a '73 truck 454 would be somewhere between the LE8 specs and the passenger car 454's for '73. The article lists an LS4 454 for 1973.

LS4 - unknown compression, 275 HP @ 4400, 395 TQ @ 2,800.

 

[Mr_Ryumaru]

Where should one look to find casting numbers?

I drove out to where its stored, and located on top of the ridge where the bellhousing mates up, was "99928". Now, after using that chart to compare the number, nothing showed up. So I figure it may have been dirty and I may have gotten the numbers wrong due to how similar they look. However, I can say that the number was only six digits long which does narrow the list considerably. And I know for certain it is a 454, which narrows it down even more. But upon camparing the casting number I have written down with the numbers left on the list, none of them really look visually similar. However, that's all assuming that this is the correct location to find the casting number. I think what I'll do is slap a wire cup in a cordless drill and go back out to clean it up. But first I need to know what to look for, and where to look.

Also, pic below of head ports. I think these are large oval ports, but feel free to correct me as I am in fact clueless.

You must be registered for see images attach

Disregard icky camshaft. Its for a 396 and the jackass previous owners had it in the 454, hence why I don't care about it rusting.

 

[nvrenuf]

The block casting number with be a raised number on the bellhousing lip on the drivers side above the oil filter boss.

The head casting number will also be a raised number between the valve springs.

Pay no attention to "HI PERF PASS" cast on to the block or heads, this is on almost every motor (except tall decks, etc).

 

[idahovette]

Most of those "icky camshaft 396's" ran a hell of a lot better than the 72 up 454's

 

[Mr_Ryumaru]

Most of those "icky camshaft 396's" ran a hell of a lot better than the 72 up 454's

well aware that the 396 was a hell of a motor, and not implying it was bad at all. Simply that 1) that camshaft picture is disgustingly rusted, and 2) a 396 cam in a 454 pretty much castrates what little power they have. Thats all my man <3

The block casting number with be a raised number on the bellhousing lip on the drivers side above the oil filter boss.

The head casting number will also be a raised number between the valve springs.

Pay no attention to "HI PERF PASS" cast on to the block or heads, this is on almost every motor (except tall decks, etc).

Great, I'll head back out tomorrow with a wire cup and clean it up so I can read the damn thing lol. I did actually grab a picture of the number on the heads, but have no idea what it means. Any help on that front would be greatly appreciated.

You must be registered for see images attach

In case its hard to read, the top one I believe says "A31 78", and the bottom I think says "353049". The other head was identical except the bottom number on it was "353048". These mean potato to me Would love to know what, if anything, they mean.

 

[nvrenuf]

Great pic, 353049 is an EXCELLENT oval port head. Head castings are typically referred to by the last 3 numbers, the 049 and 781 heads (nearly identical castings) are sought after and short of an aftermarket head they are great heads to use. These heads come factory with 2.06" int & 1.72" exh valves but can be upgraded to 2.19" int & 1.88" exh (or bigger). The combustion chambers are +/- 118cc and have +/- 250cc intake runners.

The big chambers will mean you'll need a piston with a small dome to get any compression, typical pick up truck engines with these heads yielded around 7.9:1 compression.

Edit: the head that appears to have 353048 is going to be an 049 with a poor number casting. Also, the A31 78 is likely a date code but I'm not sure.

 

[Mr_Ryumaru]

Great pic, 353049 is an EXCELLENT oval port head. Head castings are typically referred to by the last 3 numbers, the 049 and 781 heads (nearly identical castings) are sought after and short of an aftermarket head they are great heads to use. These heads come factory with 2.06" int & 1.72" exh valves but can be upgraded to 2.19" int & 1.88" exh (or bigger). The combustion chambers are +/- 118cc and have +/- 250cc intake runners.

The big chambers will mean you'll need a piston with a small dome to get any compression, typical pick up truck engines with these heads yielded around 7.9:1 compression.

Edit: the head that appears to have 353048 is going to be an 049 with a poor number casting. Also, the A31 78 is likely a date code but I'm not sure.

Wow! I'm stoked to find out. The engine came out of a 73 k20 suburban, and it was factory. That said, they could've replaced the engine/heads. Tomorrow I will get a clean reading of the casting marks. I will also check whether this is a two bolt or four bolt main. Also, I will check the pistons and see what they look like. I'm going to reuase them as they're in great shape, so hopefully they have the dome shape you talk of. I do seem remember they weren't entirely flat. Thanks for the info, will update tomorrow and would love your input!

 

[73c20jim]

Remember many, many pictures.

 

[QBuff02]

the 049's are a very good performance head, they're the large oval casting. I imagine the other casting number that you suspected to be a 78 is actually a "73" and it decodes as follows-the letter donotes the month followed by the day and then the year. so they are January 31st of 1973 castings. I literally just rebuilt, freshened up and installed a pair of late '72 049 castings for my latest 454 project. However, they are pre unleaded gas, and as I learned, needed some work to make them right. namely, they had oversized valves installed in them and the previous machine shop didn't do such a bang up job in the process so we had to cut out the factory exhaust "seats" and install hardened ones because there was literally nothing left of them. I went with 1.88 exhaust valves, and if you need to, like I did, there was plenty of meat there for installing the hardened valve seats. The retainers and locks on your valve springs don't look original, so I imagine they've been worked on at some point in the engines life. But they are a very good platform to start with in my opinion!

You must be registered for see images attach

 

[Mr_Ryumaru]

the 049's are a very good performance head, they're the large oval casting. I imagine the other casting number that you suspected to be a 78 is actually a "73" and it decodes as follows-the letter donotes the month followed by the day and then the year. so they are January 31st of 1973 castings. I literally just rebuilt, freshened up and installed a pair of late '72 049 castings for my latest 454 project. However, they are pre unleaded gas, and as I learned, needed some work to make them right. namely, they had oversized valves installed in them and the previous machine shop didn't do such a bang up job in the process so we had to cut out the factory exhaust "seats" and install hardened ones because there was literally nothing left of them. I went with 1.88 exhaust valves, and if you need to, like I did, there was plenty of meat there for installing the hardened valve seats. The retainers and locks on your valve springs don't look original, so I imagine they've been worked on at some point in the engines life. But they are a very good platform to start with in my opinion!

You must be registered for see images attach

I'll take more pictures of those as well then

 

[idahovette]

The 2.19 and the 1.88 valves do wonders for the performance over the old ones. Made a heck of a difference in my .030 427

 

[Craig 85]

Where should one look to find casting numbers?

Located on top of the ridge where the bellhousing mates up, was "99928".

The motor I just pull from my truck had a 1974 build date with this number. 3999289 (Big Block V8 1971-1979 454, 2 bolt or 4 bolt). Mine was a 2 bolt.