Graduates in my high school class...427.

My badge number when I was a police officer...427.

The engine in my '69 L71...427.

A coincidence? I think not.

 

As mentioned by another before... both are going to give you a huge difference in torque from the 350's. Since you are building this (I assume) you can build it out to last (for a long term driver) or for power and less longevity (for the track). It's up to you. Now as for which one... I will give you an opinion if I was doing it... I would go 454 with power but built for longevity. I tend to drive my cars more than the average restoration owner.

Why I mention the longevity... You can build the 427 or 454 for insane power and torque so from that point of view, don't kill yourself on which. However, you can build a 454 for more torque than a slightly more "enhanced" 427 but have more reliability. Just my two cents.

 

I think that the 427 was a much more popular engine for gm. Has that nostalgic wow factor. Gm could have easily used a 454 in the new vettes a few years ago. They chose to go back to the 427.

 

Not an engine expert here, by any means, but I would tend to think that an extra 27 cubic inches isn't going to set the world on fire. However, the longer stroke of the 454 would probably give the engine a little bit different "personality", sort of like comparing a 350 and a 383. Personally, I would go with the 454; it's been said before, but I'll say it again, "There's no replacement for displacement." You could just tell people it's a 427, if you wanted to.

Scott

 

If you're starting from scratch you could easily go 496, everyone has stated why. Another thought is that displacement is the only trouble free power adder. A 427 will pretty much do everything a 454 will after adjusting for the cube difference but at a higher RPM. I'd probably do the pros/cons thing for both and your desires for your engine to figure out which one fits your driving better.

 

Race engines are great and all, but my neighbor has a stable of awesome cars...an original GT500 Mustang, a 1970 Mach 1 with some special engine, and a 1967 Corvette Big Block.

He came into the Speed Shop I frequent (where my engine is being built now) and purchased race fuel for his cars. Has to run it. Matt has the best price in town at $9.90 per gallon. $170 later, my neighbor can't do much more than partially fill one of the cars or put enough in each to take them for a cruise around the block.

It also means he can't go on ANY type of a cruise and have any assurance of making it back. Can't fill it up anywhere.

Pump gas for me. I'm building a "race" engine, but keeping it to 10.3:1 or 10.4:1 (don't have final number yet) so I don't have any problems with 93 Octane.

 

IMCO the ~9.5:1 max CR often recommended in popular books for pump gas street builds is hyper conservative, and doesn't allow one to really open up the cam [sic] of whoopass available with a bit more. There are plenty of powerful grinds available that match well with a 10.3'ish alum head BBC. And, shall I say, the 268H may be tried and true, but which ever cid you choose please don't consider building an engine around that to be a "high-perf" mill.



...even if you fail to pick the 427.

 

I totally agree. No reason you can't get into the low 10's on compression. Big difference in power.

"Cam of whoopass"...I love it...

 

Parts are easily available for both so no advantage one over the other.
Street driving (normal) will never avail of what either are capable of delivering so no advantage one over the other.
Heads are always important, that is what makes or breaks an engines ability to deliver what it's capable of.

The question you really need to answer is what do you want from your engine.......then you run with that

IMO both are great engines and both can deliver from 250HP all the way to 750HP naturally aspirated.

If you're a real car guy, you'll want bigger and more in your heart.....always. You may settle for a nice 327 or whatever, but you'll yearn for more, it's human.

My 74 was an original LS4 454, I changed it after a few years for a LS5 454, then a LS6 454. I wanted more so I had a LS7 454 built and loved it. BUT, the darn thing needed race fuel so I supplied it. Then I started making octane by using toluene/diesel/and other components.
That engine loved it and I could advance the timing to 40 degrees. I would run low on gas, fill at the gas station and she would ping all the way home while I cringed in my seat. I ended up melting three pistons on that thing. I loved the power but hated the compression on that LS7 454 so I went with a 540 with lower compression and Vortech supercharged it with a V7-YSi. I still use the Dart Pro1 345 cc heads

Guess what..........I would stick a 632 in there if the 10,2" tall deck block would cause so many headaches with my 2 1/8' side exhaust headers, rack & pinion etc.

Do I need any of it.....no. The original LS4 454 that made 270HP was enough to get me in trouble on a daily basis. Now I just get to the speed limit faster and on the brakes quicker while I look at smoke in the rear view mirror and feel a smile that stretches from ear to ear.

You can not go wrong with either 427 or 454 but the bug that bites can cause wife problems and eat large holes out of your piggy banks

It is one of the best ways ever created by man to have a wife get pissed at you and have zero regrets over it all :-)))

 

Truer words were never spoken. I thank God every day that I was born a man and able to experience such things.