Thread: 427 or 454

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It's been a while since I have been on the site. I finally found a short bed frame for my 70 c10 which is currently a long bed truck. So I am going to build up the short bed from the ground up then transfer the cab after the rest of the truck is built. I also got my hands on a 73-75 454 block thats in awesome condition, same time period oval port heads, and Edelbrock TM 2-0 intake. I also got a Lunati 50205 cam that I am going to trade a local guy for a less extreme cam (rpm range of 4200-7600)

I always wanted a 427 but my friend thats helping me build the truck says I want a 454. As he explained it to me exact quote "you're already going to have a hard time getting power to the ground with a 427 you're going to want the extra torque a 454 has". I do not understand this logic I love the sound of 427 and its not a number you see stamped on a valve cover up here in Alaska unless its a ford flathead. He says the sound I like is all compression and cam not the fact that its a 427.

This truck is mostly going to be a street strip show truck that will be capable of hitting the drag strip and maybe win a race or two but I'm not looking to get killed with power. Any thoughts or opinions on what would be a good build for this engine?

In probably the last 200 or so BBC that we have built---------only one was a 427. Unless the block you got needs a crank, and/or you maybe have a 427 crank----ALLLLLLLLLL the parts out there are for 4 inch stroke (454) or longer. The on the shelf parts suppliers just don't have interest in doing the 427 parts because there is only a very limited demand for them. Go the 454 route and be comfortable with up to .125 overbore which will give you 481 cubes. The 454 does require (stock) an external balance dampner and flywheel but can be balanced internal if desired--

And besides, there is no substitution for cubic inches!

It wouldn't be the first 454 with 427 valve covers!

Originally Posted by Matthyj

It wouldn't be the first 454 with 427 valve covers!

Not a bad idea. One of my other friends is under the impression that 427 is only good for the track and not a street/ show truck

There is one word in your post that tells me you should have a mild 454, that word is STREET. Leave the 427's to the guys that have to figure cubic inches to car weight to make a certain class. Build a 454, 9.0:1 to 9.5:1 and use a cam that matches the static compression ratio.
http://www.crankshaftcoalition.com/w..._compatibility
This chart was made for a small block Chevy, so with a 454 you can use a little more cam than what the chart recommends, but only a little more.

The most important thing you can do for your new mill is to engineer the squish/quench to 0.035" to 0.045" to prevent detonation on pump gas.

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my buddy is trying to get me to do my 454 with 500-700 hp and 10:1 or 10.5:1 compression on pump gas I don't know how well that will work but he is convinced we can do it safely.

Originally Posted by techinspector1

There is one word in your post that tells me you should have a mild 454, that word is STREET. Leave the 427's to the guys that have to figure cubic inches to car weight to make a certain class. Build a 454, 9.0:1 to 9.5:1 and use a cam that matches the static compression ratio.
http://www.crankshaftcoalition.com/w..._compatibility
This chart was made for a small block Chevy, so with a 454 you can use a little more cam than what the chart recommends, but only a little more.

The most important thing you can do for your new mill is to engineer the squish/quench to 0.035" to 0.045" to prevent detonation on pump gas.

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My SBF stroker is running 10.3 to one compression on aluminum heads, and I have to run 91 octane or better pump gas in it. If I were doing it again I'd pull back to 9.0 to one or at most 9.5 to one like TechInspector advised, and be good on mid-range 89 octane fuel. Just my $0.02, because IMO our pump gas is not going to be getting better any time soon.

Moving up one point in static compression ratio will add 4% power, so you will only pick up 4% power going from 9.0 to 10.0 or 9.5 to 10.5:1, but it will require big bucks for aluminum heads. Not worth it. Stay with the iron heads and build it 9.0:1 to 9.5:1 so you can use 87 or 89 octane pump gas.
Bore the block 0.030" and use these pistons....
https://www.uempistons.com/index.php...roducts_id=506
If you don't like these pistons, use another piston of your choice, but do not buy pistons that have less than 1.645" compression height or less than 12cc pop-ups.
Have your machinist check the block decks and head decks for being flat so that the motor will not spit out these Mr. Gasket steel shim head gaskets....
Mr. Gasket 1131G, Mr. Gasket Steel Shim Cylinder Head Gaskets | Mr. Gasket

Your stack of parts will measure 9.780". The block deck height is 9.800". This will leave your piston down in the bore by 0.020" with the piston at top dead center. With the Mr. Gasket shim steel head gasket (0.018" compressed) added to the 0.020" piston deck height, your squish will be 0.038". Your combustion chambers are probably ~118cc's, (post the cylinder head casting number so we can make sure) so the static compression ratio of the motor will be 9.2:1. It should produce an easy 450 hp, operate detonation-free on 89 octane pump gas and pull like Jack the Bear with this Howards retro-fit hydraulic roller cam and roller lifters....
Howards Cams Retro-Fit Hydraulic Roller Camshaft and Lifter Kits CL120235-12 - Free Shipping on Orders Over $99 at Summit Racing
At the bottom where it says 9.0:1 static compression ratio advised, it means at least 9.0:1........This cam should also allow enough manifold vacuum to operate your power brakes really well.

Bolt on a set of 1 7/8" or 2" primary headers, long-tube (not those cheezy shorty headers) with minimum 3/8" flange thickness. Thinner flanges will warp up like a potato chip from the heat and spit the gaskets out. Install an X or H pipe immediately after the collectors and run the pipes and mufflers to the rear bumper of the truck. Nothing sounds quite so Ricky Racer as pipes that are terminated under the vehicle and resonating on the sheet metal.

Use this intake manifold, NOT THE AIR GAP MODEL, and mount a 750-800 CFM carb of your choice, topped with a 14" diameter by 4" tall air filter assembly so the motor can breathe.
Edelbrock Performer RPM Intake Manifolds 7161 - Free Shipping on Orders Over $99 at Summit Racing
This Weiand unit is also an excellent intake manifold....
Weiand Stealth Intake Manifolds 8019 - Free Shipping on Orders Over $99 at Summit Racing

Any of these dual-plane, high-rise intake manifolds will work great street/strip.

The relatively mild cam should coordinate well with your torque converter and stock rear gears.

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You don't need a lot in a 454 to make that lightweight pickup move out. Don't go crazy. You'll regret it if you do.

I had a slightly overbored 454 in this '72 Fleetside back in the early 1990's. I don't remember all the specs, but it had oval port heads, compression in the 9-9.25:1 range and enough cam to require a 10" Street Fighter converter in the TH-400 trans. A couple of years later, I back-halfed it and put in a 9" Ford rear axle with 3:70 gears and a pair of 16" wide Mickey Thompson's.

It was scary fast - but those wide Mickey's were hell if it rained.

Click on the photos for full size.

In your early posts here, you mentioned the sound. If you have a 427 and a 454 built to the same degree, and running through the same exhaust system, I don't think you could tell the difference by the sound alone.

You already have the 454, so you're already ahead of the game.

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I seriously appreciate all the insight. I will see what I can do to talk him down to a 9-9.5 this truck will be light but I am going to do what I can to add some extra weight with out forfeiting maneuverability.

In any of your opinions is there a cam that gives a nice choppy idle like a Comp cams Big Motha Thumpr but still can perform? Been told those cams are all show and no go. I just love the old choppy sounds that you don't really get to hear any more with most modern vehicles

Originally Posted by Lefcrak

In any of your opinions is there a cam that gives a nice choppy idle like a Comp cams Big Motha Thumpr but still can perform? Been told those cams are all show and no go. I just love the old choppy sounds that you don't really get to hear any more with most modern vehicles

You don't hear that choppy idle much anymore because it's the sound of a motor being inefficient, using a cam that, for instance, was meant to make power from 3000 to 7500 (race motor) being used on the street to try to make power from, for instance, 1500 to 5000. It's the sound of the air/fuel mixture being pushed back up the intake tract by the too-late closing intake valve and struggling to remain idling. As the fuel/air slug is pushed back up the intake tract, it passes the venturi again (first time was air going the right way, this time is air going the wrong way) and more fuel is added to the slug, because the venturi doesn't care which way the air is moving, it adds fuel every time air goes past it. Then the motor goes to the next intake stroke and the slug of fuel-rich air goes past the venturi again and guess what????????.........the venturi adds even more fuel to the slug!!!!!!!!!!!!. The motor is struggling to idle and will die if you don't continually blip the throttle to clean the motor out and start over. If you have the air cleaner off at night and shine a bright light onto the top of the carburetor, you can see this fog hovering atop the carburetor. It's called standoff and is the fuel/air mixture that has been shoved back up the intake tract by the piston coming up in its bore with the intake valve still open (race cam profile).
Late model electronically fuel injected vehicles will not tolerate these monkey shines, you can only do this stuff with a carbureted motor.

I love to hear a choppy idle at the drag strip, where the builder used a race cam because it is a race car, but on the street when I hear this, I just think to myself that the guy didn't know what he was doing when he built the motor. Race motors can and do use all the static compression ratio that they can engineer into the mix and use the appropriate fuel (ethanol, methanol, race gas) to operate the motor. On the street, you are pretty much limited to pump gas if you plan to go anywhere out of your own neighborhood, so you have to build with that in mind. 9.5:1 limit for iron heads and 10.5:1 limit for aluminum heads. With 9.5:1 static compression ratio, you can't use a race cam that lopes because the cam timing is all wrong, closing the intake valve too late to trap enough cylinder pressure to make a good bang and subsequent good power.

It is true that CompCams has found a way to grind a low compression cam so that it will make the motor idle with a lope, but you won't make the power that you could with the proper cam timing for the static compression ratio that you're using. Here are the 3 different grinds for a BBC. Where the description gives the static compression ratio, it means at least that much static compression ratio to coordinate with the cam timing.
http://static.speedwaymotors.com/ima.../BBCThumpr.jpg
The key to making this whole mess work will be the torque converter. If I were doing this, which I wouldn't, I would budget at least $600 for a quality 2800-3000 stall, 10" converter. If you don't begin with a good converter, you'll be taking the whole mess apart to do it again in a little while. Get on the phone and talk with my friends at Hughes Performance....
Welcome to Hughes Performance - Hughes Performance

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To summarize what Tech said: Choppy idling cams are for racers . . . and posers.

Who you calling a poser? Lol!
Seriously, Comp's Thumper series to a good job of show and some go. They seem to maintain enough low end that it's not a total pig. Torque converter is HUGH for getting the cam going!
And, we all love that rumpity sound, just not practical for cruiser.