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So I have a 1974 454 BBC that I'm putting in a 1958 Chevy Apache. I'm throwing some brand new rebuilt 781 heads and a 572 Lunati Cam in it. It's going to be for racing purposes of course and when racing run of 110 race gas and if daily driven off of normal 91 octane pump gas, but I was just curious what are some general guesses on how much HP this setup might potentially make, and how what would be a decently low buck way of adding HP to this setup eventually?
 

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Discussion Starter #3
You might need to add more information about the engine .


454 RATTLER
Ok, I mean from my information its the stock 4.25in stroke and 4in bore, flat head pistons, other than that general flow numbers and things like that I'm not sure of, I'm very new to engine building at the moment
 

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Lots of stuff wrong here Jimmy. Your stock static compression ratio is likely about 7.8:1. The cam you are proposing will need 10.5:1 to 12.0:1 static compression ratio, which will require a piston change and aftermarket torque converter, as well as a stiffer rear gear. And there is no way the motor will run on 91 octane fuel with a static compression ratio that is required for the cam.

Big block Chevies, when built for racing, with stiffer than stock valve springs, do not play well with flat tappet cams and lifters. You will have to use either a roller tappet hydraulic camshaft or a roller tappet solid camshaft.

A pickup truck is the worst possible body to begin racing with. It's like trying to make a barn door go fast against the wind.

There is no low-buck way to add horsepower. You step up to the window and lay down your hard-earned green and hope you chose the right pieces and that's it.

Here is a wiki article that I wrote which may help you to understand the relationship between cam timing and static compression ratio...…
https://www.crankshaftcoalition.com/wiki/Cam_and_compression_ratio_compatibility

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Don't let what I have said here discourage you from racing your truck. You will be bracket racing on either a 1/4 mile or 1/8 mile drag strip. Bracket racing means that you race in a bracket that is determined by how fast or how slow your truck is. So, your speed does not matter because you will be racing against other cars and trucks that are a little slower or a little faster than your truck. You have a chance of winning though, based on the dial-in that you write on your window, provided that you don't go quicker than your dial.
Find a drag strip and go out the next time they have races or time trials. Make several passes and talk to the other racers to get a feel of what would satisfy you.

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Tech's already said it, but I'll say it again....a 454 with flat top pistons, undecked block, and unmilled 781 head is a compression ratio disaster.

7.66:1 compression, using a common .041 x 4.370" bore head gasket.

You couldn't have picked a worse combination.

It's not like a small block where flat top pistons can get you somewhere decent on compression ratio....the huge 119cc combustion chamber needs a domed piston to get any real compression out of it...heck, it take a 20cc dome just to get to 9.5:1, and that is with the block decks cut .020" down to get the piston "zero decked".
Takes a 30cc dome and the deck cut to get to 10.4:1 compression.

We really need both advertised duration and the .050" duration to have any idea on how the cam is going to act or what engine changes it needs to work well, along with lobe separation angle (LSA) and intake lobe centerline(ICL).

Telling use "572 Lunati cam" is almost meaningless, lift is the least important figure and you can't tell squat about the cams behavior or power range off just the lift.

Since you can't buy a BBC cylinder head with a small enough chamber to get any kind of decent compression ratio, the best thing you can do at this point is buy a set of at least 22cc dome pistons for it...and 28-30cc would be better yet.

Put it together right now with flat top pistons and those 781 heads and you'll be lucky if it makes 375 HP.
 

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Yeah, when I tried to search Lunati's worthless search engine, there were at least 40 choices across something like 9 different categories...Drag Race, Marine, Circle track, Barebones, Bootlegger, Voodoo, EFI, Street/Strip, Street Master, Supercharger/NOS, Bracket Master....I wasn't going to go through them all one by one.....the OP can come back and fill us in if he's serious about fixing his problem.
 

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Yeah, I've seen hundreds of these young fellows with stars in their eyes disappear after they get a whiff of reality. I tried to soften it up for him a little by explaining that he can go and race just the way the truck sits now. Maybe he'll come back and learn something, maybe not.
 

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Yeah, I've seen hundreds of these young fellows with stars in their eyes disappear after they get a whiff of reality. I tried to soften it up for him a little by explaining that he can go and race just the way the truck sits now. Maybe he'll come back and learn something, maybe not.


Yes I like your clever way of saying what they want to do is not a good thing. Sadly so many inexperienced souls just read hot rod articles and start buying the most unrealistic combination of parts for a street car. Somebody has to direct them and you do a nice job.
 

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I'll add that fuel calibration requirements are different animals with pump gas and any 110 gas.
I'd go E85 and stick with it.
 

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Yes I like your clever way of saying what they want to do is not a good thing. Sadly so many inexperienced souls just read hot rod articles and start buying the most unrealistic combination of parts for a street car. Somebody has to direct them and you do a nice job.
Thank you. The sad part of it is that they are human beings...…. and human beings tend to fold into themselves when they learn that what they thought was a terrific idea, is not such a terrific idea and they get their feelings hurt. Then they don't show up any more. The loss is theirs. There are some pretty sharp guys on this forum and between those of us who post regularly, there is likely 300 to 400 years of experience. AND IT'S FREE FOR THE TAKING.
 

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The OP should pick up a couple of BBC books and do some heavy reading... also lots of online research. Maybe talk to a respected engine builder... but don't walk in cold, do your homework first.
 
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