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Discussion Starter · #1 ·
I have a 1970 Chevelle 454 (not an SS, just badged to one) with a rebuilt third block with 6500 miles on it and a TH350 trans, big 10-bolt rear end. I want convert the trans to a new Tremec 6-speed manual and do one of two things with the engine.

1. Keep the 454 block and increase the HP to 400-450 or
2. Upgrade the engine to a new Connect and Cruise LS3/480 HP.

Option 1 keeps the popular/famous 454 block while option 2 puts in new engine technology with high HP/torque and improved mileage (not that I'm concerned about mileage that much.

I'd like opinions on which is the best way to go for the overall upkeep and value of the car. If I do all this to the car I plan to keep if for quite some time.

Thoughts?
 

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How much will the various upgrades cost? Upgrading your current 454 to the power level you state in your post will be more cost effective.

Steve R
 

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You could build 3 big blocks for the cost of that connect and cruise package, depends more on what you want.
 

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I like big blocks in 70's. Without the big block you can't keep the SS badges. LS3's are cool but it's a small block. You could easily put some heads and efi on the 454 and have more than you want. Your LS3 will get you into fuel system, suspension, exhaust, rewiring, cooling system. They are both cool though, but in 1970 only big block cars has SS badges.
 

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I like BB's in Chevelles too. Mine is a compromise, L29 Vortec 454. Bolts right in but has factory fuel injection and ECM to run the engine and transmission.
 

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I like BB's in Chevelles too. Mine is a compromise, L29 Vortec 454. Bolts right in but has factory fuel injection and ECM to run the engine and transmission.
I've seen what you have been doing Philip and like your option of the L29 7.4 454. I run nothing but the L18 8.1 496. It is similar, it bolts in but is a beast of its own, have to custom make everything. I love having a big block that is basically an LS.
 

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1968 Malibu sport coupe, 489 ci. 590 hp 600 tq, RV T-400 Freakshow 3200 stall, 3.73 12 bolt posi
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Id upgrade the engine you already have
 

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I've done several fuel injected upgrades to muscle cars. The purest will tell you don't bother and other will tell you to upgrade and enjoy. It's a personal preferences. The LS drivability will be excellent and along with that comes the complexity of the LS install. IMO the complexity is a non issue.


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the q jet on my 454 runs perfectly starts great has good performance during warm up. the average after market fuel injection system is in no way superior to a well tuned carb in my opinion. i would keep a carbed b block mostly due to the cost
 

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Carbed 454 for a 70. I love my LS6 in my C5Z but just isn't the engine I want in a muscle car. LSx swaps are getting cheaper but still a lot of work.


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Discussion Starter · #11 ·
Thanks for all the replies and input. Looks like an overwhelming lean toward keeping the BB 454 (which is what my gut was telling me if I want to keep the badging on it. My ultimate end goal is to turn it into a full SS car once I'm done by putting al the SS options on it that would have come from the factor (swayers, boxed control arms, 12 bolt positraction rear end.
 

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A cam change and head change if the old ones are smoggers on your 454 will get you where you want to be in HP easily. If you add a simple fuel injection setup like FI tech, it will run just as nice as an LS.
 
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