454 big block or ls1 for 1967 impala convertible - Impala Tech
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post #1 of 5 (permalink) Old 10-05-2012, 01:50 AM Thread Starter
Join Date: Oct 2012
Location: chicago
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454 big block or ls1 for 1967 impala convertible

Hello, I am new to the site and am taken back by all this useful information.. I I see some older threads on LS swaps so wanted to start a new one and get the latest opinions..I have a 1967 Impala SS convertible and want to put a 454 or an LS1..Looks like the new trend goes for LS1..What is the best set up and will I have to get a new radiator and gas tank? Any information would be great..A few things I know I want for sure are tubular control arms and stock suspension..I know the car does NOT have POSI so is it a good idea to upgrade the rear end? i know i'm all over the place but any and all information would be great.

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post #2 of 5 (permalink) Old 10-05-2012, 12:23 PM
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LS1's have more power over the stock 454 but I just dont like the looks of them in classic Chevrolets Impala's. I would rather look at a nice big block under the hood than a motor covered up with coil packs and wireing. Just my opinion because Im old.
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post #3 of 5 (permalink) Old 10-05-2012, 05:24 PM
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A big block will make more torque over a broader RPM range for a noticeable seat of the pants thrill. The newer LS-x series of motors, those equipped with variable cam timing can really put you back in the seat with much better fuel economy.

Now for the good news. You can have both. Chevy made a big block that displaces 496 cubes and is fuel injected for good economy. They are just now on the market a few speed parts available for this engine (heads and cams as well as pistons and programmable engine controllers) that has been out of production for the past eight years. It is the 8200 Vortec pick-up truck motor developed by OMC (adapting a power boat motor for automotive use).

Because of the lack of demand the price should be much cheaper than a similar sized 427 cube LS-x motor. This engine uses the same cathedral style head as the LS-1 just super sized to fit a big block. The factory ECU really limited the motors performance when coupled with the factory cam. It acted like a truck engine with lots of grunt down low but all done by 4200 RPM. With a warm over head porting bigger valves and injectors with a cam swap and it will respond the same way an LS-x will to hot rodding.

Big Dave
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post #4 of 5 (permalink) Old 04-15-2017, 04:25 PM
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I too am new to this site, and I am also putting a 454 in my 66SSconvertable. It is remarkable how much a person can learn by actually doing it. I learned more in the past year about my car, than I knew before that.
I like what both BigDave and Dadstoy said about your comments.
First of all it's a 454. Your not going to get much better gas mileage. Not even with a FI. It's 10-12, that's it. This is why I am going to stay with the Rochester Quadrajet. I found a site for a FiTech single port FI. It's all computer controlled on board. NO outside components controlling it. Only sensors. Plug an play, no adjustments needed. But I was told by a FI technician at a speed shop, that it isn't always that way, and if it needs it, you will need a professional to set it up. You can't do it yourself. That said, the positives about the FiTech are; you can use your existing gas tank with no mods, and your existing mechanical fuel pump with no return line, because it uses a small stainless tank in the front by your engine or fender-well that has a gas pump in it. If you go with any other style FI, you will need an electric fuel pump, most likely dropped in your tank, and a return line from the engine area to the tank. Therefore your tank will need a mod to add the return line hose. At least mine would have. For these reasons, I am going to rebuild my RQ with new bushings and it will be much less trouble than any FI.
Radiator? oh yeah. You want at least a 3 stage with 2 electric fans. You can get them from most places like Summit or a radiator shop that drop right into your 67 and bolt up to your existing core support. Don't forget the larger trans cooler if you are upgrading to a T400.
I didn't get the tubular control arms, but I did have my frame guy reinforce my control arms on the rear end. He welded a plate lengthwise the full length to make the "U" shaped arms into a box or square shape arm. Much stronger, especially if you convert to POSI like you and both did. I am using 3.53:1 gears so that I didn't need to by a 4 speed. These gears are low enough to use the T400 3 speed off the truck engine I had without the need for an OD.
And don't forget to get a Chevy flag 454 emblem for the fenders. (grin)
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post #5 of 5 (permalink) Old 04-15-2017, 04:41 PM
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Welcome to the Team!

EFI is great with port injection, not so much with TBI. There was a Chevy service bulletin put out a few decades back encouraging owners of TBI 454 truck owners living above 3,600 feet to convert to a carburetor as the TBI would run lean at higher altitudes. Of all the fuel injection types a TBI is the least likely to be happy with cam change or any other modification.

Big block Chevys are notorious for their poor gas mileage due to their inefficient head design, and it is the reason they where banded from California back in 1970 due to failing every emission test proposed. The BBC was designed in 1961 to be a high RPM race engine that could have the tooling cost paid for by producing a truck engine variant (also runs at high RPM all the time). With emission restrictions the engine suffered greatly as it likes high compression and a lot of ignition lead, but restricted by emission laws.

They are still popular because a lot of factory hot rods shipped with one under the hood. as such dropping one into your car is easy compared to an LS-x engine series engine. In fact the LS-x costs half again more than a BBC which is half again more expensive than a SBC. So you can buy two high powered SBC engines for the price of one LS.

Big Dave
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