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My son and I are rebuilding a 67 Lemans for a street cruiser. The 326 that was in it needs a complete rebuild along with the 389 and 400 Pontiac engines I have. His first thought was to rag the 454 that I have for another project and put that in with a th400, but I told him that even though it would be fun he might get a little tired of stopping twice on the way to school to put gas in. His best friend is a GM tech and suggested dropping in a 4.3 and 700r4 that we have, keeping the fuel injection and computer. The car only weighs 3000lbs so I think it would move it alright.
Comments or ideas greatly appreciated.:confused:
 

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I may be wrong but if you look at the gas mileage of the S-10's with 4.3 I don't think you would be gaining a whole lot of mileage over a 350/700R4 combo, but if you already have it go for it.
 

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The 97 MKIII blazer we had got around 18 mpg, at 4000lbs. A 1000lbs lighter should help plus the 3:23 gears. It wouldn't be able to get out of it's own way but it would beat 8mpg with the 454 or similar with the Pontiac motors.
 

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I think there was a LT1 v8 near 4.3L out of caprices etc- likely cheap to source. Other wise any 4.3L I've driven is a gas hog.
 

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Keep it all Pontiac, rebuild the 326" with a turbo 350 or 400 from a Pontiac and put a gear venders overdrive in it if you need gas milage.
 

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Not sure if you have actually weighed that car but I have a 66 Tempest and it weighs 3650lbs. I would stick with a V8 because of the cool factor. You should be able to get one of the Pontiac motors rebuilt for cheap if it is just a cruiser.
 

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My 89 Silverado 350 same gas mileage as my 09 Silverado 4.3 bout 17mpg. Both are base model work trucks, both came with about the same hp.
 

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Keep it all Pontiac, rebuild the 326" with a turbo 350 or 400 from a Pontiac and put a gear venders overdrive in it if you need gas milage.
The 326 is a slug and the gearvenders are way to pricey.
 

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Not sure if you have actually weighed that car but I have a 66 Tempest and it weighs 3650lbs. I would stick with a V8 because of the cool factor. You should be able to get one of the Pontiac motors rebuilt for cheap if it is just a cruiser.
Manual brakes and steering, heater delete, aluminum intake, and headers. Car weighs 3018 lbs with 3/4 tank of gas. Drop in a sbc or v6 and loose another 150 lbs. The cool factor is the body style, and 80 mile round trips for school are in the plans, basically a daily driver from May to October. I have three engines but the heads are junk, small valve, high compression, and non hardened seats. Not worth the money to rebuild.
 

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My 89 Silverado 350 same gas mileage as my 09 Silverado 4.3 bout 17mpg. Both are base model work trucks, both came with about the same hp.
I had an 89 extended cab long bed Silverado that I put 318,000 miles on before the frame completely rotted off. The thing still ran great.
 

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I'd build the 400 Pontiac engine in a Pontiac, that would be kind of unique. All of my Pontiacs back in the 70's had big block chevys in them mostly because it was an easy performance upgrade but if I did it today I'd do the Pontiac engine because it would be way cool compared to the swapped engines.
 

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The whole point of the 4.3 and overdrive is for fuel mileage, and we already have them. Yes it would be great to run the 400/400 but then it becomes useless as a daily driver, especially 80 mile round trips to school during the week. This is for a 19 year old who makes $11.00 per hour, not someone who makes $50k a year and doesn't care about 8 miles per gallon. He already has his race truck and wants a cool cruiser that's good on gas. He's more comfortable with electronics and fuel injection than with carbs :)rolleyes:). He's not looking for a race car as he has that. Basically I would listen to any options people have about a drivetrain that would get deceant fuel mileage and not be a complete turd.
 

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I like the idea, but how much customizing would be necessary to fit it? I'm not sure I'd do it if you had you would have a lot of trouble putting in a v8 down the road. Also it seems like a 4.8/700r4 combo would cost nearly the same as the 4.3 and net better results. And you could even put on a car intake and the LS GTO engine covers and pretend its all pontiac.
 

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Not sure if you have actually weighed that car but I have a 66 Tempest and it weighs 3650lbs.
Manual brakes and steering, heater delete, aluminum intake, and headers. Car weighs 3018 lbs with 3/4 tank of gas.
Wow. I'm having a hard time swallowing the curb weights here. Not doubting you guys, but damn, you're talking about a full frame car that is practically a land yacht! A 66' LeMans with a 326 is what I drove right after I got my licence. I would never think to this day that car weighed anything less that 4k+.

Anyways, I know I would point and laugh if I saw a Tempest/LeMans/GTO with a 4.3 in it. OP, don't do it. IMO, you'd be better off doing an EFI LS swap if you're chasing mileage. If you're really hard up for mileage and want to retain some cool factor, put a 4bt in it.:p
 

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The whole point of the 4.3 and overdrive is for fuel mileage, and we already have them. Yes it would be great to run the 400/400 but then it becomes useless as a daily driver, especially 80 mile round trips to school during the week. This is for a 19 year old who makes $11.00 per hour, not someone who makes $50k a year and doesn't care about 8 miles per gallon. He already has his race truck and wants a cool cruiser that's good on gas. He's more comfortable with electronics and fuel injection than with carbs :)rolleyes:). He's not looking for a race car as he has that. Basically I would listen to any options people have about a drivetrain that would get deceant fuel mileage and not be a complete turd.


I understand completely what you're saying. Well except the part where you want to make a 47 year old classic car into a commuter car for a 19yo kid to tear up driving 80 miles to school every day. I kind of don't get that part.

Tell him to get a Carolla to commute in.
 

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Wow. I'm having a hard time swallowing the curb weights here. Not doubting you guys, but damn, you're talking about a full frame car that is practically a land yacht! A 66' LeMans with a 326 is what I drove right after I got my licence. I would never think to this day that car weighed anything less that 4k+.

Anyways, I know I would point and laugh if I saw a Tempest/LeMans/GTO with a 4.3 in it. OP, don't do it. IMO, you'd be better off doing an EFI LS swap if you're chasing mileage. If you're really hard up for mileage and want to retain some cool factor, put a 4bt in it.:p


I had a '65 GTO 327 Chevy and a 4 speed. It weighed 3460 iirr. Damn 327 would run circles around the 389 poncho that came in that car too.
 
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