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80's 318 2bbl to 4bbl hp gain?

junkyard junky

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Looking for a 318 to swap in a mid 60's dodge car inorder to get the car to move under its own power. Found a 1985 fifth avenue that has a bad trans. I can buy the car for $500 but I looked online and its only 150hp. The factory engine in my car was 230. Wondering what the hp gain would be with a 4bbl intake and carb. Thanks.
 
Looking for a 318 to swap in a mid 60's dodge car inorder to get the car to move under its own power. Found a 1985 fifth avenue that has a bad trans. I can buy the car for $500 but I looked online and its only 150hp. The factory engine in my car was 230. Wondering what the hp gain would be with a 4bbl intake and carb. Thanks.


No after about 1970 the government forced a standard way of reporting horsepower. The numbers before that were a bit optimistic. I would guess that the '60s was in the 180-190 range if measured the same way. Emissions in the '80s did things to drop those numbers into the 150's.
 
The "factory" HP of most 318 2 barrel engines was 150 including the 1967-1972 engines. They used to rate engine power without the air cleaners installed, no water pump, alternator, fan or power steering pump. In 1972-73, they switched to a NET horsepower rating to be more accurate.
Adding the 4 barrel to a stock 318 without the 4 barrel heads or dual exhaust will not result in much of an increase but if you are just looking to get the car running, it will work. Good luck with the car.
 
The "factory" HP of most 318 2 barrel engines was 150 including the 1967-1972 engines. They used to rate engine power without the air cleaners installed, no water pump, alternator, fan or power steering pump. In 1972-73, they switched to a NET horsepower rating to be more accurate.
Adding the 4 barrel to a stock 318 without the 4 barrel heads or dual exhaust will not result in much of an increase but if you are just looking to get the car running, it will work. Good luck with the car.

The only reason I was leaning towards a bit higher HP in the '60s was my '68 LA actually came with 9.2:1 compression over the next few years it quickly dropped back to 8:1 or so.
 
Books I have read showed 8.8 compression until the 72 model year. They started lowering the squeeze to allow for the lower octane unleaded fuel that was coming soon.
 
The engines are about the same, output wise. The 80s version has more crap on it, and more power draw from the accessories that the dyno number takes into account (AC, PS, air injection pump, etc etc). Stick a 4bbl on it, stick a hydraulic roller cam in it, and run it.
 
If your engine from the 85 is what I think it is,,It may be a 2 bbl BUT I bet it is a roller cam 318 with swirl port heart shaped heads and a compression ratio close to 9 to 1. I am running one in my D350 truck that came out of a 5th Ave. I installed a 4 bbl intake and carb. Very good 318 engine.Don't even worry about the HP "Ratings"
 
Books I have read showed 8.8 compression until the 72 model year. They started lowering the squeeze to allow for the lower octane unleaded fuel that was coming soon.

Service Manual for '69. They where creative for HP so they could have been creative for this table as well.


Compression.jpg
 
I stand corrected! I see that it was the 273 that was at 8.8 C/R. Thanks you.
 
no 273-4 in 1969

1967 (and 66 poly) 318 was 9.2:1.

Not sure when it went down but I'll bet somewhere around 1970-71).

Then the roller motors in '85-86-ish were back to 9.2:1.

There is some debate about interchange between the early LA and the roller LA pistons, and how much of that compression is in the head volume.

On an other note, I am 90% sure the LA roller rollers are the same as magnum rollers, or at least interchange.

I have a back burner project to put mag heads on a roller 318, and i'll find out for sure.
 
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