383 or 440 (Roadrunner)

[patmckinneyracing]

I've been trying to plan out the rebuild on my 71' Roadrunner but I can't make up my mind on what build to go with. I have the choice to rebuild the 383 (big block) motor and 4 speed that are #'s matching for the car. Then there's the other side of me that wants to build a bad a** 440 motor and have a sick car. I have an additional 4 speed to go with the 440 if I decide that. It's either going with a street machine or factory resto piece, I hate being 18 lol. What do you guys think and which would you go with? If you want pics of the car let me know.

 

[dan2286]

If I were you, anything that you change should be reversible so it can be brought back to stock condition. Keep the #s matching engine and trans if you decide to change them.

 

[78mali350]

I would stick with numbers matching because some day whenever it will be sold wether you decided to or someone that gets it because your dead it will have more material value being numbers matching. that being said it's your car, our charger had a 440 and it was a blast. in the end it's up to you

 

[patmckinneyracing]

That's kinda what I'm thinking too since the whole car has only 100,017 origional miles to it. Plus its alot cheaper to restore a car back to origional because all the parts are already there, just need cleaning or rebuilding.

 

[85 Cutlass Brougham]

As cool as the 440 would be to build, it would be almost pointless to do it. It is too nice of a car to race, and too rare of a car to street race and risk the damage to it. If you want to build one up, get a Satellite and build a clone. Don't risk ruining the value of a very expensive car when it is done. It may not cost you a lot to do it, but it will be worth enough when finished that you could sell it and buy a nice, clean 318 Satellite to build and have money left to spare.

 

[patmckinneyracing]

That's just it. I don't want to sell the roadrunner but I had one helluva idea. I just figured that the roadrunner will get a really clean factory build on the motor. I'll put a nice cam and set it up so it'll get over 400hp. This will become the pedigree weekend driver and fun car. Now look at my 80' Malibu. That car is absolutely perfect for all sorts of aftermarket mods and dropping in a massive motor. So the Roadrunner will be the weekend warrior and the malibu will become the street machine. What do you guys think? good plan?

 

[85 Cutlass Brougham]

That sounds like the better choice. I would not use a factory cam in a resto anyhow, seeing how cam technology has come a long way in 40 years. You could even do some sneaky Hot Rodding while leaving the engine stock appearing on the outside. Have the exhaust manifolds Extrude Honed, get someone who knows Mopars to port the heads, raise the compression slightly, install a Pertronix electronic ignition conversion, etc. The stock carb should be plenty enough for the car at 400hp, but it should be tuned by someone who knows whatever Carter carb came on it. You could also get a modern dual plane intake manifold and grind off the name of the manufacturer, then sand blast it to mimic the casting texture, and paint it orange to match the engine. I would also use a decent 2.5 in dual exhaust kit, and a good clutch too.

 

[patmckinneyracing]

The plan is to have the heads ported and polished. The motor already has the high flowing performance manifolds from the factory but your right, I probably could hone those out to make them larger on the inside. The carter carb on the car is a carter competition series (not factory) 750cfm that is almost an exact duplicate of the factory carter carb, just need to take the name plate off. I'm gonna find a really good cam that can handle that massive mopar AC pump on the front of the motor. Luckily the 4 speed opens so many doors. As far as the intake, I might just keep the numbers matching one cause it should be able to get up and go just fine with it.

 

[85 Cutlass Brougham]

So it has a Carter AFB on it then? I had thought that Chrysler switched to the AVS or Thermo-Quad in 1971. The AVS is actually a VERY good carb. It's the one carb I like better than a Quadrajet. The Thermo-Quad however is lousy because of the warpage prone plastic main body. I kind of think that is what it came with because it was replaced.

Some Carter Nomenclature for anyone interested:

WCFB: Will Carter Four Barrel (used in 1950's applications, weighed 20lbs! Also the first 4 barrel carb used on a production car.)

AFB: Aluminum Four Barrel: Used on GM and Mopar models

AVS: Air Valve Secondary. Used only on Mopars.

Thermo-Quad: Innovative design that was fatally flawed. Used on 70's Mopars.

 

[patmckinneyracing]

Yeah thats the two and only two good things the previous owner did to this car: the Carter comp. carb and the $500 aluminum radiator he put in. As far as the Carter, it's the same thing as an Edelbrock because they bought out carter years back. I looked at the carter and my malibu's edelbrock side by side and I see no difference. As far as the thermoquad, I've heard a lot of good things about them. The main body is made of phanellic resin which not only resulted in less weight, but allowed the fuel to remain cooler before being injected into the motor. Its not a bad design but people have their own preferences. I've never really liked factory Q-jets or holleys cause they seem to be somewhat of a pain and require more maintenance. But I'm only 18 and have worked mainly with edelbrocks. In 1971, almost all chrysler cars that were four barrel had a Carter AVS design carb instead of the thermoquad. I believe thermoquads were more common in the mid to late 60's. Here's a pic of the carb the previous owner put on:

The good thing is that I think the AFB design in the photo is probably better than the AVS. All I have to do is take of the competition name plate and the AFB looks identical to the AVS.