383 or 400....Which way to go?

Technical Question and Answer - On topic to 71-74 Plymouth B-bodies only.

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mopardog
Satellite Sebring Plus (RP)
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My Cars: 1972 Road Runner 400 (project)
Location: River Valley, Arkansas

383 or 400....Which way to go?

Post by mopardog » Wed Oct 08, 2014 3:17 pm

Here is my question\dilemma and I really need some advice. I have been tossing back and forth on the drivetrain for my bird (72 originally a 400 car). The original drivetrain has been long since gone, I currently have a 383 that I could build and drop in...but....I have found a '77 400 motor that I could rebuild and drop in too. Either way I have a rebuilt set of 452 cast heads that will sit on top.

What I am wondering is what is the big difference between the two? I have been told that a 400 basically has 440 pistons and a 383 stroke? Is this right? If I go back with a 400 would it help the value of the car which would make it basically numbers correct (correct cubic inch motor) but not matching. This has been the biggest conflict I have had since I bought the car over a year ago. I would really appreciate any insight I could get here guys and gals.
Long live "Ma Mopar"!!! 1972 Road Runner F7 Green, E68, build Feb 9, 1972, Deluxe trim. She's a little rough but she's mine all mine!!!!!

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road chicken
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Re: 383 or 400....Which way to go?

Post by road chicken » Thu Oct 09, 2014 12:04 pm

Go with the 400. It is virtually identical to the 383 but with a bigger bore, ( even larger than the 440's bore). That bigger bore allows you to put in the bigger valves in the head and have better flow because the valves are not as tight to the bore as a 383. Now the 77 will have a low compression 8.2:1. Not a great performance base but that ( and a few other things) can be remedied during the rebuild. Keep the 383 block around too. Never know when that will come in handy. When you rebuild, then have the block checked for core-shift first, ( the centering of the camshaft bore is a good indicator but have a shop do the cylinders too). Three places to work on are opening up the intake side of the oil pump to Hemi specs ( as laid out in the MPP Engine book) and use ARP waveloc rod bolt and ARP studs for the main caps. Those along with a good lower end build, will make the bottom end virtually bullet proof. The 77 will also have a cast crank. No worries if your keeping the HP below 500. Just make sure to use the proper balancer and converter/ flywheel.
4th generation B bodys- there is no substitute.
68 383, Street Demon 750, RPM top end,484/284/108 poo poo cam "-5 spd 4:10 SG, 4whl disk, Helwig Anti-Sway, Poly bushings,Firm Feel Box, HD Linkage, 1" t-bars, 7 leafs Springs

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mopardog
Satellite Sebring Plus (RP)
Posts: 81
Joined: Sun Jun 02, 2013 10:50 pm
My Cars: 1972 Road Runner 400 (project)
Location: River Valley, Arkansas

Re: 383 or 400....Which way to go?

Post by mopardog » Fri Oct 10, 2014 9:06 pm

thanks Road Chicken. I picked up the 400 today and met a guy (David) there from Kansas City who was picking up a 273 for his '67 barracuda project. Well, long story short. I now have an extra set of 452 heads that came with the 400 which is in excellent shape and after talking with David, I now have a OEM dual snorkel breather for $100. I also picked up a '68 383 roadrunner breather tin original OEM in perfect condition....will make a great wall hanger for the den. On the way up this morning, I found a nice project that I am gonna go back and check on. A '73 or '74 Road Runner 340 car minus engine and trans. Gonna see if I can score it. I will get pics uploaded here soon. All in all, an awesome MOPAR day!!
Long live "Ma Mopar"!!! 1972 Road Runner F7 Green, E68, build Feb 9, 1972, Deluxe trim. She's a little rough but she's mine all mine!!!!!

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