What can you do to a 73 400cid to pep it up? kinda Long

[HDCharger]

My brother in law has always been a Ford guy but I got him interested in Mopars with my 69 Charger and 76 PowerWagon.  Anyway, he fins a 73 Charger SE Brougham that has been sitting for years.  A lot of surface rust, trunk looks like new and no frame rust and very, very little floor pan rust.  The Unbelievable part of this story is we drag her to my house and the next day we change the oil, put some plugs in it and I notice the reluctor on the distributor is chipped pretty bad so I drop in a distributor from an electronic Ignition Kit that I had and some plug wires.  Fuel pump wasn't working but I had a electric one lying around so I wired it in.  The motor turned over 3 times and fired right up.  Amazing to say the least, and now he is a true Mopar believer.  Car shows 81,000 mile and i believe it to be original but can't confirm it.  We drove it around for a while and the trans shifts good, replaced the brake hoses, brakes are good.  Only problem is a freeze plug in the side of one of the heads is spitting anti-freeze.  Anyway, what can you do to a 400 low compression motor to get the most bang for the buck.

1. Please don't mention stroke it.  I did that but he doesn't have the $ at the moment.
2.  I'm thinking headers, Intake/4bbl carb (2bbl now) and maybe a purple shaft cam.
3.  Will milling the heads .030 get the compression up enough to make a difference?
4.  915 or 516 heads?

He just wants a stout runner nothing extreme.  What can we do?  Thanks, Dave

[moparguy01]

400's were plagued with low compression and bad breathing. If you want to make that stock 400 run decent, get a set of 915 heads, find a good aftermarket 4 barrel intake. I'm not sure what a good 400 intake is since i have 440s, but others on the board will be able to help with that. then toss in a lumpy cam, maybe a .484 lift purple cam, a set of cheapo headers and drive it. it'll make a night and day difference.

Milling the heads will get the compression up, but if you mill too far you need to have the intake surface machined. then no stock intake will bolt up again and if he ever sells it the next guy will have problems until he figures that out.

[firefighter3931]

The 400's are very low compression engines....usually in the high 7's to low 8's. A closed chamber head will help but the engine will run descent with the right cam and a few bolt ons. Stay away from the MP cams....too much duration for a smog motor.....it will be a dog. 

Headers, a factory 70-71 383 4bbl intake manifold and holley 750 vacuum secondary carb would be a good start. Here's the cam i would use with that engine if you were gonna keep the factory open chamber heads....which i would. 

I would just use the cam and install fresh valve springs and a new timing chain then button it back up and drive it. 


http://holley.com/60300.asp




Ron

[HDCharger]

Ron, Would you throw in another set of lifters when you installed that cam or run it like it is?

[mikepmcs]

Yes, new cam= new lifters too.

v/r
Mike

[firefighter3931]

Yes, new cam= new lifters too.

v/r
Mike

Allways new lifters with a new cam....i should have mentioned that. 



Ron

[The Ghoul]

Yes, new cam= new lifters too.

v/r
Mike

Allways new lifters with a new cam....i should have mentioned that. 



Ron

I smell roller

[Nacho-RT74]

now you touch this... for a while I get the money and find a 440 crank to make the 451 stroke I'm thinking on mill down the 452 heads and install metal head gaskets. In fact I will keep same gaskets and milled heads on the future 451... how much is able to drive the hidraulic lifters the stock pushrods lenght if I get shorten the heads height ?

[firefighter3931]

Natcho, if you take off more than .040 off the heads you will probably need a custom length pushrod. This is assuming you're keeping the stock thickness headgasket of course. 


Ron

[71charger_fan]

I've got a '77 400 in mine. Bored .030 over, stock replacement cast pistons, windage tray, the PAW equivalent of the 383 Magnum cam, Thermoquad on a Performer manifold, Hedman Hedders, and the MP electronic ignition. The car runs in the mid-14s with a 3.23 rear gear and 275/60-15s. That's pretty much what a '71 R/T 440-4V ran in magazine road tests back in '71. If I had it to do over, I would have put more compression in it, but, at the time, I was building a cruiser.

[popster9]

ya i have the exact same motor but we had it rebuilt and it was boared 2 over i to have had it sitting for years 20 to be exact and now it is all done

[RD]

i took a stock 76 400 shortblock, put on 452 heads, a DP4B edelbrock intake, a 600 cfm eddy carb and a 284/484 MP cam and put it in my ramcharger (4100lbs), and I ate ricers up all day long.  Had a 3.21SG 9 1/4 so the gears weren't that steep.  Granted that cam is not necessarily the greatest for that combo, but that 400 held its own quite well.  Boy that songun loved to rev!!!!!  It will be quick enough.

is it a scientifically or race proven combo?  NOPE!!! but its better than a 400 2bbl hehehehehe

[Chryco Psycho]

I would use a 516 /915 casting , A Engle cam would be Perfect here , something like the K 54 with enough lift & tight duration to build cylinder pressure