I just had a stock rebuild done to my 400 and man does it run well. The only problem... My buddy rebuilt his and he upped the compression a little, got an RV cam, and added a weiand intake and holly four barrel. That thing hauls ***!!! Im looking to wake mine up even more and I saw on the edelbrock webpage that they have a topend kit for the 351m/400. Im looking to give it some bang, while getting decent mileage(and by decent I mean at least 10mpg, 15 would be nice). Is there anyone out there that has used this kit? Is it a good idea?

 

Im definatly looking to change out that cam when I do get a carb and intake. Any suggestions?

 

if you are looking at cams i would get a comp xe256 for a towing application but if you just drive your truck mainly i would get a xe262.

as for intake, either the edelbrock or the weiand will be fine, i dont think either would be too much intake for your truck.

carbs, i traded my old holley for a used edelbrock and didn't really feel at home with it and sold it then bought a barry grant road demon. i dont think it matters what you get as long as it is reasonably sized for your application. remember, if you get a carb too big for your applicaion the vacuum signal will be too low and the appropriate amount of fuel and air will not be pulled into the intake.

 

Your buddies "RV cam" is most likely a copy of that old school Edelbrock cam. A lot of the off-the-shelf RV cams that you get from parts stores run that 204/214 - .484/.510 grind spec. It isn't a bad cam for 30 yr old grind technology BUT, the Crane 255DEH or 265DEH much better grinds as is the Comp Extreme Energy grind mentioned elswhere.

Intake wise, you can't go wrong with either Edelbrock or Weiand on these motors and there isn't enough difference to worry about.

Talking carbs can start arguments on some boards. The Road Demon/Road Demon Jr. are decent carbs as are the Holley Avenger series. Both take a little knowledge to tune properly but work well. On your motor, you could use either a 570-670 Avenger or a 625 Road Demon. I use a 850cfm Street Demon on my 400 but it's not pulling around a truck and it's built for modest road racing.

I've run lots of Carter 625/700 over the years and I've messed with a few Edelbrock 600 carbs. These are fairly straight forward and usually require very little tuning on a MILD motor. Once you start cranking up the compression and running stout cams, you've gotta breakout the strip kit and start swapping out metering rods and springs. With todays wide band EGO gauges, you can really wake up the Edelbrock/Carter carbs and get great strip performance out of them. Overall, when I've seen a mild motor running poorly with one of these carbs it is due to either vacuum leaks OR a ham-fisted owner who thought he was a carb tuning guru. All you need are the factory tuning instructions, a screw driver and a hand-held vacuum gauge.