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Discussion Starter #1
Well, the top end on my 400m is starting to get pretty noisy,so I've decidedd to have the whole thing rebuilt. Gonna go with a mild rv cam, and higher compression for a little more power. My question is, do I need to go with an after market manifold and 4 barrel carb afterward? I already get loisy gas mileage and was thinking of sticking with the stock manifold and carb. Do you think this will hurt the power gains I might get with the new cam and higher compression? Anybody done this? Opinions PLEASE!!!

It's a daily driver and used for towing, camping, fishing in the summer.:thumbup
 

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Gas milage is gunna be shitty regardless. My motor is old, tired, and getting worse and worse milage. It has tons of power and revs high and keeps outstandingly high oil pressure, especially for a 20 year old rebuild. High rise and carb is the way to go. Go for an edelbrock carb, I switched from holley to edelbrock and the gains were night and day. Check out Tmeyerinc.com and click purchase parts, 400. They have almost everything you will need. For all else I would look at Summit Racing. They go into great detail in describing what is included in all packages, parts, etc as well as price.

How intense of a rebuild are you doing? If you want high CR go with some flat top pistons (custom order tmeyerinc), 302 2V Aussie heads (about a grand a piece.. order from tmeyerinc - outstanding CR) Comp Cams 265DEH K-kit, Scorpion Rocker arms (tmeyerinc), and (based on your rotating assembly condition) refurbished rods & crank. You also can purchase a 434 stroker kit through tmeyerinc and any questions you have he is able to answer, but I wouldnt bug him because he is a cool guy and I'm sure he doesnt like answering emails all day;) PM me if you want a look at my parts list for my 400.

I've been asking a lot of the questions you have posed. Kind of built a parts lis with tons of help from these guys.
 

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kid78 threw a bunch of the advice you were looking for your way..so I will only address the mileage issue. If anything ..it will increase slightly! As long as you keep your foot out of it, the right mods INCLUDING the 4V intake and properly sized carb to go with, can increase the overall efficiency of the engine somewhat..which is some of the reason why you will be making more power. These engines stock are 'tuned for emissions' not peak combustion efficiency.

And..as I have said so many times..put a 514 in it..or a 250 six..no matter..if it takes 100 HP to roll 60 mph..the fuel consumption is about same for both. Specific Fuel Consumption (SFC: amount of gas burned for each HP produced) is practically the same for all 4-stroke gasoline engines. It's what you do with the 'extry' ponies, if they are there at your foot to be used, that can affect your mileage most.

IF you are concerned about mileage, make sure that the components you select are matched to the RPM and driving style you need.
 

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I just had mine rebuilt from a 351m to 400 using comp cam 255 and have a edelbrock intake with stock 2v carb single 3" exhaust on 33" c6 and it runs great. Since I just drove it today for the first time since rebuild I dont know what kind of miles it gets yet.

 

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Discussion Starter #5
I wasn't overly concerned with the mileage(just didn't want to get a lot worse.) I was mostly concerned with whether the motor would run well with the stock manifold and carb after I put in the new cam and higher compression pistons. I'm not looking for huge gains, just a little more power for offroad and towing. I'm not sure I could keep my foot out of it if I put a 4 barrell on there!!!
 
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