Tuning up an old 400

[Ancient_4X4]

I really need to breathe some new life into my trucks 400ci. I want more power. Or maybe more like 'the power back' My truck is a 1977. I have an edelbrocke 600 or is it 650 cfm carb. A friend of mine seems to think all I need to do is install some bigger cams. The engine is basically stock except for the carb and intake. My mechanic thinks my engine is starting to get tired as it's been blowing oil out of the breather for a few years now. 91,000 miles on the engine. What should I do?

 

[the professor]

I have had about 7 400's and built many for others
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The ABSOLUTE WORST part, and RESTRICTOR of HP on a 400 is the INTAKE MANIFOLD
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A cam, or any other change, will do NOTHING if you don't change the manifold...
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It is designed to run under 4200 rpm with a 350, and absolute dies on a 400 after about 3800rpm
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An Edlebrock Performer, Performer EGR, Manifold not a Performer RPM..no good on a truck..to much loss of torque
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The STOCK Q'jet..your Q'jet is a 795CFM, anything else would be a step down..Unless you want to go with an 850 Q'jet (non-emission), Edelbrock or factory Buick/Pontiac 455cid, around 1968-70 very rare
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Any "long tube" headers..Hedman, Hooker (non-emissions)..big money is not needed here for a street machine..larger tube diameters will give more hp, smaller more torque without too much loss at high rpm and are a better idea
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Full 2.5" exhaust w/duals and prefer an X over pipe, just behind the collectors...
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Crane makes several cams that are very, very good..
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The one for Computer Controlled Emissions...

119815 for a heavy truck or 4x4
Power Max 2015...Amazing torque with a 400 equipped as above, and will pull strong to 5500+ rpm

http://www.cranecams.com/master/apps/chevy5.htm#5.%20CompuCam

A 1" 4 hole plastic spacer under the carb will help it even more, and cut a 4" slot in the plenum devider in the manifold if you want power to 6500rpm

DON't go too hi in rpm, 400sb rods are not the strongest..this is not a BB...Keep it under 5500rpm

These things run BEST on 87oct...

I built on for my '68 C10 SWB..Muncie 4spe..3.73 posi...it would absolutely fry the 10" street tires through 4 th gear
/forums/images/graemlins/truck.gif

 

[Z3PR]

[ QUOTE ]
My mechanic thinks my
engine is starting to get tired as it's been blowing oil out of the
breather for a few years now.

[/ QUOTE ] I would say it's time for a rebuild when it's doing that. Now why just rebuild it when you can build it up ??? I'd think of Stroking it. (I've been known to stroke it) I've seen 415, and even 427 stroker kits for the 400 cid small block Chevy motor. Biggest favor to them in my mind is they replace the weak factory conncting rods !!!!! More torque and HP is nice too. For a intake manifold, I like the Wieand Stealth. Headers, I really like the Doug Thorley TRI-Y headers.

 

[bryguy00b]

/forums/images/graemlins/rotfl.gif /forums/images/graemlins/rotfl.gif...."ive been known to stroke it"

 

[Ancient_4X4]

Thanks for the link and the suggestions guys. The death of a 400 is so sad /forums/images/graemlins/frown.gif /forums/images/graemlins/frown.gif /forums/images/graemlins/frown.gif