Author Topic: 400 Mild Build  (Read 2299 times)

Offline Wac93

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400 Mild Build
« on: March 04, 2014, 10:15:24 PM »
I just purchased a 1976 Custom Deluxe chevy with a 400 small block. I have no experience in the motor department, and was wondering if I could get some advice from people with experience in these 1970-1980 motors. I am looking for more low end torque/power for pulling trailers and truck pulling at the local fairs in the stock class. I just want a mild upgrade and was hoping I could get some proven upgrades and results from someone with the same motor. Thanks in advance!

Offline rich weyand

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Re: 400 Mild Build
« Reply #1 on: March 04, 2014, 11:05:48 PM »
Look into re-camming it.  Aim for the 450 lbft range for torque.  That's pretty easy with a 400, but much more than stock.
Rich

"Working Girl": 1978 K-10 RCSB 350/TH350/NP203 +2/+3 Tuff Country lift

Offline 87V20Kansan

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Re: 400 Mild Build
« Reply #2 on: March 04, 2014, 11:55:26 PM »
Cylinder heads! To start with the stock piston on the 400 has a 22cc dish that yields low compression numbers. Remember these are smog era engines. The stock heads with 72cc chambers offer terrible flow numbers as well. A set of 64cc combustion chamber, 200cc intake runner Dart iron eagle heads, a decent cam and intake like the Edelbrock performer RPM stuff, a set of headers and a 650 cfm carb will get you close to 400 HP and well north of 450 ft/lbs of torque all day long. If you go that route make sure to drill the new heads for the 400 SBC steam holes so you don't run into overheating issues.
« Last Edit: March 04, 2014, 11:57:28 PM by 87V20Kansan »
Cecil: 1987 V20, TBI 350, TH400, 4:10's, 7" lift, 37" H1 beadlocked runflats. Cummins swap someday.

Offline Wac93

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Re: 400 Mild Build
« Reply #3 on: March 05, 2014, 07:36:34 AM »
Thanks for the replies. At this point I don't have the money for those new heads. Could I just stick with and intake, carb, headers, and a new distributer with a matching coil? If I were to go this route and wait on the heads, would my intake manifold like up or would I need a new intake for the heads?

Also, what cam should I put in it? Would a Comp 270 hydraulic flat-tappet cam be feasible? I'm open to sugestions

Thank you

Offline Captkaos

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Re: 400 Mild Build
« Reply #4 on: March 05, 2014, 01:39:39 PM »
I would wait on the cam until you have the heads you wanted on it.  The intake won't be different unless you get Vortec heads.

Offline Wac93

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Re: 400 Mild Build
« Reply #5 on: March 05, 2014, 11:08:10 PM »
A friend of mine has the stock intake and 4 barrel carb off a blown up 400, so I will probably just use that for now. Is there anything else that I could do to freshen it up?

Offline rich weyand

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Re: 400 Mild Build
« Reply #6 on: March 06, 2014, 12:50:14 AM »
How many miles are on it?
Rich

"Working Girl": 1978 K-10 RCSB 350/TH350/NP203 +2/+3 Tuff Country lift

Offline Wac93

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Re: 400 Mild Build
« Reply #7 on: March 06, 2014, 08:43:52 AM »
Not for sure. It's at home and I'm in Wisconsin at college. I think it has around 150,00 though

Offline rich weyand

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Re: 400 Mild Build
« Reply #8 on: March 06, 2014, 09:16:16 AM »
You would get more bang for the buck putting a new crate engine into it.  It's not worth putting a lot of money into heads, etc., with that kind of mileage on the engine.  It's near the end of its designed service life.

If you wanted to fresh it up, and get it back to original performance, you could: drop the pan and replace the main and rod bearings; pull the pistons, knurl the skirts, measure the bores, and install .010-over rings; grind the valves and the seats to clean them up; replace the lifters and install a torquier modern-grind cam; install valve seals.  I did that to an engine with 100,000 miles on it and drove it for another 150,000 miles.
Rich

"Working Girl": 1978 K-10 RCSB 350/TH350/NP203 +2/+3 Tuff Country lift