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Old 11-12-2012, 08:26 AM
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400 sbc rebuild

I recently purchased a rat rod with a sbc 400. I am looking to up the horsepower as much as possible and still maintain a reliable pump gas motor.

My budget is going to be about $2500.00- $3000.00. Some options I have looked into are boring out by .0030. Possibly a good set of aluminum heads (any recommendations would help here), it currently has a set of camel hump heads at the moment. New cam shaft (any size, type, brands, etc would help here). New pistons ( recommendations needed also). And probably a new smaller carb currently set up with a demon 850 cfm, was thinking a 750 cfm would work better (could use brand even size recommendations).

Any other suggestions or recommendations you may have would be greatly appreciated.

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Old 11-12-2012, 08:37 AM
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freshen and blue print engine,see whats inside first.that could cost north of a g note. heads and camshaft will use the rest. The 850 is fine. as far as camshaft recommendation,that depends on you and how you use the car. a roller cam will cost another g note. as far as much as possible horse power,if its a GM factory block,look for reliability first. If its a 2 bolt block and safe to bore/hone then splayed capps are in order,steel crank if you want a lot of power,,,, what rods are in this engine?
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Old 11-12-2012, 08:47 AM
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It would be rare to find an original 400 that has not been bored at least once. It could easily be past its last over bore of .060 over.

What type of car is this for? When you say rat rod. I am thinking old model t or something. Be careful 400 small block built can produce a lot of tq maybe more then your rod can handle. Fat tires skinny frame rails not always the best combo.

That being said a good cam and the humps should be able to take you to the 400 hp range along with some other upgrades. Should push a light rod like crazy. Easily more than normal sized tires will take on the street. Unless you want to spin tires at 50 mph i would stop in the 400-450 range and keep things nice and smooth. But of course you could go alot further.

I would look at Edelbrock performer RPM package. Its what most rat rods guys use. Runs smooth and not to over the top. Also they give you all the spec so getting the same stuff From some one else cheaper is always an option.
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Old 11-12-2012, 08:58 AM
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Quote:
Originally Posted by ACrat81 View Post
I recently purchased a rat rod with a sbc 400. I am looking to up the horsepower as much as possible and still maintain a reliable pump gas motor.

My budget is going to be about $2500.00- $3000.00. Some options I have looked into are boring out by .0030. Possibly a good set of aluminum heads (any recommendations would help here), it currently has a set of camel hump heads at the moment. New cam shaft (any size, type, brands, etc would help here). New pistons ( recommendations needed also). And probably a new smaller carb currently set up with a demon 850 cfm, was thinking a 750 cfm would work better (could use brand even size recommendations).

Any other suggestions or recommendations you may have would be greatly appreciated.
If this is a 400 (you've checked the numbers?), you need to know what type pistons you have. Very likely they're dished since you're running fuelie heads- which have 64cc chambers (nominal). So, before any meaningful recommendations can be made for cams, the dish volume and the piston deck clearance needs to be measured. These measurements will also dictate the head's chamber size.

If these numbers aren't known, the pistons will sometimes have a part number on the top. If they do finding the specs will be easy. Then all you'd need is the piston deck clearance, which can be easily measured using a depth mic or even w/a straight edge and feeler gauges. If not, the dish and piston deck clearance can be CC'd much as you would the combustion chamber to see what the volume is.

Another consideration before a cam can be chosen is what the converter stall rpm is now (or what you're willing to go to) and what the rear gear ratio is. Along w/how low of a ratio that you're willing to deal with- anything past 4:1 on the street- for me at least- gets tiring on the highway. The loose converter won't bother you at all after you've driven w/it for short time.

I don't know if your budget will allow for a roller cam, but if it does the job gets easier. This will depend largely on what parts you have on it now, like headers, converter stall, rear gears, intake, ignition, etc. And how strong the bottom end is: stock or aftermarket crank and rods, condition of the bores and ring seal, oil clearances, stock or aftermarket balancer, things like that.

The 850 is fine, BTW- as long as you're building a serious engine.
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