Originally Posted by ACrat81
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