Originally Posted by
fordguy67
Hi
i have a 1968 el camino and i recently discovered that i have a 400 small block produced between the years between 1970 and 1980. I looked up the engine and it said that the high horsepower is 260. What can i do to get the most horsepower out of this engine and how much can i get. what would the dimensions of the cylinder be, if it were just a stock engine?
thanks
I wouldnt consider myself an expert on GM motors but I have built a few and smoked a few Mustangs with em.
I got close to 450 HP out of many of normally aspirated small blocks easliy. Its still a small block because of the stroke, funny because the 396 is considered a big block. At any rate there are a number of HP/torque enhancements that can be made. After awhile though you will probably end up saying " damn for this price I could get a big block"
The easiest enhancements that will yeild you some big gains come one you probably already know, exaust mods, i.e headers free flowing dual exaust. Be cognizant of smog laws. Failure to meet EPA Regs is what killed produciton of the 400.
Cylinder head mods will yeild the biggest bang for the buck. But good aluminum heads are $$$ and the 400 uses siamesed bores and is prone to overheating when bored too much. Trying to keep the post short. A few quick factoids.
Larger than 4" for bore size but smaller stroke. Google it I forgot what the 400s bore size is sorry.
* Due to the siamesing of the cylinder bores in the casting - there was no space between adjacent cylinder liners - this block was rather rigid and not prone to the cylinder bore flexing of the other displacements.
* This block used a much larger 2.65 inch main bearing assuring that crankshafts from all other blocks would not fit without special oversize bearings.
* This is the only small-block that used a 5.56 inch long connecting rod compared to the 5.7 inch connecting rod in all other displacements.
* The 400 came with 4 bolt main bearings in 1971 and 1972 only.
