Originally Posted by Mouser
I currently have a 4-Bolt Main (grey caps) 350 chevy bored .040" over. Cast steel crank and a set of "powder" rods. The crank and rods were given to me by a friend and I had the necessary machine work done on them. I would like to replace the tired and worn out 305 in my 85' Chevy 4x4.
I'm at the point of considering cylinder heads, likely cast iron but possibly aluminum and cam selection, possibly even a roller.
Truck ways about 4000 lbs according to factory tag.
I would love to build a fairly high hp engine with some streetability. I was thinking around 400-450 hp would be doable, but being a 4x4 I don't want it to be a dog on the bottem rpm.
Any thoughts or suggestions would be appreciated.
A BBC is a natural for a truck. A BBC can make a LOT of torque- sometimes more than the rest of the driveline can deal with. Depending on what you're set up with now, this could mean some changes are needed for reliability.
If you want to stay w/a SBC, you'll want to build it as large as practical. So if you're starting out w/a 350, the next step upward is to use a 3-3/4" stroke crank to make a 383 stroker.
There are a bazillion 383
builds here and elsewhere, so no real point in going into it too
much more until you've made a decision on what direction you'll take.
A few things that help boost the bottom end regardless of the engine size:
• high velocity ports, which usually means a smaller port volume (170cc-180cc for a 350 SBC, 190cc-200cc for a 383; if using a 454 BBC even peanut port
heads and a mild cam can easily make 450 hp/550 tq). For a sbc, aftermarket heads are preferred but Vortec
production heads can be used if the compression ratio is kept in check. I don't personally care for swirl port
sbc heads, but they can make decent torque
• dual plane intake
• Q-jet carb, or a carb sized on the smaller side
• ignition timing curve set up correctly for the application
• an earlier intake closing point
• tighter lobe separation angle
• compression adds torque, but too much compression can cause detonation so do not get carried away- match the CR to the gasoline you want to use and then spec the cam around that CR and vehicle needs.
• long tube headers don't necessarily help the basement power but are a necessity to make good power overall. Keep the primaries at 1-5/8", using a free-flowing exhaust system. I use an H pipe connecting both sides, you can research this for yourself
• use enough final drive ratio and converter stall (if AT) to match the cam and overall combo