Mopar Action On-line – Tech Questions
Scott Lorbiecki, Wausau, WI, 1970 Plymouth Cuda 340
I was reading the article: Thar she blows. I have a ’70 340stroked out to a 416. Should I have concerns about blowing that block up?Will the stock main caps with ARP bolts be ok?
Scott, my crystal ball is out for a tune-up! So you’ll have to settle for mybest guess. If the engine is very mildly built, and never sees high RPM(over, say, 6,500) it should be OK. Otherwise, it’s well known that stocksmallblocks split open the cylinder walls at about 550 HP. And the longstroke sure increases the lateral loads on the main caps, whih you can fix(billet, 4-bolt, etc), and the main webbing, which you cannot fix.
It never fails to amaze me how much money people will spend on an engine’sinternals, heads, etc., while ignoring the key component: the block.Sometimes people will even bore the block way beyond recommendations, in themisguided belief that the small added displacement will buy them some HP. Itwon’t – it will just make the block that much closer to a grenade with thepin pulled, and the flexi cylinder walls will REDUCE HP. If the block fails,it usually takes out all your other high-dollar parts: crank, rods, pistons,at least one head, etc. This can make even a grown man cry.