Q: I’m currently running a Chevy 350 that I’ve assembled myself using a 4-bolt main block bored over .040″, a cast-iron crank, forged pistons and rods, moly rings, World Products angle-plug 64cc cylinder heads, and a bunch of other goodies.
I’ve put about 6,500 miles on it, and it starts right up, runs great, and makes plenty of power.
The problem is that it uses about a quart of 20W50 every 100 miles!
The engine doesn’t appear to have any leaks, and I don’t see any smoke coming from the tailpipe. However, I’ve noticed that the oil pressure reads 80 psi at road speed and only 40 psi at idle, and that the spark plugs all show a dark line about 3/8-inch wide along the insulator.
Can you help me figure out what’s going on?
A: Sounds like a great setup! Let’s see if we can figure out where that oil is escaping.
If your 350 is running as well as you say, then the chances are good that your rings are fine, but it’s still worth a look.
Start by checking each cylinder for leakage.
A bad ring will yield decreased compression in that cylinder, and you’ll be able to hear the compressed air from the tester escaping into the crankcase. If the rings turn out to be bad, replace them with a new set of moly rings.
Your cylinder heads could also be the culprit.
On most aftermarket heads, the rocker arm studs thread into the intake runners, making it possible for oil to get sucked down into the threads. If this turns out to be the case, that could be where some of that oil is headed.
To solve that, simply remove each rocker arm stud and apply Teflon® tape to threads before reinstalling them.
This should keep your oil from taking any unwanted detours.