I've got a question maybe can get answered for me. I built this engine a few years ago with a cam that just had .500 lift and proceeded to put pistons in it that put it .010 down in the hole at TDC. I then used .020 X 4.42 head gaskets that gave me a .030 quench. My CR is 10.7 and my DCR is 8.0. It runs fine, that's not the problem. But, from day one this engine will smoke a little when idling and a little when you've got the rpm's wound up (both pipes about the same). After 30K miles it's always remained about the same. The other engines I've built had cast pistons, this is the first forged piston engine I've built. When someone asks me about the smoke I always just told them it's because I'm running a .005 clearance on the piston walls. Don't get me wrong, it's not bad and I don't use a lot of oil. I just wondered if you guys thought it was the quench or piston clearance causing it to smoke. I'm running Viton valve seals so I really don't think it's coming from the top. Thanks, Jim
Don't think so. Your smoke is more likely to come from another issue as I've run forged with a lot more wall clearance and similar quench and C/R numbers. The normal FE checks here should be done.
-Cut up a old valve cover, run up the engine until warm, slap on the cut cover and watch how high the oil comes up at idle.
-some covers (no baffles) allow one to more easily stick a dowel or a chunk of tubing into the hole. Mark the end with the engine off, fire it up and check to see just how high the oil rises.
-fixes include restricting the oil supply by adding a restrictor under the long bolted rocker arm stand that supplies oil to the top end.
-check too that at the rear of each head no excess gasket material or sealer impedes the flow of oil draining back to the valley.
-if using a PCV valve, check it by removing it temporarily to see if the smoke subsides...although this could take awhile until the excess oil is sucked up. I'd use one but perhaps the spring it weak.
-last try a leakdown test. A compression check won't tell much here but a leakdown tester may show poorly seated rings.
Per ScotiaFE's past post:
The FE rockers are feed oil through a passage from the block up through the heads and the to the rockers.
A common practice is to restrict the oil passage.
With iron heads a Holley jet is stuck in the hole on the head below the rocker pedestal. A #70 jet is good.
On the Ed's the hole is larger and you have to make a restrictor. A 5/16" steel bar with a hole .070" drill in the centre and about 3/4" long
will do.
The rocker tins. They fit under the rocker pedestals and help direct the oil off the head and back into the valley.
There are two types. Early with the fingers and late with the square drop off. It is much easier to make the late style fit after market rockers than the early style. Although you can have go with the early ones.
