Quote:
Originally Posted by Jay S
Was the engine in question using oil? I would leave the short block alone if it is ok.
You said:" I reverse hung the pistons to reduce the force on the piston skirt on the thrust side. Especially on cast pistons in performance builds".
Mike wants to know: With my original Pistons, could this be the reason for the notch installed toward the rear?
I have honed out a ton of 10K mile engines that were using oil, that had the correct piston orientation, honed them, with new rings, and then the oil consumption stopped and ran for years. Sometimes the rings do not brake in correct or bore are not straight after engines are bore out.
I have hung Pontiac pistons on backward, and done other brands also, I never remember one using oil? Maybe I am just lucky, but I have done a lot more than one engine with the pistons reversed, several 455 Pontiacs too.. I reverse hung the pistons to reduce the force on the piston skirt on the thrust side. Especially on cast pistons in performance builds. These days, with modern pistons, there is no offset most of the time, I don’t even think of it.
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I bought this second-hand project with plenty of miles, it was not running when it was installed in the 1979 Pontiac TA. We manufactured a custom wiring harness for under the hood off the schematics in the book ourselves. Since I got this Engine running, I have only less that 10 k miles on it over the last 10 years. It runs strong and I recently discovered a noise in it. I still have not found the reason for that noise. The Engine never smoked and is clean inside, we installed new Valve guide seals both on the Exhaust and umbrella seals on the Intake side. We suspect reverb in the exhaust Manifold could be the culprit, since there were dime size holes in the crossover block off plugs that we installed during my ownership. We believe that we caused this by running this engine in the tent cover outside were it lives, when we inserted 4" dryer type hose over the 2-1/2 exhaust pipe with metal tape and ran a 10' length outside the tent so we would not smell fumes while we ran the car. We think we blew the dime size holes in the crossover plugs @ that time. This is when the change in Motor sound started. The car has been off the road for 2 years and we rebuilt the Trans. during that time. Now that we are on the road testing and tuning the Trans. and getting the bugs out of the rebuild, the Trans is great. For all I know the noise is gone once I install the new crossover block off plugs that keep the heat from under the center carb. on my Tri-powers. We found no metal in the crank area; we opened the oil filter and found no metal there either. We pulled the Heads and they need Exhaust seats.
What I need to know is if the noise is gone with the work that I have already done, how would I precede here? Do I just take my chances and assume that the reverb was the noise and just live with the Piston being backward and enjoy the extra HP? Put the degree wheel on the Engine and send the Heads out and put it back together? This is what I was just going to do. I think there are miles left on the bottom end yet that I would like to milk out for another 50 k miles? I think the rings are good for now too. The Heads seem to be the very necessary part at this time for them to be repaired. The Piston walls have .005 - .010" clearance between the Piston and cylinder wall, is that good? The Cylinder walls are not scratched and last time I measured the CR with and without oil it was fine. The long-term plan is to use this engine up, rebuild it and sell it to someone that needs a stock 1967 YK code 428ci HO engine with the Tri-power option and use that money to purchase a modern motor for this Vehicle.