OK here is the low down on this engine. My cousen was putting together a VERY low budget 383. Did not know at the time when he brought us the parts but it was a circle dirt track (claimer series kit) Anyway on the engines maiden trip down the road It grenaded. Did'nt even get 1/2 mile He tacked it out in first and half way through second boom. two things I think caused the cheap thing to blow. 12 to 1 compression on pump gas and no restriction in the thermostat. ( HOT ) detionation. #5 #8 pistons gone. Now the weird part. The entire left bank had each cylender wall groved on the back side by what had to be the wrist pins. The right bank all marked the same on the front. When the engine was completly down all the wrist pins (with the exception of 5 & 8. where still centered. What happened in this thing to possably cause that? Weird.

 

Too many questions to answer effectively. First guess is over reving. Was the engine broke in correctly and oil changed before the "maiden" voyage? Was the blocked scrubbed clean with soap and water before it was assembled? Was the engine primed with oil 2 times before starting? Once before the valves where set and the second before it was started. Did you check the bearing clearances before assembling the bottom end? What was the ring end gap? Too many things could have done you in to tell. I assume you used pressed in rods in stead of full floating. Where the wrist pin journals damaged when the pins where pushed in? Don't have enough time to ask all the questions but you get the point.

 

Yes everything was assembled and checked properly. I agree with over reveing and also am pretty sure it had to have detonation and too much heat. He would not put in a thermastat or flow restrictor like I ask #1,and #2 he was running 12 to 12 1/2 to 1 compression on pump gas. What I do not understand is how the Wrist pins groved every cylender wall like I described. I would if the wrist pins had all moved in the rods but when checked on the pistons that were left they were centered just like they all should be. Engine builders in the area thinks its really odd. It is groves from the wrist pins though, about 30 thousands in every cylender wall two groves parallel. How did every thing go back where it belonged and no bent or broken rods.

 

Maybe they were floating pins and no one put the keepers in.

 

shoebox,

That was my first thought.
I love the line "on the engines maiden trip down the road, He tacked it out in first".
Dah, I wonder what could have gone wrong???

 

12.5:1 on pump gas = NO NO

 

Yes we all know why it blew. Duhhhhhh! and yes 12.5 to 1 on pump, I tried to tell him.

THE QUESTION IS( HOW DID THE WRIST PINS MARK THE CYLANDER WALLS.) And no they were not floating pins. Duh.
I know how to build an engine.

 

Did you put this one together?

 

Obviously if you knew how to assemble an engine you would not have had this problem and you would have seen it from a mile away. But you said HE assembled this engine. If you didn't want us to ask you questions you should not have posed the question in first place. Go back to the drawing board and see what else you can draw. Maybe a Ford.

 

I assembled it but with the kit he bought. I tried to tell him but he would not listen. I told him that it was going to make way to much HP for the cheap parts he bought. I know why it blew but I have never seen cylender walls marked like this. That is what I was wondering. How did the wrist pins mark the walls and then magically go back to where they belong in all eight cylenders. I forgot to mention that the rods and pistons were assembled by the machine shop when the rotating assembly was balanced. Like I said we know how it blew. Just never saw marks like this.