75Formula350
New member
- Joined
- Mar 25, 2011
- Messages
- 2
- Reaction score
- 0
- Points
- 0
My son and I built our first Pontiac 350. It lasted 3 months and now we are working on our 1st Pontiac 350 rebuild. I just want to make sure I don't make the same mistakes again. Two things happend. 1) two lifters flatten out chewing half inch of metal of each, and 2) the thrust bearing and thrust plate on the crank was torn up. Crank must be replaced.
I have read that I didn't break the cam in correctly, which I now know to be true. We used original rocker arm bolts torqued down to 20 ft lbs. We didn't add Zinc to the oil, and we didn't get the car start easily. We almost burned up a starter trying to get it to start. (Had the distributer pointing at the number one piston instead of at the driver.) Should have actually looked at the cap.
At first, i thought the trash from the lifters caused the thrust bearing to overheat. However, the machine shop showed me a spot at the end of the crank that indicates something was putting to much forward thrust on the crank shaft. When you look where the pilot bearing was supposed to go, you could see a small circular spot where it looked like something was pushing against the crank. However, i don't know if it was already there from when the crank was originally recoditioned.
I do know we had a hard time finding a pilot bearing to fit into the crankshaft. We finally found something at the local parts store that would fit in the hole and on the transmission. The store said it was a automatic to manual transmission adapter bearing. We had a hell of a time getting the transmission to line up correctly and slide that last inch into position.
Are there differences in manual vs automatic cranks in these pontiac engines. Also, I don't know which issue is the chicken and which is the egg, or are the independent. The machine shop says they are independent, but other mechanics I trust say not so fast. They think clogged oil passages are to blame.
I didn't know to check thrust bearing clearances. We did check rods and main cap bearings. I do have Jim Hand's book, "Building Performance Pontiac Engines", but a lot is over my head still. I don't remember it talking about thrust bearing clearances, but I will read it again.
I know I am not being very specific, but I am not sure what I don't know.
Thanks for listening. It is good to just vent regardless.
Block is still at the machine shop. Additional information. I don't know if the crank on the first build was balanced or not. The original machine shop was someone recommended to help us save money which is located several hours away. Using a local shop this time.
Bern.
I have read that I didn't break the cam in correctly, which I now know to be true. We used original rocker arm bolts torqued down to 20 ft lbs. We didn't add Zinc to the oil, and we didn't get the car start easily. We almost burned up a starter trying to get it to start. (Had the distributer pointing at the number one piston instead of at the driver.) Should have actually looked at the cap.
At first, i thought the trash from the lifters caused the thrust bearing to overheat. However, the machine shop showed me a spot at the end of the crank that indicates something was putting to much forward thrust on the crank shaft. When you look where the pilot bearing was supposed to go, you could see a small circular spot where it looked like something was pushing against the crank. However, i don't know if it was already there from when the crank was originally recoditioned.
I do know we had a hard time finding a pilot bearing to fit into the crankshaft. We finally found something at the local parts store that would fit in the hole and on the transmission. The store said it was a automatic to manual transmission adapter bearing. We had a hell of a time getting the transmission to line up correctly and slide that last inch into position.
Are there differences in manual vs automatic cranks in these pontiac engines. Also, I don't know which issue is the chicken and which is the egg, or are the independent. The machine shop says they are independent, but other mechanics I trust say not so fast. They think clogged oil passages are to blame.
I didn't know to check thrust bearing clearances. We did check rods and main cap bearings. I do have Jim Hand's book, "Building Performance Pontiac Engines", but a lot is over my head still. I don't remember it talking about thrust bearing clearances, but I will read it again.
I know I am not being very specific, but I am not sure what I don't know.
Thanks for listening. It is good to just vent regardless.
Block is still at the machine shop. Additional information. I don't know if the crank on the first build was balanced or not. The original machine shop was someone recommended to help us save money which is located several hours away. Using a local shop this time.
Bern.
Last edited:
