# 67 GTO Engine problem



## 400HO (Sep 16, 2010)

Wondering if any of you old timers ever had this problem. I picked up a 67 GTO with bad 400 engine. Had a knock. Sounded like a connecting rod bearing. I pulled the motor ripped it down and sure enough #2 had a spun rod bearing. Sent the crank and connecting rod to be ground. The other rods looked good. Went through the entire motor. Ground valves, lapped, new gaskets, etc. Got the crack back w/rod and assembled the engine, new bearings, pump, the whole 9 yards. Car went together no problems. Started it up ran great, for about 10 miles. Started knocking again. Oil pressure was good, never overheated. So I pulled it out again. ripped it down and 2 different rods had spun. So I sent the entire engine to have the crank ground again and all the rods to be sized. Reassemble the engine again replacing everything again. The car went together perfectly. Drove for about 100 miles now it is knocking again. Not real happy. Now I think the machine shop may have done something wrong. I will need to rip it out again. Any thoughts would be appreciated. By the way I checked the cam bearings and they were good, was not losing oil pressure. All the oil squirter's on the connecting rod caps were facing in the right direction.


----------



## Rukee (Feb 8, 2007)

Did you platigage it when you put it together?? And did you use assembly lube on eht bearings??


----------



## Eric Animal (Oct 28, 2007)

Plastigage......someone is doing something wrong. Bad rods or crank isn't straight.


----------



## 400HO (Sep 16, 2010)

No plastigage. I was assured by the machine shop I would have no problem with it again. I guess I should have. however I think something is out of line.


----------



## jetstang (Nov 5, 2008)

I feel for you, so sorry.
Is there possibly an oil restrictor missing? Oil passage clogged on the way to the crank? Where does it pick up oil pressure for the gauge, before or after the crank? How hard was it to spin the motor over on the engine stand during/after assembly? Did you put oil on the backside of the bearing caps? I built my BBC and trusted the machine shop was right, but they were and have had no problems.


----------



## geeteeohguy (Feb 2, 2008)

Always always always check the machine shop's work. Plastigauge or mic every journal. I was working with a guy who had his 327 Chevy done, and the shop installed standard bearings with his .010" under crank.....not good (the bearings were actually mis boxed!!) You have a clearance problem, an oiling problem or an alignment problem. It sounds like the line-bore on the block needs to be checked, the crank needs to be checked for oout of round journals and bend (as well as radius and cracking), and your rods need inspection. Something caused #2 rod brg to spin in the first place. Something is causing your current troubles. All components need to be checked by a PONTIAC SAVVY machinist!!! Good luck. These engines can and do run reliably and strongly for decades....


----------



## 400HO (Sep 16, 2010)

*67 GTO engine problem*

The mains are perfect. Coated all bearings and journals with STP oil treatment, have been using it for years. I don't think it is a lube problem because the spun bearings are not over heated or burnt. I have a feeling the rods are not bored correctly to the the journal on the crank. I talked with the guy who cut it and he is coming to listen to the engine tomorrow. A lot of good listening will do. He needs to disassemble the engine for himself to see everything is put together correctly. Then put is back together at his expense. I paid him twice already, there will not be a third.


----------



## jetstang (Nov 5, 2008)

I spun a bearing in my 66 Tempest w/455 in high school. But, I'm sure the motor was slap worn out when it happened. I don't understand a new motor spinning bearings unless there is excessive clearance. But, new bearings are springy and stay in place unless there is something dragging them around, ie. lack of lube or excess clearance.


----------



## Jerry64 (Apr 20, 2010)

Did they rod the oil galleries? Put the plug back in the distributer hole.Maybe the PO forgot it....JB.


----------



## Eric Animal (Oct 28, 2007)

Jerry64 said:


> Did they rod the oil galleries? Put the plug back in the distributer hole.Maybe the PO forgot it....JB.


:agree non pontiac mechs. sometimes forget the plugs!


----------



## Rukee (Feb 8, 2007)

:agree I was just thinking the same thing.


----------



## freethinker (Nov 14, 2009)

Eric Animal said:


> :agree non pontiac mechs. sometimes forget the plugs!


i agree. it has to be oil pressure. bearings only spin from lack of lubrication. check the oil galley plugs. pontiacs have an extra plug in the distributor hole that is often missed.


----------



## geeteeohguy (Feb 2, 2008)

1n 1981, when I had the machine work done on the 389 that's now in my '65, they forgot 3 oil galley plugs: the two behind the timing chain and the one behind the dizzy freezeplug. Lifters wouldn't pump up. Tore the front of the motor down, put the two missing ones in (PITA, engine was in car and detailed), and still, the right bank wouldn't pump up. Finally, on specualation, pulled the trans, the flywheel, the freezeplug, and there it was: the final missing plug. Could be a missing plug indeed, but I'd think that engone would be noisy as heck when it ran, with valvetrain issues.


----------



## dimitri (Feb 13, 2009)

What kind of oil pump did you use?? Never use a high pressure pump unless it is a super duty or ram air engine. If you use a high volume pump you have to use an aftermarket 7 quart oil pan. 400's are really bad at getting the oil back to the pans. I always swiss cheese the windage tray with a 1/4" drill bit on the low spots where the oil can pool. The heads on the corners where the oil drains back usually has flashing from when they were originally casted at the factory. Deber all of that. Also around the lifter bores gind away all of the flashing where the oil can pool. I agree with getoguy about having your block checked for alingment. 

Good luck
Dimitri


----------

