: I made a mistake on my engine rebuild 472
05-25-11, 12:21 AM
I now realize I skipped the "check rings end gap" step when installing piston and rings.
I've got almost everything back together, do I tear down to check the gap or just go forward? Anyone know how often the ring end gap has to be modified? The piston and rings are .030 over.
05-25-11, 12:51 AM
If its a fresh bore and a fresh set of rings from a trusted supplier, you "should" be good. If you got your rings off ebay from some unknown dealer, I'd take it apart. I ordered three sets for an Olds motor before they finally got it right. Where did you get the rings from?
05-25-11, 08:35 AM
I got the engine back from the machine shop with all the rings, gaskets, bearings. I know the machine shop didn't check it because they weren't opened yet.
05-25-11, 10:29 PM
Err to the side of a safe position. Pop the pistons back out and check the gap. If the gap is too tight you'l scoure your cylinders and the pistons will lock in the bores. - Seen it before.
05-25-11, 11:16 PM
I know your right just hate the thought of going backwards.
Will i have to get new head gaskets? It's never been run just assembled.
05-26-11, 01:45 AM
I pulled one head and piston tonight, the 2 compression rings on that piston are within specs of the Cadillac manual. One gap is little large according to an online 472 engine specialist.
Not sure I have the proceedure correct, I used the piston to push the ring down the bore a little thinking that will set it at an even height. Sound right?
Do I need to check the oil rings too?
05-26-11, 10:30 PM
I would check the oil rings also. You just need to check the 2 sraper rings. You didn't say who the manufacturer was, so this is all a judgement call. Some manufacturers don't even come close to gap on all rings, but there may be some that do. It's a pain, but I try match a close ring ( one I have to gap ) with a wide ring. Make sure you get your rings in the proper land facing the right direction and the gaps 60 degrees from each other. Better safe than sorry.
05-26-11, 10:43 PM
I've done some reading about having the lower compression ring with a wider gap then the top. If i go thru this whole bank without having any out of spec i may not pull the other head.
What's everythink about reusing the head gasket?
05-26-11, 10:56 PM
I'd reuse the head gasket. I've never read that the top gap should be different. If they are in spec of the service manual, I'd be happy with that.
05-27-11, 07:43 PM
Getting back out to the garage tonight to check the rrest of the odd cylinders. Will have the Bruins on the tv & red sox on the radio. If these 4 cylinders are all good i'm not going to bother with the other head.
05-27-11, 07:58 PM
................DO NOT REUSE THE HEAD GASKET ...!!! get a new one that one has already been squished will not seal right you spent alot of money on your motor DO IT RIGHT once.
05-27-11, 08:45 PM
Uh oh, where's my disclaimer...
05-27-11, 10:06 PM
If you are using a sandwich type gasket, it should be OK to reuse it. After you have started the engine and cooled it, no. If your scepical use 5#s additional torque. I would still check the opposite bank.