: I made a mistake on my engine rebuild 472



Nhpatriot
05-24-11, 11:21 PM
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.

csbuckn
05-24-11, 11:51 PM
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?

Nhpatriot
05-25-11, 07:35 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.

deVille33
05-25-11, 09:29 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.

Nhpatriot
05-25-11, 10:16 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.

Nhpatriot
05-26-11, 12:45 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?

deVille33
05-26-11, 09:30 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.

Nhpatriot
05-26-11, 09:43 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?

csbuckn
05-26-11, 09:56 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.

Nhpatriot
05-27-11, 06:43 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.

johnnyjaws
05-27-11, 06:58 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.

csbuckn
05-27-11, 07:45 PM
Uh oh, where's my disclaimer...

deVille33
05-27-11, 09:06 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.