352 to 390
Cargo Master
Joined: Jul 2003
Posts: 2,328
Likes: 14
From: Colorado
My machine shop wrote:
4.0775
+ .0030
---------------
= 4.0805
On my piston/rods box. What does that mean?? Is that .030 over? Just when you think you know what someone is talking about theres something that confuses you.
4.0775
+ .0030
---------------
= 4.0805
On my piston/rods box. What does that mean?? Is that .030 over? Just when you think you know what someone is talking about theres something that confuses you.
Post Fiend
Joined: Feb 2001
Posts: 6,624
Likes: 8
From: Missouri
A .030 over 352 piston is 4.030. A .030 over 360/390 pistons is 4.080. To get a standard bore 390 piston to fit a 352 bore you need to have a stock bore of 4.05" If you give him a stock 390 piston he will be able to bore it out just like you need it.
Edit: Just noticed that you had wrote one too many zeros in there. I'm not sure what you machine shop meant there. I think he was messing with you. Its .030 over not .0030 over. .0030 is a good amount of main bearing clearance for you though!
If your bore is 4.07" then you are already past a standard 390 bore.
Edit: Just noticed that you had wrote one too many zeros in there. I'm not sure what you machine shop meant there. I think he was messing with you. Its .030 over not .0030 over. .0030 is a good amount of main bearing clearance for you though!
If your bore is 4.07" then you are already past a standard 390 bore.
Last edited by Ratsmoker; Nov 7, 2003 at 12:03 PM.
Post Fiend
Joined: Feb 2001
Posts: 6,624
Likes: 8
From: Missouri
You need .030 over 390 pistons. I would be getting very worried about the cylinder wall thickness if that is really a 352. That is an .080 overbore. What did the pistons say that you pulled out of it?
Cargo Master
Joined: Jul 2003
Posts: 2,328
Likes: 14
From: Colorado
Ratsmoker, the pistons that I took out were orginal 352's. The new pistons that I have say .030 on them. I don't know if thats .030 from 352 or .030 from 390. I put in a 390 crank to make it a "390".
Cargo Master
Joined: Jul 2003
Posts: 2,328
Likes: 14
From: Colorado
Originally posted by ceetwarrior
My 352 block says "32 352" right on the front of it. I wonder if mine is one of those blocks that can't be bored far like CACWBY was saying????
My 352 block says "32 352" right on the front of it. I wonder if mine is one of those blocks that can't be bored far like CACWBY was saying????
Post Fiend
Joined: Feb 2001
Posts: 6,624
Likes: 8
From: Missouri
Almost all FE engines before 1973 have 352 stamped inot the front. Even the mighty 427. Many 352 engines have 66-427 stamped in the back. Don't believe the numbers. They will decieve you every time. Measuring the bore and stroke and determining what year the engine was cast is the only way to determine its size for sure. What year vehicle did this engine come out of?
Cargo Master
Joined: Jul 2003
Posts: 2,328
Likes: 14
From: Colorado
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Cargo Master
Joined: Jul 2003
Posts: 2,328
Likes: 14
From: Colorado
Ratsmoker, I already put the new pistons in. I remember that they said .030 on the top of them. So, I'm not sure if that was .030 over 352 or .030 over 390. My block was the original bore 352 before he bored it.
All I know for sure is he wrote on my piston box:
4.0775
+ .0030
---------------
= 4.0805
All I know for sure is he wrote on my piston box:
4.0775
+ .0030
---------------
= 4.0805
Post Fiend
Joined: Feb 2001
Posts: 6,624
Likes: 8
From: Missouri
If the original pistons were std 352 and the new ones are 4.080 then you are either going to get real lucky or (most likely) you are going to have a disaster happen. Most machinists won't take a block .080 over unless you specifically state you want to go .080 over. The markings on your piston box make very little sense to me. Maybe DF will know what he was talking about. You need to call the machinist and ask him what he meant by it.
Cargo Master
Joined: Aug 2000
Posts: 2,931
Likes: 12
From: SW Michigan
390, coming soon
Ceet, what your machinist did was to measure the new pistons, 4.0775, and add the clearance he wanted, .003. This will leave you with a finished bore size of 4.0805. So you will have a .030 over 390. I would have used a standard bore 390 piston, to leave more room for future rebuiding, but standard 390 pistons may not have been available quickly. Okay, so your 352 block is now bored .080 over size....is this going to be a problem ? Probably not. I wouldn't bore a 427 or a 428 that much oversize, but there have been plenty of 390s bored .080 over to go to 428 size, and they usually don't have problems. Your 352 started even smaller, methinks you'll be okay. If you want to calm your fears, how about doing Shoe's drill bit test ? Are the core plugs insalled in the side of the block yet ? DF
Cargo Master
Joined: Jul 2003
Posts: 2,328
Likes: 14
From: Colorado
dinosaurfan, damn. Yeah, I already assembled my motor. It's going in the truck today. I'm gonna call my machinist some time and ask for sure what he did. I hope he didn't go .030 over a 390. He shoulda just went with a standard bore 390 like you said.
BTW, what's a 'shoes drill bit test'?
BTW, what's a 'shoes drill bit test'?