cylinder thickness and bore size limits

[35chevcoupe]

I,m headed to the machine shop tomorrow to discuss the plans for continuing my nail head build . The blocks are cleaned and crack free but one needs to go to .060 over and the other .040 over . The sonic testing showed the best of the 2 blocks at .105 to .150 cyl. wall thickness .
So how far over can these blocks be bored before running into problems ?
luckily the thrust side of the cylinder was the thickest .

[Buick_65]

Russ says ..060 on everything but a 425. .040 on those.

[telriv]

I would fill the bottom of the block with epoxy to help the flexing of the bottom end of the block. I do it on ALL rebuilds NO MATTER what the wall thickness. MUST be done before boring. Makes for a more stable bottom end with the end result of the rebuild lasting longer before blow-by rears it's ugly head & you have to start over/sleeve cylinders etc. A standard .040" over you will receive .030" over rings. If you go standard overbore then you are stuck with 5/64ths. rings only. 1/16th rings are a 15HP increase because of less drag with no downsides.

[WkillGS]

Tom has taught me well over the years! I've followed up on some of his recommendations.

If you want to use the better performing 1/16" wide rings, you need to find a ring set in an existing size.
Other engines with similar bore sizes to the Buick 401 include the AMC 390, Pontiac 455, Ford 427 and Chevy 400/402.
1/16" Ring sets are currently available for the following bore sizes:

[telriv]

425 options are 440 Mopar & 429 Ford

[telriv]

Walt posted what would have taken me HOURS to post.
MY Pistons come with rings included. Top Moly, 2nd cast iron, oil quality 3/16ths.

[35chevcoupe]

Thanks guys for the information , I can,t thank you guys enough for helping me out on this .
Things went pretty good today at the machine shop . Turns out he didn't sonic test the 401 yet because he seen pits in the cylinder walls of 2 cylinders and wanted to touch base with me before spending my $$$$ . ( which I greatly appreciated )
So I told him to sonic test it anyway as thats the only way i,m going to find out what i have to work with .
I,ll find out next week how the 401 turns out .

[35chevcoupe]

Tom ,
pm sent

[telriv]

John, I'll be out most of the day on Fri. the 6th. I should be back by 7pm EST.  OR a good time to call you.


Tom T.

[35chevcoupe]

Tom, I,m up till midnight every night . central time .
cell # is 763-486-0341 .
thanks

[gs spoken here]

John what did the 425 block I sold you need bored?  The machine shop I had it checked at said it need to go .40 over, thanks Bill.

[35chevcoupe]

Bill , not absolutely sure yet but we are going to block fill it first and then start at .020 over and see how far it has to go .
Unfortunately the cylinders on that block are pretty thin at the bottom so we,re gonna have to go until it cleans up but at the same time watch the size of rings that are going to be available .
I think it will be ok after we fill the block .

[telriv]

Sorry, forgot to reply on 425 oversizes.
440 mopar standard bore 4.320"+5
   "       "      .030          "    4.350"+5
429 Ford     4.360"+5
   "     "        4.370"+5
   "     "        4.375"+5

401, Walt didn't mention
Chev. 427/454 & Mopar 383/426
                 4.250"+5


These are what's also available in 1/16th. rings.


Tom T.

[35chevcoupe]

Thanks Tom .
I think I might have found an outlet for the epoxy . Going to try Grainger in Minneapolis .

[telriv]

To those looking to do this/make an improvement.
 
Brand names:

Dupont
LockTite
Fel-Pro

Called various names depending on brand:

NordBack
HardBack
StrongBack