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Old 07-12-18, 11:05PM   #1
sport65
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Default Anyone know if a 326 can be sleeved to a 4.120" bore, and ballpark what that costs?

Dying to put a .030" over 389 in my Lemans with 400 pistons/heads. Prices for A body 64 389 or 65-66 389 block seem rather much to me and most of them have been left outside.

I've got 2 known good 326 blocks. For the prices I've seen for a 389 that I don't know if good plus the costs to machine said block, I'm thinking might be better price-wise to sleeve a 326 that I have.

Don't know that much about sleeving just what I read so I don't know if I'd need dry sleeves o wet sleeves. Don't know if it's possible to do sleeves that big on a 326 or if anyone has even attempted it.

Can anyone "ball park" approximately what 8 sleeves would cost? (If plausible)

Please don't ask why LOL. Yes, I'm crazy.
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Old 07-13-18, 01:09AM   #2
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I have some 400 blocks
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Old 07-13-18, 02:24AM   #3
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Not even worth your time. Well over 1000 $, a lot more than that. Buy my std bore 400 block with splayed billet caps, 4.25 stroke rotating assembly. 1300$ for the block same for rotating assembly, Ross, billet 4340 rods,Eagle, balanced.New
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Old 07-13-18, 08:10PM   #4
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Quote:
Originally Posted by sport65 View Post
Dying to put a .030" over 389 in my Lemans with 400 pistons/heads. Prices for A body 64 389 or 65-66 389 block seem rather much to me and most of them have been left outside.

I've got 2 known good 326 blocks. For the prices I've seen for a 389 that I don't know if good plus the costs to machine said block, I'm thinking might be better price-wise to sleeve a 326 that I have.

Don't know that much about sleeving just what I read so I don't know if I'd need dry sleeves o wet sleeves. Don't know if it's possible to do sleeves that big on a 326 or if anyone has even attempted it.

Can anyone "ball park" approximately what 8 sleeves would cost? (If plausible)

Please don't ask why LOL. Yes, I'm crazy.
I have a 65 std bore 389 block for sale !
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Old 07-18-18, 03:42PM   #5
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326 castings were "thin wall" for economy car weight savings.
not meant for the big cubic inch loading.
Even if you had one of the early 326 blocks its not advisable.
The early 326s were actually oversized 334 c.i. until when in 1964 GM corporate " NO small V8 over 330" in an A body car" rules forced Pontiac to re-size the bores to yield a true 326" displacement.

We all know how long that rule lasted.

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Old 07-18-18, 07:56PM   #6
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To get 4.120 you need to bore a 389 close to .060 over. Now seeing others trying to sell you a 389 block. I will throw this out there but shipping would be a killer. I have a 66 389 block fully machined to 4.120 brass plugs dura bond cam bearing painted Pontiac blue etc with speed pro 400 std piston with speed pro race rings arp main studs.
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Old 07-18-18, 09:04PM   #7
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Quote:
Originally Posted by thomas flaherty View Post
To get 4.120 you need to bore a 389 close to .060 over. Now seeing others trying to sell you a 389 block. I will throw this out there but shipping would be a killer. I have a 66 389 block fully machined to 4.120 brass plugs dura bond cam bearing painted Pontiac blue etc with speed pro 400 std piston with speed pro race rings arp main studs.
Have you had it sonic checked ?
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Old 07-18-18, 11:03PM   #8
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Shipping cost would depend if its Glendale AZ, Glendale CA or Glendale China.
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Old 07-20-18, 02:54PM   #9
thomas flaherty
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Troy (dragncar) got your PM thank you I don't remember if it was checked for cylinder wall thickness I cant find the paper work and it was machined 7 years ago and sit in my cellar I'm not actively trying to sell it but just threw it out there
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Old 08-01-18, 03:08AM   #10
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Why did you say that?
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Old 08-16-18, 02:20PM   #11
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A 400 is about 3/8" larger bore. To put a 4.120" sleeve in you would have to bore the block to about 4.312". A 326 has a 3.72" bore. You would have to bore it .592" over it's standard bore. No way will the cylinders be that thick. You would end up boring right through the cylinder walls, and have nothing but open water jacket around the sleeve. Plus it would cost over $1000. Better off finding a 400 block and paying shipping.
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Old Today, 04:28PM   #12
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Wont an aftermarket 400 crank drop right into a 326? If so any stroker crank will drop in to wont it? 3.72 + .060 =3.78 ... could have it sonic'd and see if more available but at 3.78 with 4.00 stroke = 360ci, with 4.25 stroke = 382ci, with 4.5 stroke = 403ci. Cast aftermarket crank probably less than redoing original.
400 heads bolt right on a 326 too but the smaller bore might not mate with the head chamber perimeter well without heads having significant chamber overlap?? Larger valves might be shrouded or might even have interference. I think some blocks have "divets" in the front and rear of chamber to help with valve shrouding/clearance. Looks like even 455 has a portion of chamber extending beyond cylinder bore as I just measured that dimension on my collection and it appears to be universally 4.200. At .060 over a 455 bore = 4.210 bore, maybe thats why. Think front to rear chamber dimension is universal on 67up d-ports. Large valves installed measure approx 3.900 on my good 62's with 1.77/2.11 and approx 3.800 on my 46's with 1.96/1.66, within the front to rear dimension 4.200 dimension. I dont have any 326 heads to measure so not sure they are the same. All 326 blocks must have block divets because I dont think they have different valve diameters or valve spacing though I think they are only small valve. If sonic'd and find .125 wall min @ 3.90 or more bore size (+.180 or more overbore) might be safe to bore that far and be assured even large valves would not have a fit problem though might be shrouded alittle.

Just measured

73 46 approx 4.200 front to rear 3.200 top to bottom

75 6X approx 4.200 front to rear 3.400 top to bottom

Was wondering if 46's were higher compression, now I see "scallop" is smaller so they are most likely.

That little 326 with a 4.00 crank and .060+ bore @ 360ci might be a hard runner for a street car, especially if turbo'd or supercharged. Butler custom Ross pistons, good rods and the same Scat crank I just bought without the mods Im doing might surprise some people. I would think forced air would help the breathing aspect but if that issue was addressed and accommodated and then forced air added might be a magazine article worthy super street engine.
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