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401 pistons in an early 390

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klvn8r View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote klvn8r Quote  Post ReplyReply Direct Link To This Post Posted: Dec/02/2020 at 8:55pm
I'm currently helping my son build his first 401.....probably settling on the Wiseco + .045   Is anyone a dealer with IN STOCK?  I'm unfamiliar with DSS and Racetech.....but will gladly listen!  Thanks!

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Post Options Post Options   Thanks (0) Thanks(0)   Quote klvn8r Quote  Post ReplyReply Direct Link To This Post Posted: Dec/02/2020 at 9:16pm
I'm currently helping my son build his first 401.....probably settling on the Wiseco + .045   Is anyone a dealer with IN STOCK?  I'm unfamiliar with DSS and Racetech.....but will gladly listen!  Thanks!

Also, SC397....I posted a reply to you on the topic in the very top, regarding balancers.  Thx.


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Post Options Post Options   Thanks (0) Thanks(0)   Quote PHAT69AMX Quote  Post ReplyReply Direct Link To This Post Posted: Dec/03/2020 at 12:30am
Have ya called Wiseco direct in Ohio to see if they have any in stock?
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Post Options Post Options   Thanks (0) Thanks(0)   Quote AMXFSTBK390 Quote  Post ReplyReply Direct Link To This Post Posted: Dec/03/2020 at 12:13pm
Was I ever astonished when I tore down the 390 in my 68 AMX. It had 401 rods and pistons at .040. I was told to make that work, customs pistons are required with a different wrist pin location. At that juncture, I acquired a std bore 68-69 390 bare block from Galvin's and went a different route. 
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Post Options Post Options   Thanks (0) Thanks(0)   Quote brownspirit Quote  Post ReplyReply Direct Link To This Post Posted: Jul/31/2021 at 12:20pm
Okay, 8 months later I got a block to the machine shop, it needs to go larger than .030 over.  The bores are true at .030 but there is a small amount of rust. The block had previously had .020 taken off the deck.  Anyway, I was going to order the Wiesco PTS540A45 and a set of Molnar 5.858” 401 rods.  According to my calculations this should come out to the pistons being .010 in the hole using the 68/9 390 block decked to 9.155, 390 crank 3.574 stroke, Wiseco pistons at 1.500 compression height.  Also it should get me about 10.2 compression with the -27 cc reverse dome pistons, felpro head gaskets, and my 291c heads.  I actually bet those chambers are bigger as Adkins ported them for me.  I will get them cc’d to find out for sure, but I would imagine the compression ratio will be a little lower, which I perfer.  Does this all make sense, just asking before I order.  Thanks, Andy
69' BBB AMX 390/4-speed

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Post Options Post Options   Thanks (0) Thanks(0)   Quote 6PakBee Quote  Post ReplyReply Direct Link To This Post Posted: Jul/31/2021 at 12:32pm
Andy, before you break out the boring bar, how bad is the surface rust?  If you run a ball hone through it will it disappear?  I put a 2.2 Mopar together with a bit of rust in the bores (against the recommendation of my machinist who wanted to overbore) and five years and another 100,000 miles it was still going strong when I sold it.
Roger Gazur
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1970 Sonic Silver auto AMX

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Post Options Post Options   Thanks (0) Thanks(0)   Quote brownspirit Quote  Post ReplyReply Direct Link To This Post Posted: Jul/31/2021 at 1:13pm
I went over and saw it in his honing machine, there was still visible rust in 2 of the four bores he had done, and the 2 are at the outer limits of having acceptable wall clearance for .030 pistons.  He said if I had the pistons he’d recommend I run it, where I still have to buy them he said just go .040 or .045.  He also said the bores are so straight the he can just hone to fit the new pistons, he said it wasn’t gonna cost me any more on his end.  He is in a holding pattern until I bring him some pistons.  It made sense to me, but I don’t know. Andy
69' BBB AMX 390/4-speed

69' s/crambler project

69’ International F210d Cummins/5+4
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Post Options Post Options   Thanks (0) Thanks(0)   Quote 6PakBee Quote  Post ReplyReply Direct Link To This Post Posted: Jul/31/2021 at 2:48pm
If you have to buy new pistons anyway, and your machinist says that he can fit 0.040 oversize for the same cost as 0.030 oversize, I can see why you are leaning towards going 0.040 over. It's cost neutral and the concern over rust will be gone, or at least minimized to the point where it isn't a factor.

Tickled that you kept your SC/.  That's a decision you won't regret.
Roger Gazur
1969 'B' Scheme SC/Rambler
1970 RWB 4-spd Machine
1970 Sonic Silver auto AMX

All project cars.

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