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69 390 using 401 pistons?

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iapexl8r View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote iapexl8r Quote  Post ReplyReply Direct Link To This Post Topic: 69 390 using 401 pistons?
    Posted: Apr/26/2008 at 11:45pm

I am ready to send my block out to get hot tanked and bore/honed. looking for pistons, read this on keith blacks website

"HYPER) High compression AMC piston. See Hot Rod Magazine, March 2004 issue, for 541 Hp engine build.
AMC 390 use AMC 401 pistons with 1968-69/9.175 deck block. Use 1970 and later AMC rods or aftermarket small block Chevy 5.85 rod. Chevy rod requires grinding crank journal to small block
specifications. Stock rod use requires small end bushing to .9272. Compression ratios can be obtained by multiplying 401 compression ratios x's .975 to find approximate 390 compression ratios."
does any one know what they mean small end bushing to .9272
Also does this effect cubic inches??
   Chris
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Post Options Post Options   Thanks (0) Thanks(0)   Quote PHAT69AMX Quote  Post ReplyReply Direct Link To This Post Posted: Apr/27/2008 at 11:04am
Rods - '68-9 - 390 - 5.790" CL to CL - 1.0007 Press Pin Dia. - 1.553" Compression Height Piston
Rods - '70-0 - 390 - 5.858" CL to CL - 1.0007 Press Pin Dia. - 1.518" Compression Height Piston
Rods - '71-9 - 401 - 5.858" CL to CL - 1.0007 Press Pin Dia. - 1.508" Compression Height Piston
 
Crank stroke / throw, Con Rod, Piston Comp Ht, & Block Deck Height all work together
to determine Piston to Deck Clearance and effect CR.
Don't know the Compression Height or piston head dish volume of the KB pistons.
It must be such that the longer 401 Rods are needed to get good Deck Cearance and CR.
Understanding is the KB pistons are made for a readily available Chevy Size Piston Pin.
Believe the AMC stock size 1.0007" Piston Pins are harder to come by.
So to fit the KB pistons to the AMC Rods requires Bushing the small end of the Rods
to reduce the hole diameter to fit the Chevy Piston Pins
and believe changes them to Floating Pins instead of Pressed Pins like stock AMC.
which requires the use of retaining rings in the pistons to hold in the piston pin.
Stock AMC Piston Pins are Press Fit into the rods and float in the pistons.
Full Floating Piston Pins are "better" than Pressed in Piston Pins, free-er movement, less friction.
 
A source for CAST AMC 390 pistons is www.egge.com
They are listed under RAMBLER in the egge online catalog, not AMC.
Need to select a bore size on the egge catalog page in order for it to list a price.
Their pistons, like pretty much all aftermarket replacement pistons,
have an approx. .020" shorter compression height to allow for block and head milling
during the rebuild and yet maintain the stock Compression Ratio.
Which is convienent for reducing CR if building for "cheap" gas
if the Block deck height is left stock and the heads only skimmed for clean-up.
The stock 390 had 10.2:1 CR which may be a bit much for today's "cheap" pump gas,
or what's left of it that is, in the world today.
 
Saw your YouTube Video, looks like the "madness" has begun.
Did you see my '69 BSO AMX YouTube video(s) ?
Happy Hunting.
 
TwoCents  


Edited by PHAT69AMX - Apr/27/2008 at 11:17am
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Post Options Post Options   Thanks (0) Thanks(0)   Quote bigbad69 Quote  Post ReplyReply Direct Link To This Post Posted: Apr/27/2008 at 11:31am
Also does this effect cubic inches??

Displacement is determined by borexstroke. Changes to compression height of the piston or rod length do not change the stroke. Only altering the crank throw will change the stroke. Changes to bore diameter because of over-boring will change the displacement. a .030 over 390 is 395 IIRC.

I looked at 401 pistons when I was building my 390. They have a lower compression height than the stock 69 piston and will lower your CR, especially if you use the dished 401 piston. I forget the actual numbers but, without a lot of machining, you're better off with proper 390 pistons. The cast Badgers are available as PHAT said, otherwise you're into custom forged or a lucky find on Ebay.
69 Javelin SST BBO 390 T10
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Post Options Post Options   Thanks (0) Thanks(0)   Quote iapexl8r Quote  Post ReplyReply Direct Link To This Post Posted: Apr/27/2008 at 2:31pm

please post link to your youtube.

thanks for the tip on stock pistons will definatly check it out.

I have decided to go ahead and pull the triger on the edelbrock heads

the crank is going to need to get turned so I may just use the cough cough chevy 5.85 rods and the 401 pistons with the  17cc pistons.

descissions decessions must do more research

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Post Options Post Options   Thanks (0) Thanks(0)   Quote WiSeNhEiMeR Quote  Post ReplyReply Direct Link To This Post Posted: Apr/27/2008 at 4:11pm
Originally posted by iapexl8r iapexl8r wrote:

does any one know what they mean small end bushing to .9272
   Chris
 
The "small end" of your Connecting Rod ... needs to fit the piston's Wrist Pin ... in this case Keith Black is saying you will need a bronze bushing sized to just under an inch ie: .9272 pressed into the small end of your connecting rod to use their piston ...
 
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Post Options Post Options   Thanks (0) Thanks(0)   Quote PHAT69AMX Quote  Post ReplyReply Direct Link To This Post Posted: Apr/28/2008 at 1:36am
Nothing spectacular.  Had borrowed a friends camera.  First experience with digital video.
It was a couple few year old camera, to download in .avi had to record to camera memory,
so video length was limited to 30 seconds.  Uploaded (10) 30 sec videos.
Recently had a friend combine them all into 1 video, 5:25 long.
It was last autum and was unable to find a "camera man", so no burnout video, yet.
No premo resto car, but pretty solid.
Here's a link to the composite 5:25 video.  Or can just search "BSO AMX" on YouTube.
I'm a smoker and the camera is right next to my face, so don't mind my breathing, sorry y'all.
Oh, and had a bit of a rough time opening my hood with only the left hand, not to smooth.
First videos I have ever taken and tried to deal with with an old PC and no DVD software.
Embarrassed
 
 
Cool
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Post Options Post Options   Thanks (0) Thanks(0)   Quote SS/AMX-MM Quote  Post ReplyReply Direct Link To This Post Posted: Apr/28/2008 at 9:02am
PHAT69AMX
One question....
 
Did you ever get the main job done? Ya know what i'm talking about or were you just breathing hard LOLLOLLOLLOL
Sr.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote billd Quote  Post ReplyReply Direct Link To This Post Posted: Apr/28/2008 at 9:14am
>>I looked at 401 pistons when I was building my 390. They have a lower compression height than the stock 69 piston and will lower your CR, especially if you use the dished 401 piston. I forget the actual numbers but, without a lot of machining, you're better off with proper 390 pistons.<<
 
To expand on that, if you drop the head of the piston in the hole, you lower quench, and you can cause issues. That's not a good way to lower compression. You want generally no more than .060 clearance.
I used KB pistons in my 70 and they have full-floating pins now, the shop bushed the rods.
But I also have proper height - 0 deck height and good quench design.
 
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Post Options Post Options   Thanks (0) Thanks(0)   Quote iapexl8r Quote  Post ReplyReply Direct Link To This Post Posted: Apr/28/2008 at 9:44am

I think I will be breathing heavy just like that (probably worse) when my amx looks that good. nice vid.

the car sounds really good(as well as looks really good), just the way I like them nice and snappy on the rev.
What cam are you running?
what heads?
what headers?
Will be waiting for burn out vid! If you were in so cal I would come shoot it for you. I have mini digital vid cam. 
                          Thanks in advance    Chris
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Post Options Post Options   Thanks (0) Thanks(0)   Quote PHAT69AMX Quote  Post ReplyReply Direct Link To This Post Posted: Apr/28/2008 at 11:35am
Fresh motor was dropped in last September,
343 block +.030 with 304/360 crank offset .010, 367 C.I., Cast Zollner dished top 360 pistons.
Heads are '70 ported, 2.02/1.68 StnStl 11/32 valves, milled ~.055, unshrouded, 48cc.
HS RR's 1.6 x 7/16, Crane Retainers & Dbl Springs, Torker, Holey 850 DP #0-4781.
Good ol' low cost Cyclone 1-5/8 x 3 collector headers, 2-1/2 pipes, FlowMaster 40's.
The cam, due to limited piston to valve clearance with pistons .007 above deck,
was limited to find one with about 64 degrees overlap.
It now has an Elgin / Clevite #E-1041-P cam and lifters, .488/.488 - 284/284 - 218/218.
It'is not what it used to be before with a stock cam reground by Chet Herbert in the 80's.
That cam was .513/.528 & 280/295 adv., have no cam card for that one, but it was much better.
Found a Lunati with specs like the Chet Herbert, but it has more overlap and not enough P to V clearance.
Tried advancing and retarding but couldn't get sufficient P to V with the Lunati.
Now has better idle vacuum and low end, but the old Chet Herbert wasn't that bad
and the Elgin cam as expected runs outta steam to soon, about 5000 rpm
and the 727 has a 3000 stall B&M 10" converter and gears are 3.73's with Moser Axles.
 
Menance, disappointed the ol' girl, just couldn't put the icing on the cake Embarrassed  LOL
 
Thanks for the comments 
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