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Author Topic: 1968 Pontiac 400 Code: XW Build Sheets.. Buy?  (Read 2282 times)

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Offline Wild Bill

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1968 Pontiac 400 Code: XW Build Sheets.. Buy?
« on: March 17, 2009, 07:03:58 PM »


Just uploaded the build sheets... what do you guys think?

1968 400 Block Bore .030 Balanced, Casting #XW
Head Casting #16 72 CCS Valve Size 2.11/1,77
Comp Cam - Hyd Intake .540 Exhaust .540
Comp Cam - Valve Springs, Retainers, Lifters, Pushrods, Magnum Roller Rockers, True Race Roller Timing Chain
Pistons - Sealed Power .030
Connecting Rods - Stock Reconditions Rods, ARP Bolts
Rings - Speed- Pro
Oil Pan - Warrior High Capacity 8 " deep 7 Quart
ATI Super Damper
MSD Billet Distributer
Holley 750 Double Pumper with Quick change Jet Bowls
Edlebrock Torker II Manifold

Guy told me about 500 miles on the rebuild, emailed him back and asked him if he has the receipts to show proof of all the work, thinking about this weekend going and picking this mug up.... What do you guys think?



Here's the thing...
Do I pay the 1600 bones to grab this motor, change out the cast rods, the cam, and maybe the pistons and work it like that or what?
I really want a 68 block, it's what I've been looking for a few years now.. It'll be worth it to me to buy it and pay the money to change that s#^* out
« Last Edit: March 18, 2009, 06:42:45 PM by billknobbe »

Offline kjkjkcjkcj

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Re: 1968 Pontiac 400 Code: XW
« Reply #1 on: March 17, 2009, 08:38:14 PM »
Motor looks nice.  sounds exactly like my setup except i have the edelbrock performer and only a 650 carb.  How much power you expected to get?  im right around 300-325.  Motor looks nice.  ibelieve it is just the motor mounts.  Have fun with it
-1979 Trans Am Ws6, W72 400, holley 650, #62 heads (toy)
-Silverado 1500 (daily driver)



Offline Wild Bill

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Re: 1968 Pontiac 400 Code: XW
« Reply #2 on: March 17, 2009, 08:43:11 PM »
well the engine in 68 was at 366... he told me it "should" be around 450 on pump fuel
he sent me pics of the work sheets from the guy who built it and shows me all the parts that was put in it....
he wants 2 grand for it.... says 500 miles on the rebuild, a rebuild that was 4 years ago, said the parts in the engine is over 2 grand

Offline Rick

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Re: 1968 Pontiac 400 Code: XW JUST BOUGHT Uploaded Build Sheets
« Reply #3 on: March 17, 2009, 11:13:53 PM »
I'd have 3 concerns on first blush...

1 -- it uses cast rods.  That's a lot of goodies in an engine with cast rods, because they aren't that stong and will break pretty easily.

2.  For #16 heads that haven't been ported, the lift on that cam would seem to be beating a dead horse.  Stock Pontiac heads really don't have any additional flow past 0.480" or so, and anything further is just stressing the valve train for very, very marginal gains in cylinder filling ability.  There's a school of thought that figures it's the "area under the curve", but still -- some heads actually flow LESS at those high lifts, so really it's duration at max flow that counts.

3.  If the lift is that high, I wonder just where the power band will be, and how that matches up with your car in your application.  If you have an automatic (and all 403s were automatics, most with 2-something rear ends in them) this might *not* be the cam for you -- Pontiacs are notoriously sensitive to overcamming.  It all boils down to how the rest of your car is set up, and what you intend to do with it.  Setups for the street and for the strip are completely different matters -- so it's your intentions that count.

Offline Wild Bill

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Re: 1968 Pontiac 400 Code: XW JUST BOUGHT Uploaded Build Sheets
« Reply #4 on: March 18, 2009, 04:16:09 AM »
Oh...
So are you saying.. if it were you... you'd pull the heads, get them ported and change out the cast rods?
I do not believe that I will be running on the strip... just the street...
As far as the car goes... currently I'm running 2.41's, but in may I'm popping in my 3.41's

What you think redline max rpm's on this engine will be? I currently don't take my 403 past 4500

Offline Mr. P-Body

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Re: 1968 Pontiac 400 Code: XW JUST BOUGHT Uploaded Build Sheets
« Reply #5 on: March 18, 2009, 09:13:56 AM »


   Echo Rick's concerns. The cast rods have GOT to go. They're over 40 years old and weren't very good when new!

   That cam has to go, too. That is an old Comp Magnum grind, part number 51-242-5. It is a "single pattern", which is not recommended for any Pontiac application. It also sports 260 degrees @ .050" lift, which is WAY too rowdy for a driver.  It is no longer in Comp's catelog, and for good reason. Comp has learned over the last 20 or so years, not every engine reacts to cams the way small block Chevys do...

   Static compression with the heads is near 10.5:1 (advertiesed at 10.75:1), which is also way too high for today's 93 octane gas.  Steps must be taken to reduce static compression (larger chambers or a "dished" piston) or increase fuel octane (race gas "mix").

   If I were to guess, I would say the builder was a "Chevy guy" from the "old school". That engine needs to be brought up to minimum standards for a Pontiac. In its current form, it will not make the power you want, and it WILL NOT LIVE if "pounded on".

Jim

Offline kjkjkcjkcj

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Re: 1968 Pontiac 400 Code: XW JUST BOUGHT Uploaded Build Sheets
« Reply #6 on: March 18, 2009, 09:36:02 AM »
Yeah just by reading that it sounds like the guy didn't do his research on the pontiac motor. but judging by what he did you can tell he does know his stuff when it comes to engine rebuilds.  It may not be the best motor out there for you.  id think about passing and finding something else.  You could always rebuild your own.  Its quite fun :)
-1979 Trans Am Ws6, W72 400, holley 650, #62 heads (toy)
-Silverado 1500 (daily driver)