Re: 427 Tall Deck BBC Find 15 years Later after Long Term St
I am still thing of this 427 Tall Deck BBC for use in the 1963 Pontiac Grand Prix.
Running as is without Stroking to a 496 ci.
In stock form It has comparable HP & Torque to a run of the mill 1971-76 Pontiac 455.
Actually a hair more.
Run on piss water 87 octane gas as is. Definition of True daily driver affordability of driving 50 to 500 miles any time any where.
Factory HP & Torque was done with a Governed Holley Carb of maybe 450 cfm rating & crap stock restrictive exhaust system.
Sneak an Isky CL Kit in ASAP after engine installation.
What I found today searching for Factory HP & Torque ratings on the 1968- 1984 Tall Deck BBC Truck engines.
I think mine is 1984 Vintage................
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Old 08-29-2007, 11:14:35 PM #1
Bri69
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GM 427 Information
Hi Guys,
I have a bone stock 427CI GM Tall Deck Big block that I'm installing in a 1979 Chev 1/2ton 4X4(Replacing the 350 CI). The Casting Number on the block is 473478 I'm wondering what the Stock Horsepower and Torque ratings are for the these Tall Deck Truck engines. I can't seem to find any information anywhere else. Any help or pointers in the right direction would be Greatly Appreciated.
Thanks in Advance.
Bri69
Last edited by Bri69 : 08-29-2007 at 11:17:02 PM.
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Old 08-30-2007, 02:44:41 AM #2
rustbucket79
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HP is going to be low since they aren't intended to spin a bunch of RPM, they have low compression ratio, mild cam timing, and very small valves. The torque increase will be substantial over your 350.
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Old 08-30-2007, 12:21:29 PM #3
Bri69
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Thanks rustbucket79. I used to drive the 5 ton truck that the 427 was originally in . it was in a 1962 GMC 5 Ton CabOver. It had very little problem turning 6000 RPM between gears..(the governor was seized up) LOL My intention for this finished truck is for truck pulling, snowplowing and playing with.
Take Care,
Brian Payne
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Old 08-30-2007, 12:32:30 PM #4
80'427
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It will accept a stroker crank and a .125 over bore for big power.
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Old 08-30-2007, 10:09:35 PM #5
Bri69
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Thanks for the tips. Though I'm not up to the point where I can afford to Do much of anything to this engine just yet. I'd just like to see how the rest of the driveline takes to the bigger engine. I attached it to the standard Muncie tranny through a 12" Centerforce Dual Friction clutch /pressure plate. They told me it would hold up to what ever I can put it through. (Evil laugh) we will see if what they say is true.
Thanks again.
Take Care,
Brian Payne
Daily Driver 2001 GMC Sierra 4.8L V8 / 4 speed automatic. Eats Rear tires, Catalitic Converters and Transmissions for breakfast. LOL
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Old 08-31-2007, 12:04:49 PM #6
rustbucket79
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Brian, it makes my colon tighten up to think of those brick like pistons sliding up and down at 6K. I guess we know just how bulletproof the truck rods really are. (I est. the same stress as that same rod with a passenger car weighted piston in a 427 turning 8000 rpm)
Clutch life has more to do with the initial load it sees than the actual power of the engine. We've had dipshyte customers take those clutches and roast them in a weekends abuse on the drag strip with slicks and 6000 clutch dumps. If you have a steep first gear and reasonable gearing for your tire size, that clutch will take a bunch of abuse. Put a set of 35's coupled with 3.08 gears and a bunch of torque and a heavy truck and clutch life will be greatly reduced.
Good luck and have fun!
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Old 09-01-2007, 01:54:13 AM #7
Bri69
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Now that you say it it does sound kind of scary turning that 427 at 6000RPM. It was always working underload when doing this (I'd never let it just sit and rev the snot out of it. Dad would have killed me..LOL)
As for the drive line in the 1979 4X4 it has a Muncie SM465 6.54:1 low gear 3.57:1 second gear. New Process 205 Transfer case 1.96:1 reduction ratio in low, and 1:1 in high range., 3.08 Differentials front has Racing spool rear has factory limited slip locker. and 33 X 12.5 -15 mud terrain tires.
It ran a long time with the 350CI I tried truck pulling, mud bogs, swamp swimming (On/off road rally) , playing in deep snowy fields, even tried teaching a cocky mustang driver not to underestimate an older truck. He sailed by me when I missed the shift to third. LOL
Take Care.
Last edited by Bri69 : 09-01-2007 at 02:02:13 AM.
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Old 09-02-2007, 04:43:14 PM #8
pdq67
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You can do a couple a things w/ it, imho!
First, buy a set of 427 car pistons in the overbore and compression ratio you want using whatever cc heads and .020" thick, stock type steel shim headgaskets and a set of .400" longer BB rods, balance her and it will rpm fine w/ whatever the rest of the combination turns out!!
(And don't forget that a .100" overbore 427 is a 447" engine and one bored an 1/8" over is a 452.2" engine!!)..............
OR...
Make a 496 out of her by using the needed 1/4" longer stroked crank and longer rod/piston combination to again make what you want.
It's no-brainer to me about the long rod 496!!
pdq67
PS., hunt up Speed-O-Motive and look through their BB rotating assembly stroker combinations!!!
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Old 09-08-2007, 12:12:24 AM #9
Bri69
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I found some Stock Numbers for the 427 truck block. 260HP @ 4000 RPM and 405 FT/Lbs torque at 2600 RPM.. Both Numbers are almost double what the 350CI was producing.
The numbers seem ok for what I had in mind for it. Ive run into some trouble placing Accessories on the front of the big block. Obviously the small block mounting brackets don't fit. If anybody has any pictures of a big block with the accessories attached ( powersteering, alt. waterpump. I have a 454 waterpump and harmonic balancer installed. got some 454 Powersteering brackets for it but not totaly sure how they fit on the motor. the altenator bracket doesn't want to fit my block for some reason. any picts of these parts installed would be appreciated. HEll I went to get new rocker gaskets and the damn stock bolts wern't long enough to go through the gasket.. I had to go buy ones that were 1 inch long. Thanks in advance..
Brian P.
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Old 09-08-2007, 12:24:15 AM #10
80'427
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you need to swap to a 396/427 balancer the 454 is external balanced.
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