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Old 02-28-2006, 07:29 PM
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Bought my first BB chevy/ need help with specs!!

Okay guys need a little help here,
I've been a chevy fan all my life, ever since the day that I was brought home from the hospital in dad's 69 chevelle. And now I'm 24 and have owned my own 1970 chevelle for 9 years. My chevelle now has a 327 that I built 3 years ago, it runs great, shift it at 6200 and the thing is still pulling hard. Best et is a 12.65 @108 not bad for a 327 in a 3800 lb. chevelle. But I've got the itch to go bigger and faster. I've got a 400 SB in the garage that I was gonna use to build a 434 stroker, but that was until Sunday when I purchased my very first Big Block, actually I bought a 79 suburban, 1 owner,factory towing special, with a Turbo 400, and a massive 12 bolt rear??. I bought it for the engine and tranny,only paid $800.00 for it and I drove it home, gonna part the rest out.E-mail me if yall need anything. So to get to the point. Most of my chevy knowledge is with small blocks, I know a little about Big Blocks but what I need help with is can somone tell me the difference between Oval ports and Rectangular port heads, other than the obvious that ones oval the others rect. I've heard that ovals are better for the street and rect. for all out racing, but thats about as much as I know about BB heads. I don't have the engine out of the burban yet so I don't know which it has. Can anyone tell me any specs that chevy used on the 454's in 79, Like 4 bolt or 2 bolt block? compression ratio? are the BB heads from that era worth sinking any money into? Cast or Forged crank?. Plans for the BB will be to punch it out to 468 c.i, about 10 to 11 to 1 compr. A nice comp cam that will see about as much 1320 action as street action. Do you think I can get 500-550 horses out of this basic description of what I want to do with it. Any help or advice would be greatly appreciated.
Thanks fellow Hotrodders

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Old 02-28-2006, 10:22 PM
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richard stewart 3rd

Hi Fattire_70
Here is a place to start looking for what you have.
getting 500hp from this engine is to easy.
be safe, Rich
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Old 03-01-2006, 06:18 AM
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That horse power will be easy. I'll bet you have oval port, unless somebody really liked the Suburban. The square port flow a lot of fuel, but having said that, you can reach the horse power goal you have, and then some, with oval port heads. There are different size ports in the oval port world. If you don't have a larger port set, you may want to pick up a set and work them some. They will flow well. I don't think you have a tall block, but check to be sure. The distance from the water pump port on the front of the block will be .400 greater on the tall block than the short one. If there had been an engine swap or for what ever reason you ended up with a tall block, your part selection will change somewhat.
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Old 03-01-2006, 08:23 AM
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Tough year to predict. It could be any one of the three choices. Oval, rectangular, or Round (peanut) port. Either one of the first two will work. If they're round then you've found a couple of nice book ends.
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Old 03-01-2006, 10:15 AM
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Originally Posted by engineczar
Tough year to predict. It could be any one of the three choices. Oval, rectangular, or Round (peanut) port. Either one of the first two will work. If they're round then you've found a couple of nice book ends.
I'm new to BBC's as well.

I have a 454 out of a 79 C20 Camper Special, and it was 2-bolt main and peanut-port.

I was told not to sweat the 2-bolt main unless I was looking at frequently revving over 6500 RPM.

"781" or "049" cylinder heads have come highly recommended by others on this board, along with the recommendation to port them and put in the larger valves.

The old heads will likely be used as doorstops, as I now have a set of 781's (large oval port) that I paid way too much for.

Right now I have a Torker II intake and a 780 CFM Holley that I plan to use initially, but the long-term plan is to install one of those Weiand street blowers.

This engine was running (not well, but running) but does still have decent compression. (135-145) It will be going to the machine shop for inspection and measuring when I can afford it. If it needs to be bored, it WILL be getting a set of forged (blower) pistons installed. Otherwise, I'll probably just swap in a lumpier cam and run it "as is" while I concentrate on getting the bodywork done.

I'm looking for a "modest" 400 HP / 400 TQ (prior to supercharging), which is supposed to be dead easy.
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Old 03-01-2006, 10:45 PM
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I've been lucky enough to own TWO 454s in my time... Fastest way to 500 horses with me was roller rockers at a 1.7:1 ratio (I have oval port heads in my 73 block) my original was a TRUE LS5 in a 70 Chevy Caprice. I also stepped up to MSD ignition... I stepped up compression to 9.5:1 and that JUST keeps it from pinging... (My LS5 had 10.25:1 and I needed to add octane boosters to keep this from happening) Remember also, that although wanted by many, 1970-72 heads have a lot of bolts open to the water jackets... (Trust me, that can really SUCK!)

Modern starters are CRAP for these engines... Get a high torque (I use hitachi style) mini-starter. I'm running a high flow Edelbrock carb on a performer RPM manifold. I used a freeze plug to block the EGR... Unless you pull the valve, they'll never know! Headers are an obvious help... I hope I helped a bit...

Your 79 will probably be around 8-8.5:1 CR with rectangular ports and EGR... That Tranny will need to be beefed a bit too... It is also likely to be 2 bolt main, but on BBs that really doesn't matter (Most are lower RPM) (My LS5 was 2 bolt and stamped PASS HI PERF) <-- I thought that was COOL!

Both Vehicles were FAST... Caprice was Low 13s @100-103 and Truck is mid 12s at 106 (I put a 700R4 behind it...)
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