What will it take... - Impala Tech
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post #1 of 7 (permalink) Old 07-29-2012, 08:15 PM Thread Starter
 
 
Join Date: Jul 2012
Location: Ypsilanti, Mi
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What will it take...

Been cruising around in my new to me 66 Impala SS 396 w/ power glide and definitely want it to have some more get up and go.

I'd like to keep the car looking as stock as possible, but would like it to be significantly quicker. I'm thinking low 13's high 12's quick (assuming there was traction, I don't plan on drag racing it, but definitely want it to be fast).

So what is my best route to get there? I'm looking for details, I know I can do intake/cam/t400/rear end, but I'm not sure what options I should pick for each of those.

Also, I'm handy enough to do a lot of the work myself, but if it involves engine work I'd be curious anyones recommendations in the Detroit area (I'm sure there are 100's of options).

As far as I can tell the only options the car is a mandrel bent exhaust with 40 series flow masters on it and a aftermarket filter.

Pics of the car are in the welcome forum here...
http://www.impalas.net/forums/showthread.php?t=7245
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post #2 of 7 (permalink) Old 07-29-2012, 10:18 PM
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Right now a 406 small block motor (which is a lot more common than you might think because you can not go by the 327 valve cover decal) will put you on the trailer every time. You are running around with a motor that weighs 230 pounds more than his small block and your motor has smaller valves than his motor does. The only way a big block beats a small block is to make your displacement bigger than a small block (big enough to over come the weight advantage) and to install a better head (one that has bigger valves and modified ports to raise not only the air flow volume but the intake port velocity).

From the outside my 582 cubic inch big block looks just like your 396 (mine even has 402 decals on the air cleaner to help people identify what I am running; since you can not tell). Well actually I can tell, as can an experienced engine builder who knows what to look for; but I have been screwing big blocks together since 1965 when they first came out. Most people at a car show won't have a clue as to your engine size or if it is a Mark IV (396, 427, 454), or a Gen V (454), or Gen VI (454, 502, 572).

With the right block and heads you can make as much horsepower as you can afford. Heads are how the engine breaths and is your most important choice. The block is only important as there are three basic bore sizes offered with a big block (just think of the three bears). The middle bore size is your Goldilocks choice if your budget is limited (say you have kids to feed, or a mortgage payment to make every month). It is the 4-1/4 inch bore of the 427 and the 454. The larger papa bear 4-1/2 inch bore will make a boat load more power but they were never installed in a car, or a truck by the factory so they are the pricier choice.

So if you can find a 454 pick-up truck motor to supply the short block, and then buy a set of aftermarket heads to top off a fresh rebuild; you will be making 430 to 570 horsepower depending upon your cam and induction choices. Right now you are outputting 350 horse or so at the flywheel or about 280 horsepower at the rear wheels. Everything you have now will bolt back onto the replacement motor and as I said if you could hide the bills the wife wouldn't be any wiser as there is no visible difference. She might wonder why rear tires don't last very long though so don't tip your hand too soon.

Big Dave
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post #3 of 7 (permalink) Old 07-30-2012, 06:08 PM Thread Starter
 
 
Join Date: Jul 2012
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Thanks for the reply, if I wanted to start with an easy cam mod just to see what that does, what are the recommendations?

I'll worry about dropping in a merlin BB at a later point
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post #4 of 7 (permalink) Old 07-30-2012, 09:14 PM
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Well just remember that your cam is special (unique to 1965-'66 big blocks). It has an eighth inch oil groove carved into the rear bearing surface to provide a path for oil to get to the top of the motor. Most cam grinders charge $75 additional over and above the price of the cam to add it (or did with the last one I bought so it may have gone up since then). Big blocks love lift and compression. So keep the duration down and consider 1.8:1 ratio rockers (pro stock race motors use 2.0:1 ratio rockers) to get the valve off the seat faster without buying a long duration cam that kills your compression.

If you want a lopey cam buy a VooDoo from Lunati or a Thumper cam from Comp as the added duration is all on the exhaust side where it doesn't hurt the engine's performance as much as an X-treeme Energy cam might.

Your 396 intake valve measures 2.06" inch in diameter (same as the size in the late model 454 pick-up trucks; as only the "High Performance" heads from the factory have 2.19" intake valves). The valves in my aftermarket SBC 406 heads measure 2.08" in diameter. Aftermarket big block heads measure 2.225" to 2.300" normally with a 24 degree head (though in a racing head with 12 degree valve angle such as the Dart Big Chief, or Brodix Big Duke they grow to the same size as Hemi engines at 2.400" or bigger to feed 500 cubes). I wouldn't settle for anything smaller than 2.225" in a new head. Bigger is better with a big block. Cams are part of the solution but I would save my money for a good set of heads.

Big Dave
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post #5 of 7 (permalink) Old 07-30-2012, 09:55 PM
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You might want to consider the transmission as part of the deal A 700r4 has a squarish pan like the Powerglide, so it takes some knowledge to spot the difference between them. But the 700r4 (properly built for the power you are making) has a lower first gear and overdrive, which perks up acceleration and makes highway driving nicer with some mildly performance oriented gearing in the differential.



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post #6 of 7 (permalink) Old 07-31-2012, 08:02 PM Thread Starter
 
 
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I know it's been posted here I saw in a search, but which trans swap options are bolt in vs needing significant mods? I have no issues with modifying driveshaft length, but would rather not have to make big changes underneath to make the trans swap work.

Any recommendations on best spot to pick up a trans once i make the decision? There seem to be a ton of options out there for locations to buy.

My tentative budget is $3k, so I think that's quite good enough to get me started without worrying about tearing my motor apart and hopefully items I can get done myself starting mid August.
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post #7 of 7 (permalink) Old 07-31-2012, 11:14 PM
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I am not that familiar with '66, but the 700r4 would probably need a different crossmember (bolt in item). Some work getting shift linkage hooked up. Then there is the TV cable in place of the Powerglide's kick down. The cable normally clips into a holder that bolts to a couple of the intake manifold bolts. You can be real stealth like I did and use the kick down linkage to operate the TV cable (hidden down under) but that is a bit more work that is only worth it to nuts like me who want originality and some hidden upgrades Then there is the drive shaft, which you know about. As I recall the 200r is sometimes the same length as the Powerglide, and a 200r can be built strong as well. I am quite happy with the upgrade to a 700r5 over the TH350 that I had upgraded to back in the 80's. For comparison, I have a small block 383 making 370 HP and 420 torque hauling around a 4000 pound 64 Impala. 3/4 throttle lights up the tires with ease, so acceleration is nice.



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