more power from my 327 Help!!! - Impala Tech
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post #1 of 33 (permalink) Old 02-08-2017, 08:03 PM Thread Starter
 
 
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more power from my 327 Help!!!

I'd like to get a little more power from my 327, it's in a 65 SS Impala and bolted to a 2 speed powerglide transmission. I was thinking TH350, 3.73 gears, headers and possibly a mild cam. it has a 12 bolt rearend and 3.08 gears. any suggestions will appreciated.

Sid
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post #2 of 33 (permalink) Old 02-08-2017, 08:47 PM
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Turn your 327 into a 383 and bolt on some 190 to 215 cc intake port heads with a hydraulic roller cam.

Costs the same to build a 383 as it does to rebuild a 327.

Big Dave
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post #3 of 33 (permalink) Old 02-09-2017, 05:20 AM
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The powerglide is costing you a lot of power so the 350 would be a good upgrade. I would stay with the 308 gears at leat for the time being.
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post #4 of 33 (permalink) Old 02-09-2017, 10:56 PM Thread Starter
 
 
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Thank you very much
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post #5 of 33 (permalink) Old 02-09-2017, 10:59 PM Thread Starter
 
 
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I appreciate the feed back, can I pick your brains on why you would keep the 308 gears?
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post #6 of 33 (permalink) Old 02-10-2017, 08:59 AM
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Interested in this topic as well. I feel our SS with the 327 is a bit weak in power as well. I do not know the gearing, and thought that could be part of it. I just expected a bit more response from the gas pedal
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post #7 of 33 (permalink) Old 02-10-2017, 09:26 AM
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The engine displacement increased from a 327 to a 350 not to power light weight Camaro's but to get a heavy Impala to move. While Chevy had a 350 for it's base engine, the same body with added trim (called a Cadillac) had a 500 cube V8, Buick (in the Electra 225 which was their version of the Impala) had a 455. It was because a 350 didn't have enough ummph to move a 1969 to '70 Impala that the SBC 400 was designed and brought into production.

Chevy was the last of the GM marquees to get a V8 and very few Chevy's had the big block stuffed into them as it was an entry level car. Only the full size Impala and the Corvette got the bigger big blocks as there was an arbitrary 400 cube limit on all of the rest of the GM line. GM expected you to move away from the Chevy if you wanted a bigger motor to move your Luxury Land Yacht around town.

A BBC is not as efficient as the SBC on today's pump gas (it was designed to be a high compression race engine back in 1961 and it reacted baddly to dropping the compression down with open chambered heads) so to compensate you have to go bigger in displacement. The 454 is a good start especially when rebuilt as a 496 (costs the same to rebuild a 496 as it does a 454 with the exception of the crank).

If I where in your shoes I would pull the numbers matching original engine and tranny a save them for a future generation then stuff either a SBC 406 under the hood with 327 decals on it, or stuff a 496 in place of the 327 and call it a 427 (two out of three numbers are the same). Just remember what Stan Lee used to say "With great power comes" a greater need to cool it; or something like that (upgrade your radiator).

Big Dave
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post #8 of 33 (permalink) Old 02-25-2017, 01:31 PM
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If you drive the car any distance, the 3.73 gears are going to get old in a hurry. Engine rpm and associated noise and fuel consumption are much greater than with the 3.08's. If you're not concerned with long range driving or fuel consumption, the 3.73 gears would be my first change and see how you like that. It's about the least expensive mod to improve acceleration.

The TH 350 will give you a better gear ratio spread than the 2 speed powerglide, and the first gear ratio is a little deeper to help launch and gain rpm quicker but it isn't going to be a lot of improvement in acceleration.

A stall converter can help get the 2 ton tank moving quicker by letting the engine get to a higher torque range before engaging under full throttle start off. Under "normal" operation, it will still provide smooth starts at lower rpm.

Building a 383 out of a 327 is expensive and only practical with a '68-69 large journal block. Stroker cranks for the small journal are the expensive and harder to find component. If you want a 383, buy one done or build it from a 4 bolt main 350 block.

As for getting more power out of the 327, they are very responsive to better heads, cams and carburetion. You can buy aftermarket aluminum heads that will out-perform the stock cast heads for about what it costs to bring an old cast head to modern specs for crap fuel usage.

Strange as it sounds, an RV type cam will make more torque without sacrificing smooth idle, fuel mileage or street manners. On the street, torque is king, not necessarily hp. As the saying goes; Torque gets you moving, hp keeps you moving.

'62 Impala SS 409 TH350
'66 Chevelle SS 496 M20
'70 Chevelle SS 396 M20
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post #9 of 33 (permalink) Old 02-27-2017, 08:09 AM
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In my opinion the 308 gears are good overall. A little pick up but still good to cruise on the hwy with and decent mileage.
I just got done taking my 65 Pontiac catalina convertible from 241 to 259 to 273 to 323 gears. That wasnt planned but the 259 gear was bad. The 273 wasn't much better and when looking for parts found a complete 323 posi rear end. Overall very happy with the 323. And I snagged the whole unit for $300
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post #10 of 33 (permalink) Old 02-28-2017, 09:47 PM
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It would help to know what you're willing to spend and whether you're willing for the car to be down for a few days or a week.

I had a Powerglide/327 4 barrel combo (factory) in the gold SS in my profile picture. IMO, that tranny is a major detriment to that feeling of some power that you're looking for.
The 327 makes good HP, not a lot, and not a lot of torque really, but it's decent. That tranny is sucking it all away by making you start off in essentially, the equivalent of 2nd gear. (compared to a normal 3 speed).

Consider a tranny upgrade (especially the 700r4 or 4L60) and you may find that your motor does enough to keep you happy for quite a while. It's also a swap that's done in a single day!

I agree with the others that a 327 is low on torque for a 3900lb car so if you do decide to do any engine work I also vote moving up to a 350, preferably a 383. (I'm biased, my 383 and 3.42 gears is super nice, but does turn 3000rpm at 70mph on 275/60R17 tires.)

HOW A NOVICE REBUILDS A 66 IMPALA CONVERTIBLE:
http://www.impalas.net/forums/blog.php?u=1432
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post #11 of 33 (permalink) Old 02-28-2017, 09:53 PM
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Quote:
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It would help to know what you're willing to spend and whether you're willing for the car to be down for a few days or a week.

I had a Powerglide/327 4 barrel combo (factory) in the gold SS in my profile picture. IMO, that tranny is a major detriment to that feeling of some power that you're looking for.
The 327 makes good HP, not a lot, and not a lot of torque really, but it's decent. That tranny is sucking it all away by making you start off in essentially, the equivalent of 2nd gear. (compared to a normal 3 speed).

Consider a tranny upgrade (especially the 700r4 or 4L60) and you may find that your motor does enough to keep you happy for quite a while.


That is good to hear. Our tranny is about to get pulled. Depending on what I find, I am looking at replacing with either of these.
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post #12 of 33 (permalink) Old 03-02-2017, 06:05 AM
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Don't forget there is the 200-4r transmission too. May require less modification to the car and be cheaper than the intended 700r4. Should work fine for a mild 327, not sure if it's a good choice for a 383 though.
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post #13 of 33 (permalink) Old 03-02-2017, 07:03 AM
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Or fix it right and drop in a 4 speed or a 5 speed.
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post #14 of 33 (permalink) Old 03-02-2017, 10:51 AM
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Quote:
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Or fix it right and drop in a 4 speed or a 5 speed.
Agree 100%. A manual, even a 3 speed, will be MUCH more responsive and fun to drive. A 4 speed with 3.36 rear gears will be a significant improvement. Even if you keep the 3.08s, the car will drive like it's gotten a boost in the rear end.

If you opt for the 5 speed, make yourself aware of all the 'other' changes required.

There seems to be a good number of 327/powerglide owners who want 'more power' out of their engines. What they really need (assuming their engine is in proper condition and tune) is a drive train that they can put, and keep, the engine in its best power rpm range. That's not a power glide w/3.08.

If one still wants 'more', adding displacement is the most street friendly alternative. A 350, 383, or BBC, depending on where one's desires take them.
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post #15 of 33 (permalink) Old 03-05-2017, 01:46 AM
 
 
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Almost every SB I've had I started with Bolt-ons. But cost and goals are up to you. Be careful with a 5 speed. I grabbed one once and dropped it in Camaro after the 4 speed was lost.

It was like driving a pulp wood truck. A TH350 went in next weekend.

With a trans swap comes linkage and shifter issues. I'm sure others on this forums have sorted those out. You will need a new driveshaft made at your local driveline shop. Expect to give them a Frankin. Just "extras" to be aware of.

With a gear swap it's a give and take. The more you add to low end power the more you lose from highway power.

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post #16 of 33 (permalink) Old 03-05-2017, 10:08 AM
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People don't seem to understand that a 350 is a 350. It burns the same ratio of gas to air as every internal combustion gas engine from a Briggs and Stratton lawn mower to a 900 cube Pro Stock. The only way to make more horsepower per minute is to have more power strokes per minute. That means raising your RPM.

A long duration cam (to allow more time for the fluid that is air to flow into your motor in a minutes time) a larger cfm carb, and huge heads intake ports can allow more air into the engine. Air passing through your engine is what limits your power, not fuel (you can pour a five gallon can of gas into a running engine but it won't make more power it will hydro lock and break). This is why racers talk in terms of cfm not horse power. It is also the limiting factor on a BBC; the exhaust ports prevent air flow through the engine not the up stream side.

Problem with a high reving long duration cam and big heads is they only are efficient at high RPM which is not where you drive on the street. The ONLY way to have more power on the street is to build a bigger engine. It is the American way! European's routinely achieve two horsepower per cubic inch (the Japanese are good at copying them), but it is in a small two or three liter engine. The smallest American V-8 is a five liter but they rarely ever make even one hose per cube (exceptions being the Camaro Z/28 302 or a Boss 302 from Ford).

This is the reason I build my street engines starting with a 4.5 inch bore BBC Dart Big M block and then usually bore it 0.100 inches over, to get a 4.6 inch bore. This starts me off with a 540 cid (with a 4.5" bore) or a 555 (if I go 4.6 inch bore) with a 4.25 inch stroke crank. Strech the crank out to 4.75 inches and I have a 632 that will out put nearly a thousand horsepower on pump gas below 4,500 rpm and enough torque such that there aren't tires big enough to hold it on the street. (you can have too much power).

In your case I would build a 406 or larger small block (to go larger you really need an aftermarket block to build on). 400 cubes is about as large as you can go with a small block. It is the same bore and stroke as the BBC 402 engine (the BBC has a 3.760 inch stroke instead of the SBC 400's 3.750 inch stroke with the extra hundredth of an inch of stroke yielding two cubes more displacement).

Problem with big small blocks is you rapidly approach the design limits of the stock block (I broke my 406 into two pieces after seven years of ear to ear fun).And as you build an all aftermarket SBC to gain reliability the costs approach that of a BBC build that makes less power per cube but makers up for that inefficiency by being much larger in displacement. My last engine was a 582 displacement in an 1985 Impala four door that turned 9.39 in the quarter and I drove it daily on the street.



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post #17 of 33 (permalink) Old 09-09-2017, 01:22 AM
 
 
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I'm in the same boat. I intend to pull the 327 and store it in case I want to return to stock in the future. I am choosing between a 383 or a 496. Obviously the 383 will be cheaper and easier, but there is something special about a big car with a big block. I'm hoping that the popularity of the LS may have driven the price of big blocks down. Since I have a 68 I've got a th400 and 12 bolt so that should help make thing a little easier. Ultimately I want torque, and more power than my 2015 Ram 1500, so that means 400+ hp and torque.

Simon
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post #18 of 33 (permalink) Old 09-10-2017, 01:39 PM
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Can't believe the LS motors haven't been brought up. 500 horse is easy to make! 25 MPG $500 junkyard 4.8 or 5.3L truck motor. If you want more power go buy a turbo kit for $2K

Why go backwards in technology??

Brian

1968 Impala SS Fastback 383 stroker
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post #19 of 33 (permalink) Old 09-10-2017, 02:42 PM
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Can't believe the LS motors haven't been brought up. 500 horse is easy to make! 25 MPG $500 junkyard 4.8 or 5.3L truck motor. If you want more power go buy a turbo kit for $2K

Why go backwards in technology??

The 5.3L is still a 327 (324 actual) so it is still limited in torque. Most of the horsepower gain came from the heads, not so much the size of the ports but the fact that the heads are on a 15 degree angle that raises the ports for a straighter shot at the valve.

The SB2.2 engine that used to power NASCAR has 12 degree heads, so they make even more power using a standard SBC bottom end that is dirt cheap by comparison (of course the heads cost an arm and leg, but not as much as the cost of an LS conversion).

The only thing the SBC Gen IV and V have going for it, is it's variable cam timing, combined with direct port injection. The reason the factory settled on a 23 degree head is because the ports are wet with gas and they can not change shape of direction quickly or the gas would fall out of suspension. With direct port injection the gas doesn't enter the chamber very far from the valve or in the cylinder along side a spark plug. Add computer controlled ignition to retard timing on the fly and gas enrichment on the fly so that you can build a motor to run at the cutting edge of detonation safely. You can not do that with fixed timing and a carb.

Carb is still much easier to tune and it will make more absolute power than EFI, just won't idle or be as easy to start. But since I haven't hand cranked an engine in decades I don't worry about hard starting or idle quality.

To make torque with today's fuel you have to go larger. All EFI motors are small blocks with a 348 being the normal big engine now since they have dropped the 6.0L and 6.2L motors (the LS7 427 cost more than a 632 big block; which out performs it in every category except fuel economy). And a 632 looks better doing it: not being covered up to hide all of the wiring and tubes required to allow the LS-x live at the bleeding edge of technology.

Big Dave
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post #20 of 33 (permalink) Old 09-10-2017, 04:17 PM
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Wow! Where do I start.

At 15lbs of boost on a 5.3l LS motor the cubic inch displacement doubles. AKA: 648 CID
15lbs. of boost is nothing in a 6 bolt block that has a crank that will handle 1000 hp in stock form. Upgrade
the pistons/rods and the skies the limit with boost. Install a progressive methanol injection system and I use to run 23 lbs of boost on street gas (87 octane) in a Buick V6.

While you are getting about 10 mpg in a 496 BBC I'm getting 25, 26, 27mpg on the street. And guess what?? I can make just as much horsepower/torque as the BBC while tipping the scales about 300 pounds lighter.

It's easier to tune a carb??? Really??? You can tell when the carb is a little rich at 4600 rpm in cylinder 3 at 200 rpm increments??? You can tell whether the carb is leaning out on cylinder 1 at 6800rpm?? With the new FAST systems you can look at EVERY cylinder and tune fuel, spark, etc. A little rich at a certain RPM and you take a little fuel out of it. Getting a little spark knock at a certain RPM take some timing out of it. Fuel and Spark maps are the future and are light years ahead of carb tuning.

Nitrous, Turbo's and Blowers are the great equalizers in modern day motors. No need to have massive CID motors. I will admit a BBC does look awesome in an old classic.

Listen, I like BBC's too. My first exposure was my uncle's LS6 1970 Chevelle. Loved that car but to say that
the BBC is superior to other engine combinations is just wrong.

Brian

1968 Impala SS Fastback 383 stroker
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post #21 of 33 (permalink) Old 09-10-2017, 06:17 PM
 
 
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I agree that the LS motors are excellent motors, and have alot of potential, and generally are the cheapest way to make power. Turbos and efi are more expensive than carbs, and can get complicated quite quickly. In mt case my car is going to be a cruiser, and I'd like to run mid 12's in the quarter so I can have some fun but not invest heavily in safety gear. Personally I'm sticking with a small block or a big block because they suit my car better, and I can build one to meet my goals. With the LS becoming so popular in all it's forms they are climbing in price, and there are deals to be had on the older engines and speed parts.

Also I am building a street engine, so I want my torque lower in the power band, and in that respect BBC beats the LS all day long.
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post #22 of 33 (permalink) Old 09-12-2017, 10:53 AM
 
 
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Wow, lots of expensive options being thrown around here, when some simple bolt-ons to a 327 or 350 will do the trick.

I bought a 65 Impala a couple of months ago. It had a 283/2-bbl, 3.36 gears, and a TH350.





I immediately installed a very basic 355ci small block. Specs are;

2-bolt block .030 over, cast crank, stock roods, inexpensive cast flat-top rebuilder pistons
Now here is the key - a set of EQ heads (Engine Quest - essentially a new reproduction of Chevy Vortec cstings)
64cc EQ heads - 10:1 compression
Mild Lunati hydraulic roller cam, duration @ .050 = 219/227
Edelbrock Performer RPM intake, Holley 4bbl, headers, 2000 stall

This engine runs on 93 unleaded, idles so smoothly you would think it has a stock cam, and is a total pleasure to drive on the street with the mild 3.36 gears.

After two trips to the track to sort things out, I have already run a best of 13.93 @ 100mph in the 1/4 mile. When I am done optimizing distributor curving, carb tuning, and transmission shift points, I expect 13.50's or quicker at 102-103mph.

So, after that somewhat long-winded answer, you can go very quick with a 327 or 350 with basic bolt-ons (heads and cam).
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post #23 of 33 (permalink) Old 09-12-2017, 10:59 AM
 
 
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Here is the engine I was just describing. The new, fully assembled EQ heads were $830 delivered to my doorstep at home.





Add good heads, cam, intake, carb, & headers to a stock 327 or 350, maintain the old-school SBC look under your hood, and go enjoy your car. No LS motor, stroker, turbo, overdrive transmission, nor any of that other stuff required
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post #24 of 33 (permalink) Old 03-02-2018, 03:13 PM
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enjoyed the read.

For my 1961, a friend of mine recommended a 400 crate with a throttle body injection.

283 is in the beasty right now ... at the restoration shop ... so I'm looking at options. VIN/plates are non-factor as the quadrajet and heads aren't original on it right now anyway. Do have a sentimental attachment to the 283 ... late Father overhauled it in 85 ... it probably doesn't have 40K miles on it but could be "locked" as it's sat for 20+ years.

Any thoughts on a 400 with a 700r4 behind it?

1961 Impala. 4 door. 283, turbo 350. Imron Midnight blue metallic with silver stripe.

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post #25 of 33 (permalink) Old 03-02-2018, 04:01 PM
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Are you talking a stroker 350 built into a 400 or a true, vintage 400 block ? The 400's had some cooling problems because the passages in the block to head were smaller because of the large cylinder. A street built 383 makes for plenty of excitement when the loud pedal is pushed and are reasonably priced too.
Too bad you are on the other end of the country. I have a friend who builds engines and currently has a sweet 355 with Dart aluminum heads that dyno'd at 375 hp and 430 torque for $3500.
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'62 Impala SS 409 TH350
'66 Chevelle SS 496 M20
'70 Chevelle SS 396 M20
'67 Camaro ss/rs 350 PG
'38 Chev coupe street rod
'54 Chev 210 2 door
'69 Chev C10
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