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Old 04-23-2008, 02:24 PM
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'67 Camaro, 327 rebuild for gas mileage - Help

I'm trying to get my '67 Camaro to be a daily driver... and with the gas prices the way they are, gas mileage is a big concern when building my engine.

I'm thinking of rebuilding the stock 327 that came with the car (numbers matching)... it needs to get rebuilt anyways, so mind as well use it.

So my question is... what parts would you use on the 327 block to help it achieve good gas mileage? Transmission will probably be a TKO500.

Thanks!

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Old 04-23-2008, 02:40 PM
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9:1 pistons,edelbrock performer cam,vortec heads,performer intake,Q-jet carb.Gearing is half of it though
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Old 04-23-2008, 04:02 PM
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I would change the transmission to a 5 speed overdrive
Rochester 4 barrel carb is the best for fuel economy and power.
The primary are smaller then a two barrel. Get a cam with lots of torque at the low RPM range. No higher the 4000 RPM. Hope this helps.
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Old 04-23-2008, 04:06 PM
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Thanks to both of you, this is exactly what I'm looking for.

I thought the TKO500 had overdrive?
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Old 04-23-2008, 04:19 PM
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8.5 to 9.0:1 with hypers or cast pistons and 0.035" squish.
Isky 201256 cam with matching springs, shims. 0.425", 202/202, 112 LSA.
Any heads will work because the cam is all done by 4500.
Stock cast iron intake with Quadrajet.
1 1/2" primary tube headers with small collector. 2" pipes with X or H pipe.
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Old 04-23-2008, 04:25 PM
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I second tech inspector especially on the smaller pipes that does help on these applications
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Old 04-24-2008, 08:01 AM
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I forgot to mention this. Get a high energy ignition system like a Mallory unilite or MSD. also get some roller rockers and roller cam to reduce friction. Electric fan. With this combo, it should free up some horsepower. Fuel Injection is not a bad option. Do not use cast iron Qjet intake because it adds weight. aluminum Qjet high rise manifold is better way to go. It depends on the money you willing to spend. Fiber glass hood will help, too. TKO500 has overdrive, by all mean, use it.

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Old 04-24-2008, 10:04 AM
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Quote:
Originally Posted by lg1969
I forgot to mention this. Get a high energy ignition system like a Mallory unilite or MSD. also get some roller rockers and roller cam to reduce friction. Electric fan. With this combo, it should free up some horsepower. Fuel Injection is not a bad option. Do not use cast iron Qjet intake because it adds weight. aluminum Qjet high rise manifold is better way to go. It depends on the money you willing to spend. Fiber glass hood will help, too. TKO500 has overdrive, by all mean, use it.

Don't use a roller cam for this application.. its just a complete waste of money. Roller rockers would be too if you already have a good set of rockers- I would suggest using roller tipped rockers as they are relatively cheap and easier on valve stems. The weight of this viehicle is not a huge problem, don't worry about that, you drag is what will kill you.

For a camshaft recomendation I'd go with the Lunati 60100LK, it has a few degrees more duration at .050" which may shave a perctent off your milage, but it'll give you better perforamance and I'm sure you don't want this Camaro to be a complete dog. Also with running 9:1 (or slightly over it) you should have no problem running on the cheap gas, and you can add a nice 125 shot of nitrous for when you want to go play.
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Old 04-24-2008, 05:39 PM
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Quote:
Originally Posted by lg1969
I forgot to mention this. Get a high energy ignition system like a Mallory unilite or MSD. also get some roller rockers and roller cam to reduce friction. Electric fan. With this combo, it should free up some horsepower. Fuel Injection is not a bad option. Do not use cast iron Qjet intake because it adds weight. aluminum Qjet high rise manifold is better way to go. It depends on the money you willing to spend. Fiber glass hood will help, too. TKO500 has overdrive, by all mean, use it.
While I agree with the high energy ignition (an HEI curved at 22* centrifugal (all in by 2,800) with 14* initial and 14* to 16* vacuum will work great in my opinion), I have to disagree with the high rise manifold. The whole idea of this build is to make power from idle to about 4,500. The weight penalty of the cast iron manifold will be insignificant compared to the reduced cylinder filling afforded by the increased volume of a high rise manifold. Low volume and small runners are the key here to keeping vacuum high, resulting in increased velocity to fill the cylinders at low rpm's up to 4,500. The roller cam and rockers are of course a function of the builder's budget. Of course they would help, but would the small increase in power due to decreased friction pay for the cost of them against how much fuel could be purchased with the same money? I also don't care for electric fans, preferring instead to use a 18" steel OEM fan with thermostatically controlled fan clutch and full shroud. Bulletproof. You may think the electric fan is more efficient, but consider that it takes the same amount of electrical power to move the same amount of air as you can move mechanically. The electric fan just shifts the load to the alternator, which is ultimately driven by the crankshaft just as a mechanical fan is.
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Old 04-24-2008, 07:44 PM
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I agree a hise rise would be much being he needs cylinder filling at those cam/compression levels,if not the iron intake at most a performer Ive used cylcone intakes with good results from professional products,it was cheaper than a performer and it was polished.
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Old 04-24-2008, 09:24 PM
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Quote:
Originally Posted by 67camaro327
I'm trying to get my '67 Camaro to be a daily driver... and with the gas prices the way they are, gas mileage is a big concern when building my engine.

I'm thinking of rebuilding the stock 327 that came with the car (numbers matching)... it needs to get rebuilt anyways, so mind as well use it.

So my question is... what parts would you use on the 327 block to help it achieve good gas mileage? Transmission will probably be a TKO500.

Thanks!
Do you know which ratio set your TKO has. The lower the low the better the launch which if you need to do a lot of stop and go the better that will be for gas mileage. However, if you cruise a lot at highway speeds you want as much OD as you can get.

How committed are you to number matching parts? The key to good highway mileage is the lowest revs possible to carry the load with the least restriction from parasitic losses and the best possible combustion characteristics. This doesn't necessarily take you in the classic hot rod direction. While small tube headers and dual exhausts with not more than 1&3/4 to 2 inch pipes will help the exhaust flow at low thru moderate RPMs, big port and valves will work in the opposite direction. To finish the exhaust thought, however, you want to dump behind and under the rear bumper. This is a natural low pressure area and will minimize the work the engine has to perform to dump exhaust out. It also puts the noise behind you which makes listening to the stereo a lot easier.

Now I'm going to recommend heads that go in a really different direction. Most everyone will recommend Vortecs, I don't in this instance as the larger more efficient ports reduce torque and horsepower on the bottom thru mid RPMs, right where you need it for good mileage. If your not going to use the stock 327 head I'd highly recommend the Swirl Port truck head from the late 80s thru mid 90s. It is intended to enhance low RPM chamber turbulance which is very important when trying to extract useful power and economy with a carburetor, these were OEM production on vehicles with TBI injection which fuels the engine most like a carb and needs many of the same characteristics from a manifold and heads as a high efficiency carbed engine turning at modest RPMs like a 70 mph cruise with 2000 RPMs. Yes this will knock down the top end above 4000, but if you're turning those kind of revs then saving gas money certainly isn't at the top of your priority list. Fuel injection would really increase economy over a carb but I'm not convinced that the cost and complication would have a payback in less than 3 to 5 years.

Compression is most important to good economy and combustion chamber design is not only important to economy but is a prime element in suppression of detonation. The better the design the lower the octane fuel you have to feed the thing for a given compression. The Swirl-Port head has a lot of modern head features such as the spark plug located toward the center of the cylinder favoring the exhaust valve side, a small tight chamber and a large squish/quench deck. The latter is most important in factoring good fuel economy and detonation resistance. However, Chevy likes to use a dished piston to reduce compression. The dish results in excessive distance between the squish/quench deck and the piston making both functions lazy. You want closure here at about .040 to .060 inch. .025 of that is already in the block to piston unless you zero decked the block, another .020 or more is in the gasket, so having that plus a dish of .050 to .080 really makes squish/quench weak. This was OK when gas was cheap and octane high, now its the kiss of inefficiency and perhaps death to the engine today. You need to compute your static compression very carefully and if a dish is required to get it down around 9.2 or so then you want a piston with a "D" shaped dish which is a design that keeps a flat surface by the squish/quench side and the relief by the valve pocket where it doesn't ruin the head's combustion characteristics.

Cam, for mileage less is better, yeah it cuts out the top end power but this is a place where you can't have it both ways. Especially with carburation, long duration cams with small LSA angles and late closing intakes play hell with fuel economy, that's the way it is. High lift messes things up as well, the key to good economy with a carb is high port velocity and short cam timing. That means heads and manifolds with smallish ports and valves and cams with early closing intakes and a lot of LSA. The latter two conditions allow two conditions not conducive to good mileage. The late closing intake allows lower RPM reverse pumping back thru the carb. Now the carb doesn't really care which way the air flows thru the venturi, it adds fuel if it's goin' in or comin' out. On overlap the exhaust and intake are both open so mixture just whips on out the exhaust. The Swirl-Port will help both these situations by providing a restriction to reverse flow of the mixture while adding a spin past the open exhaust valve. This can be helped by sinking the exhaust valve a little when you have the seats refurbished. But keeping the cam's LSA at 112 degrees or more is what really does the trick.

The Q-jet is a better choice for mileage. A metering rod type carb can be held closer to optimum mixture ratios over a broader range than freely jetted carb like a Holley. Typically the Q-Jet will see a couple miles to the gallon or more over a well tuned Holley. You can dial the Holley in closer, but you'll sweat blood getting and keeping it there.

So we want:

- A low RPM motor at cruise

- A sturdy low tranny gear for a good launch without a lot of throttle (torque multiplication)

- Smallish long tube headers 1&1/2 to 1&5/8s at the biggest.

- Smallish duals to reduce backpressure but still keep velocities up in the pipes 1&3/4s to 2 inches tops. With an H or X pipe crossover.

- High Swirl heads with a centered sparkplug smallish ports 150 to 180cc smallish valves 1.9 intake 1.5 to 1.6 exhaust. Reasonably good compression in the range of 8.7 to 9.2. Lots of squish/quench.

- A decent intake with smallish intake and exhaust ports to keep velocity up at low cruise RPMs. A 180 degree type is demended. You want an exhaust heated intake, this keep fuel from pooling on the bottom of the intake at low RPMs.

- A carb that uses metering rods for close mixture control O-Jet or Carter AFB type.

- Fairly mild cam action, lift not over .45 if that. Durations close to 190 degrees measured at .050 inch lift. LSA of 112 to 116 degrees. Modern roller type OEM cam would be nice but up dating a flat tappet block is a PIA.

- Good combustion characteristics well managed by piston crown shape, either a flat top or a "D" dish which ever keeps compression in the 8.7 to 9.2 range.

- You want an engine that doesn't get hotter than 190 degrees to help keep detonation under control with high compression and a lean mixture. this probably mens a vist to the radiator shop.

Bogie
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Old 05-21-2008, 06:09 AM
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no substitute for cubic inchs
 
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wow

do you guys in the us have lp gas at all that would be my option if i wanted to drive my 68 rs ss everyday. petrol here is $1.50 a litre. lp gas is about .60 cents a litre heaps cheaper if you do heaps of miles i used to have a 72 hq holden monaro similar to a camaro that ran twin gas converters and a bigger line it got 400 kms to a tank of gas about 60 litres. and still would rip a skid into top gear and ran 8.30 1 eighth of a mile time. and it was a holden 308 5ltr motor i think i would look at the lp direction. let me know what you think. sean
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Old 05-21-2008, 06:32 AM
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Overdrive, and a lite foot, torquer cam, some sort of small port heads that have 194 intakes.
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Old 05-21-2008, 07:13 AM
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lp gas....

Hi,here in North Florida,i just filled my propane tank, (for my standby generator) as a new customer,the price was $2.19.9 per gallon,at the next fillup (in about 1 1/2 years the price will be (at todays cost) $4.90 per gallon. not any cheaper than gasoline.
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Old 05-21-2008, 06:27 PM
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no substitute for cubic inchs
 
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ok but it still works out at 57 cents a litre at 2.19 a gallon. and 77 cents at 4.90 a gallon. if gas is not an option i would go for the factory 350 hp cam 222@50 447 lift. edelbrock performer manifold holley 600 vac carb and a set of feullie heads. 9-1 comp would be heaps it will still perform well and drive good. run a 3.08 final drive with the overdrive box it will be good on the highway
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