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  #1  
Old 04-04-2008, 11:36 AM
TXPONTIAC66 TXPONTIAC66 is offline
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Default Gas Mileage for a 327

Just wondering what the estimate gas mileage would be for a 327 275hp running the rochester 2 barrel carb. My odometer is shot so theres no way I can really tell. My guess would be about 12mpg around town and possibly up to 14/15mpg on the highway. I don't currently have my shop manual but after filling up the other day I put about 14 gallons in. So on a 66' are they about 17 gallon fuel tanks? Even rough estimations are encouraged, Thanks
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  #2  
Old 04-04-2008, 04:00 PM
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I had a 66 Chevelle 327/275h.p., 4bbl. and a 4spd.
I averaged 18mpg.
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Old 04-04-2008, 08:19 PM
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with the right overall combination 15-17 in town and 21-23 on the road is not out of hte question. it also takes a proper driving style as well. i would however say that on average you will proably see something like 14 in town and 19-20 on the road with an average tune.
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Old 04-04-2008, 11:08 PM
TXPONTIAC66 TXPONTIAC66 is offline
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Much better than I initially expected then, thats good news, Installed a new TH350 tranny over the stock powerglide which should help also. But after installing a 4 barrel edelbrock and manifold it should decrease slightly as well. Thanks guys!
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Old 04-06-2008, 07:22 AM
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Default mileage

A big factor would be what rear gear you have. The glide and TH350 both final at 1:1.
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Old 04-06-2008, 12:53 PM
TXPONTIAC66 TXPONTIAC66 is offline
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Default Re: mileage

Quote:
Originally Posted by CANTED
A big factor would be what rear gear you have. The glide and TH350 both final at 1:1.
I actually have no idea, whats a good way to check? I've searched online for rear end options for the 66 but havent been able to come up with anything.
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Old 04-06-2008, 06:09 PM
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You can pull the cover and count the teeth on the pinion and the ring gear, then divide. Or mark the driveshaft with chalk and count how many revolutions it turns for one revolution of the wheel, that will get you close enough to tell.
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Old 04-09-2008, 08:43 AM
dovehunter dovehunter is offline
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Default Re: Gas Mileage for a 327

Quote:
Originally Posted by TXPONTIAC66
Just wondering what the estimate gas mileage would be for a 327 275hp running the rochester 2 barrel carb. My odometer is shot so theres no way I can really tell. My guess would be about 12mpg around town and possibly up to 14/15mpg on the highway. I don't currently have my shop manual but after filling up the other day I put about 14 gallons in. So on a 66' are they about 17 gallon fuel tanks? Even rough estimations are encouraged, Thanks
Looking at my Chiltons manual, in 66 the only 2bbl V8 listed was a 283 @ 195HP. The 327 with 275HP had a 4bbl. Was this motor a replacement or a put together motor? Look on the right side of the block "pad at right-hand side of cylinder block" & see what the engine ID code is, the code letters follows after the S/N. If the first of the letters starts with a "D" its a 283, if its starts with a "E" its a 327 per the 66 info guide.

Look at the S/N on the plate at the left front door hinge pillar. The numbers 13380 tells if was standard model with 6 cylinder & number 13480 is a standard model with a V8. Number 13580 is the Deluxe model with a 6 cylinder & 13680 is the Deluxe model with a V8.

In 66 the Chevelle had a 20gal. gas tank.

My book does not show rearend ratios, but most back then came with the standard 308.
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Old 04-09-2008, 11:26 AM
TXPONTIAC66 TXPONTIAC66 is offline
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Default Re: Gas Mileage for a 327

Quote:
Originally Posted by dovehunter
Quote:
Originally Posted by TXPONTIAC66
Just wondering what the estimate gas mileage would be for a 327 275hp running the rochester 2 barrel carb. My odometer is shot so theres no way I can really tell. My guess would be about 12mpg around town and possibly up to 14/15mpg on the highway. I don't currently have my shop manual but after filling up the other day I put about 14 gallons in. So on a 66' are they about 17 gallon fuel tanks? Even rough estimations are encouraged, Thanks
Looking at my Chiltons manual, in 66 the only 2bbl V8 listed was a 283 @ 195HP. The 327 with 275HP had a 4bbl. Was this motor a replacement or a put together motor? Look on the right side of the block "pad at right-hand side of cylinder block" & see what the engine ID code is, the code letters follows after the S/N. If the first of the letters starts with a "D" its a 283, if its starts with a "E" its a 327 per the 66 info guide.

Look at the S/N on the plate at the left front door hinge pillar. The numbers 13380 tells if was standard model with 6 cylinder & number 13480 is a standard model with a V8. Number 13580 is the Deluxe model with a 6 cylinder & 13680 is the Deluxe model with a V8.

In 66 the Chevelle had a 20gal. gas tank.

My book does not show rearend ratios, but most back then came with the standard 308.


The engine ID is as follows, T03I6HCR
The VIN, 136806K109801
So the 13680 tells me it was a deluxe model, but what differentiated a deluxe model from other models, The car has A/C but other than that im not quite sure what other options would have made the car distinct from other el caminos in 1966.
This should be the original motor that came with the automobile as the previous owner assured me and the car had been in their family since brand new. Probably what I should do is find out where I can get a copy of the Build sheet through Chevy, not quite sure where to go about that however. Also, the car has the original 327 badging, maybe the original dealership replaced the 2bbl with a 4bbl?
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Old 04-09-2008, 07:54 PM
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My book only goes up to 1970. All the motor letters at the end of the S/N shows only two letters. Yours is showing HCR... I looked & found the letters HC in the Chevrolet section (Impala) & it was for a 327, the only 327 with a 2bbl. shown was in 1969 & had 235HP.

The Deluxe model might have had some trim on the body &/or upgraded interior.
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Old 04-09-2008, 08:14 PM
TXPONTIAC66 TXPONTIAC66 is offline
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Thanks for the help Dovehunter, once I get some more time I'll research this thing some more and see what I can find out.
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Old 04-11-2008, 03:43 PM
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The cam and the vehicle weight will have a lot of bearing on the question as well. Assuming you're talking stock cam and a roughly 3500 pound Elky, a tame (say 2.73 to 3.55) ring and pinion ratio and a 1:1 tranny, I'd think getting over 20 MPG on a Rochester 2 barrel would be a near miracle. Something like 13 around town and 18 on the highway (at 55 MPH max) would be my guess. Increase the R&P ratio, the tire width and the speed driven and you'll be lucky to see 14MPG highway (IMO). My lighter, 2.73:1 rear geared 68 Camaro only got about 18MPG at 60MPH highway and about 10 to 12 MPG in town (Powerglide tranny).
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Old 04-11-2008, 06:12 PM
TXPONTIAC66 TXPONTIAC66 is offline
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It's got a 3.08 in the rear, I just installed a TH350 tranny and also installed an edelbrock 600 cfm carb with a performer rpm manifold. I think i would be lucky to get 15 mpg on the highway but until I fix this odometer theres really no telling.
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