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Old 04-28-2013, 01:53 PM   #1 (permalink)
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'71 El Camino is a GAS HOG!

Hello,
New to the EcoModder community. I was expecting to see a bunch of hippies (no offense) on this forum, however digging deeper it seems like the rest of you guys are fed up with paying high prices for gas as well.

Anyway, I picked up my '71 El Camino a couple of months ago for $3400. The car so far has needed minimum investment to have it running, but it's certainly not optimized. Right now I am getting 8mpg, mostly city driving and short commutes to and from school and work (less than 5 miles each way).

Two things I am sure need changing are carburetor and intake. The current 2 barrel Rochester 2 Jet gets dirty pretty quickly and I'm pretty sure its coming from the PCV valve that goes into my intake, PCV is getting changed when the part arrives. Carburetor's choke isn't working right either.

The second one is a wheel alignment, not sure how much of a gas killer that is but it pulls to the left.

That being said, thanks for listening. I know, I shouldn't be expecting incredible mileage but if I can get close to 15mpg like I was getting in my Crown Victoria I would be ecstatic.
-Mike



Don't worry, the loose tailpipe on a chain was fixed immediately!

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Old 04-28-2013, 04:37 PM   #2 (permalink)
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15? You need to set the bar higher. Back in the day my '74 Nova got low-mid 20's.
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Old 04-28-2013, 05:10 PM   #3 (permalink)
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Quote:
Originally Posted by Frank Lee View Post
15? You need to set the bar higher. Back in the day my '74 Nova got low-mid 20's.
What did your setup look like? I'm amazed I'm getting this mileage with a 2bbl
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Old 04-28-2013, 06:42 PM   #4 (permalink)
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I'm amazed too. It had a 2bbl Rochester, TH350.

My '59 Bel Air, 283, 2bbl, Powerglide gets low 20's too. However my driving is not intense city like yours.

8 mpg indicates something is very wrong. Could be the driving, could be not running on all 8, who knows. No burnouts or stoplight gran prix are allowed if you are seeking to maximize your economy.

You suspect alignment cuz it pulls left, but if the tire wear is even then I'd say your front left brake caliper is not releasing. Jack it up and see how easy the wheel spins. Check 'em all. Make sure the tires are all aired up properly.

Put a manual choke in. Or in CA you should be able to disable the choke altogether. The 59's choke is disabled; I just pump a few times to start. It hasn't been an issue (thus my failure to fix it or add a manual choke).

There is probably nothing wrong with the intake, although the crossover passage for intake heating could be plugged up. That would hurt mileage. There is also a crossover thermostatically controlled valve in the exhaust system that needs to be freely working if that warming system is to be functional.

It is said that a 4bbl can achieve better fuel economy than a 2bbl IF you can stay outta the secondaries. I haven't tested that theory.

You suspect excess PCV contamination. Maybe there's a stuck piston ring, or excessive wear throughout. Do compression and leak-down tests.

Maybe it's flooding. They can flood and still manage to run decently. Could be a hung-up or not floating carb float.

Could even be a fuel leak somewhere.

Does the motor oil stay clean or does it get diluted thin with gas?

Your trips are too short. That big V8 lump is not getting to operating temp. NO I'M NOT SUGGESTING YOU LET IT SIT THERE IDLING TO "WARM UP". The big old carb'd stuff was simply far worse in that respect than today's EFI stuff. To mitigate it some you can use a block heater, engine compartment blanket, convert to e-fan, perhaps some grille blocking, perhaps a warmer t-stat.

But seriously- trips of only a couple miles are better done on bicycles, scooters, or any number of things more suited for the task. What you have is a hobby car more than a daily driver.
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Old 04-29-2013, 03:01 AM   #5 (permalink)
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Quote:
Originally Posted by Frank Lee View Post
I'm amazed too. It had a 2bbl Rochester, TH350.

My '59 Bel Air, 283, 2bbl, Powerglide gets low 20's too. However my driving is not intense city like yours.

8 mpg indicates something is very wrong. Could be the driving, could be not running on all 8, who knows. No burnouts or stoplight gran prix are allowed if you are seeking to maximize your economy.

You suspect alignment cuz it pulls left, but if the tire wear is even then I'd say your front left brake caliper is not releasing. Jack it up and see how easy the wheel spins. Check 'em all. Make sure the tires are all aired up properly.

Put a manual choke in. Or in CA you should be able to disable the choke altogether. The 59's choke is disabled; I just pump a few times to start. It hasn't been an issue (thus my failure to fix it or add a manual choke).

There is probably nothing wrong with the intake, although the crossover passage for intake heating could be plugged up. That would hurt mileage. There is also a crossover thermostatically controlled valve in the exhaust system that needs to be freely working if that warming system is to be functional.

It is said that a 4bbl can achieve better fuel economy than a 2bbl IF you can stay outta the secondaries. I haven't tested that theory.

You suspect excess PCV contamination. Maybe there's a stuck piston ring, or excessive wear throughout. Do compression and leak-down tests.

Maybe it's flooding. They can flood and still manage to run decently. Could be a hung-up or not floating carb float.

Could even be a fuel leak somewhere.

Does the motor oil stay clean or does it get diluted thin with gas?

Your trips are too short. That big V8 lump is not getting to operating temp. NO I'M NOT SUGGESTING YOU LET IT SIT THERE IDLING TO "WARM UP". The big old carb'd stuff was simply far worse in that respect than today's EFI stuff. To mitigate it some you can use a block heater, engine compartment blanket, convert to e-fan, perhaps some grille blocking, perhaps a warmer t-stat.

But seriously- trips of only a couple miles are better done on bicycles, scooters, or any number of things more suited for the task. What you have is a hobby car more than a daily driver.
Frank, this is all good stuff. I'll diagnose all this ASAP. thanks again!
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Old 04-29-2013, 04:38 AM   #6 (permalink)
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Quote:
Originally Posted by Frank Lee View Post
15? You need to set the bar higher. Back in the day my '74 Nova got low-mid 20's.
San Fran is pretty hilly. I can only imagine - full sized car with V-8, short enough trip not to warm up, extra gas to go up a hill, then stoplight. Extra gas again, then another light.... Or the other way, DOWNHILL to stoplight, BRAKE. down to the next stoplight - BRAKE.

Yeah, I can see 8 .... and in those conditions, 15 would be super-human!!! (super-car? - no, that would be a Lamborghini or Veyron - - ????)

(guess that's where a hybrid would really shine, huh?)
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Old 04-29-2013, 04:49 AM   #7 (permalink)
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Quote:
Originally Posted by wmjinman View Post
San Fran is pretty hilly. I can only imagine - full sized car with V-8, short enough trip not to warm up, extra gas to go up a hill, then stoplight. Extra gas again, then another light.... Or the other way, DOWNHILL to stoplight, BRAKE. down to the next stoplight - BRAKE.

Yeah, I can see 8 .... and in those conditions, 15 would be super-human!!! (super-car? - no, that would be a Lamborghini or Veyron - - ????)

(guess that's where a hybrid would really shine, huh?)
Hills, hills everywhere! Hence why I'd be ecstatic to get the 15mpg I was used to in my '99 Crown Vic. My '86 Cutlass with a 307 V8 and 200r4 got comparable mileage to the '71 with a 350/350. Dunno what gives
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Old 04-29-2013, 05:26 AM   #8 (permalink)
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Could be this is your hint to break the V8 addiction.
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Old 04-29-2013, 09:07 AM   #9 (permalink)
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frank I was thinking the exact same thing!!!!
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Old 04-29-2013, 06:36 PM   #10 (permalink)
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Let's not get too hasty now. I do admit, I grew up with these cars so NOT having a V8 is something of a blasphemy. My overall goal is to get what I think is decent mileage (for a V8) and still get raw V8 power (cuz horsepower & torque is fun). Enough to haul some landscaping tools, which is the trade I'm going into. Frank, I do thank you for the insight though.

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