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1974, 350 emisions=lack of power?

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buck.wheat

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Discussion starter · #1 ·
i know that the late 70''s models had emisions controls on them but some people say that you can just switch a few things like new headers and exhaust and it will be like the old 350's. and some peaple say that you have to do alot to get horse up and then there is some people that say you cannot!!! internet= a love and hate relationship. but which is true? im looking at getting one and would like to know before i buy one. thank ya much
 
#2 ·
early 70's engines had higher compression, better cams, and better flowing heads. You can make a E-motor run better by removing the E-crap. But to truly make them run like the older ones, You need to swap heads, cam and get the Comp. up to at least 9.5:1.
 
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#4 ·
Back as far as '66 they were using smog pumps in some applications.
California L79 Chevy II for one. Our '69 L72 came with very lean #68 primary jets and a retarded, slow advance curve. Optimizing the jetting and advance will help performance some without affecting the visual test. Won't pass the emissions tests though.
 
#5 ·
A lot of the '73 and up cars had REALLY high gearing too (2.40s, etc.) which really made the cars dogs. A simple gear change would certainly help a ton. Of course the smog motors would run out of breath around 4-4500 rpms but IMO it was a better trade off.
 
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Discussion starter · #6 ·
well are you saying that it would be against the law to drive a oh say 1968 gto around because im sure that would not pass the test? elaborate please on how they have basicly no smog stuff but they would pass today? maybe i am understanding this wrong.
 
#8 · (Edited)
Scott,Well kinda/almost,1970 was the last yr for higher compression with GM/Chevy,then in 1971 they dropped all comp ratios in general across board in GM.

1974 350sbc in stock form even in vette & z28 were slugs,low power /trq output.

I beleive the base (or only) 350 avil in a vett in 1974-75 was approx 165hp net ,gross hp is approx 200-210hp maybe 220hp & still a whimp IMHO./LOL!!!!!)

But either way that's just piss poor in 1974-75 for a 350 sbc perf motor in a vette vs for ex the 1970 vett base 350 being 300hp & the optional 350/350hp & top dog sbc LT1 @ 370hp.

But remember to add a minimum of 30-40 hp to all published hp ratings from roughly late 1971 to early 1972 when the industry as a whole was converting from gross to net hp/trq ratings right on up thru todays ratings Then you will be comparing apples to apples when compairing 1970 & older gross hp ratings(no factory accessories on the motors) to post late 1971-early 1972 net hp ratings up thru todays net hp ratings with all the accessories attached to the motor like alt/smog pump/air cleaner/stock ex manifolds/power steering pump/ac compressor/etc.

Scott
 
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#9 ·
'74 and '75 Corvette engines:

1974 Engines:
350 V8 190 HP
350 V8 200 HP
350 LT1 V8 250 HP
454 LS5 V8 270 HP

1975 Engines:
350 V8 165 HP
350 L82 V8 205 HP


I had a L48 (low horse) '75 4-speed, and it wouldn't fall out of a tree if you pushed it.
 
#11 ·
What do you do when you want to freshen up an engine?

1. Better Exhaust
2. Better Intake
3. Better Carb
4. Heads (optimal chamber, runner, valve size, etc)
5. Bigger Cam
6. Bigger bore/stroke

After '70 the OPPOSITE of this was the idea. Emissions and fuel economy. What do you do when you want to detune an engine? Muffle the engine, lower compression, less cam, less cubes....AND understate the advertised output #s. Then, put in a set of 2.73s or worse and all of a sudden your gas mileage goes through the roof because you're not spinning 35 hundred going 55, in a car without overdrive.
 
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#12 ·
buck.wheat said:
well are you saying that it would be against the law to drive a oh say 1968 gto around because im sure that would not pass the test? elaborate please on how they have basicly no smog stuff but they would pass today? maybe i am understanding this wrong.
Click to expand...

the emissions standards are based on the standards that were in place for the model year of the car.
a car built in 1980 has a different set of standards than a car built in 2008.
 
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#13 ·
I'm sure some places are stricter, but around here, if the car is 25 years or older, all it has to pass is the safety inspection. I'm sure it is supposed to have whatever smog equipment it left the factory with, though. I have a '73 Laguna, and the only "smog" it had was the evaporative emissions charcoal cannister, which I've removed due to it's poor condition. They never even lift the hood when they inspect it, though.
 
#15 ·
For older cars, it's been my experence here in PA that if they stick the sniffer up the tailpipe and it passes the specs for the year it was made, you're good to go. Last year my nephew and I took the cat off an '86 Dodge camper, ran a Flowmaster and a single 3" pipe in the same place as stock, canned the air pump, and re-curved the dizzy & adjusted the carb and it waltzed through emmissions, plus it gets better milage and runs way better. I was told anything '69 or older doesn't need emmisions inspection here. My '69 Chevelle didn't have an emissions sticker when I bought it, and it was tagged & legal.
 
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mike pratola
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