Upgrading my C3
Thread Starter
Cruising
Joined: Jun 2009
Posts: 10
Likes: 0
From: Norfolk VA
Upgrading my C3
Okay, I have a 1973 L-82 manual with an aftermarket holley four barrel 650 cfm carb. I'd like to up the HP and torque without sacrificing the mpg too much. Also, I don't want to do anything irreversible to the engine. I'll be doing most of the work myself.
Terrorizing Orange Cones
Joined: Oct 2007
Posts: 2,572
Likes: 17
From: Northern CO
I agree with Goody.
A properly matched set of headers for the intended use, is one of the quickest improvements to yield power increase results by reducing backpressure to the entire exhaust system. If not equipped now, look into some free flowing mufflers too. A street suggestion for an unmodified L-82 is a header set with 5/8" primary pipes into a 2.5" or 3" collector.
Fine tuning the carb and maximizing the ignition output will also meet your criteria.
Intake port matching to a new aluminum intake requires the heads to come off the motor (metal chips/dust around an open oil valley is possible but why take the risk?). If possible, it is worthwhile. If the heads do come off for port matching, that opens up opportunity to freshen springs, seats and oil control; all which is helpful but requires more $ and more time.
Caution: once intake unbuttoned and removed, it may be discovered "while I'm at it" or "since I'm here" to raise its head and bite you where the sun don't shine, usually the wallet. Keep awareness high and plan ahead.
You should gain measured increases in HP, torque, and gas mileage focusing on these areas. Good luck.
A properly matched set of headers for the intended use, is one of the quickest improvements to yield power increase results by reducing backpressure to the entire exhaust system. If not equipped now, look into some free flowing mufflers too. A street suggestion for an unmodified L-82 is a header set with 5/8" primary pipes into a 2.5" or 3" collector.
Fine tuning the carb and maximizing the ignition output will also meet your criteria.
Intake port matching to a new aluminum intake requires the heads to come off the motor (metal chips/dust around an open oil valley is possible but why take the risk?). If possible, it is worthwhile. If the heads do come off for port matching, that opens up opportunity to freshen springs, seats and oil control; all which is helpful but requires more $ and more time.
Caution: once intake unbuttoned and removed, it may be discovered "while I'm at it" or "since I'm here" to raise its head and bite you where the sun don't shine, usually the wallet. Keep awareness high and plan ahead.
You should gain measured increases in HP, torque, and gas mileage focusing on these areas. Good luck.
Le Mans Master
Joined: Aug 2006
Posts: 7,426
Likes: 1,559
From: mount holly NC
2025 c3 ('74-'82) of the Year Finalist - Unmodified
2019 C3 of Year Finalist (appearance mods)
Easy fix for more HP!
If you have not done so yet you should "Re-Curve" the distributor to get 36* all in at 2,500 to 3,000 rpm. PG.
