1971 pontiac lemans 350 possible engine modification
Asked by Moko Oct 29, 2015 at 03:35 PM about the 1971 Pontiac Le Mans
Question type: Maintenance & Repair
I own a 1971 Pontiac Lemans with a stock 350 engine/2 barrel carb. I would like to try to coax a little extra performance from the engine and was wondering if adding aluminum heads and new intake along with a 4 barrel carb would give me this extra performance? Being somewhat new at this I would appreciate any advice. thanks
7 Answers
The short answer is yes. Buy heads based on the level of performance you want. You will have to match the heads, manifold and carburetor for best performance. Headers or dual exhaust will be needed to balance the exhaust with the intake. I would look into using roller rocker arms as well. Add a good electronic ignition and high performance coil while you are at it. Remember that without changing the stock cam you will be limited to a mild performance increase.
gearheadRHINO answered 9 years ago
I run a auto shop right here in west Philadelphia and I would recommend getting more performance out of your motor, definatly change the carb, possibly do a electronic ignition conversion, little things like that can get the performance back to as it was when it left the factory 40 years ago without spending much money a local specialist in vintage automobiles should be interested in this sort of work for around $40 per hour, my shop is more expensive we charge $50 per hour + $2.50 on the hour every hour.
I agree with gearhead on the little things to increase your performance, unless you are totally rebuilding the engine, stay away from the aluminum heads, just no need otherwise. Depending on how many miles are on the engine and what condition it is in, the HEI ignition conversion would be a must, aftermarket 4 barrel carb & intake, and possibly a mild cam, new flat tapit lifters & push-rods, wouldn't really need the roller stuff unless building up from new, and to top it off a tuned exhaust to match what you build. They have come along way from just running straight dual exhaust...
Thanks for all the great advise. Have already installed the electronic ignition, new coil, plugs,etc, so the advise will be helpful with the next steps.
If I were building the engine I would get a factory 4 barrel cam and factory big valves heads from a 68. This will give you a nice boost in power and will be authentic as well.
Sounds like you have a great classic car. It will probably be worth more if left unmolested. There a lot of inexpensive ways to coax more HP from an engine, without extensive and expensive modification. Consult a manual for ideas.
Keep the stock parts so the car can be returned to original condition but there is nothing wrong with using factory original hi-po parts like heads and cams.
