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Old 12-29-2009, 07:15 AM
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1971 lemans sport

i dont know much about engine work i was given this car by my grandfather after he passed away i want to fix it up the way he would. i have a 71 lemans sport with a 350 small block what can i do to the engine to get more out of it with out buying a new engine.

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Old 12-29-2009, 08:18 AM
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Sorry to here about your grandfather. The Lemans is a very nice car. It is the body that the GTO is based off. Their are a lot of aftermarket parts for the 350 Pontiac. It's like any other motor headers, carb. and intake. Changing gears in the rear end.
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Old 12-29-2009, 09:51 AM
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That kind of car can be really fun. You can do a lot of mods without the "stigma" of chopping up a GTO since it is "just a Lemans" (not my attitude, but I see a lot of that). Purely my opinion, but the 350 Pontiac is probably not as good a basis as the very flexible 350 Chevy, but it can be made to run. Pontiac seemed to put a lot more thinking into making the 389, 400, and 455's powerhouses and left the 350 as a standard, "bread n butter" engine.

Again, it can be done but you'll just have to dig a little deeper to find the right combo where there are whole books that talk about Pontiac's big 3. There are a lot of good sites to check out though; Performance Years Pontiac, Pontiac Street Perfromance, PontiacZone, and probably more. Good luck and have fun!

-J
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Old 12-29-2009, 10:15 AM
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You guys don't suppose it has a transplanted SBC already in it, do you?

FWIW, Pontiac V8 engines aren't considered 'big' or 'small' blocks, the engines are all the same physical size 'cept the 265, 301 and 303. They have a shorter deck height.
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Old 12-29-2009, 12:24 PM
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Aye; when I said "big 3" I was talking figuratively. The only block that is *significantly different in the "modern" (post 1960-ish) era is, I believe, the 301.

-J

Last edited by Pontiac_Judas; 12-29-2009 at 12:31 PM.
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Old 12-29-2009, 12:35 PM
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[QUOTE=cobalt327]You guys don't suppose it has a transplanted SBC already in it, do you?

I don't know he didn't say if it had Chevy or Pontiac in it. I guessing it has a Pontiac engine.
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Old 12-29-2009, 12:38 PM
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Quote:
Originally Posted by Pontiac_Judas
Aye; when I said "big 3" I was talking figuratively. The only block that is *significantly different in the "modern" (post 1960-ish) era is, I believe, the 301.

-J
Gotcha! My comments was aimed at the OP...

The Pontiac 265 was a very short run (80-'81 or '82?, IIRC), but shared the 301's deck height. I've never even seen a 303, so it needn't have even been mentioned. But if I didn't someone else would've pointed it out! lol
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Old 12-29-2009, 12:53 PM
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How about the 297 Pontiac it was built in the late 70's
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Old 12-29-2009, 01:07 PM
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Quote:
Originally Posted by 70455
How about the 297 Pontiac it was built in the late 70's
That's a new one on me! You sure that's not another way of saying '301'?
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Old 12-29-2009, 01:24 PM
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step one is test and assess the current condition of the stock motor,,,adding speed goodies to a worn motor (walls/rings/valves/dist/etc) gains you nothing but head aches....

change number one is deeper rear gears,,,,best bang for the buck and performance improvement at any/all rpms whether driving normal or messing around....
ex (numbers just to illustrate):
stock motor 350ft-lbs x 2.41? low gear x 2.80? stock rear gears=2361 ft-lbs of force on the tires to accelerate 3600lbs
stock motor 350ft-lbs x 2.41 x "3.50"! rear gears =2922 ft-lbs on the tires

change number two is dial in the dist (factory settings are a compromise) timing curve to work with the deeper gears which is less load on the motor so more timing sooner is possible (and often a 20hp/30tq gain at all rpms due to higher Hg)
380ft-lbs x 2.41 x 3.50=3205 ft-lbs on the tires,,,your getting close to 1ft-lb per lb of car weight!!!

when that's all done start shopping for top end power (more high rpms HP) speed goodies for the motor....
(if it's not quick enough for you)
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Old 12-29-2009, 03:00 PM
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Quote:
Originally Posted by cobalt327
That's a new one on me! You sure that's not another way of saying '301'?
I'm pretty sure they are the same engine, but I have seen some car having both listed as options.
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Old 12-29-2009, 07:15 PM
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Assuming your car has a Pontiac engine with a 2-barrel carb, I'd hit the boneyards or Ebay and dig up a '67-'71 factory Quadrajet intake and carb. '72 and later intakes have a different exhaust crossover, so don't use those. Also, don't use an HO (high-output) intake, since it won't fit on your D-port heads. An aftermarket dual-plane intake would work, but the stock Pontiac unit will likely outperform it for a lot less money. The Quadrajet carb will support all the power you can reasonably make with a 350, and it's the best by far for gas mileage. Lots of Pontiac big cars from back then had exactly what you need, just bolted to 400 or 455 engines. If it's on a 400 or 455, it will bolt to your 350 no problem, since all 3 motors are identical externally.

Dual exhaust will also help a lot. 2-1/2" pipe is plenty, and will support a bigger motor if you get the urge later on. If you don't like loud, use some type of "turbo" mufflers and an X-type crossover to connect the left and right sides. Dynomax part number 17749 is a long-case turbo muffler that will fit under your car and will not agitate law enforcement in the least.
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Old 12-29-2009, 07:45 PM
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And then there was the 303 that was never released to the public.
The 350 was accualy a 354 (353.79).
I would hope his engine is a SBC as parts are more available and cheaper than the Pontiac. The good Pontiac parts are few and far between at the bone yards anymore but can still be found at many auto swap meets.
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Old 12-30-2009, 10:28 AM
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Pontiac went so far as to build a 350 HO in '68 IIRC for the Firebirds, don't know the specs on it but if Pontiac put the "HO" label on it it must have been able to back it up. I wouldn't hesitate to massage a Pontiac 350. Back it up with a 200-4R and some 3.73 gears and it would scoot that LeMans along very nicely and probably still pull some decent mileage.

To get you started, if it's in good mechanical condition now and it doesn't already have a 4 bbl. the stock Pontiac 4 bbl. manifold is not a bad piece, I'd get that and a Q-Jet carb, a recurved later model HEI distributor to replace the points distributor and and dual exhaust. I wouldn't put headers on it at this point unless you plan to do a lot more to it later. They are a PITA on a Pontiac. A swap to some lower gears in the neighborhood of 3.42 will give it a real performance boost but might cost you some mileage on the highway. A shift kit in the stock transmission (automatic?) will help too. Those are the best mods for a beginner without getting inside the engine. If the 350 is tired then find a 400 or 455 to rebuild, they won't cost anymore to build, they will give you a much better bang for your buck and from the outside they look just like the 350.

If you want to dive right in head first and make some real power then there is all kinds of stuff available for Pontiacs, it's just a matter of how much you want to spend. I recommend trying the bolt on route with the 350 1st to get your feet wet.

Last edited by Hippie; 12-30-2009 at 10:45 AM.
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Old 12-30-2009, 10:57 AM
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Quote:
Originally Posted by Hippie
Pontiac went so far as to build a 350 HO in '68 IIRC for the Firebirds, don't know the specs on it but if Pontiac put the "HO" label on it it must have been able to back it up. I wouldn't hesitate to massage a Pontiac 350. Back it up with a 200-4R and some 3.73 gears and it would scoot that LeMans along very nicely and probably still pull some decent mileage.
'68 had a 350 w/#18 heads that made 320 HP, '69 was #48 heads and 325 or 330 HP.

Even in '74 the GTO (X-body Nova clone ) had a 200 HP 350 (#46 heads w/screw in studs) when the base 400 engine only made 190 HP (2-bbl.) and the base 400 4-bbl. made an identical 200 HP.

So yeah, the '68-'69 Pontiac 350's were pretty hot. But so was the optional 350 SBC.
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