Cam and heads for 71' lemans 350 - Pontiac GTO Forum
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post #1 of 45 (permalink) Old 12-09-2011, 02:31 AM Thread Starter
 
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Cam and heads for 71' lemans 350

I'll just apologize ahead of time for my lack of knowledge. I don't want to swap out the engine with a 400 or 455. Hoping I can get good suggestions for an aftermarket or OEM head and camshaft pairing to open up my lemans' engine. It's got a edelbrock performer intake and I'm looking for a 650cfm carb to replace the 750 edelbrock it has now.

1971 LeMans 350ci 2Barrel Carb

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post #2 of 45 (permalink) Old 12-09-2011, 05:31 AM
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IMO you're wasting your time modding that 350. Good dual exhaust, maybe some gears, good tuneup, save $$$ for 455 swap. They are still out there and you can swap in a weekend.










Pontiac 350 is not a Chevy 350 and never will be; you can't turn a sow's ear into a silk purse.
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post #3 of 45 (permalink) Old 12-09-2011, 07:45 AM
 
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Eddy heads will set you back a few grand, best (most economical and easiest) way to pep it up would be 650 carb, 1:65 rockers (a bit more lift without replacing the cam) and dual 2" exhaust. you probably also have a 2:XX rear end gear, change that to a mid 3:XX and it will get up and go a little better but wind up a little more on the freeway.

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post #4 of 45 (permalink) Old 12-09-2011, 03:01 PM
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Also, just in case you don't already know this --- you do realize that putting in either a Pontiac 400 or Pontiac 455 would literally be "plug and play", right? All real Pontiac engines are identical in physical size, shape, bolt patterns, etc.

Walk up to a line of Pontiac engines sitting on a shop floor, 326, 350, 389, 400, 421, 428, 455 ---- the only way to tell one from the other is to start reading and interpreting the various codes and stampings on them.

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post #5 of 45 (permalink) Old 12-10-2011, 01:08 PM Thread Starter
 
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I thought the 350 HO was quite the engine? but y'all say it's pretty futile to build it up, what makes the Pontiac 350 so much worse than the Chevy 350?
I did know the 350 and 400 were the same dimensionally

1971 LeMans 350ci 2Barrel Carb

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post #6 of 45 (permalink) Old 12-10-2011, 03:28 PM
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Originally Posted by SPCMarty View Post
I thought the 350 HO was quite the engine? but y'all say it's pretty futile to build it up, what makes the Pontiac 350 so much worse than the Chevy 350?
Hold on there cowboy.... It's not "worse", just different. Actually, the core of the issue is the fact that there a eleventy-gazillion bowtie 350's (and other varieties of mouse motors) out there. It was in production a very long time, a lot of them were sold, they were cheap to build, cheap to buy, cheap to work on, etc. (Did I mention they were "cheap"? ) One of the results of that situation is that there are TON's of aftermarket parts out there for them and also TON"s of research/knowledge/experience on how to build them.
They're easy. For me that also makes them BOOOOORRRRINGGGGG! (but that's just me).

The Pontiac 350 wasn't produced or sold in anywhere near the same numbers, the dimensions (bore and stroke) are different, the heads are different, etc. so that makes their personalities different. Things that work on one o' them (cheap ) orange motors don't necessarily work the same on a Pontiac. Couple that with the fact that the availability of 'go fast' parts available for them is a mere fraction of what's out there for "the others", and you can begin to understand why you don't see nearly as many fast Poncho 350's. It's not that they "can't", it's just more expensive because of lower demand for parts and also in order to build one you have to actually "think".

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I did know the 350 and 400 were the same dimensionally
Oh yeah... so if you're interested in what it sounds like you're interested in (going fast on the cheap) then you, sir, are in the cat bird seat as it were. All you have to do is be patient, find yourself a nice decent running stock Pontiac 455 in good condition that already has a 4bbl carb on it (like from Grandma's station wagon or uncle Joe's Bonneville), unbolt your 350, bolt in the 455, and then hang on to your butt....

It really is that easy.

Be too abusive and the big torque from the 455 is probably going to overpower your existing drive train (rear end and transmission) and start breaking things, but the beauty of it is that you can work on the car a little at a time, upgrading parts of it as you go, having a blast surprising and embarrassing the bowtie brigade the whole time. You'll even be able to raise the hood and say, "yeah, it's just the original 350" and get away with it most of the time

Now... don't that sound like fun???


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post #7 of 45 (permalink) Old 12-10-2011, 07:47 PM Thread Starter
 
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A new transmission is a higher priority anyway and higher rear end ratio. Likely a tremec 5 or 6 speed conversion.
I do have some money to mess with, I just don't have my own garage to house and work on a 400-455 outside the car. All the eBay ones are pick up only. A 400 is more likely to be found but I think the 1971+ 400s were hindered by emissions laws.
What about a Stroker kit for the 350? Any opinions on those.

1971 LeMans 350ci 2Barrel Carb

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post #8 of 45 (permalink) Old 12-10-2011, 08:12 PM
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Originally Posted by SPCMarty View Post
A new transmission is a higher priority anyway and higher rear end ratio. Likely a tremec 5 or 6 speed conversion.
I do have some money to mess with, I just don't have my own garage to house and work on a 400-455 outside the car. All the eBay ones are pick up only. A 400 is more likely to be found but I think the 1971+ 400s were hindered by emissions laws.
What about a Stroker kit for the 350? Any opinions on those.
Sure, you could do that. Two things are going to be problematic - really - two things... the heads. If those are 350 heads they may have eensy tiny little combustion chambers, and once you start pumping up the displacement you're very quickly going to get to the point where compression ratio will be -way- too high to live (for long) on pump gas. Building a stroker isn't cheap. There's more involved than just purchasing the "kit". You've got machine work, and also the cam and valve train, heads, exhaust, etc. have to be optimized to take advantage of the new inches - otherwise it's a waste.

Point is, you've got lots and lots of options - more than one way to skin this cat as Mr. PBody says - if you want "go fast and have fun at minimum cost", then that's the direction I was suggesting - find a reasonably healthy 455 and you're there with minimum cost and maybe a weekend's worth of work. That's not the only way to get there, though.

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post #9 of 45 (permalink) Old 12-11-2011, 01:04 AM
 
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Quote:
Originally Posted by ALKYGTO View Post
IMO you're wasting your time modding that 350. Good dual exhaust, maybe some gears, good tuneup, save $$$ for 455 swap. They are still out there and you can swap in a weekend.

If you got a 350 already running pretty good, I'd add some headers and a 2.5" to 3" performance exhaust. I'd clean it up make sure there are no leaks then paint it and touch it up with a little bit of chrome accents.

For the money spent in buying a 400/455 to build up; your $ spent to HP ratio can be maximized. Run your 350 till you can get one built then keep your 350 in case anything happens to your 400/455.

I have always been intrigued in doing a stroked Pontiac 350. I may attempt it someday, of course after my GTO is done. I would love to do a 70-73 Firebird sleeper with a Pontiac 350 stroked.

JOSHUA
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post #10 of 45 (permalink) Old 12-11-2011, 01:07 AM
 
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I put the 350 back into my Lemans, replacing the mid year 400 low comp motor with good heads, and it lost HP, unless it's a carb issue. I understand what everyone is saying, a good 455 is 500 ft lbs of torque and a tire shredder with a small cam and no compression-incredible. 350 is still powerfull and has plenty of potential to get 400 HP/400 ft lbs of torque at a cost, and can easilly smoke a Chevy. It will take some mods to make the 350 fast, while the 455 is a cheap base but will provide far superior results at less cost.

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  Pontiac GTO Forum > The 1964-1974 Pontiac Tempest, Lemans & GTO > 1964-1974 Tempest, LeMans & GTO Engine Tuning and High Performance

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