350 vs 327 revisited

[Guest Anonymous]

Ok,

 

I can get a 1971 300 horse 350 out of a chevelle for free from my granddad,

 

OR I can get a 300 horse 1962 327 with the camel hump heads for pretty cheap (around $300).

 

Both engines need new rings/bearings/gaskets ect.

 

My question is which would be better for my application. I will be installing in a 1983 280zx (I don't have to worry about smog). I know that the 327 can make more HP cheaper than the 350, but the 350 has more torque.

 

I'm not really going to be racing, I'm just wanting to build it to be a bad-ass car to tool around the beach in.

 

BUT, I want as much HP as I can get as cheap as I can get. So what motor should I get?

 

Is the long stroke or the short stroke better? All the younger mechanics say 350, but all the older ones (including Granddad) say 327. Which is better for a Z?

 

BTW, I will either be using a 400turbo (non-overdrive) or a Super-10 four speed.

[DavyZ]

If they truly do have the same power (300 hp) go with the 350 because the torque helps with acceleration. The 327 is a sweet motor too, so it really comes down to what you want. Both motors will boil the hides on the Z, no questions asked.

 

The motor is really not your problem, the tranny is. If this is a strip car--no worries with your tranny choices, but if it is a daily freeway driver, you'll be unhappy with the high revs slowly killing your motor on the freeway. 5 or 6 speed mo betta.

 

Davy

[Guest Anonymous]

I'm planning on building whichever motor I get to about 375, 400 Horsepower. I know that all the 327 needs to achieve this is a good cam, but I don't know what the 350 will need for the same effect.

 

Trannys: Both those trannies are free. If I find a good deal on a five speed that will handle that kind of HP (To my knowledge, the t5 won't), then I'd get it. But right now I'd like to go with what I've got. Hehehe.

 

I'm not going to be on the freeway much. My daily driver is a 300zx turbo that I built. So the v8Z will be for weekend cruising.

 

[ September 18, 2001: Message edited by: Jack300z ]

[Mike C]

All things being equal, the 350 will make more power than the 327. They are inherently the same except a .23" increase in stroke with the 350. HP=torque x rpm and as you say, the 350 will make more torque. I would go with the free 350 and use the $300 for carb, headers, intake etc. If you are going to go through the motor, check out the street performance rebuild kit from northernautoparts.com ($420 with forged pistons and everything else to assemble a longblock except heads)

[Guest Anonymous]

Remember the rule that every old school machinist and gear head I ahve talked to follow. THERE IS NO REPLACEMENT FOR DISPLACEMENT. Of course you can do anything with enough money but for budget power the 350 is the way to go. I like 327 motors because they rev faster and higher. I like to pull the red line on a regular basis too. But a 350 will pull my kind of rpms with a roller kit. Be patient like I did and get a used roller setup. I got a monster cam with stud gurdles guidplates roller lifters push rods and crane roller rockers for a great price. GREAT PRICE= BROKE COLLEGE STUDENT = CHEAP.

 

By the way I was going to go with a smaller cam to be more steetable so if anyone needs a monster solid roller cam that pushed 10's in a 327 I will take offers. If it doesn't sell by the time I assemble I will go with it. VROOM baby!

 

jake

[DavyZ]

Well, the one thing that the 327 has going for it is camel-hump heads. Getting to 375 hp is easier with better heads. But this begs the question of what heads are on the 350, and how do you know it is a genuine 300 hp?

 

As was stated, "all things being equal, the 350 is a better choice because of the additional displacement."

[fl327]

i always like to think the 327 is the heater, i like it because it revs like a madman and makes this great sound when its approaching redline, like a chainsaw mowing down the enemy.

but like they say, THE CUBES DONT LIE!

any car benefits greatly from more cid, increasing hp to weight, and if you can do so by increasing $ to hp, you should do so...

[383 240z]

I would not be so hung up on the "camel hump" heads they were great in their day but if they have a million miles on them and need re-done a set off new heads made with Cast-Ported Technology (GM's Fast Burn for example) or CNC heads(trick-flow comes to mind) these go for about $1000 bucks but to rebuild a set of heads that need 8 exhaust seats (for unleaded fuel),screw in rocker studs,porting, a constant radius valve job(3 angles are outdated) It can run you about $900 and then who many more times can they be freshened?? Just my thoughts, I've been in your position and made the wrong choice and it cost me twice as much as it should have. Keith

[Guest Anonymous]

Take the free 350. Save your money you will need it.

 

The cammel hump heads are no big deal at all. For what it would cost you to rebuild either heads you can buy a new set of vortec heads from chevy.

 

These heads are superior and will even outflow most aftermarket heads at low less than .400 lift which is where your cam should be for what you want to do.

 

The 327 needs low gears and light weight to do all that reving business. You dont have either.

 

The 327 also uses a small journal rod which is not as common. It would also be a 2 bolt block where as the 350 may be a 4 bolt. I do not think 4 bolts were built until 1968/69 models.

 

Alos check both blocks for a throw out piviot if you are going to use a manual trans

[Guest Anonymous]

When I bought my 240z the guy told me it had a 327. Just yesterday I tlaked to a guy who knew a lot about sbc's and he said he was sure it wasn't a 327 but a 350. I checked the casting number at mortec.com and it came up as being a 69 350. I called a local Chevy dealer and they confirmed this. So it turns out the guy I bought it from doesn't know what the hell he's talking about. I also have the camel hump heads. A book I have, How to Hot rod your SBC (something like that), said the 69 350 with camel hump heads came stock with 350 hp. I have a few bolt on mods so I should be making some pretty nice power. I know the motor is probably pretty tired, but it should still be pretty powerful.

Nick

'71 350Z

[JoeinCA]

hmmm, well. I havce to say, that almost any z is light enough to let that 327 do it's rev thing. heck, it puts out alot of power, torque, and all that good stuff, even in my malibu (68), and that is like 4 zs or soemthing to that effect.

 

hey, exactly how mechanical are the 77 350 engines? i dont want to deal with computers and stuff.

[Guest Anonymous]

Shouldn't have really any computer controls on a 77. I believe they were still carb'ed at that point. When its rebuilt get a nice aftermarket timing chain and cam gear as some of the 70's Chevy's had the cam timing I believe it was retarded a bit for emission reasons. The compression ratio will be low too, the late 70's chevy motor's were pretty much smog motors (low compression, small valves) until the return of performance in the 80's.

 

Regards,

 

Lone

 

[ September 20, 2001: Message edited by: lonehdrider ]

[JoeinCA]

well, what was the first return of powerful engines? and were they still carbed?

 

]it doesnt sound like fun to put a bogged engine into my car.

 

Maybe i will just have to engine swap around the smog time... but i need to get everything for the swap ready, lol. that will take a long time...

 

sorry if i am not making sense, i am really tired.

[Guest Anonymous]

Probably mid to late 1980's is where IMHO performance started to come back.

 

Performance returned IMHO in 1984 with the C4 vette and the 1985 Ford Mustang.

 

By '86 both companies I believe were introducing fuel injection if it hadn't used it already).

 

From there they got into a bit of a power war which ultimately Chevy won for a while, although thats changing with later cars like the DOHC mustang Cobra.

 

Don't fret if the motor's earlier, swap the heads to something better when you get a chance, and change the cam and intake manifold/carb to something better. You're motor will show alot of wake up just from doing that. You're engine will hardly remember it came in wearing bell bottoms.

 

Good luck with it,

 

Lone

 

[ September 21, 2001: Message edited by: lonehdrider ]

[JoeinCA]

actually the reason i am worrying about it at all, is the whole smog factor, i have a 77 280z. and i cant legally put the 327 in there unless it is classified as a kit car.

[Guest Anonymous]

I'm not sure about 77 chevy 350's, but my friends 76 camaro had a carbed 305 whereas the guy my roomie bought his motor from took a TPI 350 out of his 78 camaro. Supposedly, other than a mild cam, the 350 was stock. I guess with the 77's, it'd be something you might wanna consult GM about since it seems to fall right in the middle.

 

PS - I've read that chevy put FI on vettes as early as '63. My dad (who's in his mid 60's) used to dust vettes in his '59 bonneville (with a caddy motor swap, I believe) until '63.

Also, chevy had the technology for FI for something like 30 yrs before they released it's use. Car companies (I believe porsche was one) tried to imitate it on their cars back in the 70's since chevy had bought FI and was hording it. I don't know the whole story, just bits of it, so I can't support any of that, but that's what I've heard. Oh, and those new ford cobras might be pretty fast, but wasn't the zo6 vette faster? And I also heard their bringing back the zr-1 vette in the new c5 body style, so that should be a pretty sweet car. Although I also heard when gm drops the camaro/firebird line, they will start making v6 vettes...ewww.

[Guest Anonymous]

Everything else being equal, a 327 is more responsive and willing to rev than a 350, a charactaristic that makes it more suitable for the Z, but on the other hand we lose a bit of low end torque. That's not such a bad thing as it makes life easier on the tranny, driveline, tires, and chassis (less twisting). That's not all, there are more subtle advantages to be had by going with the 327. The 327 has better bore/stroke and rod/stroke ratio which gives us improvements in thermal, volumetric, and mechanical effeciencies due to less reciprocating inertia, less rod angularity, and more dwell time at TDC. Combine that with a (slight) improvement in mileage and I've we've got a combination that IMHO, is superior to the 350. But then again I'm an engineer and have always liked efficiency

[grumpyvette]

their is a 7% difference in stroke and a 7% difference in displacement with 9% difference in piston speed between the two engines, the 350 turns at 57.1 intake strokes per minuite at a piston speed of 4000fpm(about the max safe long term rpm) the 327 turns at 61.5 intake strokes per minuite at the same 4000fpm piston speed. that means that the 327 has to open and close the valves about 4.4 times more per second and the ports need to flow 7% less fuel air mix into the cylinders 4.4 times more per second. because the differences are so small the the true benefits of one over the other are also small but the 350 will fill it cylinders more effectively at most rpms simply because it has more time in which to do so! the 327 in most cases has a small journal crank, the 350 a standard dia. journal(slightly stronger) so pick what you will but the 350 will almost always give a slightly wider torque curve for the same money with the same parts with a slightly stronger and more efficient engine.

[Kevin Shasteen]

Free is Free; I agree w/the others-take the 350 & rebuild it. W/the $300 you saved by not buying the 327 you can buy the intake/carb & cam (almost depending on parts you choose).

 

The 327 is a nice topic & would be cool retro-wise but there is no replacement for displacement. The 350 is more readily available & parts are a dime a dozen.

 

If you decide to go w/a 3spd auto-that's fine as long as its just "to get it going" as 700trans are becoming rather affordable as well; plan to find a 700 once you get your car running...you will want the overdrive!

 

Kevin,

(Yea,Still an Inliner)

[Guest Anonymous]

You're right, free is free, so in your case you should go for the 350. It is also true, that there is no replacement for displacement, but in this case, the difference in displacement is small (7%), so that isn't necessarily true. I think that everything else being equal, a 327 is superior to a 350 as well being better matched with our cars. A 327 will make the same amount of power as an equivalent 350, refer to my posting on chevytalk for more ...

 

 

Now will a 350 make more torque at the low end? Yes it will, but again the difference isn't much

and is more than made up for by the 327's added responsiveness and willingness to rev due to its lesser rotational inertia. The 327 will also be more efficient by virtue of its higher rod/stroke ratio which gives it a maximum rod angularity of 16.6*, whereas a 350 would have a maxumum rod angle of 17.8*. Just for the sake of comparison, a 350 with 6" rods would have a max angle of 16.8*. This has the advantage of less side loads, and thus frictional losses on the pistons, rings, and rod bearings. Speaking of bearings, if the block in question has small journals, we get the added advantage of reduced bearing speeds and thus frictional losses (which go up with the square of bearing speeds) Adding all this up, you get a healthy 10-15bhp JUST by reducing friction, all this and I still haven't mentioned anything about dwell time at TDC... Now as some of you may know, the higher the rod length/stroke ratio the more time the piston "dwells" at TDC, giving the air/fuel mixture more time to burn, and burn completely. This makes combustion more efficient, especially at high rpms and allows us to further raise the compression ratio over what we can safely run in a 350 without detonation. Benefits , of course, are more power and efficiency/mileage. The longer dwell time also allows us to use a camshaft with a bit less overlap for the same top end, further enhancing low-end torque and mileage. And grumpy, 4000fpm works out to 6900rpms in a 350, and 7400 in a 327. While I like rpms, I don't see the need to ever take the engine above 7000, especially when max power is between 5500-6000. So your condition that the 327 has less time to perform the intake stroke doesn't apply as long as rpms are kept below 7000. However the 327 has less volume to fill, so volumetric efficiency is higher (remember, SBCs are flow limited, especially with stock heads). Basically, a 350 is superior below 2500 rpms or so, they are both roughly the same up till 6000 or so, after which the 327 is better. However the 327 has better thermal, mechanical, and volumetric efficiency so it should get slightly better mileage than a 350