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  #16 (permalink)  
Old 05-08-2013, 11:43 PM
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compare a 302 to a 305
4" borex3" stroke Vs
3.76 bore x 3.48 stroke
The 302 will make more hp,similar torque at a slightly higher RPM
do the complicated math and you will understand that comparing a 305 to a 327 will show
The 305 will reach its power band slightly sooner than the 327 because of the piston speed and other variables
The 327 will make more hp and more hp per cubic inch than the 305.
more hp because its bigger,more hp per cube because it will breathe better with the bigger bore using the same heads.The 327 will also make similar torque at a slightly higher rpm
I dont type fast enough to make a full explanation,I can do it by phone though.

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  #17 (permalink)  
Old 05-09-2013, 12:27 AM
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Your 302 vs 305 argument likely takes advantage of the factory 302s being built as high revving factory motors with big valves and a big cam. The 305 however came with small valves and a tiny cam for light duty truck and passenger car duty. Give them both 1.94/1.5 valves with the same compression ratio, same runner design, etc and give them both the same cam and I bet you they make virtually the same power. Same goes for the 307 too.

The OPs 327 as-is may be a high revving motor but like ap72 said, its more than likely in need of a rebuild. If you want to move a big car, it takes a big engine. I'd take the 327 over the 305, if I had to choose.
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Old 05-09-2013, 07:45 AM
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To the OP: Do yourself a favor; throw the engine on a stand and pop the pan off. This will give you at least some insight into what you have to work with. 1.94/1.50 valves are good for this application, though if by some miracle the shortblock is useable, vortec heads and intake would do wonders for you. By the time you refurb the old heads for hardened seats and new valvesprings and seals; you'll be money ahead with a set of GMPP vortecs and a used vortec-style intake for your QJet.

Every used 327 and 350 came out of a vette; everyone knows this.
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  #19 (permalink)  
Old 05-09-2013, 07:58 AM
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Originally Posted by AutoGear View Post
To the OP: Do yourself a favor; throw the engine on a stand and pop the pan off. This will give you at least some insight into what you have to work with. 1.94/1.50 valves are good for this application, though if by some miracle the shortblock is useable, vortec heads and intake would do wonders for you. By the time you refurb the old heads for hardened seats and new valvesprings and seals; you'll be money ahead with a set of GMPP vortecs and a used vortec-style intake for your QJet.

Every used 327 and 350 came out of a vette; everyone knows this.
Vortecs are good if they're free but there are a lot of heavier duty aftermarket heads with better performance design that can run standard intakes. If you do go with a set of heads I'd skip the Vortecs unless they're free. For a free head they're the best that came from the factory.
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Old 05-09-2013, 05:11 PM
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I already have the vortecs, they have been sitting on the work bench for a few years. Mainly I wanted to use them because of the accessory holes so I can run my serpentine belt system if I can find the proper harmonic balancer, already have the correct water pump.

I will be taking off the oil pan and inspecting everything before reassembly for sure.

One of my other friends has a set of stock heads, aluminum high rise intake, carb, cam shaft, and shorty headers he took off his 327 not to long ago, said he would sell my everything for $150. All parts were in running condition and the heads were modified to run on unleaded fuel.
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Old 05-10-2013, 03:44 AM
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Originally Posted by eighty2Bbody View Post
I already have the vortecs, they have been sitting on the work bench for a few years. Mainly I wanted to use them because of the accessory holes so I can run my serpentine belt system if I can find the proper harmonic balancer, already have the correct water pump.

I will be taking off the oil pan and inspecting everything before reassembly for sure.

One of my other friends has a set of stock heads, aluminum high rise intake, carb, cam shaft, and shorty headers he took off his 327 not to long ago, said he would sell my everything for $150. All parts were in running condition and the heads were modified to run on unleaded fuel.
You seem to be a guy that has access to some used parts, i.e., spare transmissions, heads, etc. How about a rear, either complete or gears only. A 3.42 or 3.73 would make your 305 seem like a 400!

Regarding the engine, if you have the time, then put the 327 in your car. But I have to agree with others, that selling this engine and grabbing a 350 will put you ahead in terms of power, torque and money.

Good Luck and happy trails - Jim
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  #22 (permalink)  
Old 05-10-2013, 04:26 AM
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[QUOTE=Valkyrie5.7;1674181]Your 302 vs 305 argument likely takes advantage of the factory 302s being built as high revving factory motors with big valves and a big cam. The 305 however came with small valves and a tiny cam for light duty truck and passenger car duty. Give them both 1.94/1.5 valves with the same compression ratio, same runner design, etc and give them both the same cam and I bet you they make virtually the same power. Same goes for the 307 too.QUOTE]


Val,

Connecting Rod vs. Stroke Analysis: panic Tech Paper No. 1

Check this link out. It is a relatively clear description of the effects of rod to stroke ratio. There are some others out there that have visual descriptions of what is happenning in terms of rotating stress, and piston speed (linear) in relation to crank speed (rotational) that are easier to grasp, but this describes the pros and cons well.

If you take an engine, a 327 SBC for example, and dyno it with 3 different piston/rod setup's: 1st 5.7" rods, then 6.0" rods and 3rd 6.25" rods, the torque and hp curves will move up in the rpm range as the rod/stroke ratio increases. Also the max HP and max torque will increase (minorly) until, repeat until, you exceed the capabilities of either the heads, intake of exhaust restrictions.

The issue with using longer rods, which increase rod/stroke ratio, is what happens to the low end torque. That is why most long rod builds are specific to certain applications (lightweight, high revving).

FWIW, you can cheat on your girlfriend and get away with it, you can cheat on your taxes and get away with it SOMETIMES, but you can never cheat the laws of physics (Isaac Newton)
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  #23 (permalink)  
Old 05-10-2013, 08:39 AM
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[quote=64nailhead;1674490]
Quote:
Originally Posted by Valkyrie5.7 View Post
Your 302 vs 305 argument likely takes advantage of the factory 302s being built as high revving factory motors with big valves and a big cam. The 305 however came with small valves and a tiny cam for light duty truck and passenger car duty. Give them both 1.94/1.5 valves with the same compression ratio, same runner design, etc and give them both the same cam and I bet you they make virtually the same power. Same goes for the 307 too.QUOTE]


Val,

Connecting Rod vs. Stroke Analysis: panic Tech Paper No. 1

Check this link out. It is a relatively clear description of the effects of rod to stroke ratio. There are some others out there that have visual descriptions of what is happenning in terms of rotating stress, and piston speed (linear) in relation to crank speed (rotational) that are easier to grasp, but this describes the pros and cons well.

If you take an engine, a 327 SBC for example, and dyno it with 3 different piston/rod setup's: 1st 5.7" rods, then 6.0" rods and 3rd 6.25" rods, the torque and hp curves will move up in the rpm range as the rod/stroke ratio increases. Also the max HP and max torque will increase (minorly) until, repeat until, you exceed the capabilities of either the heads, intake of exhaust restrictions.

The issue with using longer rods, which increase rod/stroke ratio, is what happens to the low end torque. That is why most long rod builds are specific to certain applications (lightweight, high revving).

FWIW, you can cheat on your girlfriend and get away with it, you can cheat on your taxes and get away with it SOMETIMES, but you can never cheat the laws of physics (Isaac Newton)
I appreciate the link and I will check it out to see what it has to say. I'm trying to talk practical applications here: 1.94 valves, keeping it below 6k, you're just not going to see a worthwhile difference between a 302, 305 or 307. 300 cubes is 300 cubes, it's the same engine with some very minor differences in bore and stroke in the grand scheme of things.
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  #24 (permalink)  
Old 05-10-2013, 08:48 AM
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[quote=Valkyrie5.7;1674526]
Quote:
Originally Posted by 64nailhead View Post

I appreciate the link and I will check it out to see what it has to say. I'm trying to talk practical applications here: 1.94 valves, keeping it below 6k, you're just not going to see a worthwhile difference between a 302, 305 or 307. 300 cubes is 300 cubes, it's the same engine with some very minor differences in bore and stroke in the grand scheme of things.
Well, the 302 should do a little better for one simple, easily understood reason- flow test a set of heads on a 3.75" bore and then on a 4" bore.

Valve shrouding can be a big factor.
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Old 05-10-2013, 05:39 PM
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You seem to be a guy that has access to some used parts, i.e., spare transmissions, heads, etc. How about a rear, either complete or gears only. A 3.42 or 3.73 would make your 305 seem like a 400!

Regarding the engine, if you have the time, then put the 327 in your car. But I have to agree with others, that selling this engine and grabbing a 350 will put you ahead in terms of power, torque and money.

Good Luck and happy trails - Jim
Yeah I have an issue with not throwing anything away that I think I mite need in the future, especially sbc stuff. I do have a spare rear end but its the smaller 7.5 inch instead of my current 8.5 and my current rear end has a nice factory posi that I don't want to part with. Not sure what im going to do with the 327, I also have a .040 over 350 one piece rear main block I can build someday but the 327 is a little more rare and that's what I like. It would be a one of a kind car, I have never heard anyone say they had a 327 in a caprice.
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  #26 (permalink)  
Old 05-10-2013, 05:52 PM
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[quote=ap72;1674528]
Quote:
Originally Posted by Valkyrie5.7 View Post

Well, the 302 should do a little better for one simple, easily understood reason- flow test a set of heads on a 3.75" bore and then on a 4" bore.

Valve shrouding can be a big factor.
To me it's not a make-or-break difference. Maybe 15 or 20hp at the peak between a 305 and 302 with an average set of heads? All this worship of certain engine configurations because there's something magic about them: there's not. Obviously bore shrouding becomes a factor when we're talking big valves, and big numbers. It's the reason the 65-67 Olds 400 is a good performance build and the 68-69 is a turd. I'm not daft, just opinionated.

I may just be the oddball in that I think there's more to making a the average car go fast than eeking every last little hp out of a given motor. And I'm fine with that. On a drag strip, 15hp is an advantage that is broken by a taking out a back seat and avoiding dinner before you head out.
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Old 05-10-2013, 07:55 PM
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I agree on the weight factor or running a higher stall or better tires, but I'm guessing since this is a caprice you can count on it having passengers and such.

You'd also be surprised what difference the larger bore can have on even 1.94" valves. It'll affect the entire power curve, not just the peak.
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  #28 (permalink)  
Old 06-16-2013, 06:44 PM
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I have found out this engine did come out of a vette but not originally. Its a 275hp 327 out of a Impala with a 4 speed. I put the engine on a stand and removed the oil pan. It actually looks pretty good. All rods and caps have numbers stamped in them and the cross hatch in the cylinders doesn't look factory. There is basically no slug build up any wear so I'm thinking this engine has been rebuilt and there is not very many miles on it. I looked in the spark plug hole and I can see that it has flat top pistons, defiantly not dished. I will not be putting this in my 82, it runs to good to pull out the 305 and put in a mystery condition 327. It's going in my 80 caprice that already has a blown V6, makes a lot more sense to put it in a car that already is in need of a engine. The plan is to run it in the 80 with full length headers (my factory manifolds won't bolt up) and dual exhaust and maybe some 3.73's in the rear. I know a lot of people think this is a waste of time but I like seeing what I can build with spare parts for next to no money invested.
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Old 06-16-2013, 10:28 PM
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I understand that they have no bearing on an engines torque output or high revving capabilities with exception to the most extreme situations.

The Cadillac 500 must have an incredible stroke right? No, actually it's got a square bore/stroke ratio. It's just a big engine that has a drive train designed for a low rpm duty.

Unless you're talking about engines with absolutely monstrous pistons (TD BBC) or very long strokes combined with bores that are strangling past the point of the heads design (the 267 SBC comes to mind) then these rules just don't apply to 90% of performance builds today. You can build a 305, 327 and 350 with nearly identical parts and I can bet they'll make very similar horsepower to one another and the bigger the engine, the faster it'll make peak torque. The smaller the engine will make it's power higher in the rpm range to make the same power as the bigger engine. You read that right, The 305 will have to rev higher to make the same power as the 327, all things being equal.

Short stroke or long stroke or big bore or small bore or freaking rotary or anything... I'll take the bigger engine if I want to make more torque, not the greater stroke. The 327 is going to make more torque at a lower rpm range than the 305 will as long as you use the right components. Valve train and heads. This isn't nitro funny cars... just some small blocks in an old caprice. Bigger is going to be better as long as it's built correctly for it's purpose.
Agreed that the Caddy's big cubes make oodles of torque, but Vinnie is spot on. Bigger rod to stroke ratio makes more torque at higher rpm. Not to be disrespectful, but Isaac Newton wasn't wrong. Check out the tech paper below :

Connecting Rod vs. Stroke Analysis

the guy that wrote it goes by 'Panic' and he's beyond pretty sharp. The math doesn't lie.

Bigger rod to stroke ratio equates into greater piston speed at the same rpm as lower rod to stroke ratios. With that being said, timing has to be more precise to maximize the effect of the faster piston speed and vice versa, at lower rpm's a larger rod to stroke ratio has a greater affect on torque.

My favorite example is, of course, a Nailhead (tiny valves), Buick made a 400+ torque motor in the late fifties by maximizing this concept with a 1.875/1.50 valve size.
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Old 06-17-2013, 12:11 AM
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Sorry if I'm out of line here, but first any 327 would be better than any 305 any day. Even the '90 or so TPI from the third gen Camaros and Firebirds that made something like 220hp. More cubes, more power. Plain and simple. But if we are talking about application, then the story changes entirely. He's replacing a V6. So to start out, first, he'll get more power anyway. But the 327 won't like those gears AT ALL!!!! It may have a 2004r, or even better, a 700r4 which means better first gear to get off the line, but the 327 just won't be happy in that car. Especially in OD at 75 around what, 1700 or so RPMs? But again, it will be more powerful than the 6 cylinder that blew.

As for comparing cubes to strokes, well, all things being equal, in a balanced set up, the longer stroke always makes more torque at a lower RPM. That's why the 327 was used in Rally racing. They wanted to use it in road racing, (Trans Am) but the 5 liter limit caused GM to build the 302. (as I have read) Both 327 and 302 are high revving motors. But they did offer both of them in very large (by today's standards) cars like the Impala that this 327 came from. My mother had a '67 Impala that had a 302.
Not to downgrade here, but in the Honda "Tuner" world, rod/stroke ratio is a huge concern. I won't bore you with specifics, but with a tiny motor, every little thing comes into play.
About the Caddy 500 having loads of torque, (550 in 1970 to be exact), well, we are talking about a 500 cubic inch motor! That's a LOT of displacement! But the 472 makes 525 foot pounds. The difference is just under a quarter of an inch of stroke. At that size, 25 foot pounds is nothing.

As for every 327 and 350 coming from a Vette, mine did too. I was a bigger four door station wagon version of a Vette!!!!

Sorry to sound like a broken record, but to have a more fun car, sell the 327 and use that money to build that 350 block. Being a roller cam, that is good enough reason for me. More torque with the 350, more horsepower in a usable range, so on and so on.... Anyways, the police package gave the Caprice a 350 with TBI and that was a great set up!

And about that 7.5" rear, if it has better gears, use that. You could always go to the scrap yard and get another posi unit for it, if you get tired of peg-leggin'! And like the rest of us, you like to hold on to things, so just hold on to the current rear with posi for later. If you have enough left over from selling the 327, get some gears for it!
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