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Old 12-25-2008, 08:23 AM
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307 performance questions

ok i just got my 1974 nova with a 307 yesterday, i have about $1000 to open her up for now can someone point me in the right direction, so far i was told the 305 heads so any other info would be great
thanks, PJ

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Old 12-25-2008, 08:39 AM
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If the engine is solid and in good shape you can do some low buck things to it. I am not really familiar with any differences between a 70 307 and a 74 307, but here goes. I suspect the 74 has smog heads and lower compression.

I will tell you what I did with my 70 Nova 307. Headers, Edelbrock Tarrantula intake, Holley 600cfm #1850, Crower 280 hydraulic cam & rev kit, Mallory ignition, and a Muncie 4 speed. If your car is an automatic these suggestions may hurt rather than improve the 307.

Vince
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Old 12-25-2008, 08:50 AM
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While many hated the 307, I sure don`t, when done right they will respond nicely. They came from the factory as a bottom of the barrell economy engine. The cams were known to go flat and take the rest of the engine with it. However, they came with flat top pistons which is a good start for you.
I would find a set of 416 casting 305 heads and do a bowl port on them. Then move up to a comp cams magnum 268H cam, this will give it a lopey idle but won`t kill off it`s low end torque. make sure you get the springs that match the cam. a double roller timing set. A set of small tube headers, dual exhaust with turbo mufflers and crossover pipe, a edelbrock performer intake, a Rochester Quadrajet carb, and a HEI ignition if it don`t have one already with the best pieces you can get for it such as spiral core plug wires, a brass terminal cap and rotor, add a advance curve kit and use one medium spring and one light spring. if the budget permits a flame thrower coil and module by pertronix. Take your time and route the plug wires carefully. Lastly add a k & n air filter. You`ll want to set the base timing at around 12 degrees btdc, then connect the vacuum advance to a full time manifold vacuum source.
One other thing, if you remove the timing cover and find it has a nylon coated timing gear I would remove the oil pan and clean the oil pump, as in time the nylon would get brittle and flake off falling into the oil pan, clog up the oil pump to the point it killed the oil pressure and seized the engine.
These small mods will wake up your 307, the best thing you can do for it next would be gears, a set of around 3.55 gears would suit you niclely.
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Old 12-25-2008, 08:58 AM
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yeah thats a lot of information to take in, yes its an automatic and the motor has 64 thousand miles on it.
1. what headers should i go with and the with 305 heads how much am i looking to get as far as power and are they just gonna bolt right up?
thanks for all the info you guys are great
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Old 12-25-2008, 09:24 AM
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I didn't have any information to base my HP figures on other than what the car weighed and what quarter mile times it ran. My best time was 13.20 and I estimated the HP at around 320-330.

Vince
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Old 12-25-2008, 03:02 PM
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ok so what am i looking at for horse power with my stock 307,

i kind of have my list of parts to order
1.hedman headers
2. 305 or 350 heads, im still finding out witch ones flow better
3.i might go with the 355 gears
4. some kind of intake manifold
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Old 12-25-2008, 04:07 PM
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If you use 350 heads it`ll have to be smaller chamber versions, some with 64cc`s. The heads on a 307 have 74cc chambers and most 350 smog heads have 76cc chambers. The early camel hump heads had 64cc chambers, but most of the time you`ll get some that needs completely rebuilt which gets expensive. Why I recommended the 416 heads is since they have a 160cc intake port, same as a 350, they have a 57cc chamber which will shoot your compression up to the 9.5:1 range where it should be, and they have a 1.84 intake valve which is bigger than the 1.71 valves your stock heads have. Plus the 416 castings are easy to find and cheap. The 305 is a small cubic inch engine like a 307, only there bore and stroke differ. Thats why the use of the 305 heads makes perfect sense.
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Old 12-25-2008, 05:34 PM
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ok so im looking for 305 heads with 416?
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Old 12-25-2008, 05:40 PM
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its gonna be a direct bolt on right?
also do you know what power gains i should expect?
thanks for all the help
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Old 12-25-2008, 07:48 PM
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If you follow the mods I gave it`ll be good for at least 100 ponies. Breathing is the point, but, thats also misleading. The engine is a air pump, the more you can push in the more performance it makes. However, you have to think of it all as a team. It has to all work together to give the given performance.
Now, I don`t recommend jumping on 350`s and larger small blocks with the same mods, as the rules are you can`t beat cubic inches and you can`t beat cubic dollars. But, even with a little guy 307, you can still make good performance when you give it the right pieces. If a 350 has the same or better mods but it don`t have gears you`ll blow it`s doors off. I watched a friend of mine`s built 350 with a bigger cam and camel hump heads get blowed away in the 1/8th mile by a stock ford ranger splash. My friends car had real high gears which was why it was easy to take the in 1/8th mile. So it goes to show, gears play a very important role as does the engine combination.
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Old 12-25-2008, 07:58 PM
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You can get surprisingly good performance out of a 307.
I build motors for, and race in a class that requires either a 305 or 307, and I build both, but prefer the 307 for myself. Even running the required cast pistons and other rules, they can run upwards of 7000 RPM's all day long, all season long. The 305 heads make a good, inexpensive choice. Some headers and a good intake would really help out, although we can't run them. A cam in the 220-225 duration range would work well.
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Old 12-25-2008, 09:03 PM
307 getting an energy boost
 
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sounds good i guess its time for me to get this project started thanks for all the info
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Old 12-26-2008, 07:15 AM
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I've had a couple of these engines(stock)and liked them.Has anyone ever put a set of Vortecs on one of these?
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Old 12-26-2008, 08:58 AM
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like any V8 chevy, a 307 will respond will to a good intake/carb, headers/exhaust, cam, and better heads.

It is very important to match all the components (gear, stall, cam, compression ratio, intake, carb, heads, ect).

If you tell us what you want from the car it would help in the parts selection. for example: mpg important? what fuel octane? idle quality important? are you going to change gears and stall?

If you need to pull out the 307 then I would find an old 350 to rebuild then do a swap in one day.
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Old 12-26-2008, 10:32 AM
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what do you mean by matching all the components?
my nova is gonna be used at the track after winter so right now its build time
im looking to really open the 307 up with some heads and headers the car came with a flowmaster exhaust and an edlebrock carb so its almost there
after i get the heads and headers ill post back looking for some advise on a cam but right now im gonna take it one step at a time
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