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Old 04-01-2007, 10:23 PM
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305 heads on a Chevy 307

I read (somewhere) that this could be a hot setup. On one of the bulletin boards, someone said that my particular 305 heads are only 53cc in the chambers. As the 307 heads I am replacing are supposed to be 70cc chambers, I am wondering what this would make the compression ratio, and it if would even work "as is" or not? One good reason for replacing the 307 heads is they only have the tiny valves,and the 305 heads have 1.84 intakes, so....

Any info or help on this would be greatly appreciated! Or - on 307 Chey buildups in general. Thanks!!

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Old 04-02-2007, 06:55 AM
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the 416 casting 305 heads will work nicely on a 307. It will raise the compression ratio up in the mid 9`s and the slightly larger valve will help midrange. I`d add a small torque cam and you`ll have a respectable daily driver.
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Old 04-02-2007, 08:54 AM
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was the tech tip from THIS PAGE...joe
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Old 04-25-2007, 11:33 PM
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Suggestion on cam grind?

Hm, OK, wondering what sort of duration/lift I should look for on the cam? Please let me know, OK? Thanks
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Old 04-26-2007, 08:36 AM
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I'm putting one together myself & I asked Fat Hack what would be the best cam to use for a street drive car. He told me to get a Crane 300hp 327 cam, he said it'll have quick response & depending on ur rearend gearing should get 12-18mpg...joe
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Old 04-26-2007, 09:15 PM
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Well...I dunno....

I checked the specs on that cam (It's Crane cam 968711, or Summit Part # CRN-968711) on the Summit Racing website (because the CRANE site mentioned it but made it impossible to find on their factory site!) and the specs are as follows:

Camshaft, Hydraulic Flat Tappet, Duration 195/ 202 at 0.50, Lift .390/ .410, Chevy, Small Block,

Somebody else had told me to find a cam with loads of lift, and no more than about 230 duration at .050. (because of the small valve size in the 305 head at 1.84 diameter) to get enough airflow in. So...I was kind of thinking of
maybe a Comp Cams cam # CCA-12-212-2, here's the specs on it:

Part Type: Camshafts
Cam Style: Hydraulic flat tappet
Basic Operating RPM Range: 2,000-6,000
Intake Duration at 050 inch Lift: 230
Exhaust Duration at 050 inch Lift: 230
Duration at 050 inch Lift: 230 int./230 exh.
Advertised Intake Duration: 280
Advertised Exhaust Duration: 280
Advertised Duration: 280 int./280 exh.
Intake Valve Lift with Factory Rocker Arm Ratio: 0.480 in.
Exhaust Valve Lift with Factory Rocker Arm Ratio: 0.480 in.
Valve Lift with Factory Rocker Arm Ratio: 0.480 int./0.480 exh. lift
Lobe Separation (degrees): 110

but...maybe that is OVERcamming it? Or not? Because they said to "Not exceed 230 duration at .050" with the stock 307 heads...so I dunno. Because I will be using the 305 heads, and doing some bowl-work porting too.

Now, I was online reading about Super Chevy magazine's "Danger Mouse" engine build-up with a 307 and aftermarket heads. In that, they used a CS x4 262H-11 cam, has has an advertised duration of 262/272, and a duration of 218/226 at .050, and they were making 315hp with 330 lbs of torque with it.
Here's the specs on it:

COMP Cams 12-239-3 CS X4 262H-11 Extreem Energy 4x4 HYDRAULIC: Excellent response, good mid-range, noticeable idle camshaft for Chevrolet 302DZ 305 327 350 383 stroker 400 small blocks.
Camshaft Specification Table

Gross Valve Lift Intake 0.462 Exhaust 0.480
Duration At 0.006 Tappet Lift Intake 262 Exhaust 272
Valve Timing At 0.006 Intake OPEN 24 CLOSE 58 Exhaust OPEN 70 CLOSE 20
These Specs Are For The Cam Installed At 107 Intake CL
Duration At 0.05 Intake 218 Exhaust 226
Lobe Lift Intake 0.308 Exhaust 0.320
Lobe Separation 111
Recommended Valve Springs 981-16

I know I would like my engine to sound like the one using the Magnum 292H cam at this Comp Cams link (scroll down and click on that cam sound link):
http://www.compcams.com/Technical/default.asp#Catalogs

I've read a lot of good things about the Comp cam part #12-242-2 , which is the XE268H you hear a lot about, with a duration of 224/230, but always from the 350 cubic inch guys, so I have no idea if we'd be happy with one or not in a 307. It's about the biggest Comp cam that they claim you can use with your stock torque convertor, whicH is of interest to me as my tranny is automatic.

While on the Comp cams website, I saw that there is a similar cam to the one that Fat Hack recommended, which is the 12-300-4, grind 240H with duration of 192/200. I think it is only a step or two above bone stock though.

I'm thinking that if we are smart, to maybe keep it at specs at or below the 262h-11 seeing as that is the one Super CHevy used on their dyno'd engine. I assume they tried others and settled on it for a good reason.


HEY -ANYONE ELSE READING THIS, FEEL FREE TO JUMP IN WITH YOUR EXPERIENCES OR OPINIONS PLEASE!
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Old 04-30-2007, 09:58 PM
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The 195/202 .390/.410 cam is the same as the stock 307 cam.
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